Behavioural adjustments for a life in the city

The effect of habitat health and environmental change on cultural diversity and richness in animals

There is increasing evidence that habitat decline via fragmentation or species loss can lead to loss of cultural diversity, complexity or richness in non-human animals. For example, a reduction in local bird species richness leads lyrebirds to sing fewer complex songs, while great apes living in fragmented landscapes have smaller cultural repertoires. However, the link between animal culture and local ecology remains understudied, and the potentially complex interactions between ongoing ecological change and animal culture are poorly understood. Here, we review the current state of knowledge on how ecology influences animal culture, focusing on vocal communication and foraging behaviour. We identify key factors affecting cultural patterning, including direct effects (e.g. environmental variability) and indirect effects (e.g. connectivity). We then review the emerging evidence for the effects of environmental change on culture, identifying three major threatening processes: habitat fragmentation, habitat degradation and urbanization. Finally, we develop a predictive framework for the effect of these threatening processes on animal culture and highlight how the loss of cultural diversity and complexity can lead to fitness costs with conservation implications.This article is part of the theme issue 'Animal culture: conservation in a changing world'.

Recovery through resistance? nesting urban female song sparrows (Melospiza melodia) have a lower glucocorticoid response to disturbance and return to parental care as quickly as rural females

Urbanization represents a dramatic and relatively rapid change in the environment that has profound impacts on wild animals. Shifts in behavior and endocrine mechanisms of stress response could allow animals to successfully survive and reproduce in urban habitats. Numerous studies have examined the behavioral and physiological responses of territory-holding male songbirds to urbanization. However, breeding females likely experience anthropogenic noise, light at night, and human disturbance more frequently, and their behavioral coping responses to these disturbances are limited during incubation. Moreover, breeding females face higher energetic demands (allostatic load). Understanding how some species cope with novel urban habitats requires studying individuals facing the greatest challenges, such as breeding females. Therefore, we compared the glucocorticoid stress response and behavioral recovery from a disturbance between urban and rural female song sparrows (Melospiza melodia) during incubation. If facultative adjustments to the glucocorticoid stress response allow birds to cope with urban habitats, we predicted that urban females would return to parental care behaviors after a standardized stressor as soon or sooner than rural females, and that urban females would have a lower glucocorticoid response to the stressor. We captured female song sparrows at the end of the incubation period and measured their glucocorticoid (corticosterone) levels at baseline and after 30 min of standardized restraint. Concurrently, we installed radio frequency identification (RFID) systems at the nest to capture the time to return to parental care behaviors. We found that incubating urban females had significantly lower corticosterone levels when controlling for sampling timepoint (baseline and restraint-induced) compared to rural. Nest return times did not differ across habitats, and latency to return was not significantly correlated with corticosterone levels. Our findings are consistent with prior work in breeding male song sparrows at our study sites; urban males provide higher parental care and have lower restraint-induced corticosterone levels. The absence of a relationship between glucocorticoids and behavior makes it unlikely that these hormones directly regulate parental care, but lower corticosterone levels in urban birds could reflect stress resistance, which has been hypothesized to permit animals to breed in challenging or novel conditions such as urban habitats.

Neophobia and exploration behavior in urban gulls: The Kelp Gulls (Larus dominicanus) as a study case

Neophobia and exploratory behavior are personality traits through which organisms evaluate and respond to environment changes by adjusting their behavior. The Kelp Gull (Larus dominicanus) is a generalist seabird that consumes a wide variety of prey. Neophobia levels and exploratory behavior in novel circumstances were analyzed in urban adult (n = 13) and immature (n = 15) Kelp Gulls captured in the landfill of Mar del Plata city. These personality traits were not significantly affected by the age of the bird. Longer feeding latencies were observed in presence of novel objects, and neophobia levels were higher in the presence of a transparent box. The exploratory events were brief and influenced by the physical properties of the objects; gulls favored complex and yellow objects. Higher neophobia levels were associated with a longer time to start the exploration and spending less time investigating the objects. Exposure to an urban environment can modulate the novelty response, partially explaining lack of difference in neophobia levels and exploratory behavior between ages, as well as the apparent absence of intrinsic attraction to unfamiliar objects when not associated with a food source. Furthermore, in relation to complex objects, unfamiliar objects likely offer richer information, driving gulls' exploratory preference.

Impact of tourism on bird behavior: A comparison of flight initiation distance between birds in areas of tourist and non-tourist attraction

Tourism, as an important manifestation of urbanization, is becoming increasingly popular. Although it offers numerous advantages for the local community, it also exerts a multifaceted impact on local wildlife. Previous research on the effects of tourism has mainly focused on protected areas or tourist spots, rarely considering the surrounding non-tourist attraction areas. Therefore, exploring the behavioral differences of wildlife in response to different levels of human disturbance in areas of tourist and non-tourist attraction will contribute to a more comprehensive understanding of the impact of tourism activities on animals. This study compared the differences in the flight initiation distance (FID) of Eurasian tree sparrows (Passer montanus) between areas of tourist attraction (Xijiang Miao Village and Zhaoxing Dong Village) and non-tourist attraction (surrounding villages) in Guizhou Province, southwestern China. We found that Eurasian tree sparrows in areas of tourist attraction exhibited shorter FIDs than those in areas of non-tourist attraction, suggesting that Eurasian tree sparrows inhabiting areas with higher levels of human disturbance demonstrate a greater ability to adapt to anthropogenic disturbance. Moreover, the FID of Eurasian tree sparrows was less influenced by flock size than by tourist attraction category. It highlights the notable impact of human activities on wildlife, contributing to the scientific management and protection of birds in urban environments.

Progress and evolution of hotspots in butterfly diversity research in green spaces

Ecosystems depend on biodiversity; therefore, protecting biodiversity is beneficial for the development of ecosystems. Butterflies are indicator species that respond quickly to environmental changes and reflect environmental conditions. Butterfly diversity is a crucial evaluation indicator of habitat quality in green spaces. We used CiteSpace and Bibliometrix to conduct a bibliometric analysis of research relating to butterfly diversity in green spaces. Based on 538 papers published from 2002-2022, we systematically reviewed the status, frontiers, and hotspots for research on butterfly diversity in green spaces. Our results showed that: (1) Research on butterfly diversity in green spaces has consistently demonstrated an upward trend between 2002-2022. Studies on this subject have garnered attention from researchers worldwide, with notable interest and contributions from scholars in the United States. (2) Early studies focused on butterfly habitat preferences and extinction concerns, and later articles appeared on the influence of external environmental factors (land use, climate change, plants, etc.). (3) Three main research topics received much attention between 2002 and 2022: biodiversity conservation, butterfly habitats, and the relationship between butterfly diversity and its influencing factors. (4) The relationship between green spaces and butterfly diversity (landscape features, vegetation features, and human activities) was discussed; these factors on butterfly communities should be considered in the planning and constructing of future green spaces. (5) Two significant future directions have been identified: more research on the impact of external factors and a need for more technical integration with the big data field. Future research on butterfly diversity in green spaces should adopt a more multi-scale, multi-disciplinary approach and aim to enhance the practicality and guidance of research findings.

