Confronting the Challenge: Integrated Approaches to Mitigate the Impact of Free-Ranging Dogs on Wildlife Conservation

Abstract

Free-ranging dogs (Canis lupus familiaris) pose a significant but often overlooked threat to wildlife populations and global conservation efforts while also having the potential to contribute positively to conservation initiatives. As generalist predators and scavengers, these adaptable animals can lead to biodiversity loss through predation, disease transmission, competition, and behavioral disruption of native species. This review synthesizes global studies on their ecological impact, highlighting notable cases of predation on endangered species, such as the markhor (Capra falconeri cashmiriensis) in Pakistan and elephant seals (Mirounga angustirostris) in Mexico, as well as the spread of zoonotic diseases like Echinococcus spp. and canine distemper. A growing concern is hybridization between free-ranging dogs and wild canids. Such genetic mixing can erode local adaptations, reduce genetic purity, and undermine conservation efforts for wild canid populations. Current management strategies—including lethal control, trap–neuter–release, and vaccination—have produced mixed results and face challenges related to data limitations, regional variability, and cultural barriers. This review advocates for integrated, context-specific management approaches that consider ecological, social, and economic dimensions. Future research should prioritize standardized definitions and data collection, long-term evaluation of intervention effectiveness, and the socio-economic drivers of dog–wildlife interactions to develop sustainable solutions for mitigating the multifaceted threats imposed by free-ranging dogs to global diversity.

1. Introduction

The relationship between humans and dogs (Canis lupus familiaris) is one of the oldest and most influential interspecies partnerships in history. Archaeological and genetic evidence suggests that dogs were domesticated from wolves (Canis lupus) at least 15,000 years ago and possibly much earlier, with the earliest dogs serving as hunting aides, guards, and companions across diverse human societies [1,2]. Over millennia, dogs have accompanied humans as they migrated, farmed, traded, and built cities, becoming the most widespread and adaptable domestic animal on the planet.

Initially, the close bond between humans and dogs was maintained through direct control—dogs were bred, fed, and managed for specific purposes. However, as human populations grew and societies urbanized, this control weakened. The rise of large urban centers, agricultural expansion, colonization, and global trade led to the movement and introduction of dogs into ecosystems far beyond their original range [3,4]. In many cases, dogs were deliberately released or abandoned, while in others, they escaped or formed free-ranging populations. Today, it is estimated that there are between 700 million and 1 billion dogs worldwide, including both owned and unowned individuals living in homes and shelters or roaming freely in urban, rural, and wild environments [5].

The consequences of this loss of control have become increasingly apparent. Free-ranging dogs (which include feral, stray, and unowned individuals), being highly adaptable generalist predators and scavengers, now thrive in a wide variety of habitats—from remote wilderness and protected areas to agricultural landscapes and bustling cities [1,5]. Their ecological impact is profound and multifaceted: dogs prey on native wildlife, compete with indigenous carnivores, transmit diseases, hybridize with wild canids [6], and cause behavioral disturbances among native species [7,8]. Unlike many other invasive species, dogs are often overlooked in conservation planning, particularly in low- and middle-income countries where data and management resources are limited [9].

The historical introduction of dogs into new environments has repeatedly resulted in dramatic ecological shifts. For example, on the Galápagos Islands, a small founding group of dogs introduced by humans gave rise to a feral population that diverged genetically and morphologically from its mainland ancestors, with significant consequences for local wildlife [10,11]. In Australia, hybridization between dingoes (Canis lupus dingo) and free-ranging dogs has blurred taxonomic boundaries and complicated conservation efforts, altering the ecological roles of these apex predators [12,13]. Similar patterns are seen worldwide, as dogs introduced into ecosystems where native species lack evolutionary defenses against canid predators often become a leading cause of wildlife decline.

In the modern era, rapid urbanization, land-use change, tourism, and ineffective animal control policies have further fueled the expansion of free-ranging dog populations [14]. This anthropogenic spread has brought dogs into increasing contact with vulnerable wildlife, undermining biodiversity conservation efforts through direct predation, disease transmission, competition, and disruption of conservation programs—particularly in and around protected areas [15,16]. Urban and peri-urban spaces, once considered separate from natural habitats, are now recognized as hotspots for human–wildlife conflict, with free-ranging dogs playing a key role in this emerging challenge.

Despite these threats, there are also examples of innovative management strategies that leverage the unique relationship between humans and dogs—for instance, the use of guardian dogs to protect livestock and reduce human–wildlife conflict [1,17]. However, the overall picture remains one of escalating conflict and ecological disruption, necessitating urgent, context-specific interventions that address ecological, public health, and socio-economic dimensions. This review focuses on the latter subject and presents information regarding the consequences of free-ranging dogs in the natural environment. Understanding the historical trajectory of dog–human relationships, the loss of population control, and the resulting ecological conflicts is essential for developing effective, culturally sensitive, and ecologically sound strategies to safeguard biodiversity in a rapidly changing world.

In seeking to accurately interpret and compare the findings of the studies included in this review, it became evident that there is considerable inconsistency in the terminology used to describe different categories of domestic dogs. This lack of standardized definitions hampers the ability to synthesize data across studies and complicates efforts to evaluate management strategies. Therefore, the following definitions are proposed to clarify distinctions and promote consistency in future research:

• Feral dogs are domestic dogs that have reverted to a wild state, living entirely independently of humans. They often form packs and subsist by hunting or scavenging, with no direct reliance on people for food, shelter, or care.
• Stray dogs are those that have been lost or abandoned by their owners and now live in human-dominated environments, such as urban or peri-urban areas. While not owned, they may still interact with people, seek food from humans, and, in some cases, may be re-adopted or return to domesticated life.
• Street dogs specifically refers to unowned dogs that inhabit urban areas and survive primarily by scavenging for food or relying on indirect support from human settlements. While they may tolerate human presence, they typically lack a primary caregiver or owner.
• Free-ranging dogs is an umbrella term that includes any dog not confined to a household or property and allowed to move freely through the environment. This category encompasses feral, stray, and street dogs, as well as owned dogs that are permitted to roam unsupervised. Hence, in this review, I have chosen this term to represent all dogs, whether solitary or in packs, as free-ranging.
• Pet dogs are companion animals entirely dependent on humans for food, shelter, and veterinary care. They live within households and are generally confined and supervised by their owners.
• Shepherd and hunting dogs are working animals kept for specific utilitarian purposes, such as herding livestock or assisting in hunting. These dogs are typically under the direct supervision and control of their owners and are trained to perform specific tasks.

