Factors influencing host nest use by the brood parasitic Asian Koel (Eudynamys scolopacea)

Abstract

Host nest use by the brood parasitic Asian Koel (Eudynamys scolopacea) has not previously been studied in detail. Here, we investigated factors that may explain patterns of nest use among three commonly used host species of the Asian Koel in Bangladesh; Long-tailed Shrikes (Lanius schach), House Crows (Corvus splendens) and Common Mynas (Acridotheres tristis). In all three host species, the risk of parasitism increased significantly as the distances between host nests and potential parasite vantage points decreased, and furthermore, there was a significant positive correlation between nest volume and risk of parasitism. The nest height above ground was an important predictor of parasitism in Long-tailed Shrikes with increased parasitism risk in nests at lower heights. In addition, nests of Long-tailed Shrikes and House Crows close to active conspecific neighbors were less likely to be parasitized than nests further away. In Common Mynas and House Crows, the risk of parasitism increased during the breeding season with their first nests initiated before the Asian Koel started its egg laying. Clutches of all three host species were parasitized during the host egg laying period. Finally, in Common Mynas, the host clutch size was higher in parasitized than unparasitized nests. The results from the present study correspond well with findings from other brood parasite–host systems, and indicate that brood parasites in general use many similar cues when selecting host nests.