Contact Information

Department of Biology
Concordia University (Loyola Campus)
7141 Sherbrooke St. W. H4B 1R6
Montreal, QC, Canada
Office: SP 434
Lab: SP434
(514) 848-2424 (ext. 4021)

justin.gagnon@mail.concordia.ca

Education

2026 – Present: MSc student in Biology at Concordia University, Montreal, Canada

2021-2024: BSc in Ecology, Université de Sherbrooke, Sherbrooke, Canada

 

My Project

Rut-Induced Hypophagia in Male Reindeer (Rangifer tarandus): Effects of Age, Herd Composition, Social Rank, and Rut Timing on Activity Budgets

Background

Among male ungulates living in polygamous mating systems, a marked reduction in foraging effort is often observed during the mating season, a phenomenon known as rut-induced hypophagia. This trade-off can be explained by the fact that the time and energy devoted to acquiring and defending mates—guarding the harem, chasing rivals, and engaging in agonistic interactions—leave little room for feeding, and this pattern has been observed in a wide range of temperate-zone ungulates, including the bighorn sheep, mountain goat, Alpine ibex, chamois, and the goitered gazelle. However, the question of whether reindeer (Rangifer tarandus) follow this same general pattern has not yet been studied, and existing data from other Rangifer populations suggest that this pattern may not be universal: at least one study of wild forest reindeer showed that a harem-guarding male did not reduce his food intake at the peak of the rutting season, raising the possibility that ecotype or social context modulates the intensity of this trade-off. Beyond the mere presence or absence of hypophagia, the extent to which males’ age, social rank, and group composition influence individual variations in this response remains poorly understood, despite growing evidence from this same reindeer population indicating that males’ behavior and weight loss during the rutting season are sensitive to the social environment (for example, an “audience effect” linked to the size of the female group on males’ weight loss and their agonistic behavior). Clarifying these patterns will help determine whether the reindeer, as a highly social and semi-domesticated cervid, fits into the general model of ungulates characterized by rutting-induced hypophagia, or whether it represents an exception shaped by its unique social and management context.

Field Work

This study will draw on long-term data (1996–2020) collected from a semi-experimental herd at the Kutuharju Reindeer Research Station in Kaamanen, Finland (69° N, 27° E), where the age structure of males and the sex ratio have changed over the years. Data on activity budgets (e.g., resting, walking, feeding) were recorded through targeted observations of individual males during the periods preceding, during, and following the rutting season, alongside body mass measurements available for a subset of years and individuals. The database also allows males to be classified into groups of varying composition (juveniles only, adults only, or mixed adult-juvenile groups) and enables the calculation of the number of males and females present in each group. Social rank was determined directly from agonistic interactions during certain years; when this information was unavailable, age-specific body mass was used as an indicator of social rank, based on validated associations between mass, antler size, and dominance status within the same population.

 

Objectives

The objectives of this study are as follows:

• To determine whether male reindeer exhibit rutting-induced hypophagia by comparing the proportion of time spent feeding during the periods preceding, during, and following the rutting season
• To assess the extent to which the age of males influences the magnitude of this reduction in time spent feeding
• To assess how the composition/structure of male groups (composed solely of juveniles, solely of adults, or mixed) influences the distribution of activities during the rutting season
• To examine the influence of sex ratio (number of males and females present) on the feeding behavior of males
• Determine whether social rank can predict the extent of the reduction in feeding among males during the rutting period
• Determine whether the timing of the rutting season leads to a gradual shift in the temporal distribution of activities

Publications

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