Consistent diel activity patterns of forest mammals among tropical regions

Spatiotemporal interactions between ocelots and agoutis in Neotropical protected forests

Understanding how predators and their prey coexist in space and time is a core interest in ecology. Vast amounts of photographic detection data are now available from a growing number of camera-trap studies worldwide. These data boost our ability to study an elusive yet important topic in ecology: species interactions in space and time. Here, we investigated the spatiotemporal configuration of the activity of a typically nocturnal and crepuscular predator and a diurnal prey in protected areas. We explored whether agoutis (Dasyprocta leporina) respond to predation risks by adjusting the timing of activity to the occurrence and timing of activity of its potential predator, the ocelot (Leopardus pardalis) and whether the ocelot's occurrence responds to that of the prey. Using a custom Bayesian occupancy model for two species, we analysed camera-trap data collected over three protected tropical forests from Brazil and Suriname (2 to 9 years). Our model distinguishes between occupancy (i.e. spatial distribution) and detection (i.e. activity in space and time). We detected a positive spatial association between predator and prey, suggesting that ocelots seek places where agoutis are present. Instead of segregating in space, agoutis appeared to respond to increased predation risk by reduced activity. The most pronounced reduction in agouti activity (i.e. probability of detection) was during twilight in sites where ocelots occurred. Our results illustrate how jointly modelling interactions in both space and time informs our understanding of predator-prey coexistence.

When the wild things are: Defining mammalian diel activity and plasticity

Circadian rhythms are a mechanism by which species adapt to environmental variability and fundamental to understanding species behavior. However, we lack data and a standardized framework to accurately assess and compare temporal activity for species during rapid ecological change. Through a global network representing 38 countries, we leveraged 8.9 million mammalian observations to create a library of 14,587 standardized diel activity estimates for 445 species. We found that less than half the species' estimates were in agreement with diel classifications from the reference literature and that species commonly used more than one diel classification. Species diel activity was highly plastic when exposed to anthropogenic change. Furthermore, body size and distributional extent were strongly associated with whether a species is diurnal or nocturnal. Our findings provide essential knowledge of species behavior in an era of rapid global change and suggest the need for a new, quantitative framework that defines diel activity logically and consistently while capturing species plasticity.

Carnivore activity across landuse gradients in a Mexican biosphere reserve

Anthropogenic activities are increasingly encroaching into wildland areas, heightening interactions between human and carnivore communities. Area-based conservation measures, such as protected areas (PAs), employ different management strategies via land-use designations to mitigate anthropogenic pressures and reduce human-wildlife conflicts in shared landscapes. Here, we assessed carnivore diel activity and temporal activity overlap in and around El Triunfo Biosphere Reserve (REBITRI) in Chiapas, Mexico, along a land-use designation gradient. We deployed 33 camera traps along the gradient, leveraging the reserve's core and buffer zones, and private lands surrounding the reserve. We calculated activity overlap between species to detect changes in interspecific competition and predator-prey interactions along the gradient. In total, we detected 14 carnivores in the core zones, 10 in the buffer zone, and 9 on private land across the 4777 trap-night survey. Significant shifts in single-species diel activity between the buffer zones and private land were detected for margay (Leopardus wiedii) and grey fox (Urocyon cinereoargenteus). Activity overlap was the highest in the buffer zone for all predator-prey pairs, and two competitor pairs, suggesting reduced diel niche partitioning in this land-use designation due to varied anthropogenic pressures. Our findings contribute to assessing PA efficacy and understanding carnivore activity in multiple-use landscapes where anthropogenic pressures are ubiquitous.

Genome assembly of a nocturnal butterfly (Macrosoma leucophasiata) reveals convergent adaptation of visual genes

Nearly all animals exhibit a preferred period of daily activity (diel-niche), strongly influenced by the light environment. Vision is a sensory system that is strongly adapted to light, and evolutionary transitions to novel light environments can impose strong constraints on eye evolution, color, and motion vision. While the genetic and neural basis of visual adaptation are well-studied in a few model systems, our understanding across the tree of life remains incomplete. Butterflies and moths are an ideal system to investigate the association between gene evolution and diel-niche transitions. While most butterflies are day-flying, hedylid butterflies are unique in being primarily nocturnal, representing an important evolutionary shift from diurnality to nocturnality. We sequenced the first Hedylidae genome and annotated it to understand genomic changes associated with diel niche shifts. Comparing Hedylidae visual genes to those of other diurnal and nocturnal Lepidoptera revealed that visual genes are highly conserved, with no major losses. However, hedylid opsins were more similar to nocturnal moths than their diurnal congeners, suggesting that these opsins convergently evovled to adapt to the nocturnal environment. Evolutionary rate tests (dN/dS) confirmed strong selection on color vision opsins, with some sites being mapped to the functional domain of the blue opsin. Our study provides new insight into the molecular evolutionary adaptations associated with species' changes to new light environments.