Urinary health indicators in folivorous-frugivorous primates with and without food supplementation

Food supplementation by humans in peri-urban and urban landscapes can lead to excessive intake of energy and certain macronutrients, and affect animal health. In this study, we evaluated the influence of food supplementation on urinary health indicators in brown howler monkeys (Alouatta guariba) by comparing supplemented and non-supplemented free-ranging peri-urban groups. We also evaluated the effect of sex, day shift, and season of sampling. Between August 2021 and August 2022, we non-invasively collected 61 samples (43 from females and 18 from males) from adult individuals (N = 10) in three supplemented groups and 56 samples (25 from females and 31 from males) from adults (N = 7) in three non-supplemented groups. The supplements, mostly raw foods (e.g., fruits, vegetables, and tubers) and bread, represented 18% of the total fresh mass ingested by the supplemented groups. We assessed pH, density, and the presence of eight urine components (glucose, bilirubin, ketones, protein, urobilinogen, nitrite, blood, and leukocytes) using reagent urine strips. Season of sampling predicted urine density (mean = 1.022), while both season and day shift predicted pH (mean = 6.5). The occurrence of supplementation was a weak predictor of these parameters. Finally, we detected leukocytes in 21% of the 117 samples. We did not identify any visible signs of disease in any individual throughout the study and found no clinical changes in urine under the conditions studied. We urge validation of the results with urine strips to facilitate monitoring of the health of howler monkeys living in anthropogenic landscapes in the presence or absence of dietary supplementation.

Human-directed sociability in the domestic dog: A Tinbergian approach

The motivation to interact with humans is central to dogs' domestication process. This review aims to provide a curated overview of the current knowledge about dogs' human-directed sociability using Tinbergen's four questions as a guiding framework. Firstly, we explore its evolutionary history, discussing wolf-dog differences in the socialization period, fear response, sociability, and attachment to elucidate the effect of domestication. Secondly, we address its ontogeny, highlighting the importance of early life experiences, examining findings on different dog populations to discern the effect of adult life experiences, and reporting changes across the lifespan. Thirdly, we analyse the adaptive value of the dog-human relationship, considering the effects of human association on different dog populations. Fourthly, we elaborate on the mechanisms involved in the dog-human relationship, discussing underlying cognitive and genetic processes and findings on the neurophysiological effects of interacting with humans. Finally, we identify issues and remaining questions that deserve more scrutiny and suggest innovative approaches that could be explored to improve our understanding of dogs' human-directed sociability.

Ontogeny shapes individual dietary specialization in female European brown bears (Ursus arctos)

Individual dietary specialization, where individuals occupy a subset of a population's wider dietary niche, is a key factor determining a species resilience against environmental change. However, the ontogeny of individual specialization, as well as associated underlying social learning, genetic, and environmental drivers, remain poorly understood. Using a multigenerational dataset of female European brown bears (Ursus arctos) followed since birth, we discerned the relative contributions of environmental similarity, genetic heritability, maternal effects, and offspring social learning from the mother to individual specialization. Individual specialization accounted for 43% of phenotypic variation and spanned half a trophic position, with individual diets ranging from omnivorous to carnivorous. The main determinants of dietary specialization were social learning during rearing (13%), environmental similarity (5%), maternal effects (11%), and permanent between-individual effects (9%), whereas the contribution of genetic heritability (3%) was negligible. The trophic position of offspring closely resembled the trophic position of their mothers during the first 3-4 years of independence, but waned with increasing time since separation. Our study shows that social learning and maternal effects were more important for individual dietary specialization than environmental composition. We propose a tighter integration of social effects into studies of range expansion and habitat selection under global change.

Adaptation of farmland mammalian specialist to urban life: Escape behavior of European hare along the urban-rural gradient

The European hare Lepus europaeus is an iconic but rapidly declining farmland specialist with recently confirmed populations in urban areas. However, their behavioral responses and adaptability to urbanization and life in human-dominated areas are fully unexplored. Here, using infrared cameras, we explored escape behavior (measured as the flight initiation distance) using 965 hare observations in urban and farmland areas in the Czech Republic and Austria (Central Europe) and its association with habitat type, distance to the city center, patch size, season, hare age and initial behavior. We found that European hares adjusted their escape behavior to habitat type and escaped significantly earlier in farmland (rural) habitats than in urban habitats. However, escape distances of hares did not differ between farmland types with different degree of habitat heterogeneity. We also revealed that urban hares escaped earlier when located further from the city center or in a larger study patch. Moreover, adult hares escaped earlier than subadults and foraging individuals escaped earlier than resting hares but both only in rural areas. Our results support high behavioral adaptability of European hares to human-dominated urban areas.

The magpie and the grapes: increasing ozone exposure impacts fruit consumption by a common corvid in a suburban environment

BACKGROUND

The Eurasian magpie Pica pica is a resident bird species able to colonize farmlands and anthropized environments. This corvid shows a wide trophic spectrum by including fruits, invertebrates, small vertebrates and carcasses in its diet. A camera-trap experiment was carried out to test the effect of different ozone (O3) concentrations on potted Vitis vinifera plants, which resulted in different grape consumption rates by suburban birds. The test was performed at an Ozone-Free Air Controlled Exposure (FACE) facility, consisting of nine plots with three ozone (O3) levels: AA (ambient O3 concentration); and two elevated O3 levels, 1.5× AA (ambient air with a 50% increase in O3 concentration) and 2.0× AA (ambient air with a 100% increase in O3 concentration). Camera-traps were located in front of each treatment area and kept active for 24 h day-1 and for 5 days at a time over a period of 3 months to monitor grape consumption by birds.

RESULTS

We collected a total of 38 videos. Eurasian magpies were the only grape consumers, with a total of 6.7 ± 3.3 passages per hour (mean ± SD) and no differences across the different O3 treatments. Grapes in the AA treatment were consumed significantly more quickly than those in the 1.5× AA treatment, which in turn, were consumed faster than those in the 2.0× AA treatment. At 3 days from the start of treatment, 94%, 53% and 22% berries from the AA, 1.5× AA and 2.0× AA treatments had been eaten, respectively. When the O3 was turned off, berries were consumed at the same rate among treatments.

CONCLUSION

Increasing O3 concentrations limited grape consumption by magpies probably because O3 acted as a deterrent for magpies, although the lower sugar content recorded in the 2.0× AA berries did not affect the consumption when O3 was turned off. Our results provided valuable insights to mitigate human-wildlife conflicts in suburban environments. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Urban sensory conditions alter rival interactions and mate choice in urban and forest túngara frogs

Sexual communication often takes place in networks with multiple competing signalers being simultaneously assessed by mate choosers. Altered sensory conditions, such as noise and light pollution, can affect communication by altering signal production and perception. While evidence of sensory pollution affecting sexual signaling is widespread, few studies assess impacts on sexual signaling during rival interactions as well as mate choice, let alone whether urban and non-urban populations have diverged in their response. Here, we investigate the effects of urban sensory conditions on sexual communication in urban and forest túngara frogs (Engystomops pustulosus). We recorded dyadic vocal rival interactions and assessed mate choice with and without noise and light pollution in the lab. We show that urban sensory conditions can directly impact the intensity of rival interactions, differences between rivals, and mate choice, though changes were often in opposite directions for frogs of urban and forest origins. Moreover, we demonstrate that urban-induced changes in rival interactions can also indirectly affect how females choose between potential mates. Our study reveals origin-dependent direct and indirect effects of noise and light pollution and suggests local adaptation of sexual communication in urban populations.

Facilitation of Evolution by Plasticity Scales with Phenotypic Complexity

Developmental plasticity enables organisms to cope with new environmental challenges. If deploying such plasticity is costly in terms of time or energy, the same adaptive behaviour could subsequently evolve through piecemeal genomic reorganisation that replaces the requirement to acquire that adaptation by individual plasticity. Here, we report a new dimension to the way in which plasticity can drive evolutionary change, leading to an ever-greater complexity in biological organisation. Plasticity dramatically accelerates the evolutionary accumulation of adaptive systems in model organisms with relatively low rates of mutation. The effect of plasticity on the evolutionary growth of complexity is even greater when the number of elements needed to construct a functional system is increased. These results suggest that, as the difficulty of challenges from the environment becomes greater, plasticity exerts an ever more powerful role in meeting those challenges and in opening up new avenues for the subsequent evolution of complex adaptations.

