Aerial drone observations identified a multilevel society in feral horses

AbstractThe study of non-human multilevel societies can give us insights into how group-level relationships function and are maintained in a social system, but their mechanisms are still poorly understood. The aim of this study was to apply spatial association data obtained from drones to verify the presence of a multilevel structure in a feral horse society. We took aerial photos of individuals that appeared in pre-fixed areas and collected positional data. The threshold distance of the association was defined based on the distribution pattern of the inter-individual distance. The association rates of individuals showed bimodality, suggesting the presence of small social organizations or “units”. Inter-unit distances were significantly smaller than those in randomly replaced data, which showed that units associate to form a higher-level social organization or “herd”. Moreover, this herd had a structure where large mixed-sex units were more likely to occupy the center than small mixed-sex units and all-male-units, which were instead on the periphery. These three pieces of evidence regarding the existence of units, unit association, and stable positioning among units strongly indicated a multilevel structure in horse society. The present study contributes to understanding the functions and mechanisms of multilevel societies through comparisons with other social indices and models as well as cross-species comparisons in future studies.

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Feral horse demography and population growth in the Kaimanawa Ranges, New Zealand

Wildlife Research ◽

10.1071/wr02067 ◽

2004 ◽

Vol 31 (2) ◽

pp. 119 ◽

Cited By ~ 22

Author(s):

Wayne L. Linklater ◽

Elissa Z. Cameron ◽

Ed O. Minot ◽

Kevin J. Stafford

Keyword(s):

New Zealand ◽

Sex Ratio ◽

Population Growth ◽

Management Problem ◽

Feral Horses ◽

Sex Structure ◽

Young Males ◽

Feral Horse ◽

Adult Sex Ratio ◽

Female Bias

Although feral horses are a common management problem in numerous countries, detailed and long-term demographic studies are rare. We measured the age and sex structure, and pregnancy, birth and death rates in a population of 413 feral horses in New Zealand during 1994–98 and used them to construct a model simulating population growth. Survivorship increased with age (0–1 years old = 86.8%, 1–2 = 92.3%, 2–4 = 92.4%, ≥�4 years old = females 94%, males 97% per annum). Birth sex ratio parity, a slight female bias in the adult sex ratio (92 males per 100 females) and higher adult male survivorship indicated lower average survivorship for young males than females that was not detectable in mortality statistics. Pregnancy and foaling rates for mares ≥�2 years old averaged 79 and 49%, respectively. Foaling rates increased as mares matured (2–3-year-old mares = 1.9%, 3–4 = 20.0%, 4–5 = 42.1%, ≥�5 = 61.5% per annum). Young mares had higher rates of foetal and neonatal mortality (95% of pregnancies failed and/or were lost as neonatal foals in 2–3-year-old mares, 70.6% in 3–4, 43.2% in 4–5, and 31% in mares ≥�5 years old). Population growth was 9.6% per annum (9.5–9.8, 95% CI) without human-induced mortalities (i.e. r = 0.092). Our model, standardised aerial counts, and historical estimates of annual reproduction suggest that the historical sequence of counts since 1979 has overestimated growth by ~50% probably because of improvements in count effort and technique.

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Seasonal mountain lion predation on a feral horse population

Canadian Journal of Zoology ◽

10.1139/z92-132 ◽

1992 ◽

Vol 70 (5) ◽

pp. 929-934 ◽

Cited By ~ 23

Author(s):

John W. Turner Jr. ◽

Michael L. Wolfe ◽

Jay F. Kirkpatrick

Keyword(s):

