Management of Free-Roaming Horses

The modern horse (Equus caballus) evolved in North America about four million years ago, dispersing into Eurasia approximately two to three million years ago. Following this emigration, several extinctions occurred in North America, as did additional migrations to Asia and return migrations to North America (see chap. 8). The final North American extinction occurred between 13,000 and 11,000 years ago (Hunt 1992). Eurasian populations persisted, and humans began domestication ~6,000-5 ,500 years ago (Outram et al. 2009) on the western Eurasian Steppe (Warmuth et al. 2012) and perhaps on the Iberian Peninsula (Warmuth et al. 2011; Achilli et al. 2012). Today, European free-roaming horse populations can be grouped into three classes: (1) traditional popu· lations, (2) true feral populations, and (3) introduced populations (for the purposes of conservation management). We consider traditional popu· lations to be free-roaming, long-established horses that are harvested by local people (United Kingdom, Spain, Portugal). Atlantic ponies from the North Iberian Peninsula and the North Atlantic Islands make up a large proportion of these animals; some consider them remnants of wild horses living in the region since the Pleistocene (Barcena 2012). Feral populations are domestic animals that were abandoned by local farmers and today live largely unmanaged (Romania, Russia), and introduced populations are used as components of various habitat restoration proj· ects across Europe (Latvia, the Netherlands) (Rewilding Europe 2012). In North America, horses reintroduced in 1493 spread across the plains after escape or release, forming feral herds throughout the United States and Canada (see chap. 8). In South America, horses introduced by the Spanish and Portuguese during the sixteenth century spread north into the Pampas, Patagonia, and the mountainous Andean regions. And in Australia, horses introduced by European settlers in 1787 spread into the hills around Sydney and into the north, west, and south as pastoral settlement spread across the continent (see chap. 8). In more recent history, the extirpation of their natural predators has led to even further feral horse expansion, resulting in increased human conflict as feral horses more heavily affected livestock, industry, and native wildlife

Decreased female fidelity alters male behavior in a feral horse population managed with immunocontraception

In social species like the feral horse (Equus caballus), changes in individual behavior are likely to affect associated animals. On Shackleford Banks, North Carolina, USA, mares treated with the contraceptive agent porcine zona pellucida (PZP) demonstrate decreased fidelity to their band stallions. Here, we assess the effects of such decreased mare fidelity on male behavior and address potential interactions with habitat visibility, a component of the environment shown to significantly affect feral horse behavior. We compared the frequency and escalation of male-male contests, rates of aggressive and reproductive behaviors directed toward females, and the percentage of time spent vigilant among males experiencing varying levels of mare group changing behavior. We found that regardless of habitat visibility, males experiencing more female group changes engaged in contests at a higher rate (P = 0.003) and escalation (P = 0.029) and spent more time vigilant (P = 0.014) than males experiencing fewer group changes. However, while visibility had a positive effect on aggression directed by stallions toward mares (P = 0.013), female group changing behavior did not influence male-female aggressive or reproductive behaviors (P \u3e 0.1), showing that decreases in mare fidelity altered male-male but not male-female interactions. These results have important implications for feral horse management; PZP-contracepted mares demonstrating prolonged decreases in stallion fidelity may have a disproportionate effect on male behavior. Moreover, our results shed light on the relative influences of female behavior and environmental factors like habitat visibility on male behavior. Such findings can ultimately improve our understanding of how the social and physical environments interact to shape male-male and male-female interactions

Rising up to the challenge of their rivals: Mare infidelity intensifies stallion response to playback of aggressive conspecific vocalizations

Management tools like immunocontraception can alter the behavior of target animals, but the extent to which they affect non-target individuals has received less attention. The feral horse (Equus caballus) population on Shackleford Banks, North Carolina is an ideal system with which these questions may be explored, as management of the population with the immunocontraceptive agent porcine zona pellucida (PZP) has resulted in an increased propensity for females to change social groups and thus, decreased social stability. During the study, on average, females made 1.4 group changes per day (range = 0—18.5 group changes per day): females previously treated with PZP made 1.8 group changes per day, while females that had never been treated made 1.2 group changes per day. Between May and August, 2017, we used playbacks of aggressive male vocalizations (squeals) and human voices (reciting “hello horse”) to assess changes in stallion responses to male rivals versus socially irrelevant stimuli in the context of female turnover. Over the course of the study, males were observed for 9.4 hours on average (range = 2.4—20.5 hr). Males spent more time vigilant (estimate = 12.431, P = 0.016, ̅squeal = 30 s, ̅control = 19 s) and were more likely to approach the speaker following squeal playbacks than controls (estimate = 2.325, P = 0.039). Males’ latency to return to normal behaviors varied depending on whether the playback was conducted in the weeks before, during, or after group changes occurred (P = 0.025, ̅before = 26 s, ̅during = 39 s, ̅after = 53 s). Male responses were not affected by the total number of female group changes a male experienced during the observation period (P \u3e 0.4), suggesting the effects are more context-dependent and not long-lasting. These findings suggest mare turnover can impact stallion responsiveness to potential rivals. As previously contracepted mares change groups more often than untreated mares and stallions exhibit prolonged responses to aggressive vocalizations after experiencing a female group change, contraception-induced changes to mare behavior may lead to increased male aggression in response to intruding rivals, which could be associated with greater energy expenditure. Finally, our work demonstrates that playback experiments are a useful tool for studying feral horse behavior in the wild. As the need for population control of different species continues to expand, rigorous investigations of immunocontraception’s effects on non-target animals are critical if agencies are to manage populations most effectively

