Friday, July 22, 2011

Great Crested Flycatcher: Anting or Sunning

On Tuesday, 19 July 2011, I was photographing dragonflies. My car thermometer read 97 degrees; the bank proclaimed 104--with record-breaking heat-index numbers for Minnesota. While I languidly scoped Odonata, a robin-sized bird flew out of a small woodlot and landed in a grassy, treeless hillside by the road. The bird plopped its belly onto the ground and spread its tail and wings.  Clearly this Great Crested Flycatcher was anting. 


Anting is a curious and unexplained phenomenon. Anting comes in two forms. Either birds pick up and rub ants on their feathers, and then eat the ants.  Alternatively, like the flycatcher in the top photo, they land on anthills and let the ants swam. The first form of anting leads researchers to hypothesize that anting is for food acquisition. Picking up the ants and getting them to discharge their folic acid may make the arthropods palatable.  Ants with their acid sacs surgically removed are not used by birds for anting.  A second hypothesis is that the acid from the ants controls feather mites, fungi, and/or bacteria, all of which can be harmful to feathers. Thirdly, the ants may prime feathers for molting or keep feathers from drying out.  


A final, fascinating hypothesis is that anting serves an autoerotic or intoxicating function.  Look at our flycatcher in the last photograph.  The wings and tail are spread, the body feathers are fuffed out, and its  beak is open.  Anting makes some birds shake and others unable to walk.  I am not sure what an erotically stimulated bird actually looks like, but my guess is that this Great Crested Flycatcher comes close.
UPDATE:  Pam quotes from About.com, "Many birds are observed sunning even on the hottest days, however, and it is believed that sunning can fulfill purposes other than just temperature regulation. Sunning can help birds convert compounds in their preening oil – secreted from a gland at the base of the tail – into vitamin D, which is essential for good health. If the birds have been in a birdbath, sunning can help their feathers dry more quickly. It is even believed that some birds sun themselves for pure enjoyment and relaxation, much the same way humans will sunbathe.


"The most important reason for sunning, however, is to maintain feather health. Sunning can dislodge feather parasites because the excess heat will encourage insects to move to other places in a bird's plumage. This will give the bird easier access to get rid of those parasites when preening, and birds are frequently seen preening immediately after sunning. It is essential to get rid of these parasites – the tiny insects that infect feathers can cause problems for a bird's flight, insulation and appearance, all of which can impact its survival."

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