More than 250 wood thrush nests have been found as part of an intensive demography study in southern Indiana. The wood thrush, the "state" bird of Washington, D.C., is victim of a long-term population decline.
Almost 75% of the nests had cowbird eggs in them. Cowbirds are nest parasites. They lay their eggs in other birds' nests so the nestlings are raised by foster parents. However, many of the cowbird eggs and nestlings disappear before the wood thrush chicks fledge, suggesting that the wood thrushes are able to identify, and remove, the interlopers.
Besides nest monitoring, about 80 wood thrushes will have geolocators attached to them so their winter range can be discovered. It is fairly well-known where wood thrushes as a whole spend the winter, but it is unknown where the birds from a particular area, in this case southern Indiana, spend the winter.
In addition, 20 radio tags will be attached so that the daily movements of the thrushes can be followed and to see if they will return to the same breeding site the following year.
The study is funded by the Strategic Environmental Defense Research Program and occurs on Department of Defense installations.