Partial. A bird species’ partial migration is when some of its individuals do not migrate. Although a few of them move, others do not. Generally, ...

This would be evidence of partial migration in the population — most leave but there is a resident population. It could be that breeding phoebes are still complete migrants, ...

There’s even variation in how partial migration works, depending on the birds. “In some species, it’s hardwired, so you’re either a migrant or resident,” Watts said.

Blue jays are a local example showing partial migration. In some years, some but not all our blue jays migrate south in the fall. In years where oaks have high acorn production, ...

Just to add to the complexity, some species show partial altitudinal migration with some species sticking out the winter at high altitude and others descending where temperatures are more moderate.

Blue jays are a local example showing partial migration. In some years, some but not all our blue jays migrate south in the fall. In years where oaks have high acorn production, ...