Standardizing these definitions across studies will enhance clarity, facilitate meta-analyses, and improve the effectiveness of dog population management and conservation planning. In this review, I have focused specifically on research about free-ranging dogs.

2. Methods

A comprehensive literature search was conducted to identify peer-reviewed articles, reviews, and reports on the ecological impacts of free-ranging dogs on wildlife and conservation efforts worldwide. The search was performed between 1990 and 2025. Multiple electronic databases were systematically searched, including Web of Science, Scopus, PubMed, Google Scholar, ScienceDirect, and CAB Abstracts [18]. In addition to these databases, reference lists of key articles were examined (backward chaining) and citation tracking of influential studies (forward chaining) was performed to ensure thorough coverage of the relevant literature [19].

The search strategy was designed to be inclusive, combining controlled vocabulary terms, such as MeSH terms in PubMed, with free-text keywords. Boolean operators (AND, OR, and NOT), truncation, and phrase searching were employed to ensure the retrieval of all pertinent studies. Primary search terms included variations of “feral dog”, “free-ranging dog”, “stray dog”, and “domestic dog”, combined with terms related to wildlife, biodiversity, conservation, and ecosystem impacts. Additional keywords focused on specific ecological effects, including predation, disease transmission, competition, hybridization, and behavioral disturbance. Spatial and contextual terms such as “urban”, “rural”, “protected area”, and “national park” were also incorporated. Studies were included if they reported empirical data or reviews on the ecological impacts of free-ranging dogs on wildlife or conservation programs, were published in English between 1990 and 2025, and focused on terrestrial ecosystems. Articles were excluded if they addressed only dog health or behavior unrelated to wildlife or were unavailable in full text. Relevant data were extracted from each included study, capturing information such as the study location, affected species, nature of dog impacts (e.g., predation or disease), and management interventions.

3. Results

The volume of scientific research on wildlife–dog interactions has grown dramatically over the past three decades, as evidenced by bibliometric data (n = 37,760). For convenience, I have grouped the publications into pentads (five-year periods). In the early 1990s, the number of scientific publications was modest, with 1050 (2.8%) articles published between 1990 and 1995 and 1390 (3.7%) between 1996 and 2000 (Figure 1). This output began to accelerate in the 21st century, reaching 2620 (6.9%) publications between 2001 and 2005 and 4210 (11.1%) between 2006 and 2010. This trend continued upward, with 6300 (16.7%) publications between 2011 and 2015 and a significant surge to 13,900 (36.8%) publications from 2016 to 2020. Although there was a slight decline in the most recent period, the number of publications remained high, with 8290 (22.0%) articles between 2021 and 2025. Overall, the data reveal a clear and exponential increase in research attention to the ecological impacts of free-ranging dogs on wildlife, particularly over the last decade, reflecting a growing global concern and increased scientific engagement with this issue.

Bibliometric analyses and systematic reviews [20,21] have documented a steady rise in the number of peer-reviewed articles on this topic, particularly after 2010. This growth has been fueled by advances in camera trapping, GPS tracking, and molecular ecology, which have enabled more rigorous documentation of dog–wildlife interactions worldwide. The trend is especially pronounced in regions experiencing rapid urbanization or where free-ranging dogs pose a threat to endangered species, such as in India, Latin America, and parts of Africa and Europe.

In recent years (2015–2025), research has diversified to include not only predation and direct mortality but also disease transmission, competition, behavioral changes in wildlife, and the socio-ecological dimensions of dog management. The literature now includes large-scale reviews, regional syntheses, and focused studies on mitigation and management strategies. Despite this growth, experts note that the research volume still lags behind that of other invasive species (such as cats Felis catus; [22]), and significant data gaps remain, particularly in low- and middle-income countries.

Although many of the papers overlap in the geographical contexts of their descriptions of feral and stray dog interactions with wildlife, I did not attempt to separate them geospatially. The distribution of scientific publications on this topic shows that research activity is robust across most continents. North America leads with 30,600 publications, followed closely by South America (29,100), Central America (29,000), and Europe (29,000). Asia (27,700), Africa (27,600), and the Middle East (26,800) also contribute substantial numbers of studies. In contrast, the Sub-Antarctic (19,200) and Arctic Circle (22,300) regions have the fewest publications. Notably, at the country level, India stands out with 23,100 publications, second only to Australia, highlighting the exceptionally high level of research interest in regions where human–dog–wildlife interactions are frequent and biodiversity is at risk. This pattern underscores the global scope of concern regarding the ecological impacts of free-ranging dogs.

3.1. Predation

The impact of free-ranging dogs on wildlife populations is a pressing issue that has been thoroughly documented in various ecosystems worldwide. These effects can be particularly disastrous, especially for endangered species and sensitive ecosystems that are already struggling with habitat loss, climate change, and human activity.

In Chitral Gol National Park in Pakistan, free-ranging dogs were responsible for the deaths of hundreds of critically endangered markhor goats (Capra falconeri cashmiriensis) between 2006 and 2020. These dogs typically target young or weak markhor, hunting and harassing them, which severely impacts the population’s recovery. This highlights the threat non-native predators pose to vulnerable wildlife, exacerbating biodiversity loss in the region [15].

Researchers documented that in the presence of free-ranging dogs, no mountain gazelle (Gazella gazella) fawns survived after six months in experimental enclosures in Israel, compared to sites without dogs where fawn survival was significantly higher [23]. This study demonstrates that free-ranging dogs can severely reduce recruitment in native ungulate populations through predation and harassment, impacting the persistence of vulnerable wildlife.

