Black-winged Redbird

I headed over to Barr Lake State Park today, just north of Denver International Airport. I was meeting my parents Jim & Karen and my niece Abby, with my little guy Garrett in tow. He idolizes Abby and was pretty psyched to see Grandpa and Grandma, too. I was anticipating a pretty mellow outing, birding a little but mostly wrangling the kid and just enjoying a nice day in the sun. We were about 5 minutes from the rendezvous when my phone rang- my dad was calling. I figured he was just calling to say he was there, which was half right, but he also mentioned that they were looking at a Vermilion Flycatcher out their windshield at the Nature Center parking lot!! Bonus!!! Abby had seen the red dart fly into a tree right in front of their parking spot- serendipity, baby! Here's the spotter and spottee, respectively:

The bird was quite cooperative, offering great looks as it dived on small moths on the ground from mullein and cottonwood perches. I hope it fully topped off the tummy- a foot or more snow is forecast for tomorrow. It is only the second VEFL I've seen in the state (indeed, it is a review species here), and my reel of pics from the day has better shots than any I've gotten before in TX & AZ. As a birding companion from Australia once commented, What A Crippler! My retinas are blistered by that unbelievable red, a most welcome focal point on a stage of browns and grays.

Hawk Watching

Over the weekend I went to the Dinosaur Ridge Hawkwatch, located near world-famous Red Rocks Park west of Denver. Sadly, the count there has seen a gradual decline in recent years, and this year there is no funding for a permanent hawkwatcher. Still, it is a nice place to hang out, tune up on on raptor ID a bit, and see what else is around in the rocky, scrubby foothills habitat. Plus, you never know what else you'll see up there- we tallied one crunching car wreck below on highway C470 and two paraglider flybys from Lookout Mountain to the north- they hardly ever make it this far down but conditions were right to ride the wind kicking up the ridge from the east that day, I guess.

The raptor flight was pretty slow, but nonetheless my dad & I had nice looks at a Cooper's Hawk and a Prairie Falcon in addition to local & migrating Red-tailed Hawks (their status judged by behavior and northerly progress. For example, the local pair will often escort lone migrants along and then turn back. Sometimes they get more aggressive, dropping talons or diving on migrants exhibiting the bad manners of flying through their airspace.) I had hoped for a few more accipiters to do a little more comparison work (particularly that big gray one, but my new theory is that they don't really exist. I think photos of that unmentioned species are just Photoshopped Cooper's Hawks...) Still, this adult Coop spread out into the classic soaring pose above us, big head projecting beyond the straight leading edge of the wings and with nicely graduated tail feathers (longest in the middle) conspicuously arranged.
Similarly, I wouldn't have minded a bit more falcon variety in the mix, but this Prairie Falcon made a few lovely turns at about eye level as it made its way northward along the eastern margin of the ridge. It certainly had its eye on me- wondering what the big eye was looking back at it, I'd guess. A bit of tail molt going on there, too- R4 missing (the 4th tail feather out from the middle), creating a light gap near the outer edge on each side.
Still, I'd have to say the action that day was better in the non-raptor category. A few sorties of Mountain Bluebirds made their way along in migration, and Ravens rode the wind in hawk-like fashion, unlike the American Crows that also went by a few times, flying with a lot less panache. One raven made a couple of laps up and down the ridge, recognizable by the missing primary in the left wing and its very tattered plumage- looks ready for a new set of feathers ASAP!
I always like the songbirds that are on the ridge, and Saturday's visit (my first in this habitat this spring), brought me my year Bushtits, Western Scrub Jays, and Spotted Towhees, along with Canyon Wren. The Canyon Wren was feeling frisky, singing from near and far- often at the edge of earshot but sometimes choosing a conspicuous post on a rocks right in the hawkwatch area. There was a calling female around, too, no doubt encouraging her mate to show off. These are the best shots I've taken of the species, which is usually out of reach up on cliffs or in rocks beyond good photography range (especially since the bird is so small.) It is one of my favorite birds, always invoking memories of canyon country and western tableaus. I particularly enjoy the combination of their descending song bouncing off towering cliffs, accompanying the soft slapping of water on canoe hull and splash of paddle on river trips through Canyonlands. I hope you enjoy these pics as much as I enjoyed taking them.

Ducky Iridescence

Many ducks, especially drakes, have wonderfully iridescent feathers on their heads & wings. This type of coloration is not due to pigmentation. Instead, it is due to microscopic structures that cause constructive & destructive interference of light waves, creating the changeable metallic sheen of iridescent feathers. For more on multiple-beam interference and some great examples of iridescent structures (non-living & living), click here.

Many birds are well-known for their distinctive iridescent feathers, including hummingbirds and peacocks. But the reason I'm bringing this up with ducks is that their head colors don't always match what you'll find in field guides. A hallmark of iridescence is that the colors you see can change depending on the angle that the light is hitting in reference to your vantage point. For ducks with iridescent heads, the color(s) illustrated in field guides may be typical under most conditions, but you will see differences if you watch ducks long enough.

