Adult survival and per‐capita production of young explain dynamics of a long‐lived goose population

Abstract

Population growth rates in geese can be sensitive to small changes in survival and/or production of young, and understanding which demographic rates explain more variation in population change can be crucial for implementing effective conservation actions. Here, we show that annual adult survival and production of young (assessed in winter) explained most variation in annual population growth rate across 36 years in Greenland White-fronted Geese Anser albifrons flavirostris, during which time the population showed a sustained increase followed by a decline. In contrast, there was no strong relationship between annual population growth rate and juvenile survival following autumn migration, suggesting that variation in this demographic parameter contributed little to the population trajectory over the same period. Quantifying the influence of decisions made by Greenland White-fronted Geese throughout the annual cycle will improve our ability to target seasonal conservation actions that reduce adult mortality and/or increase production of young where possible.

Energetic trade-offs in migration decision-making, reproductive effort and subsequent parental care in a long-distance migratory bird

“…Furthermore, we found that environmental conditions constrained decision-making in spring and autumn migration. Greenland white-fronted geese have very low rates of breeding success [38][39][40] compared to similar long-lived migratory birds [10,61,62]. Some geese (approx.…”

“…The Greenland white-fronted goose population is at its lowest since the 1980s [ 37 ], having declined by approximately 50% from 1999 to 2022, and declining breeding success is the likely cause [ 38 , 39 ]. From 1983 to 2009, only 8% of marked individuals were observed on wintering areas with offspring at least once during their lifetimes, and only 2% were observed with offspring more than once, suggesting unusually low reproductive success among Arctic-nesting geese [ 40 ].…”

Differing drivers of decline within a migratory metapopulation has implications for future conservation

“…Annual counts of juveniles and adults in wintering flocks have been conducted since 1983. Juveniles are visually separable from adult birds owing to distinctive plumage characteristics (Weegman et al, 2021). We use counts for the Islay, Scotland and Wexford, Ireland sub‐populations in further analysis.…”

“…Conservation ecology, Demography, Life history ecology, Movement ecology, Population ecology Here we focus on reproductive success as it is an important driver of the overall metapopulation trajectory in GWfG, yet differs at the sub-population level (Weegman et al, 2021). There is also mounting evidence that climate change is decreasing reproductive success of Arctic migratory birds, particularly shorebirds (Kubelka et al, 2022).…”

“…The GWfG metapopulation has declined by ~50% since 1999 (Figure 2a), driven by changes in productivity and adult survival (Figure 2b) (Weegman et al, 2021). While the metapopulation trend is an important monitoring metric for conservation and management, it is not mirrored by both sub-populations.…”