Dispersal and range expansion by the cardinal: an analysis of banding records
Patterns of dispersal by the cardinal, Richmondena cardinalis, a species that has been undergoing range expansion for over 70 years, were analyzed from banding data. About 13% of 1523 foreign retraps and recoveries were found outside the 10-min block of latitude and longitude in which they had been banded. Significantly more immatures than adults dispersed; sexual differences were not pronounced. Dispersal was more common among young birds, but was not restricted to first-year birds. More distant movements probably occur in the first year and mortality may be related to distance travelled. As cardinals become older, females may become more sedentary than males. Cardinals travelled greater distances between 1933 and 1942 than in any subsequent period, and the greatest increase in numbers dispersing occurred between 1953 and 1962. Range expansion has possibly resulted from shifts in general centers of dispersal, as banding recoveries do not suggest large-scale unidirectional movements. The relation of these results to published accounts of range expansion by the cardinal is discussed.