The Northward Expansion of the Tufted Titmouse in Maine

Abstract

The tufted titmouse (Baeolophus bicolor) was a vagrant in Maine until the 1970s. The steady increase over the last 25 years in tufted titmice in Maine is shown using Christmas Bird Count data (1976-1996) and Breeding Bird Survey data (1966-1996). Foraging data are presented on a titmouse that wintered near Flagstaff Lake (45° 14' N, 70° 17' W), the northern- most overwintering record of the species in Maine. The tufted titmouse (Baeolophus bicolor) has been dramatically expanding its range northward over the past 20 years (Kricher 1981). In Maine, the species was quite rare until the 1970s. A single specimen collected in 1890 near Orono is the only record of the species in Maine before 1950 (Knight 1908, Palmer 1949). This note was instigated by a tufted titmouse that spent the winter of 1995-1996 in undeveloped coniferous forest at the north end of Flag- staff Lake at one of the feeding stations I maintained to study the impacts of winter food supplementation on overwintering birds. This particular titmouse apparently represents the northern limit, and the climatic extreme, of the wintering range in northern New England. In this contribution, I review the status of the tufted titmouse in Maine over the period 1966-1996 and then present details of the wintering of the titmouse near Flagstaff Lake. Data on wintering populations of the tufted titmouse are available from the Christmas Bird Count (CBC) data. These CBCs, organized by the National Audubon Society, are standardized censuses. Each count is done within a circle of 7.5 miles with a fixed center. On one day between the middle of December and early January, participants divide the count circle into portions and all birds seen and heard in a 24-hour period are counted. Counts done over a period of years provide valuable data on the population dynamics of wintering birds. As a means of controlling for differences in observer effort from year to year, the number of party-hours spent searching for birds is provided in the CBC data summaries.