Central-place foraging poses variable constraints year-round in a neotropical migrant

Area of Science:

• Ornithology
• Ecology
• Animal Behavior

Background:

• Central-place foragers' habitat selection and range are limited by return frequency to a central location.
• Breeding birds with high chick-feeding demands may have smaller ranges than non-breeding birds.

Purpose of the Study:

• To compare the foraging behavior, specifically range size and habitat selection, of purple martins (Progne subis) during breeding and non-breeding seasons.
• To provide the first estimates of foraging range size for purple martins.

Main Methods:

• Utilized GPS units to track purple martin foraging behavior across North America (breeding) and South America (non-breeding).
• Analyzed foraging range size and habitat selection patterns.

Main Results:

• Foraging range size did not differ significantly among breeding regions (14.0 ± 39.2 km²).
• Foraging range was substantially larger during the non-breeding period (8840 ± 8150 km²).
• Purple martins showed a strong year-round preference for aquatic habitats, commuting between low-productivity roosts and high-productivity foraging sites.

Conclusions:

• This study provides the first estimates of foraging range size for purple martins.
• Purple martins demonstrate consistent aquatic habitat preference throughout their annual cycle.
• Understanding these foraging constraints is crucial for aerial insectivore conservation efforts.