Meeting Abstract

119.4  Monday, Jan. 7  Behavioral and Physiological Responses during Feather Replacement in House Sparrows BEN-HAMO, M*; BURNS, DJ; BAUCHINGER, U; MUKHERJEE, S; EMBAR , K; PINSHOW, B; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; University of KwaZulu-Natal; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev miri.benhamo@mail.huji.ac.il

All birds lose feathers, whether during molt or by accident, and replace them by processes that are energetically demanding. We hypothesized that house sparrows, Passer domesticus biblicus, use both physiological and behavioral mechanisms to reapportion their resources among competing functions that change when feathers are lost. We tested two predictions: 1) Sparrows growing new feathers adjust their behavior to minimize the energy costs of foraging and to increase net energy gain from their food; and 2) since house sparrows are known to carry limited energy reserves, when regrowing lost feathers they use facultative nocturnal hypothermia to save energy. To test these predictions we divided sparrows into three groups: 1) Plucked – sparrows from which we plucked 15 specific feathers; 2) cut – sparrows in which the same 15 feathers were cut off at the calamus below the barbs; and 3) control – unmanipulated sparrows with plumage intact. We recorded the amount of seeds the sparrows ate when they foraged in artificial food patches, and continuously recorded their body temperatures (T_b) by telemetry. We found that plucked sparrows growing new feathers adjust their foraging behavior by decreasing vigilance and increasing their effective encounter rate with seeds. However, these sparrows did not use facultative nocturnal hypothermia. In fact, their nighttime T_b increased significantly compared to the cut and control groups. We attribute the increase in nighttime T_b to increased metabolism during feather regrowth.