On Isla de Cedros in Mexico, free-ranging dogs have had a substantial impact on local elephant seal (Mirounga angustirostris) populations. Between the years covered in the study, free-ranging dogs were responsible for the predation of approximately 150 seal pups and 30 adults. This predation led to significant disruption of breeding colonies and is estimated to have contributed to a 20% decline in the local elephant seal population. These effects are compounded by other threats, such as climate change and human interference, illustrating how free-ranging dogs can adapt to remote environments and severely disrupt ecological relationships even within protected areas [16].

In southern Turkey, research using camera traps and GPS tracking has demonstrated that the presence of free-ranging dogs leads to notable behavioral changes in wildlife, including fallow deer (Dama dama), wild boar (Sus scrofa), and red foxes (Vulpes vulpes). The study found that fallow deer reduced their use of open areas by 48% and shifted their activity to more nocturnal hours in regions with high free-ranging dog activity. Wild boar and red foxes also altered their movement patterns, avoiding core areas frequented by dogs and increasing their travel distances by up to 32% [24]. These behavioral shifts limit access to key resources such as food and shelter, and the persistent risk of dog encounters is likely to induce chronic stress, which can negatively affect reproduction and survival rates in these wildlife populations.

In Italy, citizen science data reveal that free-ranging dogs prey on all native ungulate species, as well as colonial ground-nesting birds, and are a significant factor in the failure of roe (Capreolus capreolus) and red deer (Cervus elaphus) translocation projects, accounting for over 25% of total losses. Surveys estimate that nearly 1.2 million of Italy’s more than 6 million dogs are free-ranging at least part of the time. These dogs have also been reported attacking a wide range of wildlife, including threatened species like the European polecat (Mustela putorius) and crested porcupine (Hystrix cristata), and are a key obstacle to the recolonization of central and southern Italy by native fauna [25,26]

In Madagascar, invasive free-ranging dogs have contributed to the decline of the fosa (Cryptoprocta ferox), the island’s largest native carnivore and a key predator in its ecosystem. Field studies have documented that in some regions, up to 40% of fosa mortalities are directly attributable to attacks or competition from feral dogs [27,28]. Additionally, camera trap surveys have shown that the presence of dogs reduces fosa detection rates by as much as 36%, indicating strong spatial avoidance and displacement [28]. This introduction of non-native predators like dogs is especially concerning in Madagascar, where native, endemic species have not evolved defenses against such threats, further endangering the fosa and destabilizing the island’s unique ecosystems [28,29].

Free-ranging dogs pose a severe and widespread threat to India’s wildlife, including endangered species such as the blackbuck (Antilope cervicapra) and the snow leopard (Panthera uncia). In western Haryana, free-ranging dogs have emerged as the primary predators of blackbuck and nilgai (Bluebull; Boselaphus tragocamelus) populations [30]. Data from the Haryana State Forest Department indicate that between January 2016 and May 2020, free-ranging dogs killed 361 blackbucks, 1641 nilgai, 25 peafowl (Pavo cristatus), 29 chinkara (Gazella bennettii), and 35 monkeys (Semnopithecus entellus) in the Hisar division alone [31]. Field studies in the Badopal area of Fatehabad and Mangali-Rawatkhera in Hisar have documented that free-ranging dog predation—especially by packs—accounts for the vast majority of blackbuck mortalities, with up to 93% of deaths in some regions attributed to feral dogs, particularly targeting fawns during the breeding season [32]. In certain localities, such as Kadi in Gujarat, free-ranging dog predation has been implicated in the loss of up to 80% of local blackbuck populations. The threat extends beyond Haryana and Gujarat. Across India, free-ranging dogs have been recorded preying on at least 80 native wildlife species, including the Great Indian Bustard (Ardeotis nigriceps) and black-necked crane (Grus nigricollis). Dog predation reduced bustard egg survival rates by 60–70%. In the Indian Himalayas, free-ranging dogs are found at elevations of 5000 to 7000 m, overlapping with snow leopard habitats and competing for prey [9]. They have been observed chasing and killing livestock and wild ungulates, and their presence increases the risk of disease transmission to native carnivores [33].

Free-ranging dogs have a significant ecological impact in urban areas such as Mexico City, not just in remote or wilderness settings. In the Reserva Ecológica del Pedregal de San Ángel (REPSA), a natural area in southern Mexico City, free-ranging dogs have been documented preying on native wildlife: wild mammals were the most frequent prey category found in dog diets, with a frequency of occurrence of 62.3% and representing 40.3% of the total prey biomass, including several endemic and protected species. Notably, the presence of dogs has been linked to the displacement of native predators such as gray foxes (Urocyon cinereoargenteus) and bobcats (Lynx rufus escuinapae), whose remains were also found in dog scats, suggesting both predation and competition [34,35].

Across Europe, free-ranging dogs have become a significant ecological problem, impacting both wildlife populations and conservation initiatives [7]. Packs of free-ranging dogs have been documented preying on a wide range of native species, including red and roe deer, wild boar, rabbits (Oryctolagus cuniculus), and even Europe’s largest mammal, the European bison (Bison bonasus). Camera trap footage from the Southern Carpathians of Romania documented a pack of 15 free-ranging dogs attacking and killing individuals from a reintroduced bison herd, confirming both predation and scavenging behavior [36]. These dogs, now the dominant predators in some areas, compete directly with native carnivores such as wolves, reducing the prey base and further threatening already vulnerable populations [37]. Studies in Portugal and other parts of Europe have shown that free-ranging dogs are responsible for the majority of confirmed livestock attacks (62% in some regions), and their diets overlap extensively with those of wolves, highlighting their role as both competitors and disruptors of trophic dynamics [37].

A recent nationwide online survey in Argentina revealed the extensive and pervasive impact of dog attacks on native wildlife, affecting every ecoregion of the country and a striking diversity of species [38]. The survey, which collected 1126 verified reports from 704 respondents, documented attacks on 149 different wildlife species, including 74 mammals, 54 birds, 16 reptiles, three amphibians, and two fish. Notably, 25% of the affected species are considered threatened at the national or global level and have been reported from all 18 Argentine ecoregions. The data showed that 89% of respondents had personally observed at least one dog attack on wildlife and 41% had witnessed more than five such events. The most frequently attacked species included the southern three-banded armadillo (Tolypeutes matacus), the pampas fox (Lycalopex gymnocercus), and the guanaco (Lama guanicoe). Cases also involved rare and endangered species, such as the huemul deer (Hippocamelus bisulcus) and the Andean cat (Leopardus jacobita). The survey further indicated that both rural and urban areas are affected, with 32% of attacks occurring in or near cities and towns.