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Decreased female fidelity alters male behavior in a feral horse population managed with immunocontraception

In social species like the feral horse (Equus caballus), changes in individual behavior are likely to affect associated animals. On Shackleford Banks, North Carolina, USA, mares treated with the contraceptive agent porcine zona pellucida (PZP) demonstrate decreased fidelity to their band stallions. Here, we assess the effects of such decreased mare fidelity on male behavior and address potential interactions with habitat visibility, a component of the environment shown to significantly affect feral horse behavior. We compared the frequency and escalation of male-male contests, rates of aggressive and reproductive behaviors directed toward females, and the percentage of time spent vigilant among males experiencing varying levels of mare group changing behavior. We found that regardless of habitat visibility, males experiencing more female group changes engaged in contests at a higher rate (P = 0.003) and escalation (P = 0.029) and spent more time vigilant (P = 0.014) than males experiencing fewer group changes. However, while visibility had a positive effect on aggression directed by stallions toward mares (P = 0.013), female group changing behavior did not influence male-female aggressive or reproductive behaviors (P > 0.1), showing that decreases in mare fidelity altered male-male but not male-female interactions. These results have important implications for feral horse management; PZP-contracepted mares demonstrating prolonged decreases in stallion fidelity may have a disproportionate effect on male behavior. Moreover, our results shed light on the relative influences of female behavior and environmental factors like habitat visibility on male behavior. Such findings can ultimately improve our understanding of how the social and physical environments interact to shape male-male and male-female interactions.This is a manuscript of an article published as Jones, Maggie M., and Cassandra MV Nuñez. "Decreased female fidelity alters male behavior in a feral horse population managed with immunocontraception." Applied Animal Behaviour Science (2019). doi: 10.1016/j.applanim.2019.03.005. Posted with permission.</p

Rising up to the challenge of their rivals: Mare infidelity intensifies stallion response to playback of aggressive conspecific vocalizations

Management tools like immunocontraception can alter the behavior of target animals, but the extent to which they affect non-target individuals has received less attention. The feral horse (Equus caballus) population on Shackleford Banks, North Carolina is an ideal system with which these questions may be explored, as management of the population with the immunocontraceptive agent porcine zona pellucida (PZP) has resulted in an increased propensity for females to change social groups and thus, decreased social stability. During the study, on average, females made 1.4 group changes per day (range = 0—18.5 group changes per day): females previously treated with PZP made 1.8 group changes per day, while females that had never been treated made 1.2 group changes per day. Between May and August, 2017, we used playbacks of aggressive male vocalizations (squeals) and human voices (reciting “hello horse”) to assess changes in stallion responses to male rivals versus socially irrelevant stimuli in the context of female turnover. Over the course of the study, males were observed for 9.4 hours on average (range = 2.4—20.5 hr). Males spent more time vigilant (estimate = 12.431, P = 0.016, ̅squeal = 30 s, ̅control = 19 s) and were more likely to approach the speaker following squeal playbacks than controls (estimate = 2.325, P = 0.039). Males’ latency to return to normal behaviors varied depending on whether the playback was conducted in the weeks before, during, or after group changes occurred (P = 0.025, ̅before = 26 s, ̅during = 39 s, ̅after = 53 s). Male responses were not affected by the total number of female group changes a male experienced during the observation period (P > 0.4), suggesting the effects are more context-dependent and not long-lasting. These findings suggest mare turnover can impact stallion responsiveness to potential rivals. As previously contracepted mares change groups more often than untreated mares and stallions exhibit prolonged responses to aggressive vocalizations after experiencing a female group change, contraception-induced changes to mare behavior may lead to increased male aggression in response to intruding rivals, which could be associated with greater energy expenditure. Finally, our work demonstrates that playback experiments are a useful tool for studying feral horse behavior in the wild. As the need for population control of different species continues to expand, rigorous investigations of immunocontraception’s effects on non-target animals are critical if agencies are to manage populations most effectively.This is a manuscript of an article published as Jones, Maggie M., Leanne Proops, and Cassandra MV Nuñez. "Rising up to the challenge of their rivals: Mare infidelity intensifies stallion response to playback of aggressive conspecific vocalizations." Applied Animal Behaviour Science (2020). doi: 10.1016/j.applanim.2020.104949. Posted with permission.</p

