Monday, March 30, 2015

Common Baskettail

I photographed these Common Baskettails last summer in the University of Minnesota Landscape Arboretum.  The species occurs across the eastern United States into southeastern Canada. They are often hard to photograph, because they fly this way and that over ponds and waterways. While in flight, they often catch and eat small, flying insects (Paulson 2012).

Friday, March 27, 2015

Hermit Warbler

Many years ago, Erika and I took this photo of a Hermit Warbler in Arizona’s Organ Pipe Cactus National Monument. We were doing our college senior project, part of which included banding birds. This warbler breeds in the mountains of Washington, Oregon, and northern California. It winters in Mexico and Guatemala.

According to Pearson (2014) little is known about the Hermit Warbler’s biology. An exception is a good deal of research where its range overlaps with the Townsend’s Warbler in Oregon and Washington, where the two species are known to hybridize. In this zone, the Townsend’s Warbler replaces Hermit Warblers. Nevertheless, Breeding Bird Survey data suggest that overall Hermit Warbler numbers not declining.

Tuesday, March 24, 2015

Stemless Evening Primrose

My best identification for this flower, which we found along the Rockport, Texas beach last year, is Oenothera triloba, the Stemless Evening Primrose. (I urge you to correct me if I am mistaken.) This species flowers in March and April, so a February record is not too outrageous. These flowers are often weeds in lawns and grow in disturbed areas. They are often planted in rock gardens. The flowers turn red as they age. This plant is another species that has special value to native bees (wildflower.org).

Saturday, March 21, 2015

Western Meadowlark

I took this photo of a Western Meadowlark—you can tell it from an Eastern Meadowlark because the yellow of the throat clearly spills up into the malar region under the eye—near Randolf, Minnesota, on 9 May 2014.  I have blogged about the difficulty of telling Western and Eastern meadowlarks apart, but this clearly is the Western.

Although the two species can be very hard to identify, they do not often interbreed. Recent studies show that hybrids tend to be sterile (Davis and Layon 2008). Meadowlark populations are declining across their range—up to 6% a year in some places. Even where numbers appear to be stable, like in the Northern Great Plains, local birders remember many more birds, even in recent years. No doubt destruction of native grasslands contributes to this trend.

Wednesday, March 18, 2015

Connecticut Warbler

The Connecticut is another elusive North American warbler. The broad white eye-ring makes for a striking field-mark. Unlike the Mourning Warbler of the last post, this species does not specialize in secondary growth situations, preferring, instead, bogs and deciduous forests in central Canada and northern Minnesota, Wisconsin, and Michigan.

Connecticut Warblers winter in South America. Unlike most other warblers, this species migrates by different seasonal routes. Spring birds migrate up the Mississippi Valley. In the fall, they fly east, across Canada, and then south along the Atlantic coast. The two routes overlap only near the breeding range. Note, however, that some individuals do not obey these routes, but are the exception that make the rule.

The famous ornithologist Alexander Wilson discovered this warbler in Connecticut in the fall of 1812. The species does not breed and is not a very common migrant in Connecticut. In any event, its secretive habits and remote habitat kept ornithologists from describing its nest for the next 70 years. Recent genetic research indicates that the similar appearing MacGillivray’s and Mourning warblers are more closely related to Common Yellowthroats and are not closely related to Connecticuts (Pitocchelli et al. 2012).

Sunday, March 15, 2015

Mourning Warbler

As I have written before, Mourning Warblers are common, but elusive migrants across much of central and eastern North America. They often feed on or near the ground in early succession habitat. This habitat is hard for birders to penetrate, but is good news for the warbler. Clearings and regrowth often occur after logging (and other human-created activities) or fires. Pitocchelli (2011) reports that Mourning Warblers colonize new clearings within two years after being created, but begin to decline after severn years. Even in their South American winter range, these warblers prefer tangled, disturbed areas. Pitocchelli writes, “This warbler may be one of North America’s few Neotropical migrants that has benefited from human disturbance.”

Friday, March 13, 2015

Wilson’s Phalarope

This photo, taken in South Dakota a decade or so ago, is of a female Wilson’s Phalarope, a species in which the roles of the sexes are reversed. The males care for the young, while the more handsomely plumaged females go out in search of additional mates.

The hormonal regulation of sex-role reversal is poorly understood. When I was in college, I learned that female phalaropes harbored high levels of testosterone. This hypothesis proves not to be entirely the case. Apparently testosterone is essential for the development of reproductive organs, and, like most vertebrates, male phalaropes at least begin the season with more testosterone than females. What does differ, however, are prolactin levels. Prolactin causes birds to incubate, and is much higher in male phalaropes than in other male birds. In typical birds, females have higher prolactin levels than do males.

Phalarope hormones may be even more complex. Some research indicates that testosterone levels spike in females when they see males in the spring. This rise may result in the females courting males and defending territories. Meanwhile, these females have low levels of prolactin. Just how these hormones accomplish this sex-role reversal is not well understood, but may involve enhanced prolactin receptors in the male brain.

These musings are distilled from a paper by Eens and Pinxten, “Sex-role reversal in vertebrates: behaviors and endocrinological accounts” published in 2000 in Behavioral Processes, volume 51.

Tuesday, March 10, 2015

Black-billed Magpie and American Crow

A quick literature review reveals that American Crows and Black-billed Magpies are basically omnivorous—they will eat almost anything they can get their beaks around.  In this photo, taken several years ago, these two corvids are consuming French fries dropped on the road at a Montana rest stop.

When Lewis and Clark first discovered magpies, the birds followed bison herds and fed on refuse left by Native American hunters. The magpies stole meat from the explorers’ tents. Today magpies and crows eat carrion, small mammals and birds, reptiles, a wide variety of invertebrates, and fruit and grains. Although French fries are not specifically mentioned in the literature, both species are not above consuming discarded human food (Trost 1999, Verbeek and Caffrey 2002).

Saturday, March 7, 2015

Pink-footed Shearwater

This fairly lousy photo is of an interesting bird—a Pink-footed Shearwater. I suppose great photography does not result from standing on a small, rocking boat in the Pacific Ocean, 60 miles off Westport, Washington. I have read that shearwaters get their name because their wings appear to clip the waves when they are flying low. In fact, as you can see from this photo link, occasionally their wings actually skim the ocean surface. Like albatross, about which I have previously blogged, shearwaters often get lift from air currents rising off ocean waves.

Pink-footed Shearwaters only breed off Chile on three small islands in the eastern Pacific Ocean. This small range makes the species vulnerable to natural and human catastrophes. After breeding, birds migrate northward along the Pacific coast to waters off British Columbia and Alaska, where numbers peak between August and October. The photo on this blog was taken on 13 August 2001 and Erika and I saw a Pink-footed Shearwater off the coast of northern Peru on 21 October 1973.

The total breeding population is estimated to be about 100,000 individuals (Birdlife.org). This estimate is in stark contrast to other censuses of up to 400,000 off southern California (Carboneras and Kirwan 2014). Clearly the actual population size is unknown.

Thursday, March 5, 2015

Wild Turkey

I recently posted about Wild Turkeys.  We often see turkeys at the Dundas banding site. This winter, however, few have appeared under the feeders. This bird was one of four hens that visited on Wednesday morning. I can’t decide if this bird is handsome or ugly.

The restoration of the Wild Turkey is one of Minnesota’s “greatest conservation success stories” (MNDNR). Formerly rare, turkeys are seen throughout much of southern and central Minnesota. Today’s birds were released between 1971 and 1973. The initial release consisted of 29 individuals transported from Missouri. Now more than 70,000 Wild Turkeys roam Minnesota (MNDNR). The Department of Natural Resources warns people not to release domestic turkeys—they may spread disease to wild birds. They also warn against feeding turkeys that could become tame and aggressive. Finally they advise protecting your garden and crops from turkey depredation.