3.2. Disease Transmission

Free-ranging dogs often live near wildlife, creating opportunities for disease transmission, both directly through physical contact and indirectly through environmental contamination, such as fecal shedding or saliva. As opportunistic feeders and scavengers, dogs can link wildlife, livestock, and human populations, facilitating the spread of diseases across species.

In Argentina and Mexico, research has shown the presence of Echinococcus species in free-ranging dogs. Echinococcus granulosus specifically causes hydatid disease, a parasitic infection that affects various organs, including the liver and lungs, in both humans and wildlife. Transmission often occurs through environmental contamination by infected dog feces, which may be ingested by herbivorous wildlife or predators, thereby spreading this debilitating disease [39]. Free-ranging dogs in these regions are considered primary vectors for this disease, raising concerns about their impact on endangered species and the overall health of ecosystems.

One of the most dramatic examples of the impact of dogs on public health is the history of Cystic echinococcosis in Iceland, where, in the 19th century, nearly every fifth Icelander was infected with this severe parasitic disease, primarily due to the transmission cycle between sheep and dogs [40,41]. To combat this, Iceland implemented a comprehensive response: the government introduced taxes on all dogs, with higher taxes for non-essential dogs, and banned keeping dogs without permission, effectively reducing the dog population. Outbreaks of canine distemper in the late 1800s further diminished dog numbers. Authorities also enforced strict measures to prevent dogs from accessing raw offal, required burning of infected animal organs, promoted caution—especially among children—in handling dogs, and mandated annual anthelmintic treatment of all dogs after the slaughtering season [42]. These coordinated efforts, combined with education and changes in livestock management, led to the virtual elimination of echinococcosis in Iceland by the 20th century, making it a model for successful disease control [40,41,42,43].

In the United States, particularly in Texas and New Mexico, free-ranging dog populations have been identified as important reservoirs for Trypanosoma cruzi, the etiological agent of Chagas disease. Studies have shown that the prevalence of T. cruzi infection in free-ranging dogs in Texas can range from 8% to 36%, depending on the population and location [44,45]. This protozoan parasite, primarily transmitted by triatomine bugs (also known as kissing bugs), can infect a wide range of mammalian hosts, including wildlife and humans [46]. The presence of Trypanosoma cruzi in feral dogs not only poses a direct risk to domestic animals and humans but also increases the likelihood of spillover events that could negatively impact local wildlife populations, especially in areas where free-ranging dogs, wildlife, and human settlements overlap [45,46,47,48].

Other zoonotic diseases transmitted by feral dogs include Bartonella, Ehrlichia, and Mycoplasma, all of which have been identified in feral dog populations in Mexico City. For example, Camacho-Giles et al. [35] found that 13% of sampled feral dogs in the Reserva Ecológica del Pedregal de San Ángel tested positive for Bartonella spp., a bacterium known to cause endocarditis and chronic joint inflammation in both animals and humans. The same study reported that 8% of dogs were positive for Ehrlichia canis, the agent of canine ehrlichiosis, which can spill over to wild canids and cause fever, anemia, and bleeding disorders. Additionally, Mycoplasma haemocanis was identified in 10% of sampled dogs, posing risks of hemolytic anemia and respiratory illness in susceptible wildlife species. The overlap of free-ranging dog and wildlife habitats in urban reserves and green spaces increases the risk of cross-species transmission through direct encounters with free-ranging dogs or via contaminated environments. These findings underscore the urgent need for enhanced management and surveillance practices to prevent the transmission of these pathogens from feral dogs to urban wildlife populations [35].

Studies in the southern United States have documented the presence of Brucella suis in dogs that have had contact with feral swine populations. In southern Georgia, for example, several cases of B. suis infection were identified in dogs that had participated in feral hog hunting, with the infection likely acquired through direct contact with infected swine or their bodily fluids [49,50]. In Mississippi, a seroprevalence study found that 7.4% of shelter dogs tested positive for brucellosis, implicating exposure to feral swine as a risk factor [51]. In Florida, serologic surveys of feral swine have shown B. suis prevalence rates as high as 50% in some herds, with a statewide prevalence estimated at 10–20%. Recent increases in B. suis infection in dogs have been reported in connection with feral hog exposures [50]. These findings are concerning because B. suis is linked to reproductive failure and systemic illness in dogs, and infected animals can act as sources of transmission to other wildlife and humans. The risk of spillover is particularly pronounced in regions with high densities of feral swine, where dogs, wildlife, and livestock share environments, thereby raising the potential for broader ecological and public health impacts [52,53].

A study conducted in Nepal found that intestinal parasites with zoonotic potential are highly prevalent among street dogs [54]. The research revealed that 68.5% of the sampled free-ranging dogs were infected with at least one intestinal parasite. Notably, Toxocara spp. was detected in 30.5% of the dogs, while Ancylostoma spp. was found in 24.5%. These parasites pose a significant public health concern, as they can be transmitted to humans—especially children, who are at greater risk due to frequent contact with contaminated soil. The high prevalence of these parasites in urban and peri-urban free-ranging dog populations not only poses a threat to human health but also presents risks to local wildlife, which may come into contact with contaminated environments or infected dogs [54]. A study investigating free-ranging dogs in indigenous reserves in Guyana found a high prevalence of ectoparasite infestations [55]. The research reported that 93% of examined dogs were infested with at least one ectoparasite, with ticks (Rhipicephalus sanguineus) present on 85% of dogs and fleas (Ctenocephalides felis) found on 43%. These ectoparasites are recognized vectors for zoonotic pathogens, including Rickettsia and Borrelia species, which can cause serious illnesses in both humans and animals. The widespread presence of these parasites in free-ranging dogs raises significant concerns about the potential for transmission to local wildlife, which threatens the conservation of native species and increases the risk of disease outbreaks among both animal and human populations in these vulnerable indigenous communities [55].