Daily activity patterns in agoutis (Dasyprocta spp) in response to relaxed predation

Animals' fitness is determined in a large proportion by the balance in energetic requirements maintained during daily activities, in response to environmental factors. Predation is a major environmental factor influencing the activity patterns of prey, and the deployment of adaptive responses to predation represents a significant cost to prey populations and communities. Experimental removal of predators to study the effect on activity patterns of prey is impractical for vertebrate species. However, islands are often deprived of predators and provide an excellent arena to study prey's responses in the absence of any cue related to predation risk. Here, we investigated whether natural absence of predators in islands has influenced the activity patterns of diurnal agoutis in Panama, by monitoring activity in three sites in each habitat type (predator-free vs predator). We predicted that agoutis in predator-free sites can expand their activity patterns towards the night, which is the period of highest predation risk, in sites with predators. One of our predator-free sites showed relative high activity at night, with no evidence of nocturnality in sites with predators. A clear pattern across our three predator-free sites was that agoutis started their daily activity earlier, before sunrise, which is a period with significant predation risk as well. Our study highlights the role that felids play in regulating agoutis' daily activity patterns and we discuss the implications of our finding. Finally, we also offer a review on agoutis' activity pattern in the Neotropics.

The moon's influence on the activity of tropical forest mammals

Changes in lunar illumination alter the balance of risks and opportunities for animals, influencing activity patterns and species interactions. We examined if and how terrestrial mammals respond to the lunar cycle in some of the darkest places: the floors of tropical forests. We analysed long-term camera trapping data on 86 mammal species from 17 protected forests on three continents. Conservative categorization of activity during the night revealed pronounced avoidance of moonlight (lunar phobia) in 12 species, compared with pronounced attraction to moonlight (lunar philia) in only three species. However, half of all species in our study responded to lunar phases, either changing how nocturnal they were, altering their overall level of activity, or both. Avoidance of full moon was more common, exhibited by 30% of all species compared with 20% of species that exhibited attraction. Nocturnal species, especially rodents, were over-represented among species that avoided full moon. Artiodactyla were more prominent among species attracted to full moon. Our findings indicate that lunar phases influence animal behaviour even beneath the forest canopy. Such impacts may be exacerbated in degraded and fragmented forests. Our study offers a baseline representing relatively intact and well-protected contexts together with an intuitive approach for detecting activity shifts in response to environmental change.

Host-, Environment-, or Human-Related Effects Drive Interspecies Interactions in an Animal Tuberculosis Multi-Host Community Depending on the Host and Season

In many Mediterranean ecosystems, animal tuberculosis (TB), caused by Mycobacterium bovis, is maintained by multi-host communities in which cattle and different wildlife species establish interaction networks contributing to M. bovis transmission and persistence. Most studies have addressed wildlife-cattle disease-relevant interactions, focusing on reservoir hosts, while disregarding the potential contribution of the so-called accidental hosts and/or neglecting wildlife-wildlife interactions. In this work, we aimed to characterise interspecies interactions in an endemic TB risk area and identify the ecological drivers of interaction patterns regardless of the pre-attributed role of host species on TB epidemiology. For that purpose, spatial-temporal indirect interactions between wildlife mammals and cattle, and between different wildlife species, were investigated through camera trapping. Second, five ecological hypotheses potentially driving species pair interactions in the wet and dry seasons were tested covering water and control sites: human presence (H1), landscape composition (H2), topography (H3), weather (H4), and natural food and water resources (H5). Wild boar (Sus scrofa), red deer (Cervus elaphus), and red fox (Vulpes vulpes) were the wildlife species mostly involved in indirect interactions. We found that indirect wildlife-cattle interactions were more frequent than wildlife interactions and, for certain species pairs, interaction rates were higher in the wet season in both wildlife-cattle and wildlife groups. Natural food and water resources (H5) was the most supported hypothesis that influenced the abundance of wildlife-cattle interactions, with positive effects during the dry season and negative effects during the wet season. In contrast, the abundance of indirect interactions between wildlife species was mainly supported by the human disturbance hypothesis (H1), with negative effects exerted on the dry season and variable effects on the wet season. Other tested hypotheses also influenced wildlife-cattle and wildlife-wildlife interactions, depending on the season and host species. These results highlight that indirect interactions, and thus conditions potentially favouring the transmission of M. bovis in shared environments, are determined by different ecological backgrounds.

Cathemerality: a key temporal niche

Given the marked variation in abiotic and biotic conditions between day and night, many species specialise their physical activity to being diurnal or nocturnal, and it was long thought that these strategies were commonly fairly fixed and invariant. The term 'cathemeral', was coined in 1987, when Tattersall noted activity in a Madagascan primate during the hours of both daylight and darkness. Initially thought to be rare, cathemerality is now known to be a quite widespread form of time partitioning amongst arthropods, fish, birds, and mammals. Herein we provide a synthesis of present understanding of cathemeral behaviour, arguing that it should routinely be included alongside diurnal and nocturnal strategies in schemes that distinguish and categorise species across taxa according to temporal niche. This synthesis is particularly timely because (i) the study of animal activity patterns is being revolutionised by new and improved technologies; (ii) it is becoming apparent that cathemerality covers a diverse range of obligate to facultative forms, each with their own common sets of functional traits, geographic ranges and evolutionary history; (iii) daytime and nighttime activity likely plays an important but currently neglected role in temporal niche partitioning and ecosystem functioning; and (iv) cathemerality may have an important role in the ability of species to adapt to human-mediated pressures.