Proximity to humans is associated with antimicrobial-resistant enteric pathogens in wild bird microbiomes

Humans are radically altering global ecology, and one of the most apparent human-induced effects is urbanization, where high-density human habitats disrupt long-established ecotones. Changes to these transitional areas between organisms, especially enhanced contact among humans and wild animals, provide new opportunities for the spread of zoonotic pathogens. This poses a serious threat to global public health, but little is known about how habitat disruption impacts cross-species pathogen spread. Here, we investigated variation in the zoonotic enteric pathogen Campylobacter jejuni. The ubiquity of C. jejuni in wild bird gut microbiomes makes it an ideal organism for understanding how host behavior and ecology influence pathogen transition and spread. We analyzed 700 C. jejuni isolate genomes from 30 bird species in eight countries using a scalable generalized linear model approach. Comparing multiple behavioral and ecological traits showed that proximity to human habitation promotes lineage diversity and is associated with antimicrobial-resistant (AMR) strains in natural populations. Specifically, wild birds from urban areas harbored up to three times more C. jejuni genotypes and AMR genes. This study provides novel methodology and much-needed quantitative evidence linking urbanization to gene pool spread and zoonoses.

Fitness consequences of anthropogenic subsidies for a partially migratory wading bird

Human activities are forcing wildlife to confront selective pressures different from those under which they evolved. In seasonal environments, migration evolved as an adaptation to fluctuating resource availability. Anthropogenic subsidies modify resource dynamics by providing a steady food source that is not subject to seasonality. Globally, many migratory populations are becoming increasingly resident in response to food supplementation. While these population-level shifts are assumed to arise from changing fitness consequences of individual behaviour in response to resource dynamics, these mechanisms are often difficult to quantify and disentangle. Here, we quantified fitness consequences of responses to anthropogenic subsidies in partially migratory wood storks (Mycteria americana) in the heavily urbanized southeastern United States. First, we tested whether individual migratory behaviour is linked to different responses to anthropogenic subsidies. Second, we quantified fitness consequences of these behavioural responses. We found that, in our system, migration and residency are alternative behavioural tactics associated with different responses to food supplementation. In turn, the use of anthropogenic resources alters a fitness component by enhancing nest survival. These results provide a mechanistic examination of how animals may respond to human-modified resource dynamics and how fitness consequences of individual tactics may translate into behavioural shifts at the population level.

Experience shapes wild boar spatial response to drive hunts

Human-induced disturbances of the environment are rapid and often unpredictable in space and time, exposing wildlife to strong selection pressure favouring plasticity in specific traits. Measuring wildlife behavioural plasticity in response to human-induced disturbances such as hunting pressures is crucial in understanding population expansion in the highly plastic wild boar species. We collected GPS-based movement data from 55 wild boars during drive hunts over three hunting seasons (2019-2022) in the Czech Republic and Sweden to identify behavioural plasticity in space use and movement strategies over a range of experienced hunting disturbances. Daily distance, daily range, and daily range overlap with hunting area were not affected by hunting intensity but were clearly related to wild boar hunting experience. On average, the post-hunt flight distance was 1.80 km, and the flight duration lasted 25.8 h until they returned to their previous ranging area. We detected no relationship in flight behaviour to hunting intensity or wild boar experience. Wild boar monitored in our study showed two behavioural responses to drive hunts, "remain" or "leave". Wild boars tended to "leave" more often with increasing hunting experience. Overall, this study highlights the behavioural plasticity of wild boar in response to drive hunts.

'Ripple effects' of urban environmental characteristics on cognitive performances in Eurasian red squirrels

Urban areas are expanding exponentially, leading more species of wildlife living in urban environments. Urban environmental characteristics, such as human disturbance, induce stress for many wildlife and have been shown to affect some cognitive traits, such as innovative problem-solving performance. However, because different cognitive traits have common cognitive processes, it is possible that urban environmental characteristics may directly and indirectly affect related cognitive traits (the ripple effect hypothesis). We tested the ripple effect hypothesis in urban Eurasian red squirrels residing in 11 urban areas that had different urban environmental characteristics (direct human disturbance, indirect human disturbance, areas of green coverage and squirrel population size). These squirrels were innovators who had previously repeatedly solved a food extraction task (the original task). Here, we examined whether and how urban environmental characteristics would directly and indirectly influence performance in two related cognitive traits, generalisation and (long-term) memory. The generalisation task required the innovators to apply the learned successful solutions when solving a similar but novel problem. The memory task required them to recall the learned solution of the original task after an extended period of time. Some of the selected urban environmental characteristics directly influenced the task performance, both at the population level (site) and at individual levels. Urban environmental characteristics, such as increased direct and indirect human disturbance, decreased the proportion of success in solving the generalisation task or the memory task at the population (site) level. Increased direct human disturbance and less green coverage increased the solving efficiency at individual levels. We also found an indirect effect in one of the urban environmental characteristics, indirect human disturbance, in the generalisation task, but not the memory task. Such an effect was only seen at the individual level but not at the population level; indirect human disturbance decreased the first original latency, which then decreased the generalisation latency across successes. Our results partially support the ripple effect hypothesis, suggesting that urban environmental characteristics are stressors for squirrels and have a greater impact on shaping cognitive performance than previously shown. Together, these results provide a better understanding of cognitive traits that support wildlife in adapting to urban environments.

Wild raccoons demonstrate flexibility and individuality in innovative problem-solving

Cognitive skills, such as innovative problem-solving, are hypothesized to aid animals in urban environments. However, the significance of innovation in wild populations, and its expression across individuals and socio-ecological conditions, is poorly understood. To identify how and when innovation arises in urban-dwelling species, we used advanced technologies and new testing and analytical methods to evaluate innovative problem-solving abilities of wild raccoons (Procyon lotor). We deployed multi-compartment puzzle boxes with either one or multiple solution types and identified raccoons using radio frequency identification. Raccoons solved these novel extractive foraging tasks, and their success was influenced by age and exploratory diversity. Successful raccoons always discovered multiple different solution types, highlighting flexible problem-solving. Using a unique, comparative sequence analysis approach, we found that variation in raccoon solving techniques was greater between individuals than within individuals, and this self-similarity intensified during times of competition. Finally, the inclusion of an easier solution in the multi-solution trials enabled previously unsuccessful raccoons to bootstrap their learning and successfully open multiple difficult solutions. Our study suggests that innovative problem-solving is probably influenced by many factors and has provided novel field and analytical methods, as well as new insights on the socio-ecological dynamics of urban populations.

Food quality influences behavioural flexibility and cognition in wild house mice

Environmental change is frequent. To adjust and survive, animals need behavioural flexibility. Recently, cognitive flexibility has emerged as a driving force for adjusting to environmental change. Understanding how environmental factors, such as food quality, influence behavioural and/or more costly cognitive flexibility. Here, we investigate the effects of high-quality versus standard food as well as the effects of different housing conditions on both types of flexibility. Our results show that mice that experienced a poorer diet under seminatural conditions showed greater behavioural but not cognitive flexibility. For cage-housed mice, the results were less clear. However, mice fed a poorer diet performed better in innovative problem-solving, thus showing enhanced cognitive flexibility, which was not apparent in the reversal learning paradigm. The observed differences were most likely due to differences in motivation to obtain food rewards. Additionally, animals on poorer diet had lower brain volume, usually related to lower cognitive task performance at the between-species level. Thus, our study emphasises the importance of environmental conditions on behavioural flexibility at the within-species level, highlights that different test paradigms may lead to different conclusions, and finally shows that cage housing of wild animals may lead to patterns that do not necessarily reflect natural conditions.

