Field metabolism and water influx of communal roosting Green Woodhoopoes Phoeniculus purpureus

Abstract

Green Woodhoopoes (Phoeniculidae: Phoeniculus purpureus) are cooperative breeding birds that live throughout the year in groups of 2 to 16 individuals. Individuals roost in groups in cavities at night. The energy savings associated with communal cavity roosting has been implicated as an important determinant of survival in woodhoopoes. We measured field metabolic rate (FMR) and water influx of free-ranging adult woodhoopoes living in different group sizes in South Africa. We tested the hypotheses that woodhoopoes have a low FMR relative to other species of similar body mass, and that woodhoopoes roosting in small groups have a higher FMR than do individuals spending the night with large groups. For a male and females woodhoopoes, FMR differed from allometric predictions by -44.5% and -44.2%, respectively, supporting the idea that woodhoopoes have a markedly reduced FMR. Our data also indicated that females in small groups tended to have an elevated FMR compared with females in larger groups, but no such trends were identified for males.