Body Condition and Survival of Vagrant Long-billed Murrelets, Brachyramphus perdix, in North America

Abstract

From 1979 through 2009, 81 records of long-distance vagrancy in the Long-billed Murrelet (Brachyramphus perdix) in North America south of Alaska were examined to assess body condition and survival after first observation. Sixty-one records were of live birds, of which 38 (62.3%) were discovered at sea along the west coast of North America, 18 (29.5%) were encountered inland, and 5 (8.2%) were encountered along the Atlantic coast. Fifteen of the 20 individuals salvaged (19 adults, 1 juvenile) were discovered on lake shores (75.0%) and the other 5 (25.0%) on marine coasts; 85.0% were dead when initially found (15 dead, 2 shot), and 3 (15.0%) were moribund (2 died within one day, 1 later released). Of 10 sexed individuals, 5 were adult males, 4 were adult females, and 1 was a juvenile female. Eight of 10 murrelets observed foraging were diving on lakes, but 2 others surfaced with fish; two species of common freshwater fish were removed from stomachs of 2 birds shot by hunters. Most birds (72.1%, n = 61) disappeared after one observation, which suggests survival and moving on; one bird stayed at the same location for at least 25 days before disappearing. Dead or dying Long-billed Murrelets found on shorelines of fresh water may have been too emaciated to regain lost mass after arrival—they weighed less than those shot, presumably because they were not able to locate prey or too weak to capture it. Survival for weeks or longer on freshwater stopover sites better explains how Long-billed Murrelets move across North America, with some reaching the Atlantic Ocean. Long-surviving vagrants may establish a new breeding population of Long-billed Murrelet on the west coast of North America.