Recent studies in Northern Thailand have documented the presence of several infectious agents in semi-domesticated and free-ranging dogs, with implications for both public health and wildlife conservation [56]. A study in Nan Province found that among 149 surveyed dogs, blood parasites such as Babesia canis vogeli (10.7%), B. gibsoni (8.1%), Ehrlichia canis (3.4%), and Hepatozoon canis (0.7%) were detected using molecular methods. The prevalence of these infections was notably higher in dogs from upland forested areas (28.3%) compared to those from lowland agricultural areas (12.3%). Dogs that were kept outdoors continuously and those that were not regularly bathed or cleaned had a higher likelihood of infection. The study highlights that infected dogs can act as reservoirs for these blood parasites, thereby posing a risk of transmission to both humans and wildlife. It highlights the need for effective control and surveillance programs to minimize the transmission of zoonotic diseases in rural and semi-urban communities [57].

3.3. Competition and Spatial Displacement

The presence of feral and stray dogs has been shown to significantly influence the hunting behavior and spatial ecology of native carnivores. As highly adaptable generalists, free-ranging dogs often reach high densities in human-modified landscapes, where they compete with native carnivores for both wild prey and anthropogenic food sources [58]. This competition can be both exploitative, through direct depletion of shared prey, and interference-based, as dogs may actively harass, displace, or even kill native carnivores. For example, in the United Kingdom, street dogs contributed to increased mortality among red fox (Vulpes vulpes) cubs and occasionally adults, thereby altering local fox population dynamics [59]. Behavioral studies further highlight the impact of dogs on the foraging strategies of native carnivores. In India, Indian foxes (Vulpes bengalensis) exposed to free-ranging dogs exhibited a marked increase in vigilance and a significant reduction in food intake [60]. Foxes in areas with dog activity reduced their food consumption by up to 70% and increased vigilance behaviors fifteen-fold, indicating a substantial foraging-vigilance trade-off. Such behavioral modifications can have cascading effects on fitness, reproductive success, and, ultimately, population viability of native carnivores. Recent studies in Australia provide precise data on the interactions between wild dogs (primarily dingoes) and red foxes, demonstrating significant competition and suppression effects. Camera trap studies in South Australia found that foxes concentrated their activity at resource points with the lowest dingo activity, resulting in strong spatial segregation (SIF values: 0.12 in 2016, 0.67 in 2017, and 0.83 in 2018) and low temporal overlap (Δ4 = 0.43, 95% CI: 0.39–0.47), with foxes primarily nocturnal and dingoes diurnal [61]. Experimental evidence suggests that dingoes can directly kill red foxes. In one study, dingoes killed all seven foxes introduced into their territory within 17 days, with no pre-death interactions recorded [62]. Additionally, landscape-scale analyses indicate that fox activity is typically higher in areas where dingoes are controlled or absent, supporting the mesopredator release hypothesis and suggesting that dingoes have a greater suppressive effect on fox populations than poisoning campaigns targeting dingoes [63]. These findings highlight that dingoes not only compete with foxes for resources but also actively limit their abundance and alter their behavior, with significant implications for ecosystem management and the conservation of native species [64]. For example, both wild dogs and foxes target native mammals such as possums and gliders, as well as various bird and reptile species, which can intensify pressure on these prey populations, especially in areas where food resources are already limited due to habitat degradation or seasonal fluctuations. Empirical evidence from the region confirms that foxes and wild dogs not only share similar diets but also frequently occupy the same territories, resulting in direct and indirect interactions. The cumulative impact of these introduced predators is substantial: foxes alone are estimated to kill over 300 million native mammals, birds, and reptiles annually across Australia, with significant mortality rates recorded in the Blue Mountains and other forested regions. The overlap in resource use between wild dogs and foxes may exacerbate resource depletion, potentially displacing native carnivores and increasing the vulnerability of native prey species. This dynamic underscores the importance of considering the interactions between multiple predator species in conservation and wildlife management strategies within the Blue Mountains and similar ecosystems [65]. In South America, multiple studies have documented a correlation between the presence of free-ranging dogs and the reduced occurrence and even local extinctions of native canids, such as the maned wolf (Chrysocyon brachyurus) and the chilla fox (Lycalopex griseus), highlighting the suppressive effect of dogs on native carnivore communities [58]. Free-ranging dogs, often supported by human settlements, can reach high densities and compete with native carnivores for space and resources, sometimes directly displacing them or increasing their mortality through aggression and predation [66]. For example, in parts of Brazil and Chile, the expansion of dog populations into protected areas has been associated with declines in native carnivore sightings and increased reports of dog attacks on wildlife, including canids [67]. These impacts are particularly concerning for species like the maned wolf, which are already vulnerable due to habitat loss and fragmentation. The pervasive influence of free-ranging dogs thus poses a significant threat to the persistence and recovery of native carnivore populations in South America.

Spatial displacement is another significant consequence of free-ranging dog’s presence. Native carnivores often avoid areas heavily used by dogs, even when these habitats offer abundant food resources. This avoidance can lead to habitat fragmentation and restrict access to critical resources, further exacerbating the challenges faced by native species [58].

Camera trap studies in the Ecuadorian Andes have demonstrated that the occupancy of native carnivores such as the Andean fox (Pseudalopex culpaeus), puma (Puma concolor), striped hog-nosed skunk (Conepatus semistriatus), and Andean bear (Tremarctos ornatus) is best predicted by the presence of dogs rather than by measures of habitat loss or fragmentation, indicating a potent suppressive effect of dogs on these species [68]. In these landscapes, the likelihood of detecting native carnivores decreased markedly as dog occupancy increased, with the two largest carnivores—puma and Andean bear—showing significant threshold responses to dog presence. Furthermore, native carnivores were observed to alter their activity patterns to avoid periods when dogs were most active, leading to reduced opportunities for foraging and increased energetic costs. These findings underscore that stray dogs represent a significant threat to native carnivore communities in the Andes, often exceeding the impacts of habitat loss or fragmentation [68].

