Thursday, October 23, 2014

Caspian Tern

This Caspian Tern flew by us at Nisqually National Wildlife Refuge on 19 July 2004. The tern is flying in a typical posture, with its bill pointed downward. When a fish is spotted, the bird hovers and then plunges, often completely going under water. Fish are the Caspian Tern’s main staple.

I have blogged about these terns before; indeed, this observation is my second for the year—the first being on the Texas coast in February. This tern occurs on all continents except Antarctica. In North America, they breed both coastally and in the interior. American Caspian Terns winter south to Colombia and Venezuela. Our populations are increasing, unlike those in Europe and Africa, where they are often rare or extinct (Cuthbert and Wires 1999),

Tuesday, October 21, 2014

Barn Swallow

The Nisqually National Wildlife Refuge near Olympia, Washington, has a long boardwalk across the mudflats at the south end of Puget Sound. On 19 July 2014, Erika and I discovered this Barn Swallow family under the eaves of a covered bench along the walkway. Pandaemonium broke out every time an adult flew up to the nest, but the adult always flew in and out before I could snap a photograph.

Barn Swallows tolerate extra adults at their nests. These extras may help at the nest for an entire breeding season and are not necessarily related to the nesting pair. This situation sometimes leads to polygyny. Other helpers may replace a deceased pair member. The extra adults do not help much in feeding the young, but do assist in building the nest, incubation, and brooding. A nest with helpers is often “owned” by an older female, and the hypothesis is that male attendants are trying to secure high-quaility mates. Juveniles from first broods also help at the nest. In this case, the helpers do supply substantial amounts of food. Occasionally unrelated juveniles serve as helpers.

Sometimes extra adults are chased off. Curiously, reproductive success is not affected by the presence of adult helpers. The extra adults are most often found when swallow populations have a skewed sex ratio, and not all individuals can find a mate or a nesting site. Related juvenile helpers benefit from the experience of “baby sitting,” and assuring the survival of their parents’ genes. Why unrelated juveniles would be tolerated is less clear (Brown and Brown 1999).

Monday, October 20, 2014

Savannah Sparrow

Like the Least Sandpiper I wrote about in my last post, the abundant Savannah Sparrow has a wide range across North America. Also like the sandpiper, the sparrow usually returns to its nesting area. This behavior often results in reproductive isolation and genetic differentiation among breeding populations. Unlike the monotypic sandpiper, 17 subspecies of Savannah Sparrows have been described by ornithologists. To see some of this variation, look at my posts of birds from Minnesota and Florida. This sparrow was first named by Alexander Wilson, when he collected the first specimen near Savannah, Georgia (Wheelwright and Rising 2008).

Sunday, October 19, 2014

Least Sandpiper

Least Sandpipers are “moderately abundant,” and have the broadest and southernmost breeding range of all the small sandpipers across the arctic and subarctic (Nebel and Cooper 2008). In a previous post, I mentioned that eastern populations make nonstop 4,000 km migrations from New England to their South American wintering grounds. Western birds migrate through the Midwest or down the Pacific Coast.

Erika and I were actually a tad disappointed that such a common sandpiper was the only shorebird we listed on 19 July 2014 at Nisqually National Wildlife Refuge. (The dark back and the yellow legs are keys to its identity.) Being relatively small, bird censuses may tend to under-count this species. Nevertheless, studies suggest significant declines in numbers during recent decades (Nebel and Cooper 2008).

Least Sandpipers are monogamous and lay a single clutch, therefore one might expect them among the earliest of the fall migrants. They also have “a high degree of breeding-site fidelity,” thus it is somewhat surprising that they do not differentiate across their wide range—no subspecies are described (Nebel and Cooper 2008).

Saturday, October 18, 2014

Blue Dasher

Abudnant  across much of North America, Blue Dashers often perch at in trees and bushes.  They often hold their wings forward. The blue abdomens, yellow-striped sides, and white faces all conspire to cinch identification. Erika and I found about a dozen dashers perched on a barbed wire line, with each dragonfly facing  rather stiff wind, on 18 July 2014, south of Moses Lake, Washington.
The next day, on 19 July, we found another Blue Dasher, this time at Nisqually National Wildlife Refuge. A photo of that dragonfly is included below. This beautiful day did not produce a dragonfly until after noon.

Friday, October 17, 2014

Band-winged Meadowhawk

Until about 2000, dragonfly experts considered eastern and western populations of Band-winged Meadowhawks to be separate species. These meadowhawks tend to have pale wing bands in the east, much like in the first photo of a Band-winged Meadowhawk in the Carleton College Arboretum on 24 August 2013. Western populations tend to have much darker bands, at least at the outer edges of the wings. The middle photo was taken last July at Potholes State Park just south of Moses Lake, Washington.
The problem is that Band-winged Meadowhawks in our area of Minnesota tend to be intermediate between the eastern and western populations and lot of variation exists, even within different populations. Notice the dark outer regions of this last Band-winged Meadowhawk from Erika’s garden on 8 July 2014. