Data and code from: Spatial heterogeneity in density dependence across life-history stages drives the dynamics of a bird metapopulation

Density-dependent effects on individual vital rates play a critical role
in determining a population's equilibrium size and rate of return
following stochastic disturbances. In fragmented landscapes, spatial
variation in density dependence across life-history stages causes
heterogeneity in limitations of population growth, which influences
extinction-persistence dynamics. As habitat loss leads to increased
landscape fragmentation, understanding the factors driving variation in
the strength of density dependence across life-history stages is necessary
to assess population viability and guide conservation strategies. We
quantified spatial variation in the strength of density dependence across
life-history stages in a house sparrow metapopulation encompassing 11
islands in northern Norway, collected from 1994 to 2022. Our findings
reveal that increased density negatively affects the demographic
contributions of individuals to population growth. We found a pronounced
negative effect of density, especially on survival, which was stronger in
juveniles than in adults. In contrast, there was no clear impact on
nestling production. We recorded stronger density dependence on islands
further from the mainland, likely due to harsher environmental conditions
during winter. Furthermore, the density dependence of survival was
stronger in juveniles relative to adults on islands where adult survival
contributed more to population growth than on islands where juvenile
survival was more important. This indicates that the strength of density
dependence at different life-history stages was related to each
island's average pace-of-life. Thus, this study demonstrates
potential links between spatial variation in density dependence across
life-history stages, population dynamics, and life-history evolution.