In March 2011, Dato’ Dr Amar-Singh HSS was in Kuching, Sarawak where he photographed a White-breasted Woodswallow (Artamus leucorynchus leucorynchus) catching a butterfly. These woodswallows are common in East Malaysia (Borneo) and rather uncommon in West Malaysia (peninsula). According to Amar, “Can see them in most cities and especially in the outskirts of the city. This adult was hawking and caught a butterfly – they snatch insects with their feet (see Quentin & Karen Phillipps. Phillipps’ Field Guide to the Birds of Borneo 2009). It devoured it whole, wings and all (above).”
Khew Sin Khoon of Butterfly Circle identified the butterfly as one of the Glassy Tigers (Sub-Family Danainae), most probably Parantica sp. He finds the situation interesting as “A unique display of a bird eating what is a known species that is usually avoided by birds.” Khew further added, “…the Parantica and Ideopsis [two genera of plain tigers] are distasteful to birds. So either this is a juvenile that has not experienced the distastefulness of the butterfly or it is too hungry to care. I wonder how this scene played out, and whether the bird dropped the butterfly after realising what its prey was, or that it actually had to experience the distasteful butterfly for the first time to learn that it should not eat anything that looks like this in future. …From literature that I’ve come across, the bird will later either vomit or suffer some tummy upset effects of the mild ‘poisoning’ that the butterfly will give it.”
Further to Kiew’s comments above, Amer wrote that the bird was alone and did not look like a juvenile to him. He reviewed his sequence of images (he has three more shots after the two above) but found no sign of regurgitation or vomiting. The bird did not drop the wings or the butterfly itself and flew off soon after.
Based on Khew (2010), “The caterpillars of the majority of the species in the subfamily feed on lactiferous plants of the Asclepiadaceae and Apocynaceae families, which render the adult butterflies distaceful to predators.”
Dato’ Dr Amar-Singh HSS & Khew Sin Khoon
Khew Sin Khoon, 2010. A field guide to the butterflies of Singapore. Ink On Paper Communications, Singapore. 342 pp.