Feral horses, also known as free-roaming or wild horses, are equines that live in natural environments without direct human management. They are descendants of domesticated horses that have adapted to living in the wild over generations. These populations are found in various regions worldwide and exhibit behaviors and social structures distinct from domesticated horses. In contrast, domesticated horses are bred and raised under human care, often for specific purposes such as work, recreation, or sport. The study of feral horses involves understanding their ecology, behavior, and genetics, while research on domesticated horses often focuses on health, management, and performance. This page compiles peer-reviewed research studies and scholarly articles that explore the differences and similarities between feral and domesticated horses, including their behavior, physiology, and impact on ecosystems.
Klingel H.The basic social unit in feral horses is the family group consisting of one stallion, one to a few unrelated mares and their foals. Surplus stallions associate in bachelor groups. Stallions are instrumental in bringing mares together in a unit which then persists even without a stallion. The similarity of social organization in populations living in a variety of different habitats indicates that feral horses have reverted to the habits of their wild ancestors, and that domestication has had no influence on this basic behavioural feature.
Turner JW, Kirkpatrick JF.This field study of feral stallions in Montana and Idaho examines and correlates the seasonal pattern of plasma androgens and specific sociosexual behaviour and reports the effect of a long-acting androgenic steroid on this behaviour and on fertility. Plasma testosterone was measured by competitive protein binding assay in samples obtained by jugular venepuncture from captured animals. In samples taken from 34 sexually mature stallions in 6 different months during the year, a definite seasonal pattern in testosterone was present, with a peak in May (3.04 +/- 0.63 ng/ml) and a nadir in December...
Murray MD, Snowdon WA.The distributions of the following feral animals are given -- cattle, buffalo, pig, goat, deer, camel, horse, donkey, fox, dog and cat -- and the native dingo. The possible role these and the native rodents, marsupials and monotremes would play should an exotic disease of livestock enter Australia is discussed. It is considered that feral animals would be important in creating foci from which the disease would spread.
Feist JD, McCullough DR.The social behavior of feral horses was studied in the western United States. Stable harem groups with a dominant stallion and bachelor hermaphrodite hermaphrodite groups occupied overlapping home ranges. Groups spacing, but not territoriality, was expressed. Harem group, stability resulted from strong dominance by dominant stallions, and fidelity of group members. Eliminations of group members were usually marked by urine of the dominant stallion. Hermaphrodite-hermaphrodite aggression involved spacing between harems and dominance in bachelor groups. Marking with feces was important in hermap...
Clutton-Brock TH, Greenwood PJ, Powell RP.Recent studies of primates have questioned the importance of dominance hierarchies in groups living under natural conditions. In a herd of Highland ponies and one of Highland cattle grazing under free-range conditions on the Isle of Rhum (Inner Hebrides) well defined hierarchies were present. The provision of food produced a marked increase in the frequency of agonistic interactions but had no effect on the rank systems of the two herds. While rank was clearly important in affecting the distribution of agonistic interactions, it was poorly related to behaviour in non-agonistic situations.
Feist JD, McCullough DR.A behavioural study of feral horses was conducted on the Pryor Mountain Wild Horse Range in the western United States. All 270 horses on the Range were identified individually. The sex ratio was nearly balanced. Foal to adult female ratio was 43-2:100. Morality was concentrated among foals and old horses. Horses were organized as forty-four harem groups each with a dominant stallion, one to two immature stallions, one to three immature mares, one to three adult mares and their yearling and foal offspring, and 23 bachelor groups of one to eight stallions. Harem groups were quite stable year-rou...
Feral horses in Theodore Roosevelt National Park (TRNP) represent an iconic era of the North Dakota Badlands. Their uncertain history raises management questions regarding origins, genetic diversity, and long-term genetic viability. Hair samples with follicles were collected from 196 horses in the Park and used to sequence the control region of mitochondrial DNA (mtDNA) and to profile 12 autosomal short tandem repeat (STR) markers. Three mtDNA haplotypes found in the TRNP horses belonged to haplogroups L and B. The control region variation was low with haplotype diversity of 0.5271, nucleotide...
Grillaert K.Erection and masturbation in horses are considered unwanted behaviors in training contexts, despite recognition that these are naturally occurring behaviors that are integral to the welfare of male horses. Equestrians, especially those who use positive reinforcement in their training, expressed concern that the presence of such behaviors might be associated with aggressive or sexual behaviors aimed at humans participating in horse-human interactions. The implications of such attitudes could negatively affect male horses by excluding them from welfare-friendly training systems. In this study, f...
