Migration

Nature Of Migration In The Species

Over 60,000 Canadian banding records collected from 1921 to 1995 show that 90% of recaptured birds show no movement (Brewer et al. 2000). Long-distance movements do occur, however, generally by young birds during a period of post-fledgling dispersal. In addition, large movements occur irregularly every 2+ years; these events are best termed “irruptions” rather than true migration (Lawrence 1958, Hussell and Stamp 1965, Bagg 1969, Bock and Lepthien 1976, Smith 1991, Hussell 1996). Few adults are found in these irruptions (Bagg 1969, Smith 1991).

Timing And Routes Of Migration

Factors that can affect or even induce irruptions may include habitat destruction and, especially, lack of food. Many Black-capped Chickadee irruptions, especially in eastern populations, correlate strongly with fluctuations in northern seed crops (Bock and Lepthien 1976). Another factor, suggested by Odum (1942), is that irruptions are induced by high reproductive success, i.e., excess young. Using Christmas Bird Count data, Koenig and Knops (2001) found irruptions correlated with large coniferous seed crops in the previous year, followed by a poor crop. High breeding population size, likely a result of higher winter survivorship in the good year, was also correlated with irruption.

Fall movements tend south or southwest; spring movements, while sometimes rather aimless (Hussell and Stamp 1965), are generally northeasterly (Brooks 1987, Brewer et al. 2000). Long-term banding records from Long Point, Ontario indicate that large spring movements do not always follow fall movements (Hussell 1996). Movements in either direction tend to be halted, at least temporarily, when chickadees come to the shores of any large body of water (Bagg 1969). The birds attempt to go around the shoreline, but will cross water bodies, often after much hesitation and aborted attempts (Hussell and Stamp 1965, Brewer et al. 2000).

Migratory Behavior

Generally daytime movement, an unusual behavior for small passerines (but found in other parids as well; Bagg 1969, Smith 1991). Sometimes move singly, often in ragged groups, occasionally in large flocks (especially along the shores of larger bodies of water). Bagg (1969) reported seeing over 36,000 Black-capped Chickadees moving along the shore of Lake Ontario near Rochester, NY, in October of 1961; this is the largest group movement of chickadees ever reported, by far.

Control And Physiognomy Of Migration

No information.