ABSTRACT
Nests are typically built in nest boxes or tree cavities. Northern bluebird populations are migratory, whereas southern populations tend to remain on their breeding grounds year-round. Capture and marking are best accomplished at or near nest boxes during the long breeding period. Bluebirds may temporarily abandon territories and nest sites during late winter storms, when trapping should be discontinued. After nesting begins, adults can be captured in nest boxes with shutter traps. Shutter traps, specifically designed to occlude the opening of a given type of nest box, may be automatic (triggered by bird entering box) or manual. Potter traps and especially automatic shutter traps do not require constant vigilance and are suitable during the prenesting period when nest boxes are empty. Manual shutter traps can be used at any time of day and are least disturbing to the birds when used early in the nestling period.
