Wild hybrid birds are always of interest with regard to our understanding of the variation encountered in nature. They may also be of ore or less taxonomic significance, depending on the frequency of their occurrence and other factors. We herein report and describe an apparent hybrid Northern Waterthrush (Seiurus noveboracensis) x Blackpoll Warbler (Dendroica striata) taken by Robbins at Ocean City, Maryland, on 17 September 1965. The bird (U.S. National Museum, no. 481595), an immature male with no fat, weighed 13.7 g and had apparently normal testes, each measuring 2.0 x 0.5 mm. The hybrid was taken in a net situated close to the ground, inland from the beach north of Ocean City; both Northern Waterthrushes and Blackpoll Warblers were caught the same day in the same net.

The hybrid has the general appearance of a large, dark, immature wood warbler of the genus Dendroica. It shows a peculiar color pattern – it is streaked on its breast somewhat like a Cape May Warbler (D. tigrine), is dark olive with indistinct streaks on its back, and has distinct buffy superciliary stripes, narrowly barred wings, a yellowish white abdomen, long white under tail coverts, and an almost unmarked dark tail. The specimen resembles a Blackpoll Warbler in the length of its wings, tail, and bill, but it has longer legs and toes than members of that species.

We are indebted to Mrs. Roxie C. Laybourne, David Bridge, and Paul Slud for useful suggestions, and to Kenneth C. Parkes for a helpful reading of the manuscript. The birds were banded at the Operation Recovery banding station by Robbins, Mrs. Richard D. Cole, Mrs. Herbert M. Church, William S. Clark, Mr. and Mrs. Herman F. Kuch, and Mr. and Mrs. Aldridge pepper.