Context: Many of the smaller insectivorous birds including the warblers, hummingbirds and flycatchers migrate large distances, usually at night. They land in the morning and may feed for a few days before resuming their migration. The birds are referred to as passage migrants in the regions where they occur for short durations between the origin and destination.

Question: When do many insectivorous birds migrate?
Answer: usually at night

Question: Which kinds of birds land for a few days before resuming migration?
Answer: smaller insectivorous birds

Question: What are smaller insectivorous birds referred to?
Answer: passage migrants

Question: How long do passage migrants stop and feed before resuming migration?
Answer: a few days