Understanding what influences movement patterns in animals is important to the understanding of colonization, range expansion, and sourcesink dynamics. Rosss geese (Chen rossii) have been expanding their nesting range eastward, and, as recently as 1994, have been nesting in large numbers in such newly colonized areas. I sampled nests at the McConnell River Migratory Bird Sanctuary (MCR), the largest known Rosss goose nesting colony outside the Queen Maud Gulf Migratory Bird Sanctuary (QMG) to estimate its nesting population size. To understand whether immigration by Rosss geese to a new colony located outside traditional nesting areas has an adaptive basis, I compared nutritional, nesting, and survival metrics between geese nesting at the MCR and those nesting at Karrak Lake (KAR) in QMG. I hypothesized that because of longer nesting season, Rosss geese at MCR would have more fat and protein reserves, larger clutch sizes, and greater nest success than those at KAR. Additionally, I hypothesized that population change at MCR was due largely to in situ recruitment. To better understand factors motivating dispersal, movement by Rosss geese between nesting attempts at MCR was measured between years. I hypothesized that dispersal distance of nesting females between years t, and t+1 was a function of both a females own reproductive success as well as that of her neighbours.<p> In 1997 over 23,000 Rosss geese were counted at MCR. By 2007, population estimates (± SE) had increased to 81,408 (±12,367). Survival of both juvenile and adult geese marked at MCR was similar to those nesting at KAR; however, recovery rate estimates were greater than those for KAR. On average, Rosss geese arrived and initiated nests at MCR seven days earlier than at KAR. Abdominal fat was lower when nest initiation date was later in both areas, but was generally greater in geese nesting at MCR. Similarly, there was more indexed protein in geese at MCR than those at KAR in 2 of 3 years. Nesting indices such as clutch size and nest success did not show a consistent area effect, which interacted with a year effect.<p> Rosss geese at MCR did not appear to use individual or conspecific reproductive success when deciding if or how far to disperse between years, and temporary emigration rates also did not vary based on reproductive success the previous year. Instead, variables other than prior individual or neighbour nest success influenced Rosss goose nest site selection and colony fidelity. The number of Rosss geese nesting at MCR increased at an average rate of 11.4% per year from 20032007, despite no increase (0%) from 2006 to 2007. Vital rate information gathered during this time suggests that immigration may have contributed to this growth; however, with few assumptions it can be concluded that MCR is a sustainable population. As a result, studies of geese breeding at MCR provide evidence that arctic geese are capable of successfully colonizing nesting areas great distances beyond historic range.

Spatial variation in density of organisms can lead to challenges in estimation of population size. Associated vital rates responsible for this variation also may vary geographically and in response to local ecological conditions, with the result that subunits of a metapopulation may have different trajectories. Both temporal and spatial variation in population size occurs not only as a result of additions through birth and deletions through death, but also from gains and losses arising from immigration and emigration, respectively. Although virtually all organisms have evolved mechanisms for dispersal, the role of movement in population dynamics has received far less attention than have contributions from recruitment and losses to mortality. I used mark-recapture techniques to make inferences about the role of movement in local population dynamics of Rosss Goose (Chen rossii) colonies by estimating rates of movement between breeding subpopulations in the Queen Maud Gulf metapopulation. I also assessed decision-based philopatry (i.e., the role of previous nesting outcome; sensu Hoover 2003) and a potential cost of reproduction to female geese through experimental manipulation of nesting success. <p>Previous nest fate influenced intra-colony dispersal as failed nesters moved further between consecutive nest sites, but inter-colony movement was not affected by previous nest fate. Regardless of previous nest fate, Rosss Geese did not exhibit philopatry to nest sites, or to breeding territories, suggesting that philopatry occurs at a larger spatial scale. Breeding success accounted for a detectable, but only small amount of variation (<11%) in dispersal distance within colonies. I suggest that temporal variation in habitat availability favors flexibility in settling patterns by geese in a changing matrix of habitat availability, governed largely by receding snow cover. Such flexibility is necessary for nesting as early as possible, because recruitment is strongly linked to timing of breeding by arctic-nesting geese. Colonial philopatry may be important not only for favorable nesting but also for access to high-quality feeding areas adjacent to colonies. Such feeding areas represent a predictable food resource important not only to growing goslings, but also adult survival regardless of the outcome of their breeding attempt. <p>I concluded from experimental manipulation that successful reproduction was encumbered with a cost to survival of females. I argue that such a cost of breeding is more likely to be incurred when climatic conditions during incubation are harsh, and when the breeding population is larger. <p>I did not find evidence for geographic variation in survival, but rates of philopatry varied markedly among colonies. The substantial exchange of females among breeding colonies (1) underscores the potential for dispersal to alter breeding distribution, (2) demonstrates that the influence of immigration on colony-specific rates of population growth was nontrivial, and (3) provides behavioral evidence for extensive gene flow resulting from female dispersal. Estimates of emigration and survival from my studies were used in combination with those for fecundity parameters and colony-specific population growth rates (lambda) to interpolate the role of immigration from a simple balance equation. During years for which rates of movement were estimated, immigration constituted 9-20% of lambda at the Karrak Lake colony, suggesting that movement was an important contribution to population growth.

