Purple martins (Progne subis), the largest North American swallows, fly off transmission tower during pre-migratory roost in Ohio. They will fly off repeated times during an evening and then re-gather on the tower. At sunset they will fly off en masse to their roosting site to reed bed in nearby lake to sleep. Pre-migratory roosts are large communal gatherings that occur on large lakes in late summer before the birds start their migration to South America. Birds may use the roost for several weeks. There are dozens of known roosting sites in the eastern half of North America and the largest contain tens and even hundreds of thousands of birds. | |
Licence : | Droits gérés |
Crédit : | Science Photo Library / Matulavich, Peter |
Model Release : | Non requis |
Property release : | Non requis |
Durée : | 10 Secondes |
Aspect ratio : | 4/3 |
Restrictions : | - |