Other Things to Consider:
Migration may also be
affected by variation in the degree of competition for seasonally
available resources (food, habitat, perch sites)
More owls (good breeding
success) and/or fewer resources (fluctuation in population of prey species)
NSWO are small-bodied, with high
mass-specific metabolic costs
They migrate using powered, flapping flight,
and
They don’t tend to build up huge fat reserves
like long-distance migrants
Must continue to hunt during migration which,
as a result, may progress at a more leisurely pace
There’s competition for resources at
stopovers during migration, too