Early-life diet does not affect preference for fish in herring gulls (Larus argentatus)

Urban populations of herring gulls (Larus argentatus) are increasing and causing human-wildlife conflict by exploiting anthropogenic resources. Gulls that breed in urban areas rely on varying amounts of terrestrial anthropogenic foods (e.g., domestic refuse, agricultural and commercial waste) to feed themselves. However, with the onset of hatching, many parent gulls switch to sourcing more marine than anthropogenic or terrestrial foods to provision their chicks. Although anthropogenic foods may meet chick calorific requirements for growth and development, some such foods (e.g., bread) may have lower levels of protein and other key nutrients compared to marine foods. However, whether this parental switch in chick diet is driven by chicks' preference for marine foods, or whether chicks' food preferences are shaped by the food types provisioned by their parents, remains untested. This study tests whether chick food preferences can be influenced by their provisioned diet by experimentally manipulating the ratio of time for which anthropogenic and marine foods were available (80:20 and vice versa) in the rearing diets of two treatment groups of rescued herring gull chicks. Each diet was randomly assigned to each of the 27 captive-reared chicks for the duration of the study. We tested chicks' individual food preferences throughout their development in captivity using food arrays with four food choices (fish, cat food, mussels and brown bread). Regardless of the dietary treatment group, we found that all chicks preferred fish and almost all refused to eat most of the bread offered. Our findings suggest that early-life diet, manipulated by the ratio of time the different foods were available, did not influence gull chicks' food preferences. Instead, chicks developed a strong and persistent preference for marine foods, which appears to match adult gulls' dietary switch to marine foods upon chick hatching and may reinforce the provisioning of marine foods during chick development. However, whether chicks in the wild would refuse provisioned foods, and to a sufficient extent to influence parental provisioning, requires further study. Longitudinal studies of urban animal populations that track wild individuals' food preferences and foraging specialisations throughout life are required to shed light on the development and use of anthropogenic resource exploitation.

Behavioural changes in the city: The common black garden ant defends aphids more aggressively in urban environments

Urbanisation alters biodiversity patterns and threatens to disrupt mutualistic interactions. Aside from pollination, however, little is known about how mutualisms change in cities. Our study aimed to assess how urbanisation affects the protective mutualism between ants and aphids, investigating potential behavioural changes in mutualistic ants and their implications for aphids in urban environments. To do so, we studied the protective mutualism between the pink tansy aphid (Metopeurum fuscoviride) and the black garden ant (Lasius niger) along an urbanisation gradient in Berlin, Germany. In nine locations along this gradient, we measured aphid colony dynamics and proxies for parasitism, quantified the investment of ants in tending aphids and conducted behavioural assays to test the aggressiveness of ant responses to a simulated attack on the aphids. We found that aphid colonies flourished and were equally tended by ants across the urbanisation gradient, with a consistent positive density dependence between aphid and ant numbers. However, ants from more urbanised sites responded more aggressively to the simulated attack. Our findings suggest that this protective mutualism is not only maintained in the city, but that ants might even rely more on it and defend it more aggressively, as other food resources may become scarce and more unpredictable with urbanisation. We thereby provide unique insights into this type of mutualism in the city, further diversifying the growing body of work on mutualisms across urbanisation gradients.

Exposure to humans and task difficulty levels affect wild raccoons (Procyon lotor) learning

Cognition helps wildlife exploit novel resources and environments. Raccoons (Procyon lotor) have successfully adapted to human presence, in part due to their cognitive abilities. However, interactions between humans and wildlife can create conflict. A better understanding of the raccoon's behavioral flexibility and learning ability could mitigate some conflicts. Our objective was to evaluate wild raccoons learning in contexts varying in terms of exposure to humans (recreational and preservation zoning within protected areas) and task difficulty. Learning can be evaluated over multiple exposures to a cognitive task. Across three years of experiment, we employed 2 food extraction tasks to gauge the change in problem-solving performance over trials. This assessment considered the success probability (the number of successful trials divided by the total number of trials) and the time taken to solve the puzzles. We also looked at the effects of 2 behavioral traits, exploratory diversity and persistence. We found strong evidence for learning over consecutive trials in terms of improved success probability. Improvement in terms of success probability and solving time was more pronounced with the initially easier task. We detected an increase in success probability over trials only in the recreation zones, and there was no evidence of an effect of behavioral traits. The improved performance attributed to learning was also maintained over consecutive years. We provide additional evidence that raccoons can learn how to solve a problem, resulting in a more effective solution in consecutive trials. Finally, we consider the management implications of dealing with raccoons accessing anthropogenic resources.

Habitat structural complexity predicts cognitive performance and behaviour in western mosquitofish

Urban stream syndrome alters stream habitat complexity. We define habitat complexity as the degree of variation in physical habitat structure, with increasing variation equating to higher complexity. Habitat complexity affects species composition and shapes animal ecology, physiology, behaviour and cognition. We used a delayed detour test to measure whether cognitive processes (motor self-regulation) and behaviour (risk-taking) of female Western mosquitofish, Gambusia affinis, varied with habitat structural complexity (low, moderate and high) that was quantified visually for nine populations. We predicted that motor self-regulation and risk-taking behaviour would increase with increasing habitat complexity, yet we found support for the opposite. Lower complexity habitats offer less refuge potentially leading to higher predation pressure and selecting for greater risk-taking by fish with higher motor self-regulation. Our findings provide insight into how habitat complexity can shape cognitive processes and behaviour and offers a broader understanding of why some species may tolerate conditions of urbanized environments.

Fiddler crabs from highly disturbed beaches are more sensitive to human presence

The presence of humans frequently modifies the behavior of animals, particularly their foraging patterns, compromising energetic demands. The fiddler crab Leptuca leptodactyla inhabits mangroves with high degrees of anthropogenic influence. Thus, we tested if populations living in highly anthropized mangroves respond differently from those living in more protected areas. We predict that individuals from touristy areas will be more tolerant to humans and will resume their activities sooner after disturbance. To do so, we conducted an experiment that consisted in the approach of an observer to the burrows, recording the response of individuals to the stimuli. The experiment took place in July 2022, in Ubatuba, São Paulo, Brazil. We analysed the duration and latency of various behaviors of a total of 80 adult males from two populations (high and low anthropogenic influence). Contrary to our predictions, individuals from the anthropized population were less tolerant, spending more time inside their burrows and taking longer to resume their activities. Therefore, fiddler crabs were not habituated to human presence. These results help us understand the learning process in invertebrates and their ability to select stimuli, contributing to understanding the impacts of human-wildlife interactions.

Expanding through the Emerald Isle: exploration and spatial orientation of non-native bank voles in Ireland

Whether introduced into a completely novel habitat or slowly expanding their current range, the degree to which animals can efficiently explore and navigate new environments can be key to survival, ultimately determining population establishment and colonization success. We tested whether spatial orientation and exploratory behavior are associated with non-native spread in free-living bank voles (Myodes glareolus, N = 43) from a population accidentally introduced to Ireland a century ago. We measured spatial orientation and navigation in a radial arm maze, and behaviors associated to exploratory tendencies and risk-taking in repeated open-field tests, at the expansion edge and in the source population. Bank voles at the expansion edge re-visited unrewarded arms of the maze more, waited longer before leaving it, took longer to start exploring both the radial arm maze and the open field, and were more risk-averse compared to conspecifics in the source population. Taken together, results suggest that for this small mammal under heavy predation pressure, a careful and thorough exploration strategy might be favored when expanding into novel environments.