Spatial variation in density of organisms can lead to challenges in estimation of population size. Associated vital rates responsible for this variation also may vary geographically and in response to local ecological conditions, with the result that subunits of a metapopulation may have different trajectories. Both temporal and spatial variation in population size occurs not only as a result of additions through birth and deletions through death, but also from gains and losses arising from immigration and emigration, respectively. Although virtually all organisms have evolved mechanisms for dispersal, the role of movement in population dynamics has received far less attention than have contributions from recruitment and losses to mortality. I used mark-recapture techniques to make inferences about the role of movement in local population dynamics of Rosss Goose (Chen rossii) colonies by estimating rates of movement between breeding subpopulations in the Queen Maud Gulf metapopulation. I also assessed decision-based philopatry (i.e., the role of previous nesting outcome; sensu Hoover 2003) and a potential cost of reproduction to female geese through experimental manipulation of nesting success. <p>Previous nest fate influenced intra-colony dispersal as failed nesters moved further between consecutive nest sites, but inter-colony movement was not affected by previous nest fate. Regardless of previous nest fate, Rosss Geese did not exhibit philopatry to nest sites, or to breeding territories, suggesting that philopatry occurs at a larger spatial scale. Breeding success accounted for a detectable, but only small amount of variation (<11%) in dispersal distance within colonies. I suggest that temporal variation in habitat availability favors flexibility in settling patterns by geese in a changing matrix of habitat availability, governed largely by receding snow cover. Such flexibility is necessary for nesting as early as possible, because recruitment is strongly linked to timing of breeding by arctic-nesting geese. Colonial philopatry may be important not only for favorable nesting but also for access to high-quality feeding areas adjacent to colonies. Such feeding areas represent a predictable food resource important not only to growing goslings, but also adult survival regardless of the outcome of their breeding attempt. <p>I concluded from experimental manipulation that successful reproduction was encumbered with a cost to survival of females. I argue that such a cost of breeding is more likely to be incurred when climatic conditions during incubation are harsh, and when the breeding population is larger. <p>I did not find evidence for geographic variation in survival, but rates of philopatry varied markedly among colonies. The substantial exchange of females among breeding colonies (1) underscores the potential for dispersal to alter breeding distribution, (2) demonstrates that the influence of immigration on colony-specific rates of population growth was nontrivial, and (3) provides behavioral evidence for extensive gene flow resulting from female dispersal. Estimates of emigration and survival from my studies were used in combination with those for fecundity parameters and colony-specific population growth rates (lambda) to interpolate the role of immigration from a simple balance equation. During years for which rates of movement were estimated, immigration constituted 9-20% of lambda at the Karrak Lake colony, suggesting that movement was an important contribution to population growth.

Understanding what influences movement patterns in animals is important to the understanding of colonization, range expansion, and sourcesink dynamics. Rosss geese (Chen rossii) have been expanding their nesting range eastward, and, as recently as 1994, have been nesting in large numbers in such newly colonized areas. I sampled nests at the McConnell River Migratory Bird Sanctuary (MCR), the largest known Rosss goose nesting colony outside the Queen Maud Gulf Migratory Bird Sanctuary (QMG) to estimate its nesting population size. To understand whether immigration by Rosss geese to a new colony located outside traditional nesting areas has an adaptive basis, I compared nutritional, nesting, and survival metrics between geese nesting at the MCR and those nesting at Karrak Lake (KAR) in QMG. I hypothesized that because of longer nesting season, Rosss geese at MCR would have more fat and protein reserves, larger clutch sizes, and greater nest success than those at KAR. Additionally, I hypothesized that population change at MCR was due largely to in situ recruitment. To better understand factors motivating dispersal, movement by Rosss geese between nesting attempts at MCR was measured between years. I hypothesized that dispersal distance of nesting females between years t, and t+1 was a function of both a females own reproductive success as well as that of her neighbours.<p> In 1997 over 23,000 Rosss geese were counted at MCR. By 2007, population estimates (± SE) had increased to 81,408 (±12,367). Survival of both juvenile and adult geese marked at MCR was similar to those nesting at KAR; however, recovery rate estimates were greater than those for KAR. On average, Rosss geese arrived and initiated nests at MCR seven days earlier than at KAR. Abdominal fat was lower when nest initiation date was later in both areas, but was generally greater in geese nesting at MCR. Similarly, there was more indexed protein in geese at MCR than those at KAR in 2 of 3 years. Nesting indices such as clutch size and nest success did not show a consistent area effect, which interacted with a year effect.<p> Rosss geese at MCR did not appear to use individual or conspecific reproductive success when deciding if or how far to disperse between years, and temporary emigration rates also did not vary based on reproductive success the previous year. Instead, variables other than prior individual or neighbour nest success influenced Rosss goose nest site selection and colony fidelity. The number of Rosss geese nesting at MCR increased at an average rate of 11.4% per year from 20032007, despite no increase (0%) from 2006 to 2007. Vital rate information gathered during this time suggests that immigration may have contributed to this growth; however, with few assumptions it can be concluded that MCR is a sustainable population. As a result, studies of geese breeding at MCR provide evidence that arctic geese are capable of successfully colonizing nesting areas great distances beyond historic range.