In both California and Colorado, studies have shown that bobcats (Lynx rufus) exhibit apparent spatial and temporal displacement in response to the presence of stray dogs. Bobcats significantly reduced their use of habitats near trails when dogs were present, with avoidance effects extending at least 100 m from these trails. Additionally, bobcats shifted much of their activity to nighttime hours to minimize encounters with dogs, which are more active during the day. This displacement results in reduced access to preferred habitats and may increase energetic costs for bobcats as they alter their natural behaviors to avoid stray dogs. Several studies have demonstrated a negative correlation between stray dog activity and bobcat activity, highlighting the role of dogs as a significant source of disturbance and spatial exclusion for bobcats in human-dominated landscapes [69,70].

3.4. Hybridization

Hybridization between free-ranging dogs and wild canids is a global conservation concern, posing a threat to the genetic integrity, fitness, and long-term survival of wild populations. The issue is particularly acute for wolves and dingoes, but similar risks exist for other wild canids. Free-ranging dog–wildlife hybridization poses a multifaceted threat, necessitating coordinated genetic monitoring, population management, and public engagement to preserve the genetic integrity and ecological roles of wild canids worldwide.

In Italy, the genetic integrity of the native wolf population is increasingly threatened by widespread hybridization with free-ranging dogs. Recent studies have shown that reproductive barriers are insufficient to prevent the spread of dog genes within wolf populations, and this phenomenon is not limited to one region. However, it is likely occurring throughout the wolf’s range in Italy. The presence of approximately 80,000 free-ranging dogs exacerbates the risk, making interbreeding the greatest threat to wolf conservation in the country. To address this, a captive breeding program aims to maintain 90% of the Italian wolf’s genetic variability over the next 200 years [71,72].

In the northwest Iberian Peninsula, genetic studies have revealed multiple and widespread hybridization events between wolves and dogs during a single breeding season. While pure wolf genetic identity remains resilient, approximately 5.6% of introgression into the wolf population has been documented, indicating ongoing gene flow. These findings underscore the importance of ongoing monitoring and management, as even low levels of hybridization can have long-term evolutionary implications [73].

Research in Estonia and Latvia has documented hybridization between wolves and dogs, with genetic evidence showing that both male and female wolves can mate with free-ranging dogs. Notably, the study found the first European evidence of male wolves mating with female dogs, challenging the previously held notion that hybridization was predominantly between female wolves and male dogs. This asymmetry in mating patterns complicates management and underscores the unpredictability of hybridization dynamics [74].

The WOLFNESS project is a multidisciplinary initiative across Europe aimed at standardizing genetic identification of hybrids, quantifying admixture proportions, and developing management strategies. The project also examines the phenotypic effects of domestic introgression and assesses the social acceptance of various management options. Advanced genomic tools are being used to monitor hybridization and its impact on wolf behavior, ecology, and interactions with humans [72].

In Australia, hybridization between dingoes and free-ranging dogs is a major conservation issue. The spread of dog genes poses a threat to the survival of pure dingo lineages, complicating conservation and management efforts. Hybridization can lead to the loss of unique behavioral and ecological traits of dingoes, with potential cascading effects on Australian ecosystems [12]. However, recent genetic studies using advanced DNA testing have shown that while some hybridization has occurred, it is not as widespread as previously believed, and the majority of wild dingoes remain genetically pure. Nevertheless, the risk of hybridization persists, especially in regions where dingoes and domestic dogs overlap, and continued monitoring is necessary to safeguard the evolutionary distinctiveness and ecological role of the dingo [75].

3.5. Behavioral Changes

The presence of free-ranging dogs in wildlife habitats can lead to significant behavioral changes in native species, disrupting their natural patterns of foraging, movement, and anti-predator responses [76]. These changes often result from the increased stress and altered risk perception that wildlife experiences when they encounter unfamiliar predators or competitors [77]. While much of the research on wildlife disturbances caused by free-ranging dogs has focused on direct effects, such as predation, the behavioral impacts can be just as profound, influencing species’ survival, reproductive success, and overall ecological roles.

One commonly observed behavioral change is in foraging patterns. Animals that typically rely on specific feeding grounds may adjust their activity patterns to avoid dogs or to minimize exposure to areas where dogs are present. A study conducted in southern Turkey highlighted significant changes in the movement patterns of several wildlife species in response to the presence of free-ranging dogs [24]. For instance, fallow deer (Dama dama), wild boar, and red foxes (Vulpes vulpes) altered their foraging locations and behaviors, likely due to perceived threats from dogs. Disruptions in regular foraging habits can impact the nutritional intake of wildlife, potentially having long-term effects on their health and reproductive success. In some instances, this can lead to animals abandoning critical feeding areas altogether, forcing them into less optimal habitats that may not meet their ecological needs [24].

Additionally, the presence of free-ranging dogs can disrupt wildlife movement by compelling species to alter their home ranges or migration routes. In Italy, citizen science data documented instances where free-ranging dogs significantly impacted wildlife movements, particularly in protected areas [26]. Species such as the European polecat (Mustela putorius) and the crested porcupine (Hystrix cristata) avoid areas with high dog activity. For example, the probability of detecting European polecats was up to 30% lower in areas with frequent dog presence compared to areas with little or no dog activity. Similarly, the probability of detecting crested porcupines in core protected areas decreased by approximately 25% in the presence of frequent dog activity, while detections in peripheral or fragmented zones increased correspondingly. This increased avoidance behavior resulted in these species spending more time in suboptimal or fragmented habitats, heightening their vulnerability to other threats, such as human disturbance or habitat degradation. In some cases, animals changed their daily activity patterns, becoming more nocturnal or diurnal depending on when dogs were less active. This alteration can disrupt their natural circadian rhythms and ecological roles in their environment.

Moreover, the presence of free-ranging dogs can influence the anti-predator behavior of wildlife. In areas where dogs are perceived as direct threats, wildlife may exhibit heightened vigilance, alter their escape behaviors, or even abandon previously safe refuges. For example, a study done in urban areas of Mexico City found that feral dogs significantly increased the alertness of native wildlife species, including small mammals and birds, which could reduce their foraging efficiency and increase energy expenditure. Likewise, wild animals that rely on camouflage or shelter may change their behavior by spending more time in open areas or less secure environments, thereby increasing their risk of predation by other species, including free-ranging dogs [35].