Free-ranging dogs match a human's preference in a foraging task

Social learning is a mechanism used by many species to efficiently gain information about their environment. Although many animals live in an environment where members of other species are present, little is known about interspecific social learning. Domesticated and urbanized species provide the opportunity to investigate whether nonhuman animals can learn from heterospecifics such as humans, who are integral parts of their social landscape. Although domestic dogs Canis familiaris have been intensively researched for their ability to learn from humans, most studies have focused on dogs living as pets. However, free-ranging dogs represent the majority of the world's dog population, they live alongside humans, scavenge on human refuse, and are subject to natural and sexual selection. Thus, free-ranging dogs with extensive exposure to humans and their artifacts provide the opportunity to investigate interspecific social learning in a naturalistic setting, where learning from humans might be a benefit for them. Here we tested individual free-ranging dogs in a between-subject design: Dogs in the control group could spontaneously choose between two novel and differently patterned food-delivering boxes. In the experimental group, instead, dogs could first observe an unfamiliar human approaching and eating from 1 of the 2 boxes. We provide the first evidence that free-ranging dogs match the choice of an unfamiliar human. These results show that at least simple forms of interspecific social learning might be involved in dogs' success in living alongside humans in a complex urbanized environment.

Urbanization does not affect red foxes' interest in anthropogenic food, but increases their initial cautiousness

Human presence and activities have profoundly altered animals' habitats, exposing them to greater risks but also providing new opportunities and resources. The animals' capacity to effectively navigate and strike a balance between risks and benefits is crucial for their survival in the Anthropocene era. Red foxes (Vulpes vulpes), adept urban dwellers, exhibit behavioral plasticity in human-altered environments. We investigated variations in detection frequency on trail cameras and the behavioral responses (explorative, bold, and fearful) of wild red foxes living along an urbanization gradient when exposed to a metal bin initially presented clean and then filled with anthropogenic food. All fox populations displayed an increased interest and similar explorative behavioral responses toward the anthropogenic food source, irrespective of the urbanization gradient. Despite no impact on explorative behaviors, foxes in more urbanized areas initially showed heightened fear toward the empty bin, indicating increased apprehension toward novel objects. However, this fear diminished over time, and in the presence of food, urban foxes displayed slightly reduced fear compared with their less urban counterparts. Our results highlight foxes' potential for adaptability to human landscapes, additionally underscoring the nuanced interplay of fear and explorative behavioral response of populations living along the urbanization gradient.

Smarter in the city? Lizards from urban and semi-natural habitats do not differ in a cognitive task in two syntopic species

Urbanization occurs at a global scale, imposing dramatic and abrupt environmental changes that lead to biodiversity loss. Yet, some animal species can handle these changes, and thrive in such artificial environments. One possible explanation is that urban individuals are equipped with better cognitive abilities, but most studies have focused on birds and mammals and yielded varied results. Reptiles have received much less attention, despite some lizard species being common city dwellers. The Italian wall lizard, Podarcis siculus, and the common wall lizard, Podarcis muralis, are two successful lizards in anthropogenic habitats that thrive in urban locations. To test for differences in a cognitive skill between urban and semi-natural environments, we investigated inhibitory control through a detour task in syntopic populations of the two species, across 249 lizards that were tested in partially artificial field settings. Sophisticated inhibitory control is considered essential for higher degrees of cognitive flexibility and other higher-level cognitive abilities. In this task, we confronted lizards with a transparent barrier, separating them from a desired shelter area that they could only reach by controlling their impulse to go straight and instead detour the barrier. We found no differences between lizards in urban and semi-natural environments, nor between species, but females overall performed better than males. Moreover, 48% of the lizards in our study did not perform a correct trial in any of the 5 trials, hinting at the difficulty of the task for these species. This study is among the first to address lizard cognition, through their inhibitory control, as a potential explanation for success in cities and highlights one should be careful with assuming that urban animals generally have enhanced cognitive performance, as it might be taxa, task, or condition dependent.

Urbanization does not increase "object curiosity" in vervet monkeys, but semi-urban individuals selectively explore food-related anthropogenic items

Urban environments expose animals to abundant anthropogenic materials and foods that facilitate foraging innovations in species with opportunistic diets and high behavioral flexibility. Neophilia and exploration tendency are believed to be important behavioral traits for animals thriving in urban environments. Vervet monkeys (Chlorocebus pygerythrus) are one of few primate species that have successfully adapted to urban environments, thus making them an ideal species to study these traits. Using a within-species cross-habitat approach, we compared neophilia and exploration of novel objects (jointly referred to as "object curiosity") between semi-urban, wild, and captive monkeys to shed light on the cognitive traits facilitating urban living. To measure "object curiosity," we exposed monkeys to various types of novel stimuli and compared their approaches and explorative behavior. Our results revealed differences in the number of approaches and explorative behavior toward novel stimuli between the habitat types considered. Captive vervet monkeys were significantly more explorative than both semi- urban and wild troops, suggesting that positive experiences with humans and lack of predation, rather than exposure to human materials per se, influence object curiosity. Across habitats, juvenile males were the most explorative age-sex class. This is likely due to males being the dispersing sex and juveniles being more motivated to learn about their environment. Additionally, we found that items potentially associated with human food, elicited stronger explorative responses in semi-urban monkeys than non-food related objects, suggesting that their motivation to explore might be driven by "anthrophilia", that is, their experience of rewarding foraging on similar anthropogenic food sources. We conclude that varying levels of exposure to humans, predation and pre-exposure to human food packaging explain variation in "object curiosity" in our sample of vervet monkeys.

Risk-sensitive learning is a winning strategy for leading an urban invasion

In the unpredictable Anthropocene, a particularly pressing open question is how certain species invade urban environments. Sex-biased dispersal and learning arguably influence movement ecology, but their joint influence remains unexplored empirically, and might vary by space and time. We assayed reinforcement learning in wild-caught, temporarily captive core-, middle-, or edge-range great-tailed grackles-a bird species undergoing urban-tracking rapid range expansion, led by dispersing males. We show, across populations, both sexes initially perform similarly when learning stimulus-reward pairings, but, when reward contingencies reverse, male-versus female-grackles finish 'relearning' faster, making fewer choice-option switches. How do male grackles do this? Bayesian cognitive modelling revealed male grackles' choice behaviour is governed more strongly by the 'weight' of relative differences in recent foraging payoffs-i.e., they show more pronounced risk-sensitive learning. Confirming this mechanism, agent-based forward simulations of reinforcement learning-where we simulate 'birds' based on empirical estimates of our grackles' reinforcement learning-replicate our sex-difference behavioural data. Finally, evolutionary modelling revealed natural selection should favour risk-sensitive learning in hypothesised urban-like environments: stable but stochastic settings. Together, these results imply risk-sensitive learning is a winning strategy for urban-invasion leaders, underscoring the potential for life history and cognition to shape invasion success in human-modified environments.

Cognitive flexibility in urban yellow mongooses, Cynictis penicillata

Cognitive flexibility enables animals to alter their behaviour and respond appropriately to environmental changes. Such flexibility is important in urban settings where environmental changes occur rapidly and continually. We studied whether free-living, urban-dwelling yellow mongooses, Cynictis penicillata, in South Africa, are cognitively flexible in reversal learning and attention task experiments (n = 10). Reversal learning was conducted using two puzzle boxes that were distinct visually and spatially, each containing a preferred or non-preferred food type. Once mongooses learned which box contained the preferred food type, the food types were reversed. The mongooses successfully unlearned their previously learned response in favour of learning a new response, possibly through a win-stay, lose-shift strategy. Attention task experiments were conducted using one puzzle box surrounded by zero, one, two or three objects, introducing various levels of distraction while solving the task. The mongooses were distracted by two and three distractions but were able to solve the task despite the distractions by splitting their attention between the puzzle box task and remaining vigilant. However, those exposed to human residents more often were more vigilant. We provide the first evidence of cognitive flexibility in urban yellow mongooses, which enables them to modify their behaviour to urban environments.

