Whenever you get into a new realm of study, there are so many new words to learn! I borrowed an ornithology textbook from one of our college interns, so I could study up. I’m going to have to return it to her LONG before I can get through even a small fraction of what’s in it! Guess I’ll just have to do what I always do: take it a little bit at a time.
This week, I’m trying to learn about Rictal Bristles. At bird banding, I learned where to find them:
Now, what are they?
Well, let’s do “rictal” first. (I had never heard that word before starting bird banding, though I had heard a similar word that has nothing to do with this!) From The Free Dictionary:
ric·tus (r k t s)
n. pl. rictus or ric·tus·es
1. The expanse of an open mouth, a bird’s beak, or similar structure.
2. A gaping grimace: “his mouth gaping in a kind of rictus of startled alarm” Richard Adams.
ric
tal adj. |
OK, got it! So, rictal has do do with the mouth area, or beak – if you’re a bird. And now, rictal bristle, from encyclopedia.com:
rictal bristle
A Dictionary of Zoology | Date: 1999
rictal bristle A stiff, modified feather, with little or no vane, found around the gape of many insectivorous birds, possibly serving to aid the capture of food in flight.
So there you have it. Except, no you don’t. Because I kept googling to learn more… And I discovered that there isn’t a clear answer as to what the function of the bristles is!
For a long time, scientists assumed that the bristles may help with the capture of insects during flight. However, in one study, this was proven false:
I have direct evidence that, at least in several tyrant flycatchers, rictal bristles perform no function associated with prey capture. With the use of a high-speed motion picture camera, I photographed mid-air captures of flesh flies (Sarcophaga bullata) by the Crested Flycatcher (Myiarchus crinitus), Eastern Phoebe (Sayornis phoebe’), Eastern Wood Pewee (Cantopus virens), and some Empidonax species which could not be identified in the film. The films were taken while the birds were confined in a large glass-fronted cage into which the flies were introduced. Photographs. were taken at the rate of 375 frames per second and analyzed on a stop-action projector. Over 30 sequences of prey capture were recorded and in every instance in which a capture or near-capture was made, the insect was caught between the tips of the mandibles. The prey are captured in the bill tips, rather than farther back in the mouth as would be the case if rictal bristles were utilized. (source)
Another study, in which the bristles were either taped or removed, gave similar results: the birds were able to capture food just as easily as when their bristles were untouched. In this study, they found, however, that birds with no bristles were much more likely to be hit in the eyes with flying insects than birds with bristles intact, suggesting that the bristles’ function is protection – just as our eyelashes and eyebrows help keep stuff out of our eyes. (source)
The Cornell All-About-Birds site makes these cautious statements:
Rictal bristles project from the beak of many insect-eating birds, including flycatchers, nightjars and even the American Robin. They are believed to provide protection for the bird’s eyes as it consumes its wriggly prey. The bristles may also provide tactile feedback, like the whiskers on a dog or cat. (source)
“They are believed to…” “The bristles may…” In other words, scientists aren’t really sure what they do!
Learn more:
Filed under: bird banding, bird conservation, bird research, birds, nature
