I am processing a photo of a Grey Butcherbird taken yesterday, and because of the partial backlighting, bristles round the beak are standing out, much more apparent than they would normally be. Some are quite lon. Does anyone know what their purpose would be, or have any theories about it?
Thanks,
Sonja ===============================
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Hi Sonja,
I think they are most likely to be used to guide items of food (for eating) and droplets of water or blood/haemolymph (for drinking) towards the base of the open bill.
Grey Butcherbirds live in a range of environments, including semi-arid and arid environments where free drinking water may be scarce. Some bird species inhabiting drier environments rely largely on water in their food, dew deposited on vegetation overnight and metabolic water production. It’s possible that excess blood and haemolymph from prey items are collected by the bristles as the butcherbirds are eating their food and funnelled towards the open bill. Similarly, bristles may collect due from vegetation and funnel the water droplets towards the mouth. It is also possible that water droplets collect on the bristles themselves overnight as a result of water condensation from the bird’s respired air and from other sources of dew.
Stephen Ambrose Ryde NSW