Myriam Tougas-Dumesnil
Master student
Department of Biology
Laval University

Co-supervised by:

Steeve Côté (Regular member)

Research project description

Determinants of birth phenology in mountain goats (Oreamnos americanus)

Introduction: Climate change induces phenological changes in animals by altering the timing of key life-history events such as birth and reproduction. Phenological changes may have significant, long-lasting effects on fitness, especially when they affect the timing of reproduction. In temperate and boreal regions, the growing season is short and resource availability varies greatly. To maximize their fitness, individuals must reproduce in a timely manner. In ungulates, early-born offspring benefit from a longer period of vegetation growth and have a higher chance of survival than late-born ones. The birthdate of individuals varies according to the mother’s condition, demographic factors, and environmental conditions. Understanding the complex processes driving reproductive phenology of ungulates is crucial to anticipate the impacts of climate change on population dynamics. Alpine species such as mountain goat are among the most threatened by climate change.Objectives: I aim to identify the determinants of parturition date in mountain goat. I will evaluate the impacts of maternal characteristics, environmental conditions, and demographic factors on the birthdate of kids. I will assess the effects of maternal age, mass, social rank, and reproductive status on their parturition date. I will also consider the effects of population size and operational sex-ratio. Environmental variables will include winter harshness, length of vegetation growing season, green-up and senescence dates, temperature, snowfall, and snow cover duration.Study sites: I will study the Caw Ridge (54°03’N, 119°23’W) mountain goat population. Caw Ridge is a 28 km2 study site located 30 km northwest of Grande Cache, Alberta, in the foothills of the Rocky Mountains. At Caw Ridge, the weather is typically alpine: it changes rapidly. It is generally cold and windy. Snowfall and frost can happen at any time of the year. Terrain is rugged and elevation ranges from 1,700 to 2,180 meters, with treeline being at about 1,900 m. The vegetation is mostly alpine tundra and open subalpine forests. Hunting of mountain goats on Caw Ridge has been forbidden since 1969. Presence of goat predators such as grizzly bears (Ursus arctos), wolves (Canis lupus), cougars (Puma concolor) and golden eagles (Aquila chrysaetos) has been documented.Material and methods: The influence of maternal traits, environmental conditions, and demographic factors on the birthdate of kids will be evaluated with generalized linear mixed models. A global index of the condition of females will be established using a principal component analysis including their age, mass, social rank, and reproductive status. The Caw Ridge mountain goat population has been studied since 1989 and almost all (98%) of the individuals are marked. Therefore, their identity, sex, age, and reproductive status are known. Their mass is remotely recorded many times during the field season (mid-May to mid-September) using electronic platform scales. The social rank of females is established by observing their agonistic interactions. Births are also recorded by direct observations. Birthdates (± 1 day; n=507) are estimated using the date where the mother was last seen alone, the kid’s size and behaviour, as well as some characteristics of the umbilical cord. Expected results: Identifying the determinants of birth phenology in mountain goats is an essential first step towards a better understanding of the complex processes affecting the species’ reproduction and recruitment. My results will help anticipate the possible impacts of climate change on this vulnerable species, and on the population dynamics of other mountain ungulate populations.

Research Site Coordinates

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