The cumulative effect of behavioral disruptions in foraging behavior, movement patterns, and anti-predator responses often results in reduced access to critical resources, increased energy costs, and heightened stress, all of which can lower individual fitness and population viability [20,68]. These changes may further intensify existing conservation challenges such as habitat fragmentation, increased competition with other species, and exposure to human disturbance. Moreover, the impacts of dog-induced behavioral shifts can cascade through ecosystems. For instance, when herbivores such as deer or wild boar alter their activity patterns or abandon key feeding areas due to the presence of dogs, this can lead to changes in plant community composition and structure, which in turn affects other herbivores, pollinators, and predators that rely on those plants [20,78]. Such disruptions can destabilize food webs and ecological interactions, amplifying the ecological footprint of free-ranging dogs well beyond their immediate effects on individual species.

4. Discussion

Management strategies for controlling free-ranging dog populations vary widely by region, shaped by ecological, social, and economic factors. These approaches aim to mitigate the negative impact of dogs on wildlife. However, their effectiveness is debated due to limited data and the complex dynamics between humans and dogs, particularly in underrepresented or low-income regions. Without accurate information on dog numbers, behavior, and interactions with wildlife, it is not easy to design or implement effective, context-specific management strategies [1].

Despite growing recognition of the ecological impacts of free-ranging dogs, critical gaps remain in our understanding—especially in longitudinal studies and regional comparisons that track population dynamics and management outcomes over time [21,79]. Comparative studies evaluating the effectiveness of different strategies—such as lethal control, trap–neuter–release (TNR), and vaccination—across diverse settings would offer valuable insights [80,81].

Lethal control—via shooting, poisoning, or trapping—is a widely used but controversial strategy. Although it can temporarily reduce the number of free-ranging dog, it is often seen as inhumane and may trigger the “vacuum effect,” where new individuals quickly replace those removed [82,83]. This highlights the importance of addressing root causes, such as inadequate animal control laws, human–wildlife conflict, and a lack of community involvement.

As an alternative, TNR has gained popularity for its more humane approach. TNR involves sterilizing and releasing dogs back into their habitat. While some studies suggest a decline in population over time, success is frequently limited by funding, inconsistent monitoring, and limited community engagement [9,84]. TNR also does not fully address disease transmission or wildlife predation, making it a partial solution. Fertility control remains a promising approach; however, a better study design and reporting are necessary to accurately assess outcomes [79]. TNR is a controversial yet effective strategy for controlling and gradually reducing populations of feral and stray animals, particularly cats, despite its negative environmental impacts [85]. The researchers contend that by trapping these animals, sterilizing them, and then returning them to their original location, TNR immediately ends reproduction, stabilizes colony sizes, and prevents the birth of new litters [86]. This approach also enhances animal welfare by reducing behaviors associated with mating, such as fighting, roaming, and yowling, and by providing vaccinations and veterinary care, which in turn lowers the risk of disease [87]. Researchers contend that over time, TNR leads to healthier, more stable populations and decreases the number of animals entering shelters or being euthanized, benefiting both the animals and the surrounding community [88,89]. However, although laws have been passed on this topic, a lack of funds, implementation, and enforcement can result in a population explosion of house cats and free-ranging dogs of unimaginable proportions [90].

Vaccination campaigns targeting rabies, leptospirosis, and canine distemper have been implemented to limit the spread of these diseases to wildlife and humans [91]. These efforts are critical in areas with high zoonotic risk, but they often face logistical challenges, including remote geography, lack of infrastructure, and funding shortages [92,93]. Similarly, public education programs that promote responsible pet ownership can help reduce the number of free-ranging dogs by encouraging sterilization and supervised pet care. However, success varies with cultural context and enforcement [94].

Importantly, the human dimensions of dog management—such as cultural practices, community perceptions, and livelihood needs—are still underexplored. In many regions, dogs are culturally significant, and resistance to interventions such as TNR or vaccination may stem from deeply held cultural beliefs. Gaining community support is essential to the success of any management plan [95,96,97]. Moreover, human activities such as agriculture, tourism, and urbanization influence free-ranging dog populations and should be taken into account when designing policy.

The ecological consequences of disease transmission from free-ranging dogs are also poorly understood. While dogs are known vectors of rabies, Leptospira, and Echinococcus, the broader impacts on endangered wildlife are less clear. Outbreaks of canine distemper, for instance, have been linked to declines in wild carnivores. With the increasing overlap between free-ranging dogs and wildlife habitats, more research is needed on disease ecology and spillover risks to both wildlife and humans [53,79,98].

Innovative solutions, such as humane capture devices, offer a more efficient alternative for trapping feral dogs [99]. Integrated strategies that combine lethal and non-lethal methods—such as TNR, vaccination, public education, and humane capture—are increasingly recognized as essential, especially when considering public attitudes and opinions. Long-term monitoring, particularly through citizen science initiatives, can provide valuable data on the distribution and behavior of free-ranging dogs, aiding adaptive management [26,100,101]. A deeper understanding of socio-economic drivers, such as human mobility, dog ownership patterns, and cultural norms, is also key [102].

The One Health framework, which recognizes the interconnections between human, animal, and environmental health, offers a promising multidisciplinary approach. By aligning ecological, veterinary, and social sciences, One Health can improve feral dog management and reduce risks to biodiversity and public health [1,103,104].

A case from India’s Jhalana Reserve Forest (JRF), a tourist safari park, illustrates how native predators can contribute to controlling the dog population. In this urbanized landscape, leopards have adapted to prey on free-ranging stray dogs, which comprise up to 43% of their diet [105]. This predation reduces free-ranging dog numbers by an estimated 1150 annually, saving around $34,500 in sterilization and vaccination costs and possibly preventing up to 75 rabies-related human deaths each year. This underscores the ecological and public health value of maintaining predator populations in human-dominated landscapes [106,107].

