Friday, May 31, 2013

Western Kingbird

The hundredth is a mystical meridian (those imaginary lines on maps that run between the Earth’s poles). The 100th meridian is the line Peterson drew separating the western and eastern United States, each region with roughly its own suite of birds. In South Dakota, this line runs just east of the Missouri River, and the river marks a transition between eastern and western birds.

John Holden and I came upon our first Western Kingbirds as we approached the 100th meridian. This flycatcher breeds across most of the western United States, as well as southern Canada and Northern Mexico. The bird is even found into western Minnesota, where it is uncommon and local. We found them to be common and widespread in central South Dakota.

Western Kingbirds are aggressive birds that catch flying insects in the air and on the ground. They favor a variety of habitats, but require open areas for feeding and and trees and shrubs for perching. Western Kingbirds can also be found in urban areas. The species has become more common with the breaking of the prairies and consequent planting of trees and bushes (Gamble and Bergin 2012).

Thursday, May 30, 2013

American Avocet

American Avocets delighted John Holden and me as we travelled across northern South Dakota along Highway 10 north of Aberdeen. The avocets were tame and fed along barrow pits on both sides of the road. The species feeds with a variety of methods. They are famous for using their bills as a scythe, swishing the bills back and forth as they catch small aquatic invertebrates. They also peck, plunge, scrape, and snatch. Avocets use their exceptionally sensitive bills to feel for prey. Sometimes, like in the second photo, avocets feed while swimming. Other times, food is snatched while the avocet walks erratically in shallow water. Check out this last photo. Finally, avocets often feed near phalaropes, hoping to feed on invertebrates and small fish that the spinning sandpipers stir up from the lake bottoms (see previous post) (Robinson et al. 1997).

Wednesday, May 29, 2013

Wilson’s Phalarope

These five photographs, taken in May 2013, are a series of a male Wilson’s Phalarope. The photos are of the same bird near Leola, South Dakota. I have discussed sex role reversal shown in phalaropes in a previous post. (Females are more brightly colored than males and it is the male that tends the nests.)

Phalaropes are famous for their feeding behavior. They spin in tight circles “in a manner reminiscent of a slightly demented toy” (Rubega et al. 2000). The spinning may stir up prey from the bottom of shallow water. Other researchers hypothesize that the spinning stimulates prey immobilized in cold water. This circling creates upwelling of water that brings the phalarope’s prey up to them. This flow can be created in water with depths of up to a half-meter, thus allowing phalaropes to spin in relatively deep water.

Other research suggests that phalaropes spin only in one direction—individuals may be left or right spinners. In any case, the phalarope moves with each spin, so that the bird slowly moves across the water. As the bird does so, it inspects the surface for new prey items. Most of my information on spinning phalaropes is taken from Rubega et al. (2000). Although famous for their spinning, phalaropes often feed like more typical sandpipers, probing muddy shores for arthropods. 

Tuesday, May 28, 2013

More Sandpipers

On our recent journey, I played the role of ornithology professor and John Holden had the role of student. The advantage of these roles for me is that, as I have often informed John, the Professor is always correct—especially when it comes to identifying sandpipers. We happened upon this group of four sandpipers near Leola, South Dakota.

The identification of three of these four shorebirds in the upper photo is not too difficult. The bird in the lower left is a Spotted Sandpiper—look at the spots on its underparts. The small, dark-brown backed shorebird behind the others has yellowish legs, making it a Least Sandpiper. The larger bird on the far right, with its thin, pointed bill and chestnut body stripes is a female Wilson’s Phalarope. Female phalaropes are brighter than their mates. I will have more to write about phalaropes in a future post.

That leaves the center bird, which I identified as a Baird’s Sandpiper. Look at the photo below, taken after another shorebird landed nearby. This time the phalarope is the bird in the background. The remaining shorebirds are what birders call “peeps,” a collective name for small sandpipers. The bird I identified as a Baird’s Sandpiper is the middle bird.  Note the dark legs, sharp transition between the dark breast and the white belly, and the black spots on the back.

The first bird in the lower photo also sports black legs. But it has a less distinctly spotted back and its striped chest transitions slowly to its white belly. Finally its bill is clearly shorter than that of the Baird’s—leading me to conclude that this first bird is a Semipalmated Sandpiper. My companion felt it was unfair for me to offer a week-long workshop in shorebird identification in five minutes at a South Dakota lakeshore.

