• The figures below reflect cumulative Powdermill fall migration data from 1962-2003.  The first set of graphs show differential migration timing between adult and immature birds and the second set of graphs show differential timing between males and females.  Unlike spring migration (see Spring 2003 Summary), there appears to be little difference between timing of migration among sexes of most species in the fall.  For all species, the sample sizes are given in the upper right hand corner of each graph and a color key is located in the upper left hand corner of every other page.

• The vertical bars represent the median passage dates for each sub-class examined.  A single cross hatched bar signifies there is no difference between median passage dates for either age or sex.  For some species, namely Cedar Waxwing, American Redstart, and Eastern Phoebe, birds earlier in the season reflect the dispersal of individuals from the resident breeding population and not necessarily "true" migrants.  In addition, the median passage dates for a few species that are resident breeders and early (late July) migrants, namely Yellow Warbler, are over estimated because of the arbitrarily defined August through November fall migration season at Powdermill.  Similarly, a few late migrant species, e.g. American Goldfinch and Am. Tree Sparrow, that have a protracted fall migration even well into December, may be under estimated.

• Wood warblers, in particular, show some of the biggest age-related differential migration trends.  Some of these trends at Powdermill can even be dated as far back as 1969, as evidenced in Bob Leberman's early bird banding research reports for Carnegie Museum.  It's interesting to note the wide variation in patterns of differential migration among the wood warblers.  While the data seem to show that the first of many warbler species of the season are typically young of the year, adult Blackburnian Warblers and Northern Parulas, for example, migrate a week or more before the majority of the HY birds.  Still yet, Connecticut Warbler and American Redstart adults and immatures seem to pretty much parallel each other in migration.

Note: There is a typo in the sample size for Prairie Warbler in the graph for sexed birds below, N (should) = 110.