Geographic variation and taxonomy of the Northern Waterthrush

In this study we analyzed geographic variation in the Northern Waterthrush (Seiurus noveboracensis) and reassessed the status of the four subspecies d escribed between 1880 and 1948, three of which were recognized by the AOU C heck-list (1957) and Godfrey (1986). We examined 490 specimens that came fr om throughout the breeding range of the Northern Waterthrush and used four morphometric data sets and three color variables to investigate geographic variation. Males differed from females based on morphometric characters. Ma les, unlike females, showed a morphometric trend with latitude and longitud e. Their wing chord, tail and tarsus lengths showed a gradual decrease in l ength from north to south, while their tail and tarsus lengths gradually de creased eastward. The body shape showed a longitudinal trend where western specimens tended to have proportionally longer tails than wings compared to specimens from the eastern part of the range. Color was more strongly rela ted to geography than morphometric characters and showed both longitudinal and latitudinal trends. Specimens from the southeastern part of the range w ere more olive dorsally and yellow ventrally and had fewer underpart markin gs than most specimens from the northwestern part of the range. Only the wi ng length permitted us to discriminate between the most distant populations . These trends are clinal and cannot support the recognition of subspecies.