Dietary Niche Separation between Sympatric Free-Ranging Domestic Dogs and Indian Foxes in Central India: Table 1

Ready, set, yellow! color preference of Indian free-ranging dogs

Most of the research on color vision related behaviors in dogs has involved training the dogs to perform visual discrimination tasks. We investigated the importance of color to untrained Indian free-ranging dogs (FRDs). Using one-time multi-option choice tests for color preference in 134 adult dogs, we found the dogs to prefer yellow objects over blue or gray ones while there was no preference between blue and gray. We next pitted a yellow object against a gray object that had food. Here, the dogs ignored the food (biscuit or chicken) to approach the yellow object first indicating the color preference to be quite strong. Color preference has previously been investigated in many other animals and has implications for behaviors like mate choice and foraging. Our study provides a new perspective into the ecology of Indian FRDs and might have implications for companion dogs as well, if they too show this preference.

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.

Going back to "basics": Harlow's learning set task with wolves and dogs

To survive and reproduce, animals need to behave adaptively by adjusting their behavior to their environment, with learning facilitating some of these processes. Dogs have become a go-to model species in comparative cognition studies, making our understanding of their learning skills paramount at multiple levels, not only with regards to basic research on their cognitive skills and the effects of domestication, but also with applied purposes such as training. In order to tackle these issues, we tested similarly raised wolves and dogs in a serial learning task inspired by Harlow's "learning set." In Phase 1, different pairs of objects were presented to the animals, one of which was baited while the other was not. Both species' performance gradually improved with each new set of objects, showing that they "learnt to learn," but no differences were found between the species in their learning speed. In Phase 2, once subjects had learned the association between one of the objects and the food reward, the contingencies were reversed and the previously unrewarded object of the same pair was now rewarded. Dogs' performance in this task seemed to be better than wolves', albeit only when considering just the first session of each reversal, suggesting that the dogs might be more flexible than wolves. Further research (possibly with the aid of refined methods such as computer-based tasks) would help ascertain whether these differences between wolves and dogs are persistent across different learning tasks.

Free-ranging dogs are seriously threatening Himalayan environment: delineating the high-risk areas for curbing free-ranging dog infestation in the Trans-Himalayan region

It is becoming more widely recognised that free-ranging dogs, which have a nearly global distribution, threatening native wildlife. Their increasing population and spread to new areas is of growing concern for the long-term viability of wildlife species. Hence, it is imperative to understand the factors responsible for their infestation and map areas where native species are most vulnerable. Using the random forests algorithm, we modelled the free-ranging dog infestation in the Trans-Himalayan region to pinpoint the high-risk areas where free-ranging dogs are threatening the native wildlife species. We found that the likelihood of free-ranging dog occurrence is most in valley regions and up to 4000 m, often in proximity to roads. Our results also indicated that free-ranging dog prefers areas with wildlife near to protected areas. The predictor variables, such as potential evapotranspiration of the coldest quarter, distance to protected areas, elevation, distance to roads, and potential evapotranspiration of the driest quarter, significantly influence the distribution of the free-ranging dogs. We found that within the Ladakh region of the Trans-Himalayan area, the high-risk zones for free-ranging dogs are located in and around Hemis National Park, Karakoram Wildlife Sanctuary, and Changthang Wildlife Sanctuary. While, in the Lahaul and Spiti region the high-risk areas encompass Pin Valley National Park, Inderkilla National Park, Khirganga National Park, Kugti Wildlife Sanctuary, and several other protected areas. We identified the potentially high-risk areas for implementing strategies to mitigate the possible impact of free-ranging dogs on native wildlife of the Himalayas. Hence, the identified high priority areas can be used for implementing actions for controlling the population growth and further preventing the infestation of the free-ranging dogs into the new areas.

Understanding carnivore interactions in a cold arid trans-Himalayan landscape: What drives co-existence patterns within predator guild along varying resource gradients?

Predators compete for resources aggressively, forming trophic hierarchies that shape the structure of an ecosystem. Competitive interactions between species are modified in the human-altered environment and become particularly important where an introduced predator can have negative effects on native predator and prey species. The trans-Himalayan region of northern India has seen significant development in tourism and associated infrastructure over the last two decades, resulting in many changes to the natural setting of the landscape. While tourism, combined with unmanaged garbage can facilitate red fox (Vulpes vulpes), it also allows free-ranging dogs (Canis lupus familiaris), an introduced mesopredator to thrive, possibly more than the native red fox. We look at the little-known competitive dynamics of these two meso-carnivores, as well as their intra-guild interactions with the region's top carnivores, the snow leopard (Panthera uncia) and the Himalayan wolf (Canis lupus chanco). To study interactions between these four carnivores, we performed multispecies occupancy modeling and analyzed spatiotemporal interactions between these predators using camera trap data. We also collected scat samples to calculate dietary niche overlaps and determine the extent of competition for food resources between these carnivores. The study found that, after controlling for habitat and prey covariates, red fox site use was related positively to snow leopard site use, but negatively to dog and wolf site use. In addition, site use of the dog was associated negatively with top predators, that is, snow leopard and Himalayan wolf, while top predators themselves related negatively in their site use. As anthropogenic impacts increase, we find that these predators coexist in this resource-scarce landscape through dietary or spatiotemporal segregation, implying competition for limited resources. Our research adds to the scant ecological knowledge of the predators in the region and improves our understanding of community dynamics in human-altered ecosystems.