Blakley BR, Skelley KW.Normal cholinesterase activity in brain tissue was measured in various mammalian and avain species. The cholinesterase activity in the cerebrum of cattle, swine, sheep and horses was approximately 2-3 umoles/min/g of tissue in each instance. The whole brain cholinesterase activity of small feral mammals was approximately 2 to 5 fold greater than the domestic animals. Considerable interspecies variability was present in the feral mammals. Similar variability was also observed in the avian brain cholinesterase determinations. The avian whole brain cholinesterase activities ranged from 9.78 to 21...
Treby S, Grover SP.Peatlands are globally significant carbon sinks, but when disturbed, have the potential to release carbon back to the atmosphere as greenhouse gases. Feral horse populations in the Australian Alps degrade Sphagnum peatlands, which are highly sensitive to disturbance. However, the link between this degradation and peatland carbon cycling is not understood. Here, we compared the autumn daytime carbon dioxide (CO) and methane (CH) fluxes of 12 alpine and subalpine Sphagnum peatlands in Kosciuszko National Park, Australia. The presence of feral horses at these sites was correlated with higher carb...
Magallanes S, Llorente F, Ruiz-López MJ, Martínez-de la Puente J, Soriguer R, Calderon J, Jímenez-Clavero MÁ, Aguilera-Sepúlveda P, Figuerola J.West Nile virus (WNV) is a re-emerging zoonotic pathogen with increasing incidence in Europe, producing a recent outbreak in 2020 in Spain with 77 human cases and eight fatalities. However, the factors explaining the observed changes in the incidence of WNV in Europe are not completely understood. Longitudinal monitoring of WNV in wild animals across Europe is a useful approach to understand the eco-epidemiology of WNV in the wild and the risk of spillover into humans. However, such studies are very scarce up to now. Here, we analysed the occurrence of WNV and Usutu virus (USUV) antibodies in ...
Górecka-Bruzda A, Siemieniuch M, Lansade L, Stanley CR.Scientifically validated and standardised methods for the evaluation of the welfare of free-living horses are urgently needed by both the owners and managers of these populations and those responsible for implementing national welfare legislation. The aim of the study was to test the feasibility and usefulness of two welfare protocols that could be applied to semi-feral populations: a prototype of welfare assessment template (WAT) for Carneddau semi-feral ponies and the IFCE/INRAE Horse Welfare Protocol. Additionally, the body condition scale designed by Henneke (BCS-H) was employed. The study...
Dai F, Dalla Costa E, Minero M, Briant C.Outdoor group housing is generally reported as being beneficial to the welfare of horses compared to single boxes, being considered to show greater similarities with the living conditions of feral horses, allowing full expression of behaviours such as grazing, social interactions and free movement. However, concerns persist regarding the ability to maintain a good nutritional state and the possibility of acquiring injury. No data reporting a comprehensive assessment of welfare for horses in outdoor group-housing systems are currently available. The present study aimed at applying a scientifica...
Thompson MA, McCann BE, Rhen T, Simmons R.Theodore Roosevelt National Park (TRNP) manages a herd of feral horses () which was present on the landscape prior to the establishment of the park. The population presents a unique scenario in that it has experienced fairly intensive and well-documented management since the park's establishment, including herd size reductions, intentional introduction of diversity, and subsequent attempts to remove introduced lineages. This provides an interesting case study on the genetic effects of diverse evolutionary forces on an isolated feral population. To explore the effects of these forces and clarif...
Mekata H, Yamada K, Umeki K, Yamamoto M, Ochi A, Umekita K, Kobayashi I, Hirai T, Okabayashi T.Severe fever with thrombocytopenia syndrome (SFTS) is a fatal zoonosis caused by ticks in East Asia. As SFTS virus (SFTSV) is maintained between wildlife and ticks, seroepidemiological studies in wildlife are important to understand the behavior of SFTSV in the environment. Miyazaki Prefecture, Japan, is an SFTS-endemic area, and approximately 100 feral horses, called Misaki horses (Equus caballus), inhabit Cape Toi in Miyazaki Prefecture. While these animals are managed in a wild-like manner, their ages are ascertainable due to individual identification. In the present study, we conducted a s...
Schoenecker KA, King SRB, Hennig JD, Cole MJ, Scasta JD, Beck JL.There are two species of free-roaming feral equids in North America: horses (Equus caballus) and donkeys or "burros" (E. asinus). Both species were introduced as domestic animals to North America in the early 1500s and currently inhabit rangelands across the western United States, Canada, and all continents except Antarctica. Despite their global distribution, little is known about their fine scale spatial ecology. Contemporary research tools to assess space use include global positioning system (GPS) tracking collars, but older models were problematic due to stiff collar belting causing poor ...