Monday, May 27, 2013

Stilt Sandpiper and Hudsonian Godwit

On our recent jaunt, John Holden and I found ourselves surrounded by shorebirds north of Aberdeen, South Dakota (see last post). West of Sand Lake National Wildlife Refuge, we found Hudsonian Godwits and smaller Stilt Sandpipers. The sandpipers are easily identified by their barred breasts and chestnut cheeks. Stilt Sandpipers can also be told by their habit of standing in deep water, sometimes up to their bellies.

The godwit is known by its dark chestnut belly and, in flight (see lower photo), by its white rump. The lower photo also shows a Stilt Sandpiper in flight and, behind (and actually in focus), a Pectoral Sandpiper. The Pectoral is known by its size, relatively short bill, dark bib, and the dark-brown upperparts, a color that contiues through the center of the tail. Curiously, when I took this photo, I did not even see the Pectoral Sandpiper fly by me.
As I have written previously about Hudsonian Godwits, this species was considered to be on the brink of extinction in the early 1900s. Only in the 1940s were staging areas of migrating godwits discovered—perhaps these godwits were not as rare as previously believed. Nevertheless, hunting in South America, the effects of huge geese populations degrading arctic breeding grounds, and habitat destruction for oil extraction all threaten this species today (Walker et al. 2011).

Stilt Sandpipers are usually thought to be relatively rare shorebirds. They also winter in South America, and breed in the high arctic. Like the godwit, habitat degradation by over-abundant geese interfere with their nesting. Habitat fragmentation, both in South America and in the Arctic, does not help. Nevertheless, according to Klima and Jehl (2012), overall numbers of Stilt Sandpipers may be underestimated by ornithologists.

Sunday, May 26, 2013

White-rumped Sandpiper

On our recent trip to attend the South Dakota Ornithologists’ Union’s meeting, John Holden and I drove across the Northeastern part of that state. We came upon many shorebirds, a few of which I will share with you in this and upcoming blog posts. The first of these birds was a White-rumped Sandpiper. When not flying and showing its white rump, this sandpiper always puzzles me—until I remember that its salient field mark is its striped flanks (below the folded wings).

Note this individual’s yawn. This behavior is similar to a Spotted Sandpiper’s yawn that I posted in April 2010. I mentioned that female Spotted Sandpipers often give a choking display when courting males. Parmelee (1992) in his species account in Birds of North America, does not mentioned similar behavior in White-rumped Sandpipers.  So, perhaps, this yawn is exactly what it seems—just a yawn.

Friday, May 24, 2013

Pileated Woodpecker Recapture

On 21 May 2013, I discovered a Pileated Woodpecker in my banding net. Turns out to be a bird that I banded on 3 November 2010. In fact, it is the same bird I blogged about in November 2010. I seldom catch these large woodpeckers, and I wondered if a bird just short of three years might be one of the oldest on record. A search of the Bird Banding Laboratory’s website indicates my record is a far cry from the a record of 12 years 11 months of a bird banded in Maryland.

Thursday, May 23, 2013

Variegated Meadowhawk

Last weekend, John Holden and I attended the South Dakota Ornithologists’ Union meeting in Mobridge, South Dakota. We saw lots of birds, but this post is about my first dragonfly of the season—a Variegated Meadowhawk on 19 May 2013! This species was my first Odonate last year too, when I obtained my 2012 Variegated Meadowhawk on 20 April in Rice Co., Minnesota. That this dragonfly was the first of the season two years in a row may not be that coincidental. The species is a long-range migrant, often appearing before local populations emerge. It winters in Florida, the Gulf Coast, and warmer, southern states, south into Mexico and Central America.

The yellow spots on the thorax and the complex pattern on the abdomen make the Variegated Meadowhawk relatively easy to classify. Although odonates can be more difficult to identify, the rewards can be satisfying. In this case, even though Variegated Meadowhawks are found across the United States, southern Canada and northern Mexico, this record is a first from Walworth County, South Dakota.

Wednesday, May 22, 2013

Harris’s Sparrow

Last week, Erika and I sat on our porch mesmerized by our water feature. An odd bird flew to the stream. “Is that a Harris’s Sparrow?” I asked. “It is!” “Walk up the garden path,” I instructed, “and see if it will fly into the banding net.” And that is exactly what the sparrow proceeded to do.

I have seen a few Harris’s Sparrows in Northfield, and have banded one other, but at our Dundas station. Our Northfield home seems to be unlikely habitat for this prairie species. The bird does have a preference for streams, however, and generally favors brushy, secondary-growth areas (Norment and Shackleton 2008).