Habitat selection by free-roaming domestic dogs in rabies endemic countries in rural and urban settings

Domestic dogs can affect human health through bites and pathogen transmission, particularly in resource-poor countries where dogs, including owned ones, predominantly roam freely. Habitat and resource selection analysis methods are commonplace in wildlife studies but have not been used to investigate the environmental resource use of free-roaming domestic dogs (FRDD). The present study implements GPS devices to investigate habitat selection by FRDD from an urban site and a rural site in Indonesia, and one urban and two rural sites in Guatemala (N = 321 dogs). Spatial mixed effects logistic regression models, accounting for heterogeneous distribution of the resources, showed that patterns of habitat selection by FRDD were similar across study sites. The most preferred resources were anthropogenic, being buildings and roads, which implies selection for human proximity. Vegetation and open fields were less preferred and steep terrain was avoided, indicating that FRDD were synanthropic and that their space patterns likely optimised energy use. Results presented here provide novel data on FRDD habitat selection patterns, while improving our understanding of dog roaming behaviour. These findings provide insights into possible high-risk locations for pathogen transmission for diseases such as rabies, and can assist management authorities in the planning and deployment of efficient disease control campaigns, including oral vaccination.

Investigating the free-roaming dog population and gastrointestinal parasite diversity in Tulúm, México

Free-roaming domestic dogs (Canis lupus familiaris) pose major conservation and public health risks worldwide. To better understand the threat of domestic dogs to wildlife and people and add to the growing literature on free-roaming dog ecology, a study was conducted to estimate the dog population in Tulúm, México. A modified mark-recapture technique and program MARK were used to obtain dog population estimates along six different transects dividing the city. Population estimates ranged from 19.75 dogs in one transect to 101.841 dogs in another, with 150 total dogs identified throughout the study and an estimated minimum population density of 48.57 dogs/km2. Fecal samples were also opportunistically collected for parasite identification through fecal flotation analysis using the McMaster technique. Out of 25 samples collected, 19 tested positive for gastrointestinal parasites with the most common species found being Ancylostoma caninum, followed by Toxocara canis, Dipylidium caninum, and Cystoisospora spp. Parasite loads ranged from 50 to 10,700 ova per gram of feces. The large population of free-roaming dogs and the prevalence of three zoonotic parasites highlight the importance of understanding free-roaming dog ecology and educating the public on the health risks free-roaming dogs pose. Los perros callejeros (Canis lupus familiaris) representan un gran riesgo para la conservación de animales y la salud pública mundialmente. Para comprender mejor la amenaza que significan los perros domésticos para la fauna silvestre y los humanos y aportar a la creciente bibliografía sobre la ecología de los perros callejeros, se realizó una investigación para estimar la población de los perros en Tulúm, México. Se utilizó una técnica modificada de marcado y recaptura junto con el programa MARK para estimar la población canina en seis transectos de la ciudad. Los estimados varían desde 19.75 perros en un transecto hasta 101,841 en otro, con un total de 150 perros identificados en el transcurso de la investigación y una densidad mínima estimada de 48,57 perros/km2. Además, se hizo una recolección oportunista de muestras de heces para la identificación de parásitos por medio del análisis de flotacíon fecal, con el método McMaster. De las 25 muestras recolectadas, 19 resultaron positivas para parásitos gastrointestinales, de las cuales las especies más comunes fueron Ancylostomoa caninum, seguida por Toxocara canis, Dipylidium caninum, y Cystoisospora spp. Las cargas parasitarias variaron desde 50 hasta 10.700 óvulos por gramo de heces. La alta población de perros callejeros y la prevalencia de tres enfermedades zoonóticas resaltan la importancia de entender la ecología de los perros callejeros y educar al público sobre los riesgos que significan los perros callejeros para la salud.

The activity patterns of nonworking and working sled dogs

There are limited studies investigating the combined effects of biological, environmental, and human factors on the activity of the domestic dog. Sled dogs offer a unique opportunity to examine these factors due to their close relationship with handlers and exposure to the outdoors. Here, we used accelerometers to measure the activity of 52 sled dogs over 30 days from two locations in Canada. The two locations differ in the working demands of dogs, therefore we used linear mixed effects models to assess how different factors impact daytime and nighttime activity of working versus nonworking dogs. During the daytime, we found that males were more active than females among nonworking dogs and younger dogs were more active than older dogs among working dogs. Alaskan huskies had higher activity levels than non-Alaskan husky breeds in working sled dogs during the day. Nonworking dogs were slightly more active during colder weather, but temperature had no effect on working dogs’ activity. The strongest predictor of daytime activity in working dogs was work schedule. These results indicate that the influence of biological factors on activity varied depending on dogs’ physical demands and human activity was the most powerful driver of activity in working dogs.

