Friday, January 31, 2014

Snowy Owl Yawn 2

I drove John Holden over to the fields east of Vermillion, Minnesota, from whence Erika and I previously blogged about seeing a Snowy Owl. The day, 29 January, was beautiful but frigid. In short order we found this owl atop a utility pole. The bird paid us little attention. We were able to approach relatively close, but we took pains not to disturb the bird.  I wonder if this bird is yawning, or if it is gagging on an owl pellet. Erika’s cats wander around the house gagging as they prepare to spit up hair balls—perhaps owls behave in a similar fashion.  In any case, I never observed any pellets falling from the owl and, for fear of disturbing the owl, we did not look under the pole for pellets. A study of pellets would indicate what these owls are eating (in southern Alberta, deer mice and voles constitute about 90% of their diet (Parmelee 1992)).
Perhaps one reason for the owl's tameness is that the bird appeared to be sound asleep. Once or twice the bird half-opened its eyes, but the owl seemed to be more concerned about a snow grader approaching down the road. The bird never flew, and we left before the arrival of the snow plow.

Wednesday, January 29, 2014

Yellow-billed Cuckoo

Yellow-billed Cuckoos don’t begin to breed until local food supplies—caterpillars and/or cicadas—are abundant. Cuckoos build flimsy nests. Once begun, the breeding cycle is rapid—only 17 days from egg-laying to fledging. But the story is even stranger, as both Yellow-billed and Black-billed cuckoos are North America’s only altricial “facultative, interspecific brood parasites.” (Cowbirds are obligatory brood parasites.) Sometimes they lay their eggs in other species’ nests—usually robins, catbirds, and Wood Thrushes (and, occasionally, eight others).  The biology of this parasitism is not understood. The cuckoos may time extra egg production with abundant food and may choose their hosts so that their egg color matches the host eggs. Finally, Yellow-billed Cuckoos have nested cooperatively, with three or four adults occupying a single nest (Hughes 1999).

A folk name for the Yellow-billed Cuckoo is Rain Crow. Cuckoos may call most frequently on cloudy days, but their ability to predict rainfall in unproven. 

Monday, January 27, 2014

Chestnut-collared Longspur

As we suffer yet another series of bitterly cold winter days, I find myself searching my digital photo albums for species as yet not written about in this blog. One of these birds is the Chestnut-collared Longspur. The numbers of these grassland birds have declined with the disappearance of native prairies. Curiously, however, the species prefers disturbed grasslands, such as those created by fire or herds of buffalo.

This photo was taken in western South Dakota.  In the Dakotas, Chestnut-collared Longspurs are still often abundant. Their territories are often clumped near each other and the species is often double-brooded. They are socially monogamous, but  often engage in extra-pair copulations. Most extra-pair young occur in the second nest of the season (Hill and Gould 1997).

Saturday, January 25, 2014

Red-billed Scythebill

Scythebills are woodcreepers. They look a bit like woodpeckers or creepers, but are not closely allied to either. Instead they are closely related to another South American family, the ovenbirds.

Red-billed Scythebills inhabit the Amazon Basin, where they can be fairly common but are patchily distributed.  The species forages for arthropods in bamboo. Most of its prey (about 75%) is extracted from holes made by other birds in the bamboo. The species is intolerant of human activities in the forest, and is considered to be an indicator species of forest health (Birds of the World—Alive).

Erika and I worked very hard on our dissertations while we were in eastern Ecuador. We had little time for recreational birding or photography. One exception was a project to take photographs of a few birds we netted. To get closeup portraits, yet retain an illusion natural background, we released the birds in a parachute-covered box.

Thursday, January 23, 2014

Eurasian Collared-Dove

On 21 January, I photographed this collared-dove in Dennison, Minnesota. A dozen or so were reported from this small town the day before by Dave Bartkey. Erika and I had little trouble relocating the birds—a new check for my Goodhue County bird-list.

As I peered through my lens, a nearby house-owner asked what I was looking at. As in a recent post on this blog, I explained how this species had begun in the Middle East and spread across Europe and, eventually, North America. The woman with whom I was speaking seemed genuinely interested and expressed surprise that a Middle Eastern dove could survive Minnesotan temperatures below zero. I pointed out that several bird-feeders graced Dennison, as did the local, and rather large, grain elevator. Actually the reasons for this dove’s success are unknown, with suggested hypotheses of genetic changes in the bird’s DNA, and changes in the world's environmental conditions.

Tuesday, January 21, 2014

American Goldfinch

Mid-January seems early for an American Goldfinch to begin molting into its breeding (alternate) plumage. Attaining breeding plumage is a prolonged process, but some goldfinches have just molted into their winter (basic) feathers by this time (McGraw and Middleton 2009). In any event, we can see this male is in its second year, since the shoulders are not uniformly yellow. As spring approaches, the crown will become black and the body, bright yellow. In its present plumage, this bird might give beginning birders some trouble—I can find no illustrations of an Eye-browed Goldfinch!

Sunday, January 19, 2014

Bald Eagle

Last week John Holden and I ended up in Prescott, Wisconsin, at the confluence of the Mississippi and St. Croix rivers. We missed the target species of the day, Snowy Owl and Long-tailed Duck. With ambient temperatures around zero degrees F., we found the little open water to be full of goldeneyes and mergansers. We did enjoy watching a dozen Bald Eagles fishing along the Mississippi River. 

Bald Eagles are opportunistic feeders. Generally they prefer fish, alive or dead.  They also take birds and mammals, and are not adverse to carrion. They congregate at Alaskan garbage dumps (Buehler 2000). As you can see in these photos, the ducks paid little attention to the eagles, unless the raptors came too close. Note the splash to the right of the eagle made by the diving goldeneye in the center photo. The goldeneye probably had cause for alarm, because, as reported by observers, a local eagle did carry off the Black Scoter that John and I saw last December.

Friday, January 17, 2014

Pileated Woodpecker

My first Pileated Woodpecker for the year was at the Holden’s feeder. Once on the list, the species appeared in our back woods. I was surprised to see that the tips of the bill don’t meet. I thought the tips would form a solid surface to enable the pounding. A quick and cursory review of some of the literature fails to find mention of this trait. Can woodpeckers flex their bill tips, perhaps aiding in consumption of tree fruit or suet?
Jerry Jackson, a woodpecker expert, writes that having a bill tip gap is normal. He continues, “the jaws also have some flexibility so that a woodpecker can manipulate small things. Ivory-bills have similar gaps at the tip of a bill that is at rest.” 

Wednesday, January 15, 2014

Merlin IDs House Finch

Merlin is a new, free iPhone/iPad app from the Cornell Laboratory for Ornithology to assist beginning birders. When you see a bird, what Merlin does is ask you five questions. Where are you? (Merlin automatically knows your present location—but perhaps you want to identify a bird from somewhere else.) When did you see the bird? (Merlin knows today’s date.) What size is the bird? (Sparrow, robin, crow, goose?) What are the main colors? (You have nine colors to pick from, and you can pick more than one.) What was the bird doing? (At a feeder, swimming, soaring, etc.) 

And, voila, you are presented list drawn up from current, local eBird records of possible birds matching your answers. Despite only including 285 species of birds, the odd thing is that this app seems to work. Merlin had no trouble identifying both sexes of House Finches currently flocking at my bird feeder. My non-birding son in Seattle only looks at birds in his backyard and was pleased when Merlin identified a Red-breasted Nuthatch for him.

If you are a beginning birder or know someone who is, I think it is worth your time to investigate Merlin by clicking on this link: Merlin Bird ID. Note that you do need a WIFI connection to download and use the app—included are many photos and sound recordings, as well as its use of eBird. An Android version is due out later this spring.

Monday, January 13, 2014

Snowy Owl

I was glum because everyone seemed to be reporting Snowy Owls from nearby Dakota County. Erika and I already had made three unsuccessful trips to see the birds. Sunday morning I was moping around the house.  “OK,” announced Erika, “One more try.” We had just arrived when we spied a Snowy Owl perched on a roadside telephone pole.

Taking these photos, I looked in the rear view mirror and was surprised to see a line of two or three cars. Usually I am not thrilled to be among a mob of birders. In this case, however, I make an exception—it sure was nice of these folks to help us push our car out of the snow drift in which I had parked! A heartfelt thanks to them all!

In previous posts in this blog (2011, 2012), I wrote that Snowy Owl invasions were the result of low Arctic lemming populations. A fascinating article on the eBird website offers a different hypothesis. High lemming populations result in large owl clutches with consequent huge owl numbers. The owls are forced to move south in search of food. One piece of evidence for this idea is that many of the owls that move south are immatures, which would be a major component of the population if there were too many owls. The  eBird website contains a great deal of Snowy Owl information and describes how this year’s invasion is slightly different than previous influxes.
As do all raptors, Snowy Owls regurgitate pellets containing the bones and fur of their prey. I believe this owl is yawning. Snowy Owls are daytime hunters, which is lucky for them, considering the nearly 24-hour daylight of the Arctic summer. Perhaps this owl was just getting ready for the day. We watched the owl for about 20 minutes before a friendly farmer drove up and asked what we were doing. We pointed to the top of the telephone pole. He gasped so loudly and with such surprise at seeing the owl perched so close, that the owl flew off, low over the surrounding fields.

Sunday, January 12, 2014

Common Goldeneye

I photographed this rather bedraggled-looking Common Goldeneye at the west outlet of Black Dog Lake in northern Dakota Co. I am not sure how to explain this appearance, since this species is a hearty duck, often found in Minnesota winters.

I was surprised to learn in Eadie et al. (1995) that fish constitute only a very small portion of a Common Goldeneye’s diet (4%). Crustaceans, insects, and mollusks are their prized prey (70%), filled out by vegetation (26%). Goldeneyes are diving ducks, and can remain under water for almost a minute. They swim underwater with closed wings. They can capture more than one prey item per dive and usually consume their catch while submerged.

Friday, January 10, 2014

American White Pelican

On Wednesday, Erika and I found a solitary American White Pelican sitting on the ice at the west outflow of Black Dog Lake in northern Dakota County, Minnesota. This water, as it enters the Minnesota River, is often open, since the lake is heated by a nearby power plant. The water is aerated and attracts an abundance of small fish. Consequently this location often supports a number of waterfowl and gulls during the cold, winter months.
This pelican probably was hurting. Possibly its wing is broken. On these photos, notice the ice on the black of the wing feathers. A bird capable of flight would likely shed such ice. It seemed odd to me that the bird chose to stand and rest with its feet in the cold water. Perhaps, however, the water was warmer than the surrounding ice.