Advances in the Field Identification of NA Dowitchers

Advances in the Field Identification of North American Dowitchers TheNorth American dowitchers are superficially so similar that, up until the 1950s (Pitelka 1950), the taxonomy of dowitchers was not yet agreed upon due to difficulty in field identification; see Jaramillo et al. (1991) for a synopsis of the historical changes in taxonomy. Part of this confusion stems from seasonal variability in dowitcher plumages and from subspecific variation in Short-billed. However, it is now agreed that dowitchers can be divided into two species, the Long-billed (Limnodromus scolapaceus) and Short-billed (L. griseus) Dowitchers, the latter comprising three subspecies: griseus, which breeds in the Maritime provinces; hendersoni, which breeds in Alberta and Manitoba; and caurinus, which breeds in southwestern and southern coastal Alaska (Pitelka 1950, AOU 1957, Takekawa and Warnock 2000, Jehl et al. 2001). Advances in the field identification of dowitchers have been made over the past few decades by numerous field ornithologists (Wilds and Newlon 1983, Hayman et al. 1986, Kaufman 1990, Jaramillo et al. 1991, Paulson 1993, Chandler 1998, Dunn 1999, NGS 1999, Sibley 2000). It is now common knowledge that the flight calls of the two species are different enough that voice can be used for reliable and easy field identification. There have also been considerable advances in the field identification of dowitchers in fresh alternate and juvenal plumage (Jaramillo et al. 1991, Paulson 1993). However, silent birds in basic and worn alternate plumage still represent identification challenges. Here we present new structural field marks and more-refined plumage field marks (plate, p. 37; Fig. 1) which, taken together, provide a new system for identifying North American dowitchers. The results presented here are based on almost a decade of observing dowitchers at all seasons (in California, Massachu-