Take, for example, these nice male Northern Shovelers I saw last weekend. In situations where the bird is well-lit by sunlight from generally behind the observer, the nice metallic green head exhibits itself, matching my field guide illustrations.
But when the bird is backlit, the head looks about black. Iridescent feathers often have very dark pigmentation, and when sunlight is insufficient to create the wave interference patterns responsible for iridescence, the ground color shows through instead.
It gets fun when sunlight hits the shoveler at an obtuse angle (a nearly backlit bird), resulting in an intense purple iridescence where the bird normally would look black or green.

In some guides, our two scaup species are shown with different head colorations on the males. Lessers are painted with purplish heads while Greaters show greenish heads. Again, this may be the case in many light conditions, but either species can show plain black along with metallic green or purple sheens depending on the lighting. In other words, I'd rely on other field marks besides head color in Scaup. So why is this a Lesser Scaup? I first key in on head shape. While that, too, can vary depending on how the bird holds its feathers (relaxed vs. alert, for example), the peak of the crown is consistently behind the eye, often quite obvious as a little tuft vs. the subtler peak on Greaters. On a Greater, the peak is above or in front of the eye. Also, the nail (black tip area) on the bill of this Lesser Scaup is fairly small and parallel-sided, vs. the larger, wedge-shaped nail on a Greater. Greater bills also look bigger to me- more dramatically-schnozzed birds. Here's the same cooperative Lesser Scaup that I posted previously, in various poses showing purple, black, and green head aspects:

So keep an eye out on iridescent duck heads- even the classic "green head" Mallard can look black or purple instead.

Catch Me If You Can

I know it's short notice, but if you are in the Boulder area and want to catch my talk Out of Breath Birding: The Timberline & Tundra Ecosystems of the Central Rocky Mountains, I'll be presenting it tonight for the Flatirons Ski Club at the Boulder Best Western Inn. Social time starts at 7, business & announcements at 7:30, and my talk at 8. Hope to see you there!

A Simpler ID

After my adventures with the Slaty-backed-like Gull yesterday, I went to Belmar Park in Lakewood, which sports a lake that waterfowl (including divers) are fond of. The lake also has several good vantage points including several viewing decks, and some fairly tame birds. Much to my delight, a couple came along armed with a bag of bread and attracted this Lesser Scaup along with the usual Ring-billed Gulls, Mallards, and Canada Geese. The hilarious thing is that even though the scaup was picking up some bread, it kept diving while it fed- force of habit, I guess. The tricky part was getting the bird framed clear of the rest of the birds, but I stayed with it and got probably my best shots of this species, which I've usually found to stay frustratingly far out from shore.

More Gull Puzzling

Here's an interesting gull that I found today with my dad Jim & Mike Freiberg at Cherry Creek Reservoir in the SE Denver Metro Area. Much about it reminds me of a potential 1st-cycle Slaty-backed Gull that Christian Nunes found in Boulder last November. Size was quite similar to a nearby adult Herring Gull. Getting a little zonked for much analysis now (here's my post to Cobirds for a little more description), but check it out & let me know what you think. As always, click images to enlarge.

Ross's Portraits

Yesterday, I found a cooperative Ross's Goose at Golden Ponds in Longmont, Colorado. A birding pal had told me about the bird a week earlier but I hadn't been able to find it then. Checking yesterday, I noticed a very small white bird in with large Canada Geese on a little residual ice shelf- cha-ching! This is about the only case where I like these big park geese- since they are so tame, they keep interesting birds like this Ross's Goose calm. They weren't even very nice to the Ross's- when it got too close to a massive Canada, the big goose would shoo it away, biting at its tail. Whatever the case, I slowly worked down to get some shots from the bank, waiting for chances to tunnel through the big geese to get some shots of the Ross's by itself. After a while it retired to the water but stayed nearby, paddling along in the mini iceberg-laden water, accompanied by its reflection. I think this bird makes a great comparison to the Snow Geese and odd Ross's Goose hybrids I recently posted- check them out if you haven't done so yet.

Four Corners Fun

Folks- I'm happy to announce that I'll be the keynote speaker at the 5th annual Ute Mountain-Mesa Verde Birding Festival based in Cortez, Colorado, 14-17 May 2009. Come on down to the fabulous Four Corners region to do some birding & take in the sights! If you've never been to Mesa Verde then that alone is worth the price of admission! And there's nothing like standing in 4 states at once. Hope to see some of you faithful readers there!

