Yellow-rumped Flycatcher “vomited” wasp it swallowed earlier

William Tan was photographing a female Yellow-rumped Flycatcher (Ficedula zanthopygia) in Singapore’s Bidadari Park in September 2012 when the flycatcher suddenly caught a wasp. On swallowing the wasp, it ‘vomited’ a crushed specimen a few minutes later.

Flycatchers generally feed on insects that include bees and wasps. Why this particular flycatcher was unable to retain the wasp after swallowing it can be because it failed to effectively remove the sting earlier.

Wasps sting repeatedly, unlike bees that sting once and die. And if the sting is still intact, it can inflict undue pain.

Ng Bee Choo is of the opinion that it was because of the sting that the flycatcher threw out the wasp after swallowing.

Wang Luan Keng similarly believes that this was the reason, adding that, “…usually birds that eat bees and wasps would beat the insect on a branch to remove the sting before swallowing them (eg bee-eaters LINK). There have been reports of flycatchers eating bees and wasps but nothing was mentioned if they removed the sting earlier. If birds that remove bees and wasps stings can eat the insect afterwards, it might suggest that it is the sting that might bother the birds, not the ‘taste’ or knowledge of poison. I don’t think the bodies of bees and wasps are poisonous – but that remains to be found out.”

Dr Leong Tzi Ming added: “If this is a young flycatcher, then this would be an important life lesson in prey recognition. From personal experience, I can testify how painful wasp stings can be. This flycatcher may lack the skill and finesse of bee-eaters with regards to disarming bees and wasps prior to swallowing, so it may have been ill-prepared and ignorant of the inherent dangers. Moral of the story – better stick to a diet of flies for the time being.”

Has anyone ever seen any species of birds swallowing and throwing out a bee, wasp or even a butterfly? If so do let us know…

Note: All photographs by William Tan.

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