Free-ranging dogs as a potential threat to Iranian mammals

Free-ranging domestic dogs Canis familiaris threaten wildlife species through predation, hybridization, competition for resources, and by contributing to the transmission of pathogens. The impacts of predation may be problematic, but in many regions the interactions of free-ranging dogs and wildlife are poorly studied. To determine the extent of the impacts of attacks by free-ranging dogs on Iranian mammals, we reviewed nearly 2 decades of social and traditional media reports and the scientific literature to gather data from across the country. We identified 160 free-ranging dog attacks (79 from academic articles, 14 from social media, and 67 from a variety of news websites) from 22 of the country's 31 provinces. Attacks by dogs were reported on 17 species, including nine Carnivora, six Artiodactyla, one Rodentia, and one Lagomorpha species. Most of the reported attacks on carnivores were on felids, including the Asiatic cheetah Acinonyx jubatus (n = 19), Eurasian lynx Lynx lynx (n = 18), caracal Caracal caracal (n = 10) and Pallas's cat Otocolobus manul (n = 8). Attacks on Artiodactyla were primarily reported for goitered gazelle Gazella subgutturosa (n = 47). Most of these attacks occurred within or adjacent to protected areas (n = 116, 73%), suggesting that free-ranging dogs are one of the most important human-associated threats to wildlife species even in protected landscapes. The impact of free-ranging dogs may be hampering conservation, and therefore we suggest some practical policy guidance for managing the impacts of free-ranging dogs on threatened species.

Detection criteria and post-field sample processing influence results and cost efficiency of occupancy-based monitoring

Optimization of occupancy-based monitoring has focused on balancing the number of sites and surveys to minimize field efforts and costs. When survey techniques require post-field processing of samples to confirm species detections, there may be opportunities to further improve efficiency. We used scat-based noninvasive genetic sampling for kit foxes (Vulpes macrotis) in Utah, USA, as a model system to assess post-field data processing strategies, evaluate the impacts of these strategies on estimates of occupancy and associations between parameters and predictors, and identify the most cost-effective approach. We identified scats with three criteria that varied in costs and reliability: (1) field-based identification (expert opinion), (2) statistical-based morphological identification, and (3) genetic-based identification (mitochondrial DNA). We also considered four novel post-field sample processing strategies that integrated statistical and genetic identifications to reduce costly genetic procedures, including (4) a combined statistical-genetic identification, (5) a genetic removal design, (6) a within-survey conditional-replicate design, and (7) a single-genetic-replicate with false-positive modeling design. We considered results based on genetic identification as the best approximation of truth and used this to evaluate the performance of alternatives. Field-based and statistical-based criteria prone to misidentification produced estimates of occupancy that were biased high (˜1.8 and 2.1 times higher than estimates without misidentifications, respectively). These criteria failed to recover associations between parameters and predictors consistent with genetic identification. The genetic removal design performed poorly, with limited detections leading to estimates that were biased high with poor precision and patterns inconsistent with genetic identification. Both statistical-genetic identification and the conditional-replicate design produced occupancy estimates comparable to genetic identification, while recovering the same model structure and associations at cost reductions of 67% and 74%, respectively. The false-positive design had the lowest cost (88% reduction) and recovered patterns consistent with genetic identification but had occupancy estimates that were ˜32% lower than estimated occupancy based on genetic identification. Our results demonstrate that careful consideration of detection criteria and post-field data processing can reduce costs without significantly altering resulting inferences. Combined with earlier guidance on sampling designs for occupancy modeling, these findings can aid managers in optimizing occupancy-based monitoring.

The effect of competing carnivores on the feeding behaviour of leopards (Panthera pardus) in an African savanna

Knowledge of competition dynamics among Africa's large carnivores is important for conservation. However, investigating carnivore behaviour in the field can be challenging especially for species that are difficult to access. Methods that enable remote collection of data provide a means of recording natural behaviour and are therefore useful for studying elusive species such as leopards (Panthera pardus). Camera traps and Global Positioning System (GPS) collars are powerful tools often used independently to study animal behaviour but where their data are combined, the interpretation of a species' behaviours is improved. In this study we used data from baited camera trap stations to investigate the feeding habits of leopards at Malilangwe Wildlife Reserve, Zimbabwe. We investigated the influence of spotted hyenas, lions and other competing leopards on the feeding duration of leopards using Generalized Linear Mixed Effects Modelling. To test the influence of competing predators on resting distances from bait sites, eight leopards were fitted with GPS collars. Results showed that leopards spent the shortest time feeding on the baits in the presence of competing male leopards compared to other predators while lion presence caused animals to rest farthest from bait sites. Interaction analysis indicated that small-bodied leopards spent significantly shorter durations feeding when spotted hyenas were present. Our findings demonstrate that competition from guild carnivores has negative impacts on the food intake of leopards, which may have implications for fitness and survival. This study provides a snapshot of the competition dynamics at bait sites which may give insight to ecosystem level interactions among large carnivores in savanna ecosystems.

Humans Dominate the Social Interaction Networks of Urban Free-Ranging Dogs in India

Research on human-animal interaction has skyrocketed in the last decade. Rapid urbanization has led scientists to investigate its impact on several species living in the vicinity of humans. Domesticated dogs (Canis lupus familiaris) are one such species that interact with humans and are also called man's best friend. However, when it comes to the free-ranging population of dogs, interactions become quite complicated. Unfortunately, studies regarding free-ranging dog-human interactions are limited even though the majority of the world's dog population is free-ranging. In this study, we observed twelve groups of free-ranging dogs in their natural habitat, the streets. We quantified their interactions at the intra (dog-dog) and interspecific (dog-human) levels. The study areas were divided into two zones, namely - intermediate and high flux, based on human activity or movement. Social network analysis revealed higher instances of interspecific than intraspecific interactions, irrespective of the human flux zones. Humans, in significantly higher occasions, initiated both positive and negative behaviors in comparison to dogs. Our findings conclude that humans are a crucial part of the interaction network of Indian free-ranging dogs.