Survival Rate ◽

First Year ◽

Horse Population ◽

Feral Horses ◽

Mountain Lions ◽

Mountain Lion ◽

Felis Concolor ◽

Feral Horse ◽

Annual Cohort ◽

Demographic Impact

A population of feral horses (Equus caballus) was studied from 1986 to 1991 to determine the demographic impact of predation by the mountain lion (Felis concolor). The population, inhabiting a 600-km2 area on the central California – Nevada border comprised approximately 162 individuals > 1 year old, with an average of 9 yearlings, 8 two-year-olds, and 144 adults. Numbers of horses varied by only 4–8% and showed no consistent trend. The parturition peak spanned May and June, when 80% of foaling occurred. One-third of the average annual cohort of 33 foals was missing by July and only half of the cohort remained by October. The mean first-year survival rate estimated from the differential incidence of foals and yearlings in successive years was 0.27, which was less than one-third of the foal survival rate reported for other feral horse populations. A minimum of four adult mountain lions used the study area each year between May and October. Of 28 foal carcasses located from May to mid-July, at least 82% were the result of mountain lion kills. No evidence of predation on older horses was observed, but mountain lions preyed on mule deer (Odocoileus hemionus) during winter. We conclude that the growth of this horse population is limited by predation.

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Feral Horse Distribution, Habitat Use and Population Dynamics in Theodore Roosevelt National Park

The UW National Parks Service Research Station Annual Reports ◽

10.13001/uwnpsrc.1990.2907 ◽

1990 ◽

Vol 14 ◽

pp. 123-125

Author(s):

Clayton Marlow ◽

Leonard Gagnon ◽

Elena Hovland ◽

Lynn Irby

Keyword(s):

National Park ◽

Home Range Size ◽

Home Ranges ◽

Theodore Roosevelt ◽

Horse Population ◽

Feral Horses ◽

Population Growth Rates ◽

Feral Horse ◽

Theodore Roosevelt National Park ◽

Reproductive Rates

Description of the ecological niche feral horses fill in Theodore Roosevelt National Park requires information on reproductive rates, home range size, individual and band affinity to home ranges, food and shelter requirements and seasonal diets. Therefore, the initial objectives will be to: 1. identify the number, size and location of home ranges for harem and bachelor stallion bands; 2. describe daily and seasonal movements of bands within identified home ranges; 3. describe the vegetation habitat types and landform types used by horses for mating, foaling, foraging, and resting cover; 4. describe seasonal horse diets; and 5. collect data on sex, age and social hierarchy within respective bands to facilitate estimation of horse population growth rates. Ultimately, this information will be used to accomplish the project goal; integrate horse requirements with those of elk, bison and the Park's vegetation communities to determine the large ungulate carrying capacity of Theodore Roosevelt National Park.

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The Contribution of Mutual Grooming to Affiliative Relationships in a Feral Misaki Horse Herd

Animals ◽

10.3390/ani10091564 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1564

Author(s):

Masaki Shimada ◽

Nae Suzuki

Keyword(s):

Social Network ◽

Size Structure ◽

Social Rank ◽

Significant Negative Correlation ◽

Herd Size ◽

Structure Stability ◽

Social Grooming ◽

Feral Horses ◽

Feral Horse ◽

Partial Correlations

Although herd size, structure, stability, and social rank among Misaki feral horses have been reported, no studies have been conducted on the affiliative relationships and interactions among members in a Misaki horse herd. The validity of three hypotheses regarding the function of social grooming, the affiliative relationship strengthening hypothesis, the worsened relationship restoring hypothesis, and the grooming parasite removal hypothesis, were tested in a Misaki feral horse (Equus caballus) herd in Cape Toi, Japan. All the nine horses in the “6m” herd were investigated in terms of kinship, grooming, aggression, proximity, social rank, and social network. Mutual grooming occurred only in pairs and was almost perfectly symmetrical. For each member, there was a significant negative correlation between total grooming received from other individuals and self-grooming. Controlling for kinship, there were significant positive partial correlations between mutual grooming and proximity and between aggression and proximity. No correlation was observed between aggression and mutual grooming. The results suggest that mutual grooming symmetry may contribute that both participants simultaneously benefit from parasite removal and strengthen affiliative relationships between seasonally changing herd members; however, mutual grooming did not foster restoring the worsened relationship following aggression promoted by physical proximity. The findings of this study may elucidate the mechanisms by which interactions between herd members are maintained or strengthened.

