Field Studies of Wilson's Phalarope

Abstract

In northwestern Montana and northeastern Washington Wilson's Phalarope females arrive on the breeding grounds before the males and normally outnumber the males. Monogamy or promiscuity is the usual mating relationship. The female appears to be a determinate layer whose parental obligation ceases with deposition of the usual four eggs in the nest. Copulation is performed most often while afloat with the male perched lightly on the female's back. Light head pecking by the male often accompanies this act. Incubation performed solely by the male requires between 15 and 18 days, exceptionally as long as 21 days. The precocial, nidifugous chicks leave the nest area a few hours after hatching and are able to swim when 1 hour old. The often reported spinning habit of phalaropes in water, while appearing to be a useful feeding mechanism, is performed under varied conditions and is an inherent behavior pattern displayed by incubator-hatched chicks with no previous contact with adult birds, even in the absence of water deep enough for swimming. Adult birds display certain behavioral patterns during late summer indicative of the fall gonadal recrudescence observed in some other avian species. This behavior is commoner in females and becomes more apparent just before their essentially unisexual flock departure for the south