Wolves and Dogs May Rely on Non-numerical Cues in Quantity Discrimination Tasks When Given the Choice

A wide array of species throughout the animal kingdom has shown the ability to distinguish between quantities. Aside from being important for optimal foraging decisions, this ability seems to also be of great relevance in group-living animals as it allows them to inform their decisions regarding engagement in between-group conflicts based on the size of competing groups. However, it is often unclear whether these animals rely on numerical information alone to make these decisions or whether they employ other cues that may covary with the differences in quantity. In this study, we used a touch screen paradigm to investigate the quantity discrimination abilities of two closely related group-living species, wolves and dogs, using a simultaneous visual presentation paradigm. Both species were able to successfully distinguish between stimuli of different quantities up to 32 items and ratios up to 0.80, and their results were in accordance with Weber’s law (which predicts worse performances at higher ratios). However, our controls showed that both wolves and dogs may have used continuous, non-numerical cues, such as size and shape of the stimuli, in conjunction with the numerical information to solve this task. In line with this possibility, dogs’ performance greatly exceeded that which they had shown in other numerical competence paradigms. We discuss the implications these results may have on these species’ underlying biases and numerical capabilities, as well as how our paradigm may have affected the animals’ ability to solve the task.

Human disturbance has contrasting effects on niche partitioning within carnivore communities

Among species, coexistence is driven partly by the partitioning of available resources. The mechanisms of coexistence and competition among species have been a central topic within community ecology, with particular focus on mammalian carnivore community research. However, despite growing concern regarding the impact of humans on the behaviour of species, very little is known about the effect of humans on species interactions. The aim of this review is to establish a comprehensive framework for the impacts of human disturbance on three dimensions (spatial, temporal and trophic) of niche partitioning within carnivore communities and subsequent effects on both intraguild competition and community structure. We conducted a systematic review of the literature on carnivore niche partitioning (246 studies) and extracted 46 reported effects of human disturbance. We found evidence that human disturbance impacts resource partitioning, either positively or negatively, in all three niche dimensions. The repercussions of such variations are highly heterogeneous and differ according to both the type of human disturbance and how the landscape and/or availability of resources are affected. We propose a theoretical framework of the three main outcomes for the impacts of human disturbance on intraguild competition and carnivore community structure: (i) human disturbance impedes niche partitioning, increasing intraguild competition and reducing the richness and diversity of the community; (ii) human disturbance unbalances niche partitioning and intraguild competition, affecting community stability; and (iii) human disturbance facilitates niche partitioning, decreasing intraguild competition and enriching the community. We call for better integration of the impact of humans on carnivore communities in future research on interspecific competition.

Demographic characteristics of free-roaming dogs (FRD) in rural and urban India following a photographic sight-resight survey

An understanding of the core demographic characteristics of the sub-populations of FRD is essential to effectively implement both rabies control interventions through mass vaccination of FRD, and dog population control programmes. This study compares the data obtained following photographic sight-resight surveys in rural (Shirsuphal village in west India) and urban (Municipal Corporation Panchkula in north India) locations . A total of 263 and 1408  FRD were seen at least once through 617 and 3465 sightings in the rural and urban sites, respectively. The rural location had a lower proportion of females (OR 0.5, 95% CI 0.4-0.7) and a higher proportion of poor and fair conditioned dogs (OR 1.8, 95% CI 1.3-2.3) compared to the urban setting. The rural site also had fewer active FRD (OR 0.6, 95% CI 0.5-0.7) and FRD were less likely to be sighted within 20 m of garbage points (OR 0.3, 95% CI 0.2-0.3) compared to the urban site. The demographic composition of the FRD population was found to vary within the urban location, with the odds of sighting a de-sexed dog being significantly higher in residential areas compared to other areas. The study underlines the importance of knowing the demographic composition of FRD for implementation of effective interventions against rabies. Fewer female dogs in the rural location indicate that spaying could be an effective tool for dog population management in this setting, while presence of dogs within 20 m of garbage points in urban settings highlights that an improved garbage management may reduce the carrying capacity of the urban locality resulting in smaller FRD population. It is concluded that quick and low cost surveys can generate useful demographic data for FRD in urban and rural settings which can be useful to understand the epidemiology of rabies and its control.