Faces in the Crowd

I headed over to a local birding hotspot in southern Boulder County, Colorado the other day to follow up on some reports of interesting geese. Pulling in to Stearns Lake with tasty late afternoon light, I immediately saw that I'd be able to burn lots of 1's and 0's on my memory cards. I toted my DSLR rig but also got set up to digiscope, as the geese out on the lake were mostly out of telephoto reach (at least for detailed photos.) One notable exception, though, was this white-morph Snow Goose, which for a while was about the closest bird to shore. Gotta photograph something that bright! I then scanned a sleeping bunch of geese on some fairly close residual ice, finding two with white heads and dark bodies. One obligingly woke up and looked around- a dark-morph Snow Goose (aka Blue Goose.) Sharp bird- after churning around for a while looking for accomplices it headed east, presumably to feed in nearby corn fields. Interestingly, the two Snow Geese were about the biggest geese on the lake- almost all of the white-cheeked geese present (a few thousand) were lesser Canada Geese (parvipes subspecies) or Richardson's Cackling Geese (hutchinsii subspecies.) Mainly, though, I was interested in studying and photographing birds that had been reported as possible dark-morph Ross's Geese (a very rare form, one I've never seen.) The other white-headed, dark bodied ice sleeper soon awoke and began swimming, clearly one of the birds of interest. I digiscoped a bunch of snaps and got a flight sequence on the ol' DSLR when it shuttled towards the main crowd of wee white-cheekers, where it soon immersed itself. I immediately saw why it was a noteworthy bird, but as others had noted, it didn't quite fit the (few) illustrations, photos, and descriptions available for a dark-morph Ross's Goose. Neat looking bird, but danged confusing. As if that wasn't enough, there was another similar bird on the lake, but with a gray bill instead of the pink (indicative of an immature bird.) The bill shape on this one was a bit more Snow Goose like, but the bird is tiny, the size of a Cackling Goose or perhaps even a bit smaller. And there was one more immature bird present with a more gray face, looking a bit like a juvenile Blue Goose but again too small for even lesser Snow Goose.

Unsure of what to call these, I sent photos to some waterfowl ID pros who concurred none were clean Ross's Goose, instead probably hybrids (with Ross's x Cackling Goose high on the suspicion list for the adult bird.) Waterfowl expert Steve Mlodinow of the Puget Sound Bird Observatory offered these comments, comparing similar goofy birds he's observed in Washington:

These birds remind me of a series of birds that appeared in se. WA (and one in sw. WA). Ours were all adults, and all had this very dark body, darker than any white-cheeked goose, much like your adult. Head patterns varied, were all something between a Snow or Blue and a Canada. Size was similar to a parvipes. Bill kind of in-between Snow and Lesser Canada. In other words, they looked like your adult, but yours looks more like it has Ross's and Cackling as parents.

And the imms are even more confusing, because the bills seem to look like they have Snow Goose in 'em, not Ross's, but the birds seem too small to have Snow Goose as a parent. In any case, none of these are blue morph Ross's, nor are they some dwarf Lesser Snow. The head and bill would argue that they couldn't be an aberrantly plumaged Richardson's. At first blush, it seems almost inconceivable that the adult is not part Richy and part Ross's, but then how does one get the super dark body plumage. Then one would have to postulate a BLUE MORPH Ross's x Richardson's, which starts to seem increasingly improbable. But if it waa a blue morph Ross's x Richardsons, then how does the head and neck get to be so white.

If he was a bit stymied, then I don't feel so bad for being confused by these birds, too. Steve surmised:

The answer, in the end, to this brand of oddity is likely to be had in an aviary... we need to find someone who has a blue morph Snow x white-cheeked Goose and see what they look like and the variation therein. Particularly a heterozygote Blue morph x white-cheeked might produce some of these odd features. In your case, it would likely have to be a heterozygote Ross's x white cheeked. Or then you wonder, could this be one of those odd birds with more than two species genes involved. It happens in captivity, but I don't know if it happens in the wild.

Fellow appreciator of odd birds (master bander, ornithologist and my pal, too) Tony Leukering added these comments (ROGO= Ross's Goose, SNGO= Snow Goose, CACG= Cackling Goose in banding codes):

I agree with Steve that none of these birds are blue ROGO. The last one certainly looks a lot like an imm SNGO, but smaller than CACG??? I think that most of us believe that F1 hybrids have to have some combination of parental traits and intermediate traits, but if one looks at dabbler hybrids, we can see that most F1 male hybrids have some patch of white/pale on the head that is not expressed in either parental species. Perhaps, hybrid geese do similar things. Of course, white head and neck could be a dominant gene expressed in such hybrids, too. The adult is certainly somewhat ROGO-like, but, possibly, SNGO x CACG could account for its parentage. However, the bit of blue at the base of the bill (but not nearly as much as is typical of adult ROGO) does suggest ROGO genes (though I don't see much expression of the usual tubercles on the bill of that taxon).

So what's going on here? Any one of these would be a head-scratcher, but three such birds at the same spot? I guess the two juvs could be from the same clutch but what about the adult?
And none of the three were associating with each other within the large flock- you'd think if they got there together they'd stick together. Anyone know a waterfowl breeder who may have combos that look like these?

One more odd bird was at least a lot easier to explain- a leucistic Canada Goose. Interesting that the neck and head pigmentation is normal while the body is "dilute", although I've seen other similarly differentiated geese where the head was normal but body abnormal, or visa-versa.