Anhingas, oil glands, and corrugated tail feathers

Erika and I saw many Anhinga during our recent Florida trip.  Anhingas are also called snakebirds because of their habit of swimming with only their long necks above water.  (The word Anhinga comes from a Brazilian Indian word for devil bird.)

Before writing up this blog entry, I had always assumed that birds' oil glands water-proofed their feathers, and that the Anhinga's habit of habitually holding their wings out to dry might mean they might lack an oil gland.  I have learned, however, that oil glands do not water-proof feathers--ducks with their glands removed still have water-resistant feathers.  The water proofing is in the feather structure. (Cornell Lab of Ornithology Handbook of Bird Biology)

Anhinga feathers are less resistant to water than other birds such as cormorants, which allows Anhingas to do that neck-above-the-water swimming, with their bodies submerged.  But, compared to cormorants, they must spend more time drying themselves out.

Ornithologists are well aware of the transverse corrugations on Anhinga central tail feathers.  These can be seen on the tail of the Anhinga photographed above (click on the photo for a larger image).  I am unaware of similar structures on other birds (perhaps some hornbills?)  None of my sources suggest a reason for this structure. (Notice that this bird has speared what appears to be a sunfish, and that its head feathers are remarkably wet.)

Florida

When folks return from trips, I always ask what was the best bird they saw.  In January 2010, Erika and I traveled to Florida, where friends invited us to spend two weeks at their condo on Sanibel Island.  We had a wonderful trip, adding about 120 species to my 2010 bird list.  Ever since Audubon's time, Florida has been famous for the tameness of its birds.  There are fewer birds in Florida now, but many of them are remarkably tame--a bonanza for a photographer.  My ever-growing Picasa site, http://picasaweb.google.com/danerika/Florida, has many of the pictures we took.

So what was my favorite bird?  Has to be the Florida Scrub Jay, since this was my 713th "North American" bird sighting.  (North American is in quotes since I count my North American birds wherever I see them, even outside the continent.)  We found the Florida Scrub Jay in the Merritt Island National Wildlife Refuge, just north of Cape Canaveral.  We had unsuccessfully searched for the jay for a day and a half, when Erika suggested we try the "Scrub Jay Trail."  "Unlikely," I replied, "How can they know there will be Jays down that particular trail?"  But, sure enough, at the far point along the trail, this Florida Scrub Jay tamely awaited us.

Erika's favorite bird is probably the Limpkin, found by some local birders for us.  They took us right to the spot, just east of Fort Myers, and there they were, three of them.  We walked for about an hour, but upon our return the Limkins were nowhere to be found (although we did hear them wail from the swamp).  The Limpkin is a bird we first found in Ecuador, so it was not new for our list, but this was our first North American sighting.

We missed seeing any Sail Kites.  This species apparently disappeared from the Fort Myers region just before the recent Florida freeze.  Nobody knows exactly why.  The kite was common enough in early December.

Falcon Nasal Baffles

A structure almost unique to the falcons is a baffle in each nostril.  Conventional wisdom is that these baffles regulate airflow, which would be handy if you were diving at speeds up to 200 mph or so.  Other hypothesis, however, include that the baffles measure air speed or in some way help with the sense of smell.  Curiously hawks, which also dive, lack these baffles.

A baffle can be easily seen in this young Peregrine Falcon, which was recovered in Canon Falls, Minnesota in July 2009 and was transported to the Minnesota Raptor Center.  Unfortunately, this bird did not survive. (It had fledged from the Wells Fargo building in Bloomington, MN.)