Do human-wildlife interactions predict offspring hiding strategies in peri-urban fallow deer?

Human activities can induce significant behavioural changes in wildlife. Often explored through extractive interactions (e.g. hunting) that can favour certain behavioural traits, the implications of non-extractive ones, such as wildlife feeding, remain understudied. Research shows that people tend to favour bolder individuals within populations despite their dynamics and consequences being unclear. Using fallow deer in a peri-urban environment, we studied whether mothers that show reduced fear of humans and consistently approach them for food adopt weaker anti-predator strategies by selecting less concealed fawning bedsites closer to human hotspots. This would provide the advantage of additional feeding opportunities in comparison with shyer mothers while keeping their fawns close. Our dataset encompassed 281 capture events of 172 fawns from 110 mothers across 4 years. Surprisingly, mothers that regularly accepted food from humans selected more concealed bedsites farther from human hotspots, giving their offspring better protection while also benefitting from additional food during lactation. Our results show behavioural adaptations by a subset of females and, for the first time, link the tendency to approach humans and strategies to protect offspring. Given previous findings that these begging females also deliver heavier fawns at birth, our research further investigates human-wildlife feeding interactions and their behavioural implications.

Natural Patterns in the Dawn and Dusk Choruses of a Neotropical Songbird in Relation to an Urban Sound Environment

Urbanization is one of the more important phenomena affecting biodiversity in the Anthropocene. Some organisms can cope with urban challenges, and changes in birds' acoustic communication have been widely studied. Although changes in the timing of the daily organization of acoustic communication have been previously reported, there is a significant gap regarding possible variations in song structure between dawn and dusk choruses. Considering that urbanization imposes different soundscapes for dawn and dusk choruses, we postulate two hypotheses: (i) there are variations in song parameters between dawn and dusk choruses, and (ii) such parameters within the city will vary in response to urban noise. We studied urban and extra-urban populations of Chiguanco Thrush in La Paz, Bolivia, measuring in dawn and dusk choruses: song length; song sound pressure level; minimum, maximum, range and dominant frequency; and the number of songs per individual. The results support our two hypotheses: there were more songs, and songs were louder and had larger band widths at dawn than at dusk in urban and extra-urban populations. Urban Chiguanco Thrushes sing less, the frequency of the entire song rises, and the amplitude increases as compared with extra-urban Chiguanco Thrushes. Understanding variations between dawn and dusk choruses could allow for a better interpretation of how some bird species cope with urban challenges.

Face masks in action: Birds show reduced fear responses to people wearing face masks during the COVID-19 pandemic in three Asian countries

The 2019 zoonotic pandemic (COVID-19), has led to a massive global lockdown that provides a good opportunity to study how wildlife responds to changes in human activity. Wearing a mask after the COVID-19 outbreak was widely used to prevent the spread of the causative pathogen. It has been shown that tree sparrows (Passer montanus) at two sites in south China exhibit reduced fear responses to people with face masks after a period of heavy exposure to them, whereas European studies showed the opposite, with no changes in the behaviour of the birds towards mask wearers in either rural or urban areas. To further study this, from October 2021 to January 2022, we conducted a flight initiation distance (FID) survey in Pakistan, Bangladesh, and Xi'an, China for a variety of field bird species by comparing the FID for researchers wearing masks to that for researchers not wearing masks to assess whether wearing masks in public places caused birds to adjust their flight response. Results from the three Asian countries showed that after a period of sustained contact with people wearing masks, in both rural and urban areas, birds were significantly more adapted to them and had a shorter FID to people wearing masks. We suggest that the rapid habituation of birds to people wearing masks with a reduced fear response could have some fitness advantage, allowing them to adapt rapidly to the new environmental conditions induced by COVID-19.

Integrating learning into animal range dynamics under rapid human-induced environmental change

Human-induced rapid environmental change (HIREC) is creating environments deviating considerably from natural habitats in which species evolved. Concurrently, climate warming is pushing species' climatic envelopes to geographic regions that offer novel ecological conditions. The persistence of species is likely affected by the interplay between the degree of ecological novelty and phenotypic plasticity, which in turn may shape an organism's range-shifting ability. Current modelling approaches that forecast animal ranges are characterized by a static representation of the relationship between habitat use and fitness, which may bias predictions under conditions imposed by HIREC. We argue that accounting for dynamic species-resource relationships can increase the ecological realism of range shift predictions. Our rationale builds on the concepts of ecological fitting, the process whereby individuals form successful novel biotic associations based on the suite of traits they carry at the time of encountering the novel condition, and behavioural plasticity, in particular learning. These concepts have revolutionized our view on fitness in novel ecological settings, and the way these processes may influence species ranges under HIREC. We have integrated them into a model of range expansion as a conceptual proof of principle highlighting the potentially substantial role of learning ability in range shifts under HIREC.

Noise and light pollution elicit endocrine responses in urban but not forest frogs

Urban areas are characterised by the presence of sensory pollutants, such as anthropogenic noise and artificial light at night (ALAN). Animals can quickly adapt to novel environmental conditions by adjusting their behaviour, which is proximately regulated by endocrine systems. While endocrine responses to sensory pollution have been widely reported, this has not often been linked to changes in behaviour, hampering the understanding of adaptiveness of endocrine responses. Our aim was, therefore, to investigate the effects of urbanisation, specifically urban noise and light pollution, on hormone levels in male urban and forest túngara frogs (Engystomops pustulosus), a species with reported population divergence in behaviour in response to urbanisation. We quantified testosterone and corticosterone release rates in the field and in the lab before and after exposure to urban noise and/or light. We show that urban and forest frogs differ in their endocrine phenotypes under field as well as lab conditions. Moreover, in urban frogs exposure to urban noise and light led, respectively, to an increase in testosterone and decrease in corticosterone, whereas in forest frogs sensory pollutants did not elicit any endocrine response. Our results show that urbanisation, specifically noise and light pollution, can modulate hormone levels in urban and forest populations differentially. The observed endocrine responses are consistent with the observed behavioural changes in urban frogs, providing a proximate explanation for the presumably adaptive behavioural changes in response to urbanisation.

Genetic diversity, gene flow, and landscape resistance in a pond-breeding amphibian in agricultural and natural forested landscapes in Norway

Genetic diversity is a key part of biodiversity, threatened by human activities that lead to loss of gene flow and reduction of effective population sizes. Gene flow is a result of both landscape connectivity and demographic processes determining the number of dispersing individuals in space and time. Thus, the effect of human impact on processes determining the level of genetic diversity must be interpreted in the context of basic ecological conditions affecting survival and recruitment. When the intensity of human impact and habitat suitability correlate, the effect on genetic diversity and gene flow may be challenging to predict. We compared genetic diversity, gene flow and landscape resistance in two contrasting landscapes in Norway for the pond-breeding amphibian Triturus cristatus: a highly human-impacted, agricultural landscape with ecologically productive habitats, and a forested landscape with less productive habitats and lower levels of human impact. Our results show that genetic diversity was higher and gene flow lower within the forested landscape. Microclimatic moisture conditions and vegetation cover were important determinants of landscape resistance to gene flow within both landscapes. There were indications that landscape resistance was increased by minor roads in the forested landscape, which was not the case for the agricultural landscape, suggesting a higher vulnerability to human interference within the landscape matrix for the populations in less productive habitats. Our findings suggest that the effect of human impact on genetic diversity may not be straightforward but modulated by the ecological conditions underlying local demographic processes. Populations within both landscapes seem to be vulnerable to loss of genetic diversity, but due to different mechanisms. This has implications for the choice of relevant management actions, that is, increasing population stability may be more relevant within an agricultural landscape still permeable for dispersal, while conserving dispersal corridors may be more appropriate in the forested landscape, to avoid isolation and increased genetic drift.