Despite significant advances in wildlife research technology, there are still too few studies applying these modern tools to the study of free-ranging dog ecology. Technologies such as GPS collars, accelerometers, and advanced data-logging devices have revolutionized the study of animal movement, behavior, and physiology in many wild species, providing high-resolution, continuous data that were previously unattainable with traditional observation or basic radio telemetry [108,109,110,111,112]. These methods can reveal detailed spatial patterns, activity levels, and interactions with the environment, offering critical insights into how free-ranging dogs use landscapes, interact with wildlife and livestock, and potentially spread disease. However, the application of such technologies to free-ranging dog populations remains limited, resulting in significant knowledge gaps about their ecological roles and impacts. Expanding the use of these modern tools in dog ecology could significantly enhance our understanding and inform more effective management and conservation strategies.

Molecular ecology offers a suite of tools for documenting and understanding dog–wildlife interactions with high precision and minimal invasiveness. One prominent application is DNA metabarcoding of fecal samples, which allows identification of prey species consumed by free-ranging dogs, revealing patterns of predation and scavenging that would otherwise go undetected [113,114]. This is particularly valuable for assessing the impact of dogs on endangered wildlife. Molecular techniques are also instrumental in the surveillance of zoonotic and wildlife-transmitted pathogens, such as canine distemper virus, Echinococcus spp., rabies, and Leptospira, which can threaten both biodiversity and public health [115,116,117]. Pathogen genotyping helps trace transmission pathways and identify reservoir hosts [118]. Another critical use of molecular ecology is the detection of hybridization and genetic introgression between free-ranging dogs and wild canids (e.g., wolves, jackals, and dingoes). Techniques such as mitochondrial DNA sequencing, microsatellites, and single nucleotide polymorphisms (SNPs) can reveal genetic admixture and assess its threat to the genetic integrity of wild populations [74,119]. Moreover, genetic fingerprinting through non-invasive samples enables individual identification and monitoring of movements and population structure in both dogs and wildlife [120]. When integrated with stable isotope analyses, molecular tools also shed light on trophic ecology and dietary shifts toward anthropogenic food sources [121]. Collectively, these applications highlight the essential role of molecular ecology in quantifying and mitigating the ecological impacts of free-ranging dogs.

5. Conclusions

In conclusion, addressing the challenge of feral and stray dog populations requires integrated, adaptive, and context-sensitive approaches [122]. Bridging knowledge gaps through improved data collection, long-term studies, and a focus on human dimensions will enhance the effectiveness of management. By incorporating humane devices, fertility control, and citizen science, we can move toward more holistic and sustainable conservation solutions.

Free-ranging dogs are increasingly recognized as significant threats to global biodiversity and public health. Their impacts extend beyond direct predation—which can cause population declines in vulnerable wildlife—to include disease transmission, competition for resources, and disruption of wildlife behavior. Zoonotic diseases such as rabies, canine distemper, and Leptospira, commonly carried by dogs, threaten both human and wildlife populations. In parallel, behavioral changes in wildlife in response to the presence of dogs—such as altered foraging patterns, avoidance behavior, and increased stress—add complexity to already strained ecosystems.

Despite rising awareness, existing management strategies remain inconsistent and frequently ineffective. Approaches such as lethal control, trap–neuter–return, and vaccination campaigns have shown mixed outcomes, often due to poor baseline data, a lack of long-term monitoring and funding, and limited adaptability to regional socio-cultural conditions. Additionally, differences in community attitudes toward dogs, wildlife, and conservation complicate the implementation of universal solutions. This underscores the urgent need for integrated, context-specific, and adaptive management strategies.

Several key research gaps must be addressed to improve conservation outcomes:

• Reliable population data: There is a global scarcity of accurate estimates for the abundance, distribution, and ecological impact of free-ranging dogs, especially in biodiversity hotspots and low-income regions.
• Ecological and regional variability: Dog–wildlife dynamics differ across ecological zones and cultural landscapes, necessitating locally tailored research and intervention models.
• Complex ecological roles: Free-ranging dogs act as predators, competitors, behavioral disruptors, and disease vectors. Interdisciplinary research is necessary to comprehend these complex, multi-layered interactions fully.
• Evaluation of management efficacy: Many existing strategies are implemented without rigorous or long-term assessments of their ecological success or social acceptability.
• Socioeconomic drivers, including urbanization, poverty, land-use changes, and cultural practices, strongly influence dog proliferation and conflict dynamics, necessitating targeted socio-ecological approaches.
• Overcoming professional biases: Overcoming professional and societal biases is essential, as veterinarians, policymakers, and segments of the general public who sympathize with “man’s best friend” may not fully recognize or appreciate the ecological impacts of free-ranging dogs on native wildlife and ecosystems. This lack of awareness can hinder the development and implementation of effective management strategies aimed at mitigating the environmental consequences associated with uncontrolled dog populations.

Promising future directions include humane capture technologies, the development of novel contraceptives and non-surgical sterilization methods, and the utilization of technological tools such as AI-enhanced camera traps, non-invasive sampling techniques, and citizen science platforms. These innovations can significantly improve monitoring efforts and reduce human and wildlife risks when appropriately adapted to local contexts.

However, such tools must be applied with caution to avoid sampling biases, technological limitations, or inequities in community participation. Incorporating social-ecological systems thinking and emphasizing community engagement is critical for ensuring the sustainability and legitimacy of interventions. Citizen science, in particular, has proven valuable for both data collection and fostering local stewardship of conservation goals.

Looking ahead, the future implications of unchecked interactions between free-ranging dogs and wildlife are profound. As human populations expand and land-use patterns shift, incursions of dogs into wildlife habitats will likely increase, intensifying ecological and epidemiological conflicts. These include not only biodiversity loss but also the risk of emerging zoonotic diseases with global public health implications.

Adopting a One Health approach—which emphasizes the interconnectedness of human, animal, and environmental health—is essential for addressing the full scope of this issue. By bridging veterinary science, ecology, public health, and social science, One Health frameworks provide a holistic approach to managing dog populations while safeguarding biodiversity and human well-being.

Ultimately, addressing the challenges posed by free-ranging dogs will require coordinated global efforts. These must integrate improved data collection, region-specific interventions, community participation, and policy reform. Only through an internationally recognized and coordinated multidisciplinary, inclusive, and adaptive approach can we mitigate the threats free-ranging dogs pose to wildlife and ensure the long-term resilience of both natural and human ecosystems.