Consequences of porcine zona pellucida immunocontraception to feral horses

Porcine zona pellucida (PZP) immunocontraception was developed to provide a more humane, eff ective, and inexpensive method of population regulation for wildlife species. It has been used to regulate populations of several species including white tailed deer (Odocoileus virginianus), elk (Cervus elaphus), black bear (Ursus americanus), and the feral horse (Equus ferus caballus) with varying levels of success. Early studies on Assateague Island National Seashore, Maryland, USA, suggested PZP was as an ideal form of fertility control because it reduced the likelihood of conception to This article is published as Nuñez, Cassandra M.V. (2018) "Consequences of Porcine Zona Pellucida Immunocontraception to Feral Horses," Human–Wildlife Interactions: Vol. 12 : Iss. 1 , Article 14. Posted with permission.</p

Management of wild horses with porcine zona pellucida: History, consequences, and future strategies

The advent of immunocontraception with porcine zona pellucida (PZP) has all but revolutionized wild horse management, providing a more humane method of population control than earlier strategies. Early studies on Assateague Island National Seashore have described it as an ideal form of fertility control in that it reduces the chance of conception to below 10%, can be delivered remotely, is reversible (after short-term use), lacks debilitating physiological side effects, cannot pass through the food chain, and shows minimal effects on social behaviors. However, recent research in other populations has revealed behavioral and physiological side effects of long-term PZP use. These results indicate that studies from one population may not necessarily be applicable to another, regardless of similarities in habitat and population structure. Careful study of the animals\u27 demography, physiology, and behavior is necessary prior to and during treatment to ensure that a) the potential effects of PZP can be assessed accurately, and b) within managerial constraints, PZP effects are ameliorated as much as is possible. Here I explain the history of PZP use in wild horses, its side effects on the horses of Shackleford Banks, North Carolina in comparison to other populations, and offer management suggestions based upon wild horse biology and behavioral ecology, which may minimize or prevent these side effects in other populations

Consequences of Porcine Zona Pellucida Immunocontraception to Feral Horses

Porcine zona pellucida (PZP) immunocontraception was developed to provide a more humane, effective, and inexpensive method of population regulation for wildlife species. It has been used to regulate populations of several species including white tailed deer (Odocoileus virginianus), elk (Cervus elaphus ), black bear (Ursus americanus ), and the feral horse (Equus ferus caballus) with varying levels of success. Early studies on Assateague Island National Seashore, Maryland, USA, suggested PZP was as an ideal form of fertility control because it reduced the likelihood of conception t

Management of Free-Roaming Horses

The modern horse (Equus caballus) evolved in North America about four million years ago, dispersing into Eurasia approximately two to three million years ago. Following this emigration, several extinctions occurred in North America, as did additional migrations to Asia and return migrations to North America (see chap. 8). The final North American extinction occurred between 13,000 and 11,000 years ago (Hunt 1992). Eurasian populations persisted, and humans began domestication ~6,000-5 ,500 years ago (Outram et al. 2009) on the western Eurasian Steppe (Warmuth et al. 2012) and perhaps on the Iberian Peninsula (Warmuth et al. 2011; Achilli et al. 2012). Today, European free-roaming horse populations can be grouped into three classes: (1) traditional popu· lations, (2) true feral populations, and (3) introduced populations (for the purposes of conservation management). We consider traditional popu· lations to be free-roaming, long-established horses that are harvested by local people (United Kingdom, Spain, Portugal). Atlantic ponies from the North Iberian Peninsula and the North Atlantic Islands make up a large proportion of these animals; some consider them remnants of wild horses living in the region since the Pleistocene (Barcena 2012). Feral populations are domestic animals that were abandoned by local farmers and today live largely unmanaged (Romania, Russia), and introduced populations are used as components of various habitat restoration proj· ects across Europe (Latvia, the Netherlands) (Rewilding Europe 2012). In North America, horses reintroduced in 1493 spread across the plains after escape or release, forming feral herds throughout the United States and Canada (see chap. 8). In South America, horses introduced by the Spanish and Portuguese during the sixteenth century spread north into the Pampas, Patagonia, and the mountainous Andean regions. And in Australia, horses introduced by European settlers in 1787 spread into the hills around Sydney and into the north, west, and south as pastoral settlement spread across the continent (see chap. 8). In more recent history, the extirpation of their natural predators has led to even further feral horse expansion, resulting in increased human conflict as feral horses more heavily affected livestock, industry, and native wildlife.This is a chapter from Nuñez, C.M.V., A. Scorolli, L. Lagos, D. Berman, A. Kane. 2016. Management of freeroaming horses in J.I. Ransom and P. Kaczensky, eds. Wild Equids. The Johns Hopkins University Press.</p