Short-billed Dowitcher

Short-billed and Long-billed Dowitchers can be identified by call. The flight call of the Short-billed is a “tu” note repeated up to three or four times. Long-billed Dowitchers gives a high “keek” note, given once or repeated several times (Jehl et al. 2001). When I began birding, the dowitchers were considered to be one species. Peterson, in his early field guide, wrote, “the Dowitcher feeds like a sewing-machine, rapidly jabbing its long bill perpendicularly into the mud.” You can see this feeding strategy in the second photo.

Silent dowitchers, like this one Erika and I photographed last Saturday at the Jirik Sod Farm in Dakota County, are another matter. Some dowitchers, depending on the season and the birds’ race, are probably not separable in the field. Long-bills can have shorter bills than some Short-billed Dowitchers. Most plumage characteristics are shared by at least some birds of both species. 

I think, nevertheless, that our bird is clearly a Short-billed Dowitcher. Compare it to a Long-billed Dowitcher that I photographed some time ago in South Dakota (see last photo). The Minnesota bird clearly has a much shorter bill than the Long-billed. The Minnesota dowitcher also appears to be a much smaller bird, although females of both species are smaller than their males. As a result, the relative size of the bird can only be used in extreme individuals. Note the speckles along the Minnesota bird’s flanks. The Long-billed has barred flanks. The Short-billed Dowitcher is a much paler species. Finally, if you use a bit of imagination, you can see that with wing tips of the Minnesota bird extend a few millimeters beyond the tail tip. Long-billed Dowitcher wing tips usually do not extend beyond the tail.

Baird’s Sandpiper

This wet August has resulted in many flooded fields, especially in area sod farms. Birders often visit the Jirik farm in Dakota County during shorebird migration. Erika and I have made several trips there this season. We have not had much luck, although you may recall a recent photo of a Stilt Sandpiper. On 27 August 2016, we found a Baird’s Sandpiper in one of the pools at the farm.

This shorebird is one of the last North American sandpipers to be described. It breeds in northern-most Canada, Alaska, and parts of Russia. In 1861, Elliot Coues named it for Spencer Fullerton Baird, the secretary of the Smithsonian Institution. It makes a rapid migration, in as few as five weeks, to South America—some all the way to Tierra del Fuego (Moskoff and Montgomerie 2002).

This Baird’s Sandpiper behaved oddly, stretching out its neck and yawning. I have seen a Spotted Sandpiper behave similarly. Female Spotted Sandpipers gape when courting males. The Baird’s fed close to a Short-billed Dowitcher and a few Killdeer. Possibly the Baird’s was defending a feeding territory—other shorebirds defend feed territories during migration—or perhaps it was regurgitating arthropod shells. The Baird’s also stretched its wings, which is also similar to breeding territory displays. In this case, wing stretching may have served as an intra-species feeding territory defense. At the time, however, I assumed the sandpiper was only stretching.

Eastern Tailed-Blue

On 21 August 2016, Erika and I found a dozen Eastern Tailed-Blues. Many butterflies feed on pollen, but others prefer urine and, in this case, excrement. Larvae eat various legumes, which are common along our trail in the Carleton arboretum. The larvae secrete substances that attract ants, which, in turn, protect the larvae from various predators.

Tailed-blues are hard to photograph, since, when they perch, they keep their wings folded. They look gray, until, suddenly they flutter away in a blaze of azure. On this day, they looked like sailboats keeling against the wind. Occasionally a gust knocked a few completely over.

These butterflies’ tails are just visible in this photograph. Note the tails along the wing edges, opposite the orange spots, on the furthest left butterfly. Often the tails wear off as the season progresses. 

Wasps

Last week in Carleton College’s arboretum I took two wasp photos. I used Scott King’s new Minnesota wasp book to identify them. I based my identification of the first wasp on its black-tipped abdomen and orange legs—a Great Golden Digger Wasp. These wasps are not aggressive towards people. They dig tunnels to which they bring paralyzed prey. The females lay eggs in the prey and then cover the tunnels. The wasps do not actively defend their nests (www. insectidentification. org).

I had more trouble identifying the second, other-worldly looking wasp. Note the long ovipositor. I got additional help from Scott, who confirmed this species is an American Pelecinid Wasp. This pollen-consuming wasp is found from Canada to Argentina. They lay their eggs in June Beetle larvae The beetles are not necessarily eaten alive, as the wasp is not adverse to consuming dead tissue (University of Wisconsin).

Black-throated Green Warbler

I banded this Black-throated Green Warbler on 25 August 2016. In the spring, this warbler’s black throat contrasts sharply with its golden face. Even in the fall, this bird is striking. The eastern ranging Black-throated Green Warbler is similarly plumaged to a number of western species (Golden-cheeked, Hermit, Townsend’s warblers). These species seem to be closely related. Their ancestors may have been a single population that became fragmented and isolated by Pleistocene glaciations (Morse and Poole 2005). In any event, Black-throated Green Warblers, which breed in northern and Appalachian forests, are one of our most common warblers.