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A Scheme for Evaluating Feral Horse Management Strategies

International Journal of Ecology ◽

10.1155/2012/491858 ◽

2012 ◽

Vol 2012 ◽

pp. 1-5

Author(s):

L. L. Eberhardt ◽

J. M. Breiwick

Keyword(s):

Management Strategies ◽

Nonparametric Model ◽

Data Sets ◽

Parametric Approach ◽

Feral Horses ◽

Density Dependent ◽

The Public ◽

Feral Horse ◽

Management Techniques ◽

Model Fits

Context. Feral horses are an increasing problem in many countries and are popular with the public, making management difficult.Aims. To develop a scheme useful in planning management strategies.Methods. A model is developed and applied to four different feral horse herds, three of which have been quite accurately counted over the years.Key Results. The selected model has been tested on a variety of data sets, with emphasis on the four sets of feral horse data. An alternative, nonparametric model is used to check the selected parametric approach.Conclusions. A density-dependent response was observed in all 4 herds, even though only 8 observations were available in each case. Consistency in the model fits suggests that small starting herds can be used to test various management techniques.Implications. Management methods can be tested on actual, confined populations.

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Multiscale analysis reveals restricted gene flow and a linear gradient in heterozygosity for an island population of feral horses

Canadian Journal of Zoology ◽

10.1139/z09-019 ◽

2009 ◽

Vol 87 (4) ◽

pp. 310-316 ◽

Cited By ~ 12

Author(s):

Z. L. Lucas ◽

P. D. McLoughlin ◽

D. W. Coltman ◽

C. Barber

Keyword(s):

Gene Flow ◽

Spatial Scales ◽

Restricted Gene Flow ◽

Island Population ◽

Feral Horses ◽

Linear Gradient ◽

Linear Habitats ◽

Feral Horse ◽

Feral Population ◽

Sand Bar

We studied the genetic (microsatellite) diversity of a feral population of horses ( Equus caballus L., 1758) on Sable Island, Nova Scotia, Canada (1983–2003), at two spatial scales: (1) for the island as a whole and (2) at the level of four equally sized subdivisions along the length of Sable Island, which is a long (42 km) and narrow (1.5 km) vegetated sand bar. At the island scale (n = 264 horses), observed heterozygosity over 10 loci was 0.647 ± 0.035 (mean ± 1 SE), while expected heterozygosity was 0.696 ± 0.029; we observed significant heterozygote deficiency with all loci considered (P < 0.0001). At the subdivision scale, observed heterozygosity ranged from 0.589 to 0.694 in a gradient from west to east. We observed a corresponding gradient in effective number of alleles and allelic richness. Pairwise values of FST were significant for most subdivision pairs, ranging as high as 0.067 from west to east. Western areas showed highest levels of inbreeding (FIS = 0.113) with outbreeding indicated in the east (FIS = –0.008). Our results suggest that for a large mammal that lives in polygynous social groups, like the feral horse, gene flow along linear habitats (corridors) may be restricted (relative to the dispersal capabilities of the species), even over short distances.

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The feral horse foot. Part B: radiographic, gross visual and histopathological parameters of foot health in 100 Australian feral horses

Australian Veterinary Journal ◽

10.1111/avj.12017 ◽

2013 ◽

Vol 91 (1-2) ◽

pp. 23-30 ◽

Cited By ~ 5

Author(s):

BA Hampson ◽

MA de Laat ◽

PC Mills ◽

DM Walsh ◽

CC Pollitt

Keyword(s):

Feral Horses ◽

Foot Health ◽

Feral Horse

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The relationship between mineral composition, crystal structure and paragenetic sequence: the case of secondary Te mineralization at the Bird Nest drift, Otto Mountain, California, USA

Mineralogical Magazine ◽

10.1180/minmag.2016.080.001 ◽

2016 ◽

Vol 80 (2) ◽

pp. 291-310 ◽

Cited By ~ 12

Author(s):

Andrew G. Christy ◽

Stuart J. Mills ◽

Anthony R. Kampf ◽

Robert M. Housley ◽

Brent Thorne ◽

...