Macrobehaviour: behavioural variation across space, time, and taxa

We explore how integrating behavioural ecology and macroecology can provide fundamental new insight into both fields, with particular relevance for understanding ecological responses to rapid environmental change. We outline the field of macrobehaviour, which aims to unite these disciplines explicitly, and highlight examples of research in this space. Macrobehaviour can be envisaged as a spectrum, where behavioural ecologists and macroecologists use new data and borrow tools and approaches from one another. At the heart of this spectrum, interdisciplinary research considers how selection in the context of large-scale factors can lead to systematic patterns in behavioural variation across space, time, and taxa, and in turn, influence macroecological patterns and processes. Macrobehaviour has the potential to enhance forecasts of future biodiversity change.

Urban and rural male song sparrows (Melospiza melodia) differ in territorial aggression and activation of vasotocin neurons in response to song challenge

When living in urban habitats, 'urban adapter' species often show greater aggression toward conspecifics, yet we do not understand the mechanisms underlying this behavioral shift. The neuroendocrine system regulates socio-sexual behaviors including aggression and thus could mediate behavioral responses to urbanization. Indeed, urban male song sparrows (Melospiza melodia), which are more territorially aggressive, also have greater abundance of the neuropeptide arginine vasotocin (AVT) in nodes of the brain social behavior network. Higher abundance of AVT could reflect long-term synthesis that underlies baseline territoriality or short-term changes that regulate aggression in response to social challenge. To begin to resolve the timeframe over which the AVT system contributes to habitat differences in aggression we used immediate early gene co-expression as a measure of the activation of AVT neurons. We compared Fos induction in AVT-immunoreactive neurons of the bed nucleus of the stria terminalis (BSTm) and paraventricular nucleus of the hypothalamus (PVN) between urban and rural male song sparrows in response to a short (< 5 min.) or long (> 30 min.) song playback to simulate territorial intrusion by another male. We found that urban males had a higher proportion of Fos-positive AVT neurons in both brain regions compared to rural males, regardless of the duration of song playback. Our results suggest that AVT neurons remain activated in urban males, independently of the duration of social challenge. These findings that Fos induction in AVT neurons differs between rural and urban male song sparrows further implicate this system in regulating behavioral responses to urbanization.

A comprehensive database of squirrel distribution and occurrence in South Asia

Background

The Squirrels of South Asia (SOSA) database compiles comprehensive distribution and occurrence information on all squirrel species that occur in this region (34 species). These 34 squirrel species, including tree, flying and ground squirrels, represent 14% of global sciurid diversity. The database collates curated data from various sources such as museums, literature, primary fieldwork, citizen science and social media platforms and covers the entire distributional ranges of the target species, including countries in Central Asia and Southeast Asia when required. The SOSA database enhances our understanding of squirrel distribution, population dynamics and their conservation needs in South Asia by consolidating information. It aims to be a valuable resource for researchers, conservationists and wildlife enthusiasts.

New information

As of March 2023, the database comprises over 40,000 records of 34 species in over 30 countries globally. Spending an average of 334 hours on each species, more than 20 data collectors put in over 10,000 hours to gather, curate and build this database. The database has resulted in novel records of species occurrence in regions and countries that are poorly represented in currently available global data repositories. The current version which has been made public via GBIF comprises of 1187 records of all 34 species across multiple sources. This is a subset of the SOSA database.

Urbanization drives adaptive evolution in a Neotropical bird

Urbanization has dramatic impacts on natural habitats and such changes may potentially drive local adaptation of urban populations. Behavioral change has been specifically shown to facilitate the fast adaptation of birds to changing environments, but few studies have investigated the genetic mechanisms of this process. Such investigations could provide insights into questions about both evolutionary theory and management of urban populations. In this study, we investigated whether local adaptation has occurred in urban populations of a Neotropical bird species, Coereba flaveola, specifically addressing whether observed behavioral adaptations are correlated to genetic signatures of natural selection. To answer this question, we sampled 24 individuals in urban and rural environments, and searched for selected loci through a genome-scan approach based on RADseq genomic data, generated and assembled using a reference genome for the species. We recovered 46 loci as putative selection outliers, and 30 of them were identified as associated with biological processes possibly related to urban adaptation, such as the regulation of energetic metabolism, regulation of genetic expression, and changes in the immunological system. Moreover, genes involved in the development of the nervous system showed signatures of selection, suggesting a link between behavioral and genetic adaptations. Our findings, in conjunction with similar results in previous studies, support the idea that cities provide a similar selective pressure on urban populations and that behavioral plasticity may be enhanced through genetic changes in urban populations.

Grow up, be persistent, and stay focused: keys for solving foraging problems by free-ranging possums

Individuals within a species often vary in both their problem-solving approach and ability, affecting their capacity to access novel food resources. Testing problem-solving in free-ranging individuals is crucial for understanding the fundamental ecological implications of problem-solving capacity. To examine the factors affecting problem-solving in free-ranging animals, we presented three food-extraction tasks of increasing difficulty to urban common brushtail possums (Trichosurus vulpecula). We quantified two measures of problem-solving performance: trial outcome (success/failure) and time to solve and tested the influence of a range of potential drivers, including individual traits (personality, body weight, sex, and age), mechanistic behaviors that quantify problem-solving approach (work time, functional behavior time, behavioral diversity, and flexibility), and prior experience with the puzzles. We found that mechanistic behaviors were key drivers of performance. Individuals displaying greater persistence (higher work and functional behavior time) were more likely to solve a food-extraction task on their first attempt. Individuals also solved problems faster if they were more persistent and had lower behavioral flexibility. Personality indirectly affected time to solve one of the three problems by influencing time allocated to functional behaviors. Finally, adults solved the most difficult problem faster than juveniles. Overall, our study provides rare insight into the drivers underlying the problem-solving performance of wild animals. Such insight could be used to improve management strategies and conservation efforts, such as food or bait deployment, tailored to suit the innovative foraging abilities of target individuals in new and changing environments.

Urban birds become less fearful following COVID-19 reopenings

Following the COVID-19 pandemic, many people around the world stayed home, drastically altering human activity in cities. This exceptional moment provided researchers the opportunity to test how urban animals respond to human disturbance, in some cases testing fundamental questions on the mechanistic impact of urban behaviours on animal behaviour. However, at the end of this 'anthropause', human activity returned to cities. How might each of these strong shifts affect wildlife in the short and long term? We focused on fear response, a trait essential to tolerating urban life. We measured flight initiation distance-at both individual and population levels-for an urban bird before, during and after the anthropause to examine if birds experienced longer-term changes after a year and a half of lowered human presence. Dark-eyed juncos did not change fear levels during the anthropause, but they became drastically less fearful afterwards. These surprising and counterintuitive findings, made possible by following the behaviour of individuals over time, has led to a novel understanding that fear response can be driven by plasticity, yet not habituation-like processes. The pandemic-caused changes in human activity have shown that there is great complexity in how humans modify a behavioural trait fundamental to urban tolerance in animals.

Wild mockingbirds distinguish among familiar humans

Although individuals of some species appear able to distinguish among individuals of a second species, an alternative explanation is that individuals of the first species may simply be distinguishing between familiar and unfamiliar individuals of the second species. In that case, they would not be learning unique characteristics of any given heterospecific, as commonly assumed. Here we show that female Northern Mockingbirds (Mimus polyglottos) can quickly learn to distinguish among different familiar humans, flushing sooner from their nest when approached by people who pose increasingly greater threats. These results demonstrate that a common small songbird has surprising cognitive abilities, which likely facilitated its widespread success in human-dominated habitats. More generally, urban wildlife may be more perceptive of differences among humans than previously imagined.

