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.