Saturday, February 28, 2015

Dunlin

A basic-plumaged Dunlin can be a difficult bird to identify. Birders pay attention to the relatively long, slightly down-curved bill. Sometimes they are confused with the smaller and streakier Western Sandpiper.

Across their huge, circumpolar range, Dunlin have evolved into about nine subspecies. Ornithologists debate the number that occur in North America. Many scientists say one species breeds here, others recognize two or three. Genetic studies indicate two races exist, Pacific Dunlin breeding in western and northern Alaska, and Hudsonian Dunlin across Northern Canada. These breeding birds differ in size (Canadian birds being the largest), their backs’ brightness and their undertail covert’s streaking.

Pacific Dunlin winter from southern Alaska south along the Pacific Coast at least through Mexico. Hudsonian Dunlin winter along the Gulf Coast and eastern Mexico south South America (although the race of Latin American birds is often not determined (Warnock and Gill 1996). Based solely on range, the bird in this post is probably a Pacific Dunlin, since this photo was taken at Westport, Washington, along a Pacific beach.

Thursday, February 26, 2015

Snowy American Crow

This cold and snowy American Crow huddled above the bird feeder on Wednesday morning. Look at the ice on its head, eyes, and back. Finally it dropped down and fed on scraps below the feeders. I have previously blogged on crows—you can search for these posts by using the search-box in the right column on this page. After you search once, remember to return to the whole blog before performing a second search.

A a few physiological adaptations allow crows to survive Minnesota winters. In warm weather, crows keep their body temperature near 40 degrees C (104 F).  In colder weather, crows are able to reduce their body temperatures as low as 38 degrees C (100.4 F). Obviously this plasticity saves energy. Their large size results in a relatively low surface to body mass ratio, also resulting in relatively lower heat loss (Verbeek and Caffery 2002). Finally, notice that, like many chilly birds, this crow has fluffed out its feathers, creating warm spaces near its body.

Monday, February 23, 2015

Common Goldeneye

Female birds often get a short shrift in art and photography. I was surprised that I have very few decent photos of Common Goldeneyes of either sex, and this one is my only closeup of a hen. The females can be difficult to tell apart from the similar Barrow’s Goldeneye, but the Common can be recognized by their larger bills usually being more black than yellow. A few of my other photos of both species can be found in this previous post. I took this photo several years ago in Duluth, Minnesota.

Saturday, February 21, 2015

Sharp-shinned Hawk

On Friday morning, Erika and I were reading in our sunroom, which looks out at our bird feeders. Suddenly a small Accipiter swooped around the feeders, narrowly missing our picture window, and perched on an overhanging tree branch. Its square-ended tail feathers indicate Sharp-shinned Hawk. The small size probably means it is a male. The iris color, between yellow and orange, signifies a second-year bird. The good news is that I had my camera on the table in front of me. Unfortunately this gray day was not ideal for photography. After a couple of minutes, the hawk launched itself back towards the empty feeders, banking sideways, with its feet towards the feeders, and disappeared into the woods.

Sharp-shinned Hawks are renown for consuming small birds. This species often takes songbirds at bird feeders (Bildstein and Meyer 2000). These authors cite studies that show birds comprised 91 to 100 percent of Sharp-shinned diets in various samples around the country. Mammalian prey, however, sometimes made up a greater mass of the diet than did birds, especially late in the breeding season.

Thursday, February 19, 2015

California Gull

The top two photographs are of California Gulls. The species breeds in western, interior North America. The eastern-most breeding colonies are in the Dakotas, Colorado, and Manitoba. Most of these gulls winter along the Pacific Coast, from British Columbia south to central Mexico. Only a few winter in the continent’s interior. Wintering coastal populations are interesting because they appear to slowly drift southward during the winter, with juveniles dispersing the longest distances. Off the coast of Washington, adults are normally found close to shore, presumably forcing younger birds out to sea.

As birders become better at identifying gulls, California Gulls are being reported with increasing frequency from the Great Lake, the Mississippi River, and the Gulf Coast (Winkler 1996). Most of these out-of-range birds are expected to be immatures, like the bird in the first photo. The young birds have dark-tipped and relatively thin, pinkish bills. Adults’ bills are also relatively narrow bills with black and red spots on them (see middle photo).
I took the last gull photo a couple of years ago in Duluth, Minnesota. I was perplexed, because this gull’s bill looks “spot-on” for a California Gull. I noticed, however, that the legs were the wrong color—pink instead of gray and the back was too pale for a California Gull (also note the difference in iris color).  Turns out that, not only do young Herring Gulls often have black and red spots on their bills, banding studies show that even older adults often retain black bills spots David Bell (pers. com.). The moral of this blog post is to be careful when identifying out-of-range California Gulls.

Tuesday, February 17, 2015

Glaucous-winged Gull

Recently I blogged about “Olympic” Gulls, the hybrid swarm between Western and Glaucous-winged Gulls breeding around Puget Sound, Washington. Previously I posted notes about Western and Glaucous-winged species, but I have only a few photographs of the later. These gulls breed along the Pacific Coast from Alaska to the Olympic Peninsula. They winter from there to Baja California and the Gulf of California.

In recent years, populations of Glaucous-winged Gulls have greatly increased. Apparently this trend is in response to increasing supplies of human garbage and fish offal.  Declines in Bald Eagle numbers may have contributed gull increases—with fewer eagles, more dead fish are available to the gulls. With Bald Eagle numbers recovering, some populations of Glaucous-winged Gulls are declining (Hayward and Verbeek 2008).

Sunday, February 15, 2015

Red Squirrel

Another creature that crossed my path during Sunday's stroll in the Carleton College arboretum was this Red Squirrel.  I have written twice previously on this species—you may recall that Red Squirrels do not hibernate, though they may be inactive during ugly weather. This squirrel watched me fidget with my camera, only fleeing just before I remembered to try to use my flash attachment. The squirrel held on to a Black Walnut fruit that it had probably cached in the fall.

Friday, February 13, 2015

Canada Goose

On Sunday, one hundred Canada Geese loitered along the Cannon River in Carleton College’s arboretum.  I took a photo for BirdsEye.com.  This bird stood on one foot, but, after ruffling its feathers, walked to the water on both feet.  I believe these geese were small Canada Geese rather than large Cackling Geese, which would have sported shorter bills.  

Canadas are the most abundant of North American geese. They are monogamous and form life-long pairs.  During the first year, offspring remain with parents. In many areas, increases in breeding populations have mixed migrants and local birds. The result has been a confusing mixture of genes and general genetic chaos among flock members.  Flocks have become so large, that they become a nuisance in many urban areas. Over 27,000, for example, have been reported from Minneapolis (Mobray et al. 2002).

Wednesday, February 11, 2015

Mallard

On Sunday, I finally got out with camera in hand this cold, gray Febraury.  I did not see much of note in the Carleton College arboretum. I did photograph several of the hundred Mallards loafing along open water along the Cannon River. My goal was to get a few shots with the dimensions preferred by BirdsEye.photo.
The mallard is North America’s most abundant duck, breeding across most of Canada and the United States. The species is adaptable in its habitat preferences and will eat a wide variety of food items. It is cold-hearty, and will winter as far north as open water persists. Despite being heavily taken by sport-hunters, populations remain steady (Drilling et al. 2002).

Monday, February 9, 2015

Common Yellowthroat

This Common Yellowthroat flew by the 180th Street March in nearby Dakota County last summer. I have blogged about the species before. Allow me to add today that yellowthroat taxonomy is a mess. Thirteen races are recognized by Guzy and Ritchison (1999). The problem is that few, if any, field marks are consistent within populations. On top of that, field marks tend to blend together where ranges meet.

Pyle (1997)merged the US and Canadian races of Common Yellowthroats into three groups: the Pacific Coastal, Western Interior, and Midwestern/Eastern.  Even with this merge, racial identification is, at best, tricky. Pacific birds are small, dark and dull. Pacific and Western Interior birds have a relatively wide, white band behind their black masks. This field mark is pale gray in Midwestern/Eastern yellowthroats. Although Western Interior birds may inhabit northwestern Minnesota and southeastern North Dakota, my photo clearly shows the grayish band typical of Midwestern and Eastern yellowthroats.

Why are races of birds important to understand?  Knowing how bird populations vary is essential to understand diversity. This knowledge is critical if we are intent in preserving robust and healthy ecosystems. You can not preserve what you can’t identify.

Saturday, February 7, 2015

Ring-billed Gull

I took this photo of a passing Ring-billed Gull last spring near Dallas, Texas. Unbelievably these gulls were almost eradicated by human persecution and habitat destruction between 1850 and 1920. Populations have rebounded.  By 1990, perhaps four million Ring-bills were to be found in North America.  Ten years later, this number had increased by 250% (Pollet et al, 2012). The species is still often considered a pest, for example as they swarm around garbage dumps or soil cars in parking lots, but current efforts to control populations have not been very successful.

Ring-billed Gulls, in any event, are opportunistic feeders. When they are not consuming human trash, they eat grain, a wide variety of insects, earthworms, fish, and even small rodents. I have previously blogged about this gull.

Thursday, February 5, 2015

Northern Pintail

For a time now, I meant to post these pintail photos. Seeing them in Duluth last month has finally pushed me to write. This duck breeds regularly across Minnesota, the northern United States, and Canada. It mainly winters from the southern US into Central America.  They are not normally found this far north in the winter, but several, like the bird in the first photo, have delighted Duluth birders this winter. The second photo is of a breeding male in South Dakota, the third is a South Dakota migrant female.

Pintails eat grain, seeds, and aquatic invertebrates. In normal years, they are among our earliest spring migrants. Pairs form anew every spring. Males, however, are promiscuous, and leave shortly after incubation begins. Breeding pintails are threatened by predators (such as coyotes, fox, and raccoons), drought, and nest destruction by farming operations. Pintail populations have declined from six million birds in the 1970s to under three million by the early 1990s (Austin and Miller 1995).

Tuesday, February 3, 2015

Wild Turkey

I took these photographs of a tom Turkey last June in Rice County, Minnesota. Turkey flocks develop complex and somewhat poorly understood patterns, which may vary among turkey subspecies. Often males and females establish separate pecking orders. Apparently these pecking orders are the result of kin selection, wherein a lower-ranked individual may sacrifice his or her chance of reproduction in exchange for the safety of the flock and the success of a related bird (McRoberts et al. 2014). The alpha male often mates with more than one female.

Males display by making a gobbling call to attract females or competing males. The male then struts, with his tail fanned, wings lowered, and head thrown back and pressed into the area between the scapulars.  He struts about in front of females, regardless of their indication of interest. When females are not present, he may gobble but he seldom struts.

Sunday, February 1, 2015

Magpie-lark

Magpie-larks are Australian birds in the family Grallinidae.  The only other species in the family is a New Guinea bird called the Torrent-lark. Molecular studies surprisingly suggest Grallinidae are closely related to monarch-flycatchers, another Old World bird family.

In any event, Magpie-larks are abundant in Australia and are often found in cities and farm-country. Before the advent of Europeans and subsequent conversion of habitat to farmland, Magpie-larks were not as common and restricted to areas near wetlands. Attempts to introduce the species to New Zealand, Fiji, and Hawaii have all been unsuccessful (Handbook of Birds of the World—Alive).