Variación de la abundancia relativa de perros en un gradiente de presencia humana en dos reservas privadas (Tabio, Cundinamarca)

Los perros son una problemática importante para la conservación en las diferentes áreas protegidas al poder actuar como competidores, predadores y/o trasmisores de enfermedades a la fauna silvestre. Las reservas privadas por su reducido tamaño y por estar comúnmente rodeadas de zonas rurales desde las cuales pueden entrar los perros son particularmente vulnerables a esta amenaza, lo cual causa un problema para el manejo de estas áreas de conservación. En este estudio se analiza la variación de la abundancia al interior del área conjunta de dos zonas de conservación privadas contiguas, en el municipio de Tabio-Cundinamarca. Se utilizaron los siguientes métodos para la toma de datos: 1) fototrampeo 2) recorridos por la red de caminos de ambas zonas de conservación para la búsqueda activa de rastros o perros individuales, y 3) encuestas a los dueños de perros de la zona rural circundante al área de conservación.Se encontró que la abundancia relativa de los perros en las reservas varió a lo largo de un gradiente de presencia humana y no estuvo relacionada con el tipo de cobertura vegetal. La mayor abundancia de perros estuvo entre >100 a 200 m al interior de las reservas medidos desde el límite de las mismas. Se demostró que los perros que ingresan a las reservas provienen de los hogares rurales localizados en la zona circundante a las reservas.

The role of life experience in affecting persistence: A comparative study between free-ranging dogs, pet dogs and captive pack dogs

Persistence in object manipulation has been consistently associated with problem-solving success and it is known to be affected, at the individual level, by life experience. Differences in life experiences are particularly poorly studied in the problem-solving context and mainly refer to the comparison between wild and captive animals. Dogs represent interesting study subjects, since dog populations differ widely in their life experiences. In this comparative study we investigated subjects' persistence when presenting a novel object containing food that could not be accessed (impossible task) to three dog populations with very diverse life experiences: free-ranging village dogs (in Morocco), pet dogs (in Vienna) and captive pack living dogs (Wolf Science Center-WSC). We found that pet dogs and captive dogs (WSC) were more manipulative and persistent than free-ranging dogs. The low persistence of free ranging-dogs is unlikely the effect of a lack of exposure to objects, since they are confronted with many human’ artefacts in their environment daily. Instead, we suggest that the higher persistence of captive dogs and pet dogs in comparison to free-ranging dogs might be due to their increased experience of human-mediated object interaction. This provides subjects with a socially guided experience in manipulating and interacting with objects increasing their motivation to engage in such tasks.

Assessment of bias in morphological identification of carnivore scats confirmed with molecular scatology in north-eastern Himalayan region of Pakistan

Scats are often used to study ecological parameters of carnivore species. However, field identification of carnivore scats, based on their morphological characteristics, becomes difficult if many carnivore species are distributed in the same area. We assessed error rates in morphological identification of five sympatric carnivores’ scats in north-eastern Himalayan region of Pakistan during 2013–2017. A sample of 149 scats were subjected to molecular identification using fecal DNA. We used a confusion matrix to assess different types of errors associated with carnivore scat identification. We were able to amplify DNA from 96.6% (n = 144) of scats. Based on field identification of carnivore scats, we had predicted that out of 144 scats: 11 (7.6%) scats were from common leopard, 38 (26.4%) from red fox, 29 (20.1%) from Asiatic jackal, 37 (25.7%) from yellow throated martin, 14 (9.7%) from Asian palm civet and 15 (10.4%) from small Indian civet. However, molecular identification revealed and confirmed nine were scats (6.24%) from common leopard, 40 (27.8 %) from red fox, 21 (14.6%) from Asiatic jackal, 45 (31.25%) from Asian palm civet, 12 (8.3%) scats from small Indian civet, while 11 scats (7.6%) were found from Canis lupus Spp., three (2%) from dog, one (0.7 %) scat sample from porcupine, and two (1.4%) from rhesus monkey. Misidentification rate was highest for Asian palm civet (25.7%), followed by red fox (11.1%) and Asiatic jackal (9.7%) but least for common leopard scats (4.2%). The results specific to our study area concur with previous studies that have recommended that carnivore monitoring programs utilize molecular identification of predator scats. Using only morphological identification of scats can be misleading and may result in wrong management decisions.

Anthropogenic Food Subsidy to a Commensal Carnivore: The Value and Supply of Human Faeces in the Diet of Free-Ranging Dogs

Simple Summary

Free-ranging dog populations are growing worldwide, posing threats to human health and wildlife conservation. Dog population management requires a better understanding of the supply and quality of human-derived food. We studied the diet of free-ranging dogs in a remote area of Zimbabwe to explore the relationships between human waste, dog condition, and fertility, with a focus on the value of human faeces. We found that mammal remains, ‘sadza’ (maize porridge, the human staple) and human faeces were the most important food items, and unlike other items, faeces and sadza were consistently available. Nutritional analysis showed that human faeces was comparatively high in protein and energy content, exceeding that of sadza, and equivalent to mammal remains. Adult female dog condition was good throughout the year, indicating a diet sufficient to maintain fertility, and dogs largely fed alone, suggesting that food was abundant. We conclude that the lack of sanitation allows an important food subsidy to free-ranging dogs, but improved sanitation is unlikely to limit population growth as long as alternative human waste is available. Reproductive control by owners is more likely to reduce fertility rates.

