Asian koels recognize the host, but not their nests, for brood parasitism

<p>Avian brood parasites depend upon finding host nests to lay their eggs. However, how brood parasites find the nests of their hosts and select the nests for parasitism remains mostly unresolved. Here, we examined how a non-evicting brood parasite, the Asian koel (<em>Eudynamys</em> <em>scolopaceus</em>) selects the hosts' nests to lay their eggs. We provided a novel habitat (nest box, n=100) to the Asian koel and its host, the common myna (<em>Acridotheres</em> <em>tristis</em>), at a field site in central Bangladesh. A total of 99 nests across 59 boxes were used by common mynas, of which 21.2% of these nests were parasitized by the Asian koel. Moreover, non-host species, the Oriental magpie robin (<em>Copsychus</em> <em>saularis</em>) (n=8) and jungle myna (<em>Acridotheres</em> <em>fuscus</em>) (n=6) also built nests in the boxes but none of these nests were parasitized. We found that active boxes were significantly more parasitized than inactive nest boxes. Among the active nest boxes, only common myna nests were parasitized by the Asian koel. We found a strong tendency for Asian koel selecting common myna nests more than the non-host species, Oriental magpie robin and jungle myna. Our results provide robust experimental support for the importance of host activity suggesting that Asian koels actively select occupied boxes. Our study shows support for the host imprinting hypothesis, where the Asian koel uses the host activity as a cue to search for potential nests, and then decide whether to parasitize.</p>