Races of White-crowned Sparrow

Z. l. leucophrys

 

 Z. l. gambelii

Look carefully the next time you see a White-crowned Sparrow, Zonotrichia leucophrys.  Four races (= subspecies) are currently recognized by the American Ornithologists' Union.  Two can be found in Minnesota--see photos above.  They can be told apart by the lore color (between their eyes and bills) and perhaps by bill color. These races are shown in Sibley, but the illustrations are not labeled scientifically.   The National Geographic guide (third edition) does a better job

The range information quoted below is from Chilton, G., M. C. Baker, C. D. Barrentine and M. A. Cunningham. 1995. White-crowned Sparrow (Zonotrichia leucophrys), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/species/183

Birds with black lores,  Z. l. leucophrys, breed "in north tier east of Hudson Bay, in Rocky Mountain ranges from s.-cen. Canada south through n. New Mexico, in various Intermountain Ranges south to cen. Nevada and s. Utah, and in Cascade-Sierra Nevada axis south to s. California; winters in lowlands across southern tier of United States, generally rarer westward." Their bills are pink. (The photo above was taken near Dundas, MN.)

Birds with gray lores, Z. l. gambelii, breed "across northern tier from Alaska to Hudson Bay; winters south through cen. Mexico, generally rarer eastward." Their bills are orange or pinkish orange.  In the Hudson Bay region, birds intermediate between these two races can be found (although I have never seen an intermediate bird). (The photo above was taken in Aberdeen, SD.)

The other two races of White-crowned Sparrow are found along the Pacific coast from British Columbia south--Z. l. pugetensis is the most widespread (the slightly larger Z. l. nuttalli is found south of Los Angeles).  Both of these coastal races are unlikely to be found inland, even in winter.  I took the photo below at Morro Bay, California.  Note the brownish back and underparts, dusky white head stripes, and yellow bill.

 

Z. l. pugetensis

First Year Downy Woodpecker

If you ever get a chance to closely observe Downy (and other) Woodpeckers closely, note their primary coverts. These are the feathers that cover the outer flight feathers.  Notice in these photographs that these feathers are not as jet-black as either the flight feathers or the other feathers near them. This dullness of color indicates a bird born in the immediate past breeding season. The reason for this color differences is that North American Woodpeckers retain their juvenile primary coverts even after they molt their other wing feathers.

Pileated Woodpecker 1, Bander 1

Score one for the bird--my banding notebook was covered with my blood after the woodpecker finished with me.  Score one for me, this Pileated Woodpecker is only the second of my banding career.  This species is fairly common in Minnesota but was not found where we lived in South Dakota. Notice that the bird closes her eye as she pounds my finger. 

Mike Hendrickson of Duluth recently commented that this fall has been relatively slow for birders state-wide.  I am sorry to report that I agree with his assessment, at least as banding has fared here in the east-central part of the state.

The few animated .gif files like the one above are made at the website: http://www.gifninja.com/  

Favorite Bird

I am sometimes asked what is my favorite bird.  Erika says my favorite bird is the last one I've seen.  I maintain my favorite is the Common Loon.  I love their long dives, their ability to slowly submerge like a submarine, and, of course, their yodels and cries echoing across the northern wilderness.

Black-throated Blue Warbler

I banded and released this Black-throated Blue Warbler on 20 October 2009 in Northfield, Rice Co., Minnesota.  One of the joys of banding birds is encountering uncommon species.  This warbler breeds  in Minnesota only in the far northeast and is an uncommon to rare migrant elsewhere in the state.

Hermit Thrushes

I have been banding many Hermit Thrushes this fall.  If you look at fall thrushes, especially Hermit Thrushes, carefully, you will notice that they often have spotted secondary coverts.  These are unmolted juvenile feathers, indicating that you have a bird hatched this calendar year. (Birds without secondary spots are not necessarily adults, however, since the spots eventually wear away.)

How does one find joy in common birds?

Al Schirmacher of Princeton, MN, asked the MN-listserv, "How does one find joy in common birds?"

Digital photography has revolutionized my birding.  Today I caught only my second crow, which I banded and photographed--a common bird but not so common in the bird net.  This  bird was with about six others drinking at our backyard water feature. (Note the dull alula feather--an indication that this bird was hatched this year.)

Now I am just as likely to chase after a good bird photo as an unusual bird report.  One day in South Dakota I went out in search of displaying Red-winged Blackbirds.  Imagine my surprise when I found this odd Red-wing!

It also proved hard to find a decent House Sparrow photo.  I spent the greater part of a day in search of this photo: