Each year, as the world's forested areas become more and more fragmented, ornithologists become more and more alarmed. Many forest songbirds occur less often than expected in small forest fragments. Part of the problem, researchers determined a few years ago, is that forest fragments and edges contain larger numbers of brood parasites, such as the brown-headed cowbird. Now, a team of scientists working in Australia has also discovered that forest fragments may not offer enough food for some songbirds.
Working in forested areas in the southeastern corner of Australia, Liana Zanette (University of British Columbia) and her two colleagues, Paul Doyle and Steve Tremont (University of New England in New South Wales) studied the nesting and feeding habits of the Eastern Yellow Robin (Eopsaltria australis) in forest fragments both large and small. As a part of their study they also examined the type and amount of food available to these birds in the different sizes of forest plots, to see if food would make any difference to the birds' ability to successfully reproduce. The results of their study appear in this month's Ecology (volume 81 issue 6) , a journal published by the Ecological Society of America.
Yellow Robins have a reproductive life history similar to many of the forest-interior migrant birds currently of conservation concern in North America. They lay relatively small clutches of eggs and have short nesting cycles. Their nests are often found in tree forks or bushes about three meters off the ground. While female Yellow Robins incubate their eggs, male Yellow Robins forage for food. The male will bring food to his mate and will also bring food to the young nestlings once they have hatched. Occasionally, the female will leave the nest to search for her own food. She usually also helps find food for the nestlings late in the nesting period. Yellow Robins employ a "sit and wait" foraging tactic to capture insects and small lizard
Contact: Alison Gillespie
Ecological Society of America