Stothart MR, McLoughlin PD, Medill SA, Greuel RJ, Wilson AJ, Poissant J.Gut microbiomes are widely hypothesised to influence host fitness and have been experimentally shown to affect host health and phenotypes under laboratory conditions. However, the extent to which they do so in free-living animal populations and the proximate mechanisms involved remain open questions. In this study, using long-term, individual-based life history and shallow shotgun metagenomic sequencing data (2394 fecal samples from 794 individuals collected between 2013-2019), we quantify relationships between gut microbiome variation and survival in a feral population of horses under natural...
Rutberg AT, Grams KA.Wildlife managers and the public have expressed considerable interest in the use of contraception to help manage the populations of wild horses and burros (Equus caballus and E. asinus). Field testing has shown that two preparations of the porcine zona pellucida (PZP) vaccine, a simple emulsion (ZonaStat-H) and PZP-22 (which supplements ZonaStat-H with a controlled-release component) effectively prevent pregnancy in individual mares and can substantially reduce population foaling rates. To determine whether some PZP preparations might have secondary effects that harm treated mares or their foa...
Ahn S, Redman EM, Gavriliuc S, Bellaw J, Gilleard JS, McLoughlin PD, Poissant J.Identifying factors that drive among-individual variation in mixed parasitic infections is fundamental to understanding the ecology and evolution of host–parasite interactions. However, a lack of non-invasive diagnostic tools to quantify mixed infections has restricted their investigation for host populations in the wild. This study applied DNA metabarcoding on parasite larvae cultured from faecal samples to characterize mixed strongyle infections of 320 feral horses on Sable Island, Nova Scotia, Canada, in 2014 to test for the influence of host (age, sex and reproductive/social status) and ...
Nuñez CMV, Adelman JS.It is unclear how habitat features alter animal responses to social instability. Only by uncovering such interactions can we fully understand the evolutionary drivers and fitness consequences of sociality. We capitalize on a management-induced manipulation of social stability in an island population of free-ranging feral horses (), living across three distinct habitat types. We tested whether female group-changing behaviour (a reliable measure of social instability) affected (i) female-female aggression, (ii) rank within female dominance hierarchies, (iii) stability of female hierarchies (in t...
Bercy A, Ceacero F, Komárková M.Rewilding can play a vital role in safeguarding biodiversity, with the grazing pressure exerted by large ungulates and controlled by their predators being a significant factor, particularly in European contexts. Domestic horses are becoming integral to such ungulates' biomass, but they may differ from truly wild species due to their domesticated origin. This raises concerns about whether feral horses retain adequate antipredator behaviours, especially in the presence of expanding, large predators like wolves. The field of antipredator behaviour research is hampered by inconsistent results and ...
Thulin CG, Chen Y, Garrido P.European grasslands and their biodiversity are declining rapidly due to land use changes, which highlight the need to develop effective restoration strategies. This study investigates the impact of reintroducing the Swedish national horse breed (the Gotland Russ) on grassland plant diversity and evenness in abandoned agricultural landscapes in Southeast Sweden. Twelve horses were introduced into three 10-13-hectare enclosure replicates (four horses per enclosure) in a three-year (2014-2016) rewilding experiment. Plant species richness, evenness, and diversity were investigated in both grazed a...
Hain-Saunders NMR, Knight DR, Harvey A, Bruce M, Hampson BA, Riley TV.Clostridioides difficile is a known cause of diarrhea and colitis in human and non-human animals. While C. difficile is regularly isolated from domesticated horses, little is known about its prevalence in wild or feral populations. In Australia, the horse population encompasses a mix of both domesticated and feral animals, with the feral population of 400,000 estimated to be the largest in the world. This study investigated the presence and characteristics of C. difficile in Australian feral horses and evaluated their potential as a source or reservoir of C. difficile in the wider community. F...
Ochigbo GO, Ahn S, Belhumeur KA, Poissant J, Rosa BV.Unmanaged feral horses, naïve to dewormers, offer a unique opportunity to study natural communities of equine parasites. These communities may include parasites that are rare in managed populations, and these may be transmitted to domestic horses in areas where there is contact between feral and domestic equine populations. There have been only a few studies of gastrointestinal parasite populations in horses, and very few from North American equine populations. This study aimed to gain insights into parasite biology through identification of the strongyle parasite species infecting feral hors...
