As the human population spreads across the globe, forested areas become more and more fragmented. There has been some question as whether the tiny patches of green interspersed between urban areas are sufficient to sustain the animals that once lived in those areas. For one little bird, the answer appears to be ‘yes’.
Swainson’s thrushes (Catharus ustulatus) migrate between Canada and South America. Along the way, they require refueling stopovers where they fill up on insects and berries. Paul Rodewald and Stephen Matthews from The Ohio State University trapped and radio-tagged the birds while they were migrating north through Columbus Ohio, and released them into seven woodlots, ranging in size from one hectare (1.7 acres) to about 38 hectares (93.9 acres). The researchers then observed whether the birds remained within the small forest patches where they were originally placed until ready to continue migrating, or moved to other nearby regions. It turned out that almost all the birds found sufficient food in even the smallest sites.