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Body size relationships and reproductive ecology of female feral horses on Sable Island, Nova Scotia

dc.contributor.advisorMcLoughlin, Philip D.en_US
dc.contributor.committeeMemberClark, Boben_US
dc.contributor.committeeMemberChivers, Dougen_US
dc.creatorWeisgerber, Jordanen_US
dc.date.accessioned2015-04-18T12:00:17Z
dc.date.available2015-04-18T12:00:17Z
dc.date.created2015-03en_US
dc.date.issued2015-04-17en_US
dc.date.submittedMarch 2015en_US
dc.description.abstractBody size is an important determinant of reproduction in capital breeding animals, including large mammals. However, it is not always practical to hand-measure body size of free-ranging species. In recent years, parallel-laser photogrammetry has been used to obtain remote estimates of body size for some animals, though it remains unknown how well this technique might capture variation in curvilinear body features or if the distance between parallel-laser calipers is altered when projected onto a curved surface. In this thesis, I describe a photogrammetric system that may be useful for obtaining body-size measurements from unrestrained large mammals that permit approach, using domestic horses (Equus ferus caballus) as a model (Chapter 2). I then apply this technique in the field to a wild (feral) population of horses at Sable Island National Park Reserve, Nova Scotia, Canada, where I include body size measurements as variables in a detailed analysis of factors affecting reproduction in females (Chapter 3). Using my parallel-laser photogrammetric system, I show how curvilinear hand-measurements (e.g., across the barrel of a horse) are stongly correlated with their respective linear photogrammetric estimates (R2 ≥ 0.998), and most photogrammetric estimates using my system had high reliability. Using three variables of body size, photogrammetric estimates and hand-measurements explained 86.0% and 96.2%, respectively, of the variation in body weight of a sample of domestic Newfoundland ponies. On Sable Island, Nova Scotia, I examined the relationship of numerous variables (including skeletal body size and body condition) with the probability of yearly reproductive success for female Sable Island horses (years 2008–2012), where I define reproductive success as production of an offspring surviving to one year of age. Age class was a dominant factor predicting reproductive success, as expected from trends previously associated with body size or reproductive experience iii in other populations. Age-class specific energy budgets or social and sexual behaviour caused a more pronounced relationship with body condition at parturition in sub-adults, and body condition at conception and stability of consort relationships were associated with reproductive success in adults. In addition, relationships with local density suggested limited forage around the time of conception and limited water during lactation might also influence reproductive success in adult females. Although relationships were evident for age class, which is correlated with body size, reproductive success was not related to skeletal body size, past reproductive experience, age of primiparity, or band structure. The capital breeding strategy and year-round social associations seen in horses make their reproductive ecology a combination of patterns observed for large ungulates and social primates.en_US
dc.identifier.urihttp://hdl.handle.net/10388/ETD-2015-03-1977en_US
dc.language.isoengen_US
dc.subjectbody sizeen_US
dc.subjectconformationen_US
dc.subjectEquus ferus caballusen_US
dc.subjecthorseen_US
dc.subjectmorphometricsen_US
dc.subjectparallel-laser calipersen_US
dc.subjectphotogrammetryen_US
dc.subjectSable Islanden_US
dc.subjectreproductive ecologyen_US
dc.subjectreproductionen_US
dc.subjectdensityen_US
dc.subjectageen_US
dc.subjectsocio-ecologyen_US
dc.subjectbody conditionen_US
dc.subjectreproductive successen_US
dc.subjectweatheren_US
dc.titleBody size relationships and reproductive ecology of female feral horses on Sable Island, Nova Scotiaen_US
dc.type.genreThesisen_US
dc.type.materialtexten_US
thesis.degree.departmentBiologyen_US
thesis.degree.disciplineBiologyen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science (M.Sc.)en_US

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