Tuesday, May 21, 2013

Two Vireos

Two vireos, a Red-eyed and a Blue-headed, also foraged with the warbler wave of mid-May 2013. Here are photos and links to previous posts about each species.

Monday, May 20, 2013

Seed-eaters in the Wave

Among the warblers in our recent wave of migrants, we banded several spectacular seed-eating birds. As in the previous two posts on warblers, the birds’ names are linked to past postings. The goldfinches were most amazing. Very small numbers visited our feeders most of the winter. But our banding station was overrun by goldfinches on 13 May. The woodlot behind our home looked like it was decorated with yellow lights—oddly the vast majority of birds were males. Although they can be found in Minnesota year-round, goldfinches are migratory—so wintering individuals may not be the same birds as those breeding here. Years ago in Aberdeen, South Dakota, I retrapped a goldfinch banded in southeastern Colorado. One of my Minnesota goldfinches was banded near Dundas in April and recovered in July of the same year in far west-central Saskatchewan.

Sunday, May 19, 2013

Black Phoebe

Black Phoebes are common in California, New Mexico, and elsewhere in the extreme Southwest south through Central and South America. These phoebes are almost always seen near water. This bird hawked insects along the coast at Morro Bay, California. Breeding birds use natural nest cavities, cliff-sides, riverbanks, and hollows in trees. In modern times, most nest in bird boxes. The species is monogamous and often raises two broods per season (Wolf 1997).

Friday, May 17, 2013

Warbler Wave 2

This post is the second of a series from a migrant bird wave from the second week of May 2013. I have linked the names of each bird to previous posts in which each warbler is discussed. In the middle two photos, note the difference in intensity of the Northern Parula’s chestnut breast patch.

Thursday, May 16, 2013

Warbler Wave 1

The second week of May delighted us with a heavy wave of migrating warblers. I wish to share with you a few of the birds we photographed during our banding operations. This photos will occupy the next several blog posts. I have linked the names of each bird to previous posts in which each warbler is discussed.

I noticed that the numbers of migrants were greatest just prior to the passage of two warm fronts through eastern Minnesota. Just before the fronts, winds were from the north. Afterwards, southerly winds prevailed. Presumably those north winds concentrated the migrants, whereas south winds assisted the migrants on their way north. Being a scientist, however, I have entertained two other hypotheses. Migrants appear to flock to my nets just as Erika is setting dinner and 15 minutes before I have appointments away from the banding station. Could these last two hypotheses be coincidental?

Wednesday, May 15, 2013

Mountain Sheep

I took this photo of Mountain Sheep (also known as Bighorn or Rocky Mountain Bighorn sheep) in the Black Hills of South Dakota. Originally these sheep ranged from the Canadian Rockies south as northern Mexico. The race in the Black Hills, the Audubon’s Bighorn, became extinct by 1910. Reintroductions from Montana and Wyoming occurred in 1922, but these animals succumbed to disease in the early 1960s. In 1964 and 1991, sheep from various western states and Canada were again reintroduced (Higgins et al. 2000).

To the best of my recollection, the pictographs of Mountain Sheep come from the Capitol Reef National Park in Utah. I may be mistaken, however, as most rock art in the park were created between AD 600 and 1300 (Utah.com). The two upper figures are clearly on horseback, arguing for a time frame after 1492. (If any of my readers recognize these pictographs as being from somewhere else, please let me know.)

Tuesday, May 14, 2013

Palm Warbler

I previously blogged about Palm Warblers last May. On Friday, Erika and I visited the recently burned prairie at the Carpenter Nature Center in nearby Washington Co., Minnesota. I have never seen so many Palm Warblers in one place. The birds actively fed in the burned grass of their managed prairie. Perhaps the ground was warmed by the blackened earth, thereby releasing an insect hatching. Burned prairies do heat up and support elevated plant growth. Prairies are also managed in this was to destroy invasive and non-fired resistant plant species. Unfortunately, frequent burns in relatively small grasslands destroy many rare, prairie-inhabiting butterfly larvae.

Among the Palm Warblers flitted an utterly nondescript bird. What was it? This little gray bird appeared to have few discernible field marks. The presence of a faint wingbar and faint flank and back streaks, along with the slightly brighter crown all add up, for me, to this bird being a female Palm Warbler in basic plumage. Add to that, the fact that this bird was among a large flock of more typically patterned Palm Warblers. Any other suggestions?

Sunday, May 12, 2013

Grounded Warblers

On Saturday, Erika strolled in the East Unit of the Cannon Valley Wilderness Area. The weather was chilly (50 degrees F.) and extremely windy (40 mph gusts). This weather resulted in our finding nine warbler species, many feeding on the ground. On top of that, most of the forest trees lacked leaves, leaving the warblers little opportunity to hide. Here are three of the species we observed:
American Redstart
Blackburnian Warbler
Black-throated Green Warbler

Saturday, May 11, 2013

Blackburnian Warbler

The male Blackburnian Warbler is among the most striking of North American birds (see also this August 2010 post)—but, hey, this female banded on Friday, 10 May, is not too shabby! Actually, it is a bit strange to band a female of this species earlier than a male. Males usually arrive at their breeding grounds at least a week before their mates (Morse 2004). I assume that our 2013, weather-delayed migration may be the cause of this anomaly.

Friday, May 10, 2013

Nashville Warbler

You may recall my post from last Friday in which I shared a photograph of an Orange-crowned Warbler’s (usually) hidden orange crown. Nashville Warblers, like the bird in this post, are another warbler with a hard to observe crown patch—a chestnut one in this case. Male and female Nashville Warblers are similar, the male being brighter, and both sexes have the crown patch, which is even less evident in the female. I have previously posted a few notes on this species, which, as a lover of secondary habitats, thrives in these days of clear-cutting and landscape disruption.

Thursday, May 9, 2013

Golden-winged Warbler

Previously I have posted extensively on the Golden-winged Warbler (see 14 June and 27 August 2010). This gorgeous migrant was the highlight of a warbler swarm that flew into my Northfield banding station yesterday. Actually I was busy with other obligations, and only had my nets open for an hour, beginning at 11:30 in the morning. In that time I ringed 14 Nashville Warblers, 12 Yellow-rumped (Myrtle) Warblers, 4 Orange-crowned Warblers, 1 Black-and-White Warbler (and saw two others), and observed, but did not catch, a Black-throated Green Warbler and a Blue-headed Vireo. The day was hot (almost 80 degrees) and sunny, but with approaching rain storms. I suspect this “migrant wave” was caused by the birds’ being bottled up to our south over the past few days by snow and cold in Minnesota and a large, low-pressure cell to our south.

Wednesday, May 8, 2013

Pied-billed Grebe

This Pied-billed Grebe, a species about which I have previously posted, preened, as the species often does, while on the water, in this case Lake Byllesby in Goodhue Co., Minnesota. Preening often consists of oiling the feathers. The bill and head are used to rub oil on their feathers. The oil is collected from their uropygial gland, an oil gland located near the dorsal base of their tail.

Tuesday, May 7, 2013

Tree Swallow

Back on 20 April 2013, Erika and I listed our first Tree Swallows of the spring. The swallows swooped over the Bass Bonds in the Minnesota Valley National Wildlife Refuge along the Minnesota River in Bloomington. We wondered how these insectivores were surviving. These swallows eat mostly flying insects, although they are known to consume vegetable matter during adverse weather (Winkler et al. 2011). This bird appears to be preening, a behavior certainly practiced by Tree Swallows, but not mentioned by the aforementioned authors.

Sunday, May 5, 2013

Sapsucker Sucking

Sapsuckers are famous for drilling holes in trees and then feeding on the sap that flows into the cavities. Yellow-bellied Sapsuckers maintain these holes daily to keep the sap flowing. They defend their wells against other birds—Yellow-rumped Warblers, hummingbirds, other sapsuckers—that may wish to share the sap. Breeding sapsuckers also take various arthropods, but often dip their prey in sap to add to the nutritional value.

This female Yellow-bellied Sapsucker, photographed in late April in Northfield, fed on a maple—but the woodpecker is known to drill into about 100 species of woody plants. In the spring, wells are drilled in xylem, to capture upward flowing sap. Later the birds drill into phloem for downward moving sap. If you look closely, you can see a few wells drilled to the right of this sapsucker. Often sapsucker trees look like they have been machine-gunned by sap wells.

The photo, by the way, was taken on a snowy day and the background is not photoshopped to produce the white background.

Saturday, May 4, 2013

Yellow-rumped Warbler

Yellow-rumped Warblers, Setophaga coronata, until recently were placed in the genus Dendroica. DNA studies, however, conclude that Dendroica, plus the genera Wilsonia and Parula, all comprise a single genus, Setophaga, once containing only the redstarts. Setophaga comes from the Greek and means insect-eater (Gruson 1972). I include this photo because I notice that none of my other posts of Yellow-rumped Warblers show their yellow rump. This bird hawked for insects in late April along Lake Byllesby in nearby Goodhue County, Minnesota.