Here are a couple of photos that show two excellent see-through specializations of Turkey vulturedom: the pervious nostril (already discussed here) and an inner protective eyelid called the nictitating membrane. The camera caught the vulture in mid-blink, so the membrane is visible in this photo as a bluish milky cast over the eye of the vulture — if you click to enlarge the photo to the left, you can easily see it, including the leading edge of the inner eyelid, which slides closed toward the back of the eye. Notice that you can faintly see the bird’s pupil through the membrane: if you can see it, it can see you (like a truck-driver’s rear-view mirror). The lower photo shows the membrane fully closed, and the vulture apparently looking through it at something to the left. (Top photo A. Shock; bottom photo E. Shock)

Most birds have a nictitating membrane (as well as some other animals, like manatees and horned lizards), and in every animal it has the same basic function — to provide a see-through protective lens over the eye which can be deployed during high-risk activities, such as rummaging through a ripe porcupine carcass with a couple of sharp-beaked buddies (in the case of vultures); plunging into a thorny mesquite bosque in pursuit of a road runner (Harris’s hawk); stooping at 100 mph after a mid-air dove (Peregrine falcon); digging in sandy soils, then cleaning and moistening the gritty cornea (horned lizard).

Brief etymology: “nictitating” is derived from Latin nictare, to blink.

HEN UPDATE: The Hen is still tight-on-Nid, having weathered yesterday’s quite breezy atmosphere.

Not much larger than the Verdin is another small gray bird of the Sonoran Desert, the Black-tailed Gnatcatcher.  A tiny, long-tailed, streamlined bird with a narrow gleaning bill, both sexes sport cool gray plumage, and in breeding season the male has a full black cap.  They actively forage for insects in desert vegetation, and are almost always found in pairs since they remain with their mate year-round.  (The similar Blue-gray gnatcatcher comes through the desert around Phoenix in migration, but Black-tailed gnatcatchers are permanent residents here.)  Like the Verdin and hummingbirds, Gnatcatchers are champion nest-builders, and build complex and neatly constructed nests inside thorny trees and shrubs like Palo Verde and Catclaw acacia.  (For more detail, see this life history from the Sonoran Desert Museum website)

On a recent desert hike in the Hell’s Canyon Wilderness west of Phoenix, E and I watched a pair of Black-tailed gnatcatchers nesting, repeatedly disappearing into the interior of a Palo verde just off the trail, only about 4 feet from the ground, which is a typical nest location for these tiny birds.  In the branches midway to the trunk we could see the oblong cup-shaped nest they were working on.

They were working on it, but not in the way we first assumed.  On closer observation, we realized that although the Gnatcatchers were a nesting pair, they weren’t building the nest we could see — they were robbing from it.  Here’s a photo of the male (to the right of the nest) leaving the scene with a bit of white fluff in his beak, on his way to the current construction site somewhere else.  A second later, he flew off, but was back for more in less than a minute.  The bird and the nest are both very well camouflaged in the gray sticks and twigs spotted with sunlight in the depths of the green-branched Palo Verde tree.  (Photo by E. Shock)

And, speaking of camouflage:

Bonus Nidification Challenge — Find the Hen

Obvious hint: look for the bright black eye.  Here’s a bonus if blurry photo of the backyard Anna’s hummingbird hen, from an upper window.  During the morning the Nid-bough is in the sun, and when the Hen sits on the nest with her back to the hot sunlight, it makes her glow like an emerald in the needles. At times when the sun would strike either eggs or nestlings, her incubating actually provides shade and insulation from overheating, rather than the usual keeping warm of eggs or offspring.  A previous successful nest built in the same general area also had the morning sun issue.  Every morning, that Hen would stick tight to the nest until shade returned, holding her wings out over the two nestlings under her, the sun beating down on her own head and back.

(Photo A. Shock.  The resolution of the photo suffers from being shot through a window screen.)

By now I’ve managed to get a look at the nest from the upper window when the Hen is away, and discovered you can’t see the interior from the angle that view provides.  I was hoping to actually see eggs, but no luck…

Here is the Hen today, sitting tight on her tiny cup nest built on two pine cones in our backyard Aleppo Pine.  She fills the whole opening like a cork, horizontally oriented.  Usually we see hummers either air-born or perched, in vertical orientation: it’s the horizontal arrangement, with her tail sticking out behind her and her back practically parallel to the ground, that makes her so Henlike.

She sits absolutely still for long stretches of time, with only the blink of her tiny eyelid to give away her presence.

I’ve been peeking up at the Hen infrequently, so as not to stress her with “eyeball pressure”.  She seems to be on-Nid most of the day.  I’ve tried a couple of times to catch her away from the nest, looking down on the Nid-bough from an upper bedroom window, to try to see eggs, but she’s always been there, strongly suggesting there are.  (The views from above are through a screen, so efforts at pictures from there have been unsatisfactory.)

Assuming she’s incubating now, and has been for a day or two — I’ll use 16 March as an estimated laying date — she will sit on her eggs with no help from the male for about 14 -19 days.  The young will fledge around the 23rd to the 26th day.  That would mean if the nest succeeds (and my calcuations are in the ballpark) the eggs should hatch around April 1, and the young will be in the nest for about another week after that.  That puts the Hen right at the peak of Anna’s breeding phenology according to the Arizona Breeding Bird Atlas, which shows nesting records for the species in the state peak around the start of the month, with a second shorter peak near the beginning of May.

While she’s incubating, an Anna’s female will leave the eggs periodically to feed, primarily on tiny insects like gnats, but fueled with nectar from flowers or sugar water feeders.  We’re keeping our feeders well-stocked and particularly clean (thanks, E!), with the first hot weather of the year.  The garden is more than doing its part, with hummer favorites like penstemon, aloes, desert lavender and above all, chuparosa all in peak bloom.

(Digiscoped photo A. Shock)

Much building activity: as of today the Anna’s hummingbird hen in our Aleppo pine is still finessing her nid.  This morning, she could be seen bustling and fussing at the site (yes, I anthropomorphize, get over it please, I’m not an ornithologist!), making frequent trips away and to, coming back with light-colored fibers, some of which could be seen stuck to her beak in the morning sun.

Beautiful looks through the scope, but focus continues to be a challenge with the camera, as my digiscoping is low-tech (camera lens hand-held to scope eye-piece).  Above is a new shot from this morning.  It’s an action shot, with the downwards-pointed bill apparently in the act of applying fluffy material to the outside of the nest and smoothing it.  The nest is getting taller, and very slightly narrower.

To the left is a photo from this afternoon, where the Hen is screened through the needles at the top of the cones.  Again, click on the photo to enlarge it a little.  You can see her scattering of throat-spangles, which look black because the sun is on her other side.

She seems to be sitting tighter now than in the middle of the day.  Anna’s will sometimes lay before the nest is complete, or rather, continue improving the nest even as they are incubating.

(This photo is with a 250mm lens, not digiscoped, and focus seems a little easier, although obstructions like pine needles are still a bit of a problem for photography, clever nest concealment though they are).

More as it happens, or if I get better pics.

(All photos A. Shock)

The Anna’s hummingbird hen is on the nest! This morning I saw her bringing small beakfuls of fluffy white material like spider web or some kind of aerial seeds and adding them. She would then settle in the cup of the nest, and wiggle a little, as if to get the shape perfect, and run her bill across the outer surface of the nest in what looked like a smoothing gesture.  Being a clever little hen, she’s chosen her site well — it’s hard to see from either above or below, but here is a picture, not well digiscoped but recognizable.

The tiny nest is built on the top of a pair of pinecones about ten feet off the ground.  Though the angle of the photo is from below, you can see the well-compacted mix of material packed onto the cones, with the hen’s little head and beak (pointing to the right) above it.

We have the scope set up a reasonable distance away from the spot on a walkway below the pine, and we can check on her throughout the day. We don’t know if she’s incubating yet, although as I mentioned, construction was still underway earlier today.  Stay tuned!

Photo by A. Shock.

Today I saw the First-of-Season Black-chinned hummingbird for our yard at the back door feeder.  It was a male, as the first birds always are.  He whirred in and made his characteristic little “chup-chup” feeding noise, pumping his longish tail and being generally tidy and well-defined in his gorget feathers, without moustaches.  Black-chinneds typically have longish, slightly-down-curved bills, a fairly flat crown, a sharp color difference between their breast and their chin (the lower edge of which flashes purple in the right light, but looks black otherwise), a graceful silhouette including a narrowish neck (compared to the no-necked Costa’s) and a distinctive s-shaped posture while drinking nectar.