Abstract

As the global population of free-ranging domestic dogs grows, there is increasing concern about impacts on human health and wildlife conservation. Effective management of dog populations requires reliable information on their diet, feeding behavior, and social ecology. Free-ranging dogs are reliant on humans, but anthropogenic food subsidies, particularly human faeces (i.e., coprophagy) have not previously been fully quantified. In this study we assess the contributions of different food types to the diet, and their influences on the social behaviour of free-ranging dogs in communal lands of rural Zimbabwe, with a focus on coprophagy. Free-ranging dog diets, body condition, and sociology were studied amongst 72 dogs over 18 months using scat analysis and direct observations. Human faeces constituted the fourth most common item in scats (56% occurrence) and contributed 21% by mass to the observed diet. Human faeces represented a valuable resource because relative to other food items it was consistently available, and of higher nutritional value than ‘sadza’ (maize porridge, the human staple and primary human-derived food), yielding 18.7% crude protein and 18.7 KJ/kg gross energy, compared to 8.3% and 18.5 KJ/kg for sadza, respectively. Human faeces had protein and energy values equivalent to mammal remains, another important food item. Dog condition was generally good, with 64% of adult females and 74% of adult males in the highest two body condition scores (on a five point scale), suggesting a plentiful and high quality food supply. Dogs largely fed alone, perhaps as a consequence of the small, inert, and spatially dispersed items that comprise their diet, and its abundance. We discuss the relationships between sanitation, human development, the supply of human faeces, female dog fertility, and population control.

Free-ranging dogs prefer petting over food in repeated interactions with unfamiliar humans

Dogs (Canis lupus familiaris) are the first species to have been domesticated and, unlike other domesticated species, they have developed a special bond with their owners. The ability to respond to human gestures and language, and the hypersocial behaviours of dogs are considered key factors that have led them to become man's best friend. Free-ranging dogs provide an excellent model system for understanding the dog-human relationship in various social contexts. In India, free-ranging dogs occur in all possible human habitations. They scavenge among garbage, beg for food from humans, give birth in dens close to human habitations, and establish social bonds with people. However, there is ample dog-human conflict on the streets, leading to morbidity and mortality of dogs. Hence, the ability to assess an unfamiliar human before establishing physical contact could be adaptive for dogs, especially in the urban environment. We tested a total of 103 adult dogs to investigate their response to immediate social and long-term food and social rewards. The dogs were provided a choice of obtaining food either from an experimenter's hand or the ground. The dogs avoided making physical contact with the unfamiliar human. While immediate social reward was not effective in changing this response, the long-term test showed a strong effect of social contact. Our results revealed that these dogs tend to build trust based on affection, not food. This study provides significant insights into the dynamics of dog-human interactions on the streets and subsequent changes in behaviour of dogs through the process of learning.

Free-ranging dogs show age related plasticity in their ability to follow human pointing

Differences in pet dogs' and captive wolves' ability to follow human communicative intents have led to the proposition of several hypotheses regarding the possession and development of social cognitive skills in dogs. It is possible that the social cognitive abilities of pet dogs are induced by indirect conditioning through living with humans, and studying free-ranging dogs can provide deeper insights into differentiating between innate abilities and conditioning in dogs. Free-ranging dogs are mostly scavengers, indirectly depending on humans for their sustenance. Humans can act both as food providers and as threats to these dogs, and thus understanding human gestures can be a survival need for the free-ranging dogs. We tested the responsiveness of such dogs in urban areas toward simple human pointing cues using dynamic proximal points. Our experiment showed that pups readily follow proximal pointing and exhibit weaker avoidance to humans, but stop doing so at the later stages of development. While juveniles showed frequent and prolonged gaze alternations, only adults adjusted their behaviour based on the reliability of the human experimenter after being rewarded. Thus free-ranging dogs show a tendency to respond to human pointing gestures, with a certain level of behavioural plasticity that allows learning from ontogenic experience.

The influence of social relationship on food tolerance in wolves and dogs

ABSTRACT

Food sharing is relatively widespread across the animal kingdom, but research into the socio-ecological factors affecting this activity has predominantly focused on primates. These studies do suggest though that food tolerance is linked to the social relationship with potential partners. Therefore, the current study aimed to assess the social factors which influence food tolerance in two canids: wolves and dogs. We presented wolves and dogs with two paradigms: dyadic tolerance tests and group carcass feedings. In the dyadic setting, the affiliative relationship with a partner was the most important factor, with a strong bond promoting more sharing in both species. In the group setting, however, rank was the primary factor determining feeding behavior. Although the dominant individuals of both species defended the carcass more than subordinates, in the dogs, the subordinates mostly stayed away from the resource and the most dominant individual monopolized the food. In the wolves, the subordinates spent as much time as dominant individuals in proximity to, and feeding from, the carcass. Furthermore, subordinate wolves were more able to use persistence strategies than the dogs were. Feeding interactions in the wolves, but not dogs, were also modulated by whether the carcass was on the ground or hanging from a tree. Overall, the social relationship with a partner is important in food distribution in wolves and dogs, but the precise effects are dependent on species and feeding context. We consider how the different socio-ecologies of the two species may be linked to these findings.

SIGNIFICANCE STATEMENT

Despite the fact that food sharing is relatively widespread in the animal kingdom, the specific factors underlying whether an animal will share with a specific individual are little understood. When it comes to decisions about food sharing in wolves and dogs, friendship is the deciding factor if it is just two of you, but in a bigger group rank position decides your access to the spoils. What is more, it seems that rank positioning is even more important in dogs than wolves as dominant dogs keep the food for themselves while each wolf pack member has a chance to eat. This is the first evidence that the importance of the social relationship in food sharing is dependent on the feeding context in canids.

Do females use their sexual status to gain resource access? Investigating food-for-sex in wolves and dogs

While food sharing among related individuals can be explained by kin selection, food sharing between unrelated individuals has been more of an evolutionary puzzle. The food-for-sex hypothesis provides an explanation for the occurrence of food sharing among nonkin. However, little is known about the socio-ecological factors that can promote such a commodity exchange. A species mating system is a factor potentially influencing food-for-sex patterns of behavior. Here, we compared wolves, which form pair-bonds, with dogs, which are typically promiscuous in free-ranging contexts, to investigate the effect of reproductive stages on the behavior around a food source in 2 different contexts. Furthermore, we considered the roles of both the males and the females in the potential food-for-sex exchange. Results indicate that in both species and for both sexes the breeding period promotes decreased aggression. Additionally, females were more persistent in their attempts to access the food and were able to monopolize the resource more when in heat as compared to outside the breeding period. Finally, in dogs, but not wolves, females spent more time in proximity to the male's bone and had a shorter latency to start eating it when in heat. Overall, this study demonstrates that the food-for-sex hypothesis plays a part in intersexual food sharing in canids, and highlights the role of females in the interaction. These effects were especially the case in dogs, suggesting a potential effect of mating system on food-for-sex responses.

Practice makes perfect: familiarity of task determines success in solvable tasks for free-ranging dogs (Canis lupus familiaris)

Domestic dogs' (Canis lupus familiaris) socio-cognitive faculties have made them highly sensitive to human social cues. While dogs often excel at understanding human communicative gestures, they perform comparatively poorly in problem-solving and physical reasoning tasks. This difference in their behaviour could be due to the lifestyle and intense socialization, where problem solving and physical cognition are less important than social cognition. Free-ranging dogs live in human-dominated environments, not under human supervision and are less socialized. Being scavengers, they often encounter challenges where problem solving is required in order to get access to food. We tested Indian street dogs in familiar and unfamiliar independent solvable tasks and quantified their persistence and dependence on a novel human experimenter, in addition to their success in solving a task. Our results indicate that free-ranging dogs succeeded and persisted more in the familiar task as compared to the unfamiliar one. They showed negligible amount of human dependence in the familiar task, but showed prolonged gazing and considerable begging behaviour to the human experimenter in the context of the unfamiliar task. Cognitive abilities of free-ranging dogs thus play a pivotal role in determining task-associated behaviours based on familiarity. In addition to that, these dogs inherently tend to socialize with and depend on humans, even if they are strangers. Our results also illustrate free-ranging dogs' low competence at physical cognitive tasks.

Motivational Factors Underlying Problem Solving: Comparing Wolf and Dog Puppies' Explorative and Neophobic Behaviors at 5, 6, and 8 Weeks of Age

Background: Wolves have been shown to be better in independent problem-solving tasks than dogs, however it is unclear whether cognitive or motivational factors underlie such differences. In a number of species problem solving has been linked to both persistence in exploration and neophobia, suggesting both these aspects may underlie dog-wolf differences in problem solving. Indeed adult wolves have been shown to be more likely to approach a novel object and more persistent in their investigation of it, but also slower in making contact with it and more fearful of it than dogs. Methods: In the current study we investigated potential differences in equally-raised dogs' and wolves' explorative and neophobic behaviors in a novel environment and with novel objects at 5, 6, and 8 weeks of age. Results: Results showed that wolves were more persistent in exploring both the environment and the objects than dogs, and this was the case at all ages. There were no differences in the frequency of fear-related behaviors and time spent in proximity to humans. Stress-related behaviors were similarly expressed at 5 and 6 weeks, although wolves showed a higher frequency of such behaviors at 8 weeks. Discussion: Overall, results with puppies confirm those with adult animals: wolves appear to be more explorative than dogs. Such motivational differences need to be taken into account when comparing dogs and wolves in cognitive tasks.

Exploring Differences in Dogs' and Wolves' Preference for Risk in a Foraging Task

Both human and non-humans species face decisions in their daily lives which may entail taking risks. At the individual level, a propensity for risk-taking has been shown to be positively correlated with explorative tendencies, whereas, at the species level a more variable and less stable feeding ecology has been associated with a greater preference for risky choices. In the current study we compared two closely related species; wolves and dogs, which differ significantly in their feeding ecology and their explorative tendencies. Wolves depend on hunting for survival with a success rate of between 15 and 50%, whereas free-ranging dogs (which make up 80% of the world dog population), are largely scavengers specialized on human produce (i.e., a more geographically and temporally stable resource). Here, we used a foraging paradigm, which allowed subjects to choose between a guaranteed less preferred food vs. a more preferred food, which was however, delivered only 50% of the time (a stone being delivered the rest of time). We compared identically raised adult wolves and dogs and found that in line with the differing feeding ecologies of the two species and their explorative tendencies, wolves were more risk prone than dogs.

Denning habits of free-ranging dogs reveal preference for human proximity

Dens are crucial in the early development of many mammals, making den site selection an important component of parental care in such species. Resource availability and shelter from predators primarily govern den selection. Species inhabiting human-dominated landscapes typically den away from human disturbance, often shifting dens to avoid humans during the early life of their young. Domesticated dogs have evolved in human proximity over centuries, being bred and reared in human homes for generations. While pets rely on their owners for shelter and care, free-ranging dogs roam uncared, and typically whelp in dens. We conducted a study on 148 free-ranging dog dens in India to understand their denning habits. Distance from resources influenced den choice, but anthropogenic disturbance did not. Dens were found in areas of high human activity, and begging from humans was preferred over scavenging. A study on 15 pregnant females revealed that females actively searched for denning sites, rejecting several intermediate ones before selecting the final den. We propose that the obvious preference of dogs for denning close to humans is a behavioural adaptation that helps them to survive in the urban landscape, in spite of the high human induced mortality during the early life of pups.

High early life mortality in free-ranging dogs is largely influenced by humans

Free-ranging dogs are a ubiquitous part of human habitations in many developing countries, leading a life of scavengers dependent on human wastes for survival. The effective management of free-ranging dogs calls for understanding of their population dynamics. Life expectancy at birth and early life mortality are important factors that shape life-histories of mammals. We carried out a five year-long census based study in seven locations of West Bengal, India, to understand the pattern of population growth and factors affecting early life mortality in free-ranging dogs. We observed high rates of mortality, with only ~19% of the 364 pups from 95 observed litters surviving till the reproductive age; 63% of total mortality being human influenced. While living near people increases resource availability for dogs, it also has deep adverse impacts on their population growth, making the dog-human relationship on streets highly complex.

When Love Is in the Air: Understanding Why Dogs Tend to Mate when It Rains

Seasonality of reproduction is observed in many species of organisms, across taxa, and is influenced by both biotic and abiotic factors. While such seasonality is easy to understand in temperate species exposed to extreme climates, it is more difficult to explain in the tropics. In many tropical species offspring are born during the season of high precipitation, which also coincides with high resource availability. Interestingly, in India, free-ranging dogs seem to mate, and not whelp, when it rains—an observation that cannot be explained by the resource abundance hypothesis. We carried out an extensive study to identify the mating seasons of free-ranging dogs, and observed a strong correlation between both the incidence and frequency of mating related behaviours of dogs, and precipitation levels. There are two clear mating seasons, of which the primary mating season coincides with the monsoon (rainy season) and the secondary mating season coincides with the nor’westerlies in this part of India. We speculate that this strong correlation is an effect of chemistry, rather than biology. While male dogs can mate round the year, females come into estrous seasonally. In the urban environment, dogs are exposed to a lot of olfactory noise, which can dilute the signal present in sex pheromones of the females in heat. A shower leads to increased humidity and reduced temperature of the air, leading to intensification of pheromone signals that trigger a sexual response in the dogs.

Human-related factors regulate the presence of domestic dogs in protected areas

The presence of domestic species such as dogs Canis familiaris in protected areas can cause problems for native species as a result of competition, predation and disease transmission. To improve our ability to design effective control policies we investigated the factors affecting detection of dog tracks in a Mediterranean national park.

We investigated the presence of dogs across 69 2 × 2 km grid squares in Doñana National Park in south-west Spain and used logistic regression models to analyse the associated environmental and human constraints. We did not detect dogs in areas away from the edges of the national park close to human settlements (track census effort > 470 km) and the detection of dog tracks was correlated with human presence. We conclude that domestic dogs occasionally enter the Park from the surrounding area and are a direct threat to wildlife at the edges of the Park. Management actions to reduce the effects of domestic dogs in protected areas where feral dog populations are not established should focus on the spatial extent of local settlements, regulation and awareness-raising to encourage responsible dog-ownership, and control measures such as removing un-owned dogs from boundaries and areas close to human dwellings, and forbidding unleashed dogs in public facilities.

Role of India's wildlife in the emergence and re-emergence of zoonotic pathogens, risk factors and public health implications

Evolving land use practices have led to an increase in interactions at the human/wildlife interface. The presence and poor knowledge of zoonotic pathogens in India's wildlife and the occurrence of enormous human populations interfacing with, and critically linked to, forest ecosystems warrant attention. Factors such as diverse migratory bird populations, climate change, expanding human population and shrinking wildlife habitats play a significant role in the emergence and re-emergence of zoonotic pathogens from India's wildlife. The introduction of a novel Kyasanur forest disease virus (family flaviviridae) into human populations in 1957 and subsequent occurrence of seasonal outbreaks illustrate the key role that India's wild animals play in the emergence and reemergence of zoonotic pathogens. Other high priority zoonotic diseases of wildlife origin which could affect both livestock and humans include influenza, Nipah, Japanese encephalitis, rabies, plague, leptospirosis, anthrax and leishmaniasis. Continuous monitoring of India's extensively diverse and dispersed wildlife is challenging, but their use as indicators should facilitate efficient and rapid disease-outbreak response across the region and occasionally the globe. Defining and prioritizing research on zoonotic pathogens in wildlife are essential, particularly in a multidisciplinary one-world one-health approach which includes human and veterinary medical studies at the wildlife-livestock-human interfaces. This review indicates that wild animals play an important role in the emergence and re-emergence of zoonotic pathogens and provides brief summaries of the zoonotic diseases that have occurred in wild animals in India.