The Carlisle Mosquito Online

Friday, December 7, 2007

Features


Ash-throated Flycatcher

(Photo by Ian Davies)
Now and then, a bird turns up in an area, way outside its usual range and gives people an opportunity to see a species they would otherwise have to travel far to see or be content with pictures in books. Remember the sandhill cranes that made a brief stop at the Cranberry Bog in April 2005? A similar situation occurred this November when Jan Sacks and Marty Schafer of Acton Street spotted a bird that turned out to be an Ash-throated Flycatcher. The normal winter range for this bird is Arizona, southern California, and northern Mexico. Its summer range is also in the west and extends no further east than central Texas. This particular little flycatcher is what birders call a "vagrant." It is not like the sandhill cranes that were taking a break on a journey. It is somewhere it shouldn't be, and its chances of surviving the winter are grim.

Name. The Ash-throated Flycatcher is Myiarchus cinerascens. It is a member of the Tyrannidae family, the Tyrant Flycatchers, which also includes Pewees, Phoebes and Kingbirds. The genus name, Myiarchus, is derived from the Greek where "myia" means a fly and "archos" means a ruler. There are several species in the genus but only one, the Great Crested Flycatcher, breeds in our area. Flycatchers — as you might guess — eat flies. They eat other insects too and small fruits but their name is apt because flies are their staple. I'm not sure about the "tyrant" name but Myiarchus flycatchers are known to occasionally take prey as large as dragonflies, hummingbirds and small lizards.

Identification. The Ash-throated Flycatcher is easily mistaken for the Great Crested Flycatcher. The differences are subtle. Like all Myiarchus flycatchers, they both have bushy crests and long tails. The coloring is similar — back is brown, tail reddish, throat and chest are gray and the belly is yellow although the throat, chest and belly are paler in the Ash-throated. Expert birders came to Carlisle to look at this bird and agreed that it was indeed an Ash-throated. Markings on the tip of the tail feathers provided confirmation. Coloring is similar for both genders. This one is probably a male — it didn't ask for directions along the way. Now it's a vagrant. Enough said.

Behavior. Some birds are adept at keeping a few twigs or some kind of cover between themselves and any potential threat. This flycatcher was not at all shy of humans, which was a great help to the birders in getting a good enough look for identification. It got so close to one birder that he couldn't focus the telephoto lens of his camera. Marty has noticed that the bird follows him about the yard and perches nearby. It is probably watching for flies that he might disturb since these birds are sit-and-wait predators. They don't use their bills to fossick in the litter and flush out their own prey. When an insect happens to fly into view, they catch it in the air with their bills. They also spot insects in plain view on the ground or on vegetation and pick them off. Jan and Marty's bird has been finding insects attracted to the warmth on the sunny side of the house.
The Ash-throated Flycatcher is caught in mid-flight. The tail-feather markings helped in identifying the bird. (Photo by Marshall J. Illiff, project leader for eBird, www.ebird.org)


Nesting. Flycatchers in the genus Myiarchus nest in tree cavities or in suitable man-made structures — like blue-bird boxes. As a group, the genus is noted for using snakeskin in their nests but the Ash-throated Flycatcher is the renegade. Only about 5% of Ash-throated nests have snakeskin while almost all of them have mammal hair, mostly from rabbits.

Keep looking — there may be more. Paul Buckley, senior scientist emeritus, Pawtuxent Wildlife Research Center, Maryland, and a past resident of Carlisle, provided the following information on the subject of western vagrants. For 10 or 15 years, western species have been turning up in the east, usually after a period of very strong winds from the southwest. These vagrants normally include an occasional Ash-throated Flycatcher. This year has seen the largest influx ever of western species, including a higher number of Ash-throated Flycatchers. So far, there have been approximately 20 sightings in the east from Newfoundland down to Virginia. Simon Perkins, staff ornithologist at Mass Audubon, confirmed that the Carlisle bird is the only one from Massachusetts.

References. National Geographic Field Guide to the Birds of North America; Sibley Guide to Birds by David Allen Sibley; Sibley Guide to Bird Life and Behavior by David Allen Sibley; Cornell Lab of Ornithology at www.birds.cornell.edu.

Submissions for the Biodiversity Corner are encouraged from everyone. What are you finding? Write the whole column or just send a note or a photo to Kay Fairweather at kayfair@comcast.net.


2007 The Carlisle Mosquito