Diurnal activity time budget of Grevy's zebra (Equus grevyi, Oustalet 1882) in a protected savannah area

Understanding natural history such as diurnal activity of wildlife species is important for their conservation intervention. The aim of the current study was to examine Grevy's zebra diurnal activity time budget in Hallaydeghe Asebot Proposed National Park (HAPNP) considering both wet and dry seasons. Scan sampling method was used. Activities of the species were recorded based on age and sex. Species were observed for 15 min (10 min activities recording followed 5 min rest). Analysis of Variance (ANOVA) was used to analysis data. Grazing (31.26%) was the highest followed by resting (30.24%) during the wet season and grazing (37.13%) was the highest followed by moving (27.25%) during dry season. The peak grazing time of species was morning 6:00-9:00 a.m. and late afternoon 16:00-18:00 p.m. while resting was observed during midday. The time the species spent over grazing (df = 1, F = 27.15, p = 0.000132), Grooming (df = 1, F = 24.082, p = 0.000231), mating (df = 1, F = 24.850, p = 0.0002) and moving (df = 1, F = 5.550, p = 0.0336) activity during both seasons were significantly different. There is statistical difference for grazing (df = 2, F = 9.336, p = 0.002653), mating (df = 2, F = 6.216, p = 0.0117), moving (df = 2, F = 5.604, p = 0.0163) and other (df = 2, F = 5.006, p = 0.0229) activities based on sex of species. The current study examined only diurnal activity time budget of the species. As a result, future research shall be conducted by taking into account the impact of different factors (temperature and livestock) that can influence the activity time budget of Grevy's zebra in HAPNP. Lastly, we recommend thorough species management plan in HAPNP for sustainable conservation of Grevy's zebra.

The macroevolutionary dynamics of activity pattern in mammals: Primates in context

Activity pattern has played a prominent role in discussions of primate evolutionary history. Most primates are either diurnal or nocturnal, but a small number are active both diurnally and nocturnally. This pattern-cathemerality-also occurs at low frequency across mammals. Using a large sample of mammalian species, this study evaluates two macroevolutionary hypotheses proposed to explain why cathemerality is less common than diurnality and nocturnality: 1) that cathemeral lineages have higher extinction probabilities (differential diversification) and 2) that transitions out of cathemerality are more frequent, making it a less persistent state (differential state persistence). Rates of speciation, extinction, and transition between character states were estimated using hidden-rates models applied to a phylogenetic tree containing 3013 mammals classified by activity pattern. The models failed to detect consistent differences in diversification dynamics among activity patterns, but there is strong support for differential state persistence. Transition rates out of cathemerality tend to be much higher than transition rates out of nocturnality. Transition rates out of diurnality are similar to those for cathemerality in most clades, with two important exceptions: diurnality is unusually persistent in anthropoid primates and sciurid rodents. These two groups combine very low rates of transition out of diurnality with high speciation rates. This combination has no parallels among cathemeral lineages, explaining why diurnality has become more common than cathemerality in mammals. Similarly, the combination of rates found in anthropoids is sufficient to explain the low relative frequency of cathemerality in primates, making it unnecessary to appeal to high extinction probabilities in cathemeral lineages in this clade. These findings support the hypothesis that the distribution of activity patterns across mammals has been influenced primarily by differential state persistence, whereas the effect of differential diversification appears to have been more idiosyncratic.

When death comes: linking predator-prey activity patterns to timing of mortality to understand predation risk

The assumption that activity and foraging are risky for prey underlies many predator-prey theories and has led to the use of predator-prey activity overlap as a proxy of predation risk. However, the simultaneous measures of prey and predator activity along with timing of predation required to test this assumption have not been available. Here, we used accelerometry data on snowshoe hares (Lepus americanus) and Canada lynx (Lynx canadensis) to determine activity patterns of prey and predators and match these to precise timing of predation. Surprisingly we found that lynx kills of hares were as likely to occur during the day when hares were inactive as at night when hares were active. We also found that activity rates of hares were not related to the chance of predation at daily and weekly scales, whereas lynx activity rates positively affected the diel pattern of lynx predation on hares and their weekly kill rates of hares. Our findings suggest that predator-prey diel activity overlap may not always be a good proxy of predation risk, and highlight a need for examining the link between predation and spatio-temporal behaviour of predator and prey to improve our understanding of how predator-prey behavioural interactions drive predation risk.