A woodpecker’s hyoid apparatus

KC Tsang started it all (again!) when he posted the account of a dead female Common Flameback (Dinopium javanense) hanging from a branch of a tree. He returned to the spot the next day and witnessed a flameback feasting on the maggots from the carcass.

One of KC’s images showed the dead bird dislodged and lying on the ground (left). “K” noticed something and commented, “I’m very curious as to what the thin white coils are. To me it appears to be made of plastic but if I’m not wrong, one end seems to be originating from the dead bird’s throat and another appears to be coiling around the tree branch that the carcass had fallen next to. What can it be?”

Thanks to K, we sent the image to our field ornithologist Wang Luan Keng, who responded: “Bird tongues are usually not muscular structures but operate by means of a bony extension that points backwards. This bony extension is referred to as the hyoid apparatus. In woodpeckers, the hyoid extension is very long and wraps around the back of the skull and rest on top of the skull, near the right nostril. Powerful muscles surround the entire length of the hyoid apparatus, which when contracted, extend the length of the tongue to allow the woodpecker to reach deep into the tree trunk.”

Luan enclosed two images of the hyoid apparatus of a flicker (Colaptes sp.), a large, brown North American woodpecker (above). The image looks exactly like the piece emerging from the dead bird’s throat and also extending out from near the nostril. However, the coils round the tree branch appears plant-like.

So Yong Ding Li could be right when he commented that the cause of the death could be that the tongue somehow got stuck in the tree branch cavity. After all, the tip of the tongue is covered with backward-pointing barbs as noted in an earlier post.

Joseph Lai’s suggestion that we could do an autopsy of the dead flameback did not go well with KC at first. He initially resisted collecting the rotting carcass that smelt awful. Eventually he did go collect the skull of the bird when the smell was less overpowering (left). However, we are not sure that an autopsy at this stage can point to the cause of the bird’s death.
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