Data from: Loss of flockmates weakens winter site fidelity in golden-crowned sparrows (Zonotrichia atricapilla)

Animal social interactions have an intrinsic spatial basis—individuals
must be close in space to interact, whether directly (e.g., co-occurrence,
allo-grooming) or indirectly (e.g., interact with latrines or with
parasites at communal nests). This presents a dilemma when determining
causality: do individuals interact socially because they happen to share
space, or do they share space because they are socially linked? We present
a method that uses demographic turnover events as a natural experiment to
investigate the links between social associations and space use in the
context of inter-annual winter site fidelity in a migratory bird. We
previously found that golden-crowned sparrows (Zonotrichia atricapilla)
show consistent flocking relationships across years, and that familiarity
between individuals influences the dynamics of social competition over
resources. Using long-term data on winter social and spatial behavior
across 10 years, we show that (i) sparrows exhibit inter-annual fidelity
to winter home ranges on the scale of tens of meters and (ii) the
precision of inter-annual spatial fidelity increases with age, but (iii)
this fidelity is weakened when sparrows lose social partners from the
previous year. Furthermore, the effect of social partner loss on spatial
fidelity was higher for older birds, suggesting that social fidelity may
play an increasingly important role on spatial behavior across the
lifetime of this migratory bird. Our study provides evidence that social
relationships can influence spatial fidelity, and shows the potential of
long-term studies for disentangling the relationship between social and
spatial behavior.