“Black-chins” are breeding hummers here in the Phoenix area, but don’t stay year-round.  They’re with us from about now until late September or the beginning of October, when they return to their wintering grounds along the western coast of Mexico, north-central Mexican highlands or the Gulf Coast of the US.

In other yard hummer news, yesterday E found a female Anna’s building a nest on top of a pinecone cluster in the big Aleppo pine in the backyard.  It’s in the same general area we’ve seen Anna’s nest before in previous years, so it’s either the same bird re-nesting in a favorite area, or just a good place in the tree for Anna’s to build.   This branch has a mixed record of nesting success in the past: one Anna’s nest successfully hatched two fledgelings, but the most recent attempt was destroyed by a predator, perhaps a rat. We’ll try to get pictures and post progress.

The photo above is a male Black-chinned hummer from Wikimedia Commons.  The detail on this photo is excellent; be sure to click on it to enlarge!

…just because this photo of Jack’s King vulture waiting to be taken home makes me laugh.

In the last post on scoters, I forgot to add that there is a surprising Arizona angle to these sea ducks. Some years, one or two are found wintering or in transition on desert lakes around and about the state.  They are categorized as “casual” here.  This winter (Dec. ’08), there was a handful of female or immature-type Black scoters (white cheek patches) seen along the Colorado River near Parker Dam, and a White-winged scoter at Kearney Lake east of Phoenix (Jan. ’09; white cheek patches and white on the wings).

Arizona lakes and rivers contain populations of what are locally called “mussels”, both native and non-native bottom-dwelling bivalves.  Presumably these are what these wayward scoters are living on.

The bird above is a well-documented female Black scoter (Melanitta nigra), photographed at Butcher Jones Recreation Area on Saguaro Lake NE of Phoenix in October 2007.  Find more info and photos at the Arizona Field Ornithologists page.  If you’d like to check out the view or hike or kayak from Butcher Jones beach, here is a link with a map and other info.  Saguaro Lake is an excellent place for birding and hiking Fall through Spring.

Etymology

The etymology of the word “scoter” is obscure, with no satisfactory concensus. The scoter genus, Melanitta, is a Greek compound from Gr. melas, black, and “nitta” which Choate says “appears to be a misspelling for Gr. netta, duck”.  Most scoters are mostly or entirely black, so the choice is apt.  The Black scoter species, nigra, is the feminine form of Latin niger, black, which makes it a black black-duck.  The Surf scoter species, perspicillata, is from Latin and means “conspicuous” (like the Spectacled owl, Pulsatrix perspicillata).  They should just get it over with and say “clownlike”, right?

Photo: A. Shock/Three Star Owl

I’ve been working hard on pieces for the San Diego Audubon Birding Festival, which is coming right up.  While glazing a wall tile with the portrait of a male Surf scoter and looking at photo resources of scoters, I realized I was being treated to another pervious nostril!

It doesn’t show so much in this photo, but scoters, like cathartid vultures, have pervious, or “see-through” nostrils.  In Audubon’s professionally terse words:

Nostrils sub-medial, elliptical, large, pervious, near the ridge.

–John James Audubon, Birds of America, Family XXXIX. ANATINAE. DUCKS. GENUS V. FULIGULA. SEA-DUCK.

If you don’t know scoters, they’re sturdy North American sea ducks who breed in Alaska and northern Canada and winter along both coasts of the U.S.  They dive for a living.  The picture above, by photographer Alan D. Wilson, is a male Surf scoter (Melanitta perspicillata) at Bolsa Chica reserve, in California.  It shows the handsome bird with what is too frequently described as a “clownish bill”, gliding in the blue backwater of Bolsa Chica Wetlands.  If you’re wondering why the “clownish bill” is so big, scoters eat hard food, some of which — like blue mussels — needs to be pried off of rocks underwater.  In summer, they favor marine invertebrates, in winter, mostly molluscs.

As for the pervious nostril in scoters, I haven’t turned up a definitive discussion yet, but most sea birds need to rid their systems of salt, often by sneezing or dribbling it out through the nostrils, and have evolved various nostrillar adaptions (again, a technical term) to do so: pervious nostrils would not easily become clogged with expelled salt crystals.

To the left is Audubon’s plate of Surf scoters — at the time called Surf Ducks — from Birds of America

Three Star Owl will be at the San Diego Birding Festival in Mission Bay San Diego, 5-8 March 2009.