HONEST ADVERTISEMENT OF PAIRING STATUS - EVIDENCE FROM A TROPICAL RESIDENT WOOD-WARBLER

This paper reports the first investigation of the mate attraction func tion of song in a tropical resident wood-warbler. Male Adelaide's warb lers, Dendroica adelaidae (Emberizidae: Parulinae), which sing two cat egories of song (A and B), maintain territories and monogamous pair bo nds year-round. Males that were naturally or experimentally unpaired d elivered A songs at significantly higher rates than did paired males d uring both breeding and non-breeding periods. In contrast, use of B so ngs and singing at dawn did not vary with pairing status. The dawn cho rus, characterized by intense and versatile displays of the B song cat egory by neighbouring males, was absent from the non-breeding season. Dawn singing and the B song category thus appear relatively unimportan t in mate attraction in this species. Results are consistent with the hypothesis that the A song category functions in mate attraction in wo od-warblers. Furthermore, data from the non-breeding season show that the mate attraction function of song is not narrowly tied to the breed ing season in a resident species. These data provide evidence for hone st signalling of male pairing status in a socially monogamous species. Throughout the year, male Adelaide's warblers reveal their pairing st atus honestly, with a comparatively higher rate of A song delivery sig nalling that a male is unpaired. Paired and unpaired males were distin guishable based on their singing behaviour. Honest advertisement of pa iring status may have been favoured in this species by female defence of mates and a habitat saturated with territories, which would limit o pportunities for polygyny or polyterritoriality. (C) 1996 The Associat ion for the Study of Animal Behaviour