Keyword(s):

Spatial Association ◽

Structural Complexity ◽

Intermediate Stage ◽

Degree Of Polymerization ◽

Exact Nature ◽

Bird Nest ◽

Paragenetic Sequence ◽

Chemical Systems ◽

Association Data ◽

The Relationship

AbstractAn unusually diverse array of 25 secondary Te oxysalt minerals has been documented from Otto Mountain, California, and 18 of these from the Bird Nest drift sublocality. A paragenetic sequence for these minerals is proposed, using observed overgrowth relationships plus spatial association data and data from other localities. Apart from Te and O, the components Pb, Cu and H are essential in the majority of the minerals. The atomic Cu/Te ratio decreases through the paragenetic sequence. This, and the occurrence of minerals with additional components such as Cl–, CO32–, SO42–and Fe3+at an intermediate stage, suggests nonmonotonic evolution of the parent fluids, reflecting differing access to or spatial distribution of various components. For the minerals with known crystal structures, two alternative 'structural units' were identified, one consisting only of the Te4+or Te6+oxyanion, while the other also included small, strongly-bound cations such as Cu2+. The degree of polymerization for the Te oxyanion correlated with the paragenetic sequence: the monomeric tellurate anions of early minerals were replaced progressively by dimers, chains and sheet structures, which may relate to a decreasing abundance of the 'network modifying' Cu2+cation, analogous to Bowen's discontinuous reaction series in igneous rock-forming silicates. No relationship was seen between paragenetic order and the larger type of structural unit, or structural complexity as defined by information content. This contrasts with results in the literature for evaporite sulfates and pegmatite phosphates. While structure–paragenesis relationships may be widespread, the exact nature of such relationships may be different for different chemical systems and different paragenetic environments.

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Prospects for immunocontraception in feral horse population control: exploring novel targets for an equine fertility vaccine

Reproduction Fertility and Development ◽

10.1071/rd14280 ◽

2016 ◽

Vol 28 (7) ◽

pp. 853 ◽

Cited By ~ 7

Author(s):

Aleona Swegen ◽

R. John Aitken

Keyword(s):

Vaccine Development ◽

Population Control ◽

Future Research ◽

Economic Damage ◽

The Novel ◽

Horse Population ◽

Feral Horses ◽

Feral Horse ◽

Species Specific ◽

Free Ranging

Feral horses populate vast land areas and often induce significant ecological and economic damage throughout the landscape. Non-lethal population control methods are considered favourable in light of animal welfare, social and ethical considerations; however, no single effective, safe and species-specific contraceptive agent is currently available for use in free-ranging wild and feral horses. This review explores aspects of equine reproductive physiology that may provide avenues for the development of specific and long-lasting immunocontraceptive vaccines and some of the novel strategies that may be employed to facilitate appropriate antigen discovery in future research. Potential antigen targets pertaining to spermatozoa, the ovary and oocyte, as well as the early conceptus and its associated factors, are reviewed in the context of their suitability for immunocontraceptive vaccine development.

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Ecological and human dimensions of management of feral horses in Australia: a review

Wildlife Research ◽

10.1071/wr06102 ◽

2007 ◽

Vol 34 (5) ◽

pp. 408 ◽

Cited By ~ 63

Author(s):

Dale Graeme Nimmo ◽

Kelly K. Miller

Keyword(s):

Management Practices ◽

Current Knowledge ◽

Human Dimensions ◽

Successful Management ◽

Feral Horses ◽

Public Controversy ◽

Contentious Issue ◽

Feral Horse ◽

The World ◽

Introduced Pest

In Australia, the management of feral horse populations is a contentious issue, owing to their pluralistic status as an introduced pest and a national icon. In this review, we synthesise current knowledge of the ecological effects of feral horses and the human dimensions of feral horse management, using case studies from around the world to illustrate contentious and successful management practices. We highlight gaps in the literature and suggest that more peer-reviewed research would be beneficial in reducing the current public controversy surrounding management of feral horses.

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