Quantifying population- and individual-level processes in Greenland white-fronted geese (Anser albifrons flavirostris) for holistic conservation planning

Migratory animals have complex life cycles as they move across large geographic ranges in response to seasonal conditions. These life history traits make them especially vulnerable to anthropogenic-induced climate change and land use change, as they experience a broad range of environmental conditions and threats throughout the year. However, this also makes migratory animals difficult to study and therefore conserve. In this thesis, I used novel quantitative approaches to analyse long-term and emerging data types to better understand the population dynamics and behavioural decision-making in a long-distance migratory bird, the Greenland white-fronted goose (Anser albifrons flavirostris). I used population count, age-ratio, and capture-recapture data sets to quantify heterogeneity in abundance trends and reproductive, survival, and movement rates among Greenland white-fronted goose wintering subpopulations. I found that subpopulations in the southwestern part of the wintering range have been declining more severely than northeastern ones. Survival, reproductive, and movement rates varied considerably among subpopulations, explaining abundance patterns. I conducted hypothesis tests about how environmental conditions contributed towards heterogeneity in subpopulation dynamics. I found that abundance of wintering subpopulations breeding in the northern portion of the breeding range were more negatively affected by weather on breeding areas, including cold temperatures during late spring and precipitation during brood-rearing. I also found that earlier spring phenology on staging areas negatively affected reproductive rates of geese staging in southern Iceland and increased snow on breeding areas negatively affected reproductive rates of geese breeding throughout the breeding range. I used high-frequency location and behaviour data collected from GPS-acceleration devices deployed on individual Greenland white-fronted geese to better understand the effects of behavioural decision-making throughout the annual cycle on reproductive success and survival. I found that behaviour throughout spring migration influenced reproductive outcomes; geese that adequately prepared (i.e., spent more time feeding and expended less energy during spring migration) were more likely to successfully reproduce, while geese that did not adequately prepare were more likely to defer reproduction, presumably to avoid high energetic costs of egg laying, nest incubation, and parental care. I also found that while Greenland white-fronted geese were highly philopatric to wintering subpopulations, individuals made intra- and inter-winter movements based on locally available foraging conditions; geese were more likely to move within a winter to areas with fewer croplands and boglands, potentially in response to local food depletion, and move between winters to areas with more boglands and “greener” grasslands. Individual- and population-level analyses provide important and complementary information about the ecology of migratory species, yet many studies focus on one scale or the other. In this thesis, I combined population- and individual-level analyses, which provided new insights about Greenland white-fronted goose population dynamics and behavioural decision-making processes that will help inform holistic conservation planning for these birds. More broadly, I presented a comprehensive approach to tackling long-standing questions about the complex relationships among changing environmental conditions, behavioural decision-making, and demography in migratory animals. Taken together, my work provides a framework for other researchers to similarly tackle their pressing ecological questions for discovery and targeted management.

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