Traffic noise inhibits inhibitory control in wild-caught songbirds

Anthropogenic noise is ubiquitous across environments and can have negative effects on animals, ranging from physiology to community structure. Recent work with captive-bred zebra finches demonstrated that traffic noise also affects cognitive performance. We examined whether these results extend to animals that have experienced noise in the wild. We collected black-capped chickadees from areas frequently exposed to road traffic noise and tested them on a detour reaching task, a commonly used measure of inhibitory control. Those chickadees exposed to traffic noise playback had much lower performance on the task than control birds, indicating that noise negatively impacts inhibitory control. These data corroborate previous findings in lab-reared zebra finches. Furthermore, these results suggest that prior experience with traffic noise is not sufficient for animals to habituate to noise and overcome its negative effects on cognitive performance. Instead, noise-induced cognitive effects might have broad impacts on animal species living in noise-polluted habitats.

Lockdown effects on fear revealed direct and indirect effects of human presence on perceived predation risk

The Covid-19 lockdown reduced drastically human presence outdoors, providing an uncontrolled experiment for disentangling direct and indirect effects of human presence on animal fearfulness. We measured 18,494 flight initiation distances (FIDs, the distance at which individual animals fly away when approached by a human) from 1333 populations of 202 bird species taken in four European cities both before, during and after the lockdown. FIDs decreased during lockdown in rural habitats but increased in urban habitats, especially for singing birds. Height above ground increases during lockdown in non-singing birds only, and birds adjusted horizontal tolerance to approach according to height outside lockdown, in rural habitats and while not singing. Responses showed lagged effects after lockdown in urban but not in rural habitats. Differential responses to lockdown among habitats and between signing and non-singing birds were consistent with relaxation of direct disturbance effects on birds in rural habitats during lockdown, as well as with increased indirect fear effects mediated by predator release in cities. FIDs seemed to measure the balance of direct and indirect effects of humans on predations risk and food needs rather than direct effects of humans on fear.

The role of climate change and niche shifts in divergent range dynamics of a sister-species pair

Species ranges are set by limitations in factors including climate tolerances, habitat use, and dispersal abilities. Understanding the factors governing species range dynamics remains a challenge that is ever more important in our rapidly changing world. Species ranges can shift if environmental changes affect available habitat, or if the niche or habitat connectivity of a species changes. We tested how changes in habitat availability, niche, or habitat connectivity could contribute to divergent range dynamics in a sister-species pair. The great-tailed grackle (Quiscalus mexicanus) has expanded its range northward from Texas to Nebraska in the past 40 years, while its closest relative, the boattailed grackle (Quiscalus major), has remained tied to the coasts of the Atlantic Ocean and the Gulf of Mexico as well as the interior of Florida. We created species distribution and connectivity models trained on citizen science data from 1970-1979 and 2010-2019 to determine how the availability of habitat, the types of habitat occupied, and range-wide connectivity have changed for both species. We found that the two species occupy distinct habitats and that the great-tailed grackle has shifted to occupy a larger breadth of urban, arid environments farther from natural water sources. Meanwhile, the boattailed grackle has remained limited to warm, wet, coastal environments. We found no evidence that changes in habitat connectivity affected the ranges of either species. Overall, our results suggest that the great-tailed grackle has shifted its realized niche as part of its rapid range expansion, while the range dynamics of the boat-tailed grackle may be shaped more by climate change. The expansion in habitats occupied by the great-tailed grackle is consistent with observations that species with high behavioral flexibility can rapidly expand their geographic range by using human-altered habitat. This investigation identifies how opposite responses to anthropogenic change could drive divergent range dynamics, elucidating the factors that have and will continue to shape species ranges.

Land-use changes interact with geology to facilitate dispersal of the rock hyrax (Procavia capensis) and leishmaniasis across Israel and the West Bank

Geology plays a fundamental role in establishing species' habitats, determining both physical (e.g., landscape morphology, soil texture) and chemical (e.g., mineral composition, water availability) properties. In the current Anthropocene epoch, human activity is transforming Earth's geology and ecosystems. Yet to date, there have been almost no studies incorporating geology when examining the effect of such land-use changes on species distribution. This study seeks to uncover how specific land-use changes interact with geology, in order to explain the recent and rapid expansion of the rock hyrax (Procavia capensis) across the mountains of central Israel and the West Bank. Hyraxes are dependent on rock mounds for their habitat, and their expansion seems to be correlated with increasing infrastructure construction. However, their expansion patterns differ among locations, even when the human land-use is similar. To explain the patterns of hyrax distribution observed over the past 46 years, we converted geological data into ecological data, which present the probability of the local bedrock breaking into boulders, whether due to either natural or anthropogenic weathering processes. We applied species distribution models (SDMs) and found that the expansion of rock hyrax populations was facilitated by means of the interaction of specific geological units with land-use practices (e.g., roads and construction), which resulted in the accumulation of large boulders, creating novel habitats and stepping stones in previously unsuitable areas for hyraxes. Since rock hyraxes are major hosts of the leishmaniasis pathogen, the findings from this study offer important insights into the progression and potential outbreaks of the disease in human populations. Understanding the role that geology plays in shaping a species' niche is expected to prove useful in studying the distribution of other wildlife species and is fundamental in studies seeking to predict the potential ecological impacts on local biodiversity associated with land-use change.

Do Suburban Populations of Lizards Behave Differently from Forest Ones? An Analysis of Perch Height, Time Budget, and Display Rate in the Cuban Endemic Anolis homolechis

Urbanization transforms natural ecosystems into novel habitats, which can result in negative consequences for biodiversity. Therefore, it is important to understand the mechanisms of maintenance of native species in urbanized environments, including behavior—which can act as a fast response to rapid environmental changes. We compared some behavioral traits between two suburban and two forest populations of Anolis homolechis. Direct observations of 779 individuals revealed that perch height was positively influenced by body size, but not by sex. Suburban individuals perched higher than forest ones, and even more so in the afternoon compared to the morning; a behavior that was not observed in forests populations. These differences might be due to a change from foraging activities in the morning to vigilance, display, and/or thermoregulation in the afternoon, promoted by suburban habitat conditions (e.g., higher predator abundance, open habitat structure, and urban heat). Video recordings of 81 focal individuals showed that males were more active than females (i.e., spending less time in stationary behavior and having a higher display rate), with no significant effect of habitat type. As some of our results diverge from previous studies on invasive anoles, we recommend extending comparative studies of urban and non-urban populations to other native Anolis.

House Sparrow (Passer domesticus) escape behavior is triggered faster in smaller settlements

A recurrent behavioral trait model to study adaptation to urban environments is the flight initiation distance (FID), measured as the distance at which animals flee from an approaching threat. It has previously been shown that urban birds display shorter FID than their non-urban (rural) counterparts. However, discerning whether this is the result of habituation to human presence and frequentation, or of ecological factors related to the size of the city (considered as "systemic habituation"), has not yet been addressed. In this study, we analyzed House Sparrow (Passer domesticus) FIDs in a network of 26 small towns and villages within the same region in northeastern Spain. Our aim was to relate FID to human population density and settlement size. If the habituation to human presence hypothesis was supported, we should expect FIDs to decrease with the density of the human population across the human settlements, since this type of habituation is related to the rate of human exposure and this is proportional to human density. However, if the systemic habituation hypothesis was supported, FIDs should instead relate to the size of the human settlements, as the abundance of predators, similarly to other ecological variables, is often proportional to the size of towns. Results showed House Sparrows to be bolder in larger human settlements, but not necessarily the ones with a higher density of human population. This supports the idea that the fact that urban birds display shorter FIDs than their rural counterparts is the result of systemic ecological factors rather than the results of a simple habituation to humans.