August Warblers

Fall Warblers are notoriously difficult, but not impossible, to identify. They are often referred to as CFW’s, Confusing Fall Warblers. Here I post six I banded in Northfield on 22-23 August 2016. I have linked each to previous blog posts showing spring birds and to some ecological notes. Here I discuss only their field marks. The first photo is of a Golden-winged Warbler. Because in the fall this species looks similar to spring birds, this CFW is one of the easier ones to identify. This warbler is a female, and is easily recognized by its dark cheeks, yellow crown, and golden wing bars.

This second warbler is also not difficult. Canada Warblers are proclaimed by their golden lores, white eye rings, and black necklaces. Males have darker necklaces than females, but many fall birds are intermediate, making sexual identification difficult.

This third bird is a hard one. The gray head, white eye ring, and pale throat proclaim it to be a Nashville Warbler. Even in the fall, many Nashville Warblers have much brighter yellow throats than this drab-plumaged immature. In the two days that I took these photos, I banded 32 birds—20 were Tennessee Warblers.

Chestnut-sided Warblers are a bit easier. Their gray underparts contrast with their white eye-rings. Their crowns are bright yellow, such as occasionally found in tropical tanagers.

Tennessee Warblers show considerable variation.  Often they are muted shades of yellow. This gray-headed individual is one of the few adult warblers I banded this August. In any plumage, a good key to identification is the black line through the eye. The predominance of young birds has me a bit puzzled.

This final bird is the toughest of the lot to identify. Note the bright yellow underparts and weak white line surrounding the eye. The bill is relatively robust, at least compared to the other warblers on this page. One key to the identity of this Mourning Warbler is the dark line below the throat. 

Black Turnstone

eBird posts monthly challenges to contributors. Those meeting the goals—numbers of lists per month, lists with breeding notes, lists with birds noted flying overhead—are then placed in a pool from which a single prize of binoculars and bird books are drawn. Your chance of winning are poorer than collecting something from Power Ball. (You have a 1 in 27 chance of winning $4 if you hit the Power Ball.)

I am enjoying this month's challenge to submit bird lists containing at least three photographs. This quest proves entertaining and surprisingly difficult. I did not realize how many birds I identify from a great distance or by call. Along the way, I notice that the links to many of my previous photographic submissions to eBird are corrupted. Before, the images were linked to Flickr or Google Album pages. Now you submit the photos through eBird directly to the Macaulay Library at Cornell University. I have spent the month correcting my list links and moving photos to Macaulay. 

I found a few birds for which I have photographs but have not appeared in this blog. One is this Black Turnstone I from La Jolla, California, on 8 January 2008. This species breeds on the Bering Strait coasts of Alaska and winters along the Pacific Coast from Alaska to Baja California and northwestern Mexico. It occurs on rocky shores, where it flips stones in search of algae, invertebrates, and “all sorts of supratidal jetsam” (Handel and Gill 2001).

Northern Map Turtle

On 11 June 2016, Erika and I were biking the Cannon Valley Trail. Near a bench, we found this Northern Map Turtle laying her eggs in the sand by the trail. This encounter was strange, since map turtles usually prefer large rivers and lakes. This turtle had a long haul, perhaps a quarter mile up hill, from the Cannon River. You would expect her to nest on sandy beaches or sandbars, not in a wooded area.

Breeding occurs in the spring and fall. Most mating occurs in deep water. Judging by the algae on this turtle’s carapace, this individual does spend most of her time in the river. Hatching happens in the late summer. A dozen eggs are laid a few times a year. Warm temperatures produce females, cooler weather results in males. When young hatch late in the year, they may overwinter in the nest (Savannah River Ecology Lab, Wikipedia)

Bobolink

Last Tuesday I checked out the Dennison Sewage Treatment Plant on the eastern edge of Rice County, Minnesota. Sewage treatment plants and garbage dumps often harbor interesting birds. I  found none of my hoped for shorebirds—but I did find some good birds. Among them were a flock of eight Bobolinks. Winter Bobolinks are drab, compared to the males’ black and white spring plumage.

Curiously, I saw Bobolinks at the Dennison treatment plant almost exactly a year ago. Then I commented that the males in winter plumage tend to be brighter breasted than the duller females. I assume the bird in this photo is a male. In another bobolink post, I wrote “Bobolinks are long-distance migrants, wintering in southern South America, a round-trip distance of about 12,500 miles. A banded female Bobolink was recaptured after nine years, thus “presumably made this trip annually, a total distance equal to traveling 4.5 times around the earth at the equator” (Martin and Gavin 1995). Studies indicate that Bobolinks orient using magnetic clues.”

Skimming Bluet

Skimming Bluets often fly low and hover over open water—hence their name. They are partial to algae mats and vegetation in otherwise clear-water lakes and ponds. They fly in the middle of day when temperatures are high. These are exactly the behaviors and habitat that Erika and I found them in along the outflow to Hiawatha Lake in Minneapolis on 26 July. All bluets look more or less the same—Erika says, “you’ve seen one bluet, you’ve seen them all.” The Skimming Bluets are small with mostly black, black-tipped abdomens. If you look closely at the eyes of the perched bluet, you may notice that they have a blue streak, but are otherwise brown. This field mark is diagnostic. You should also note the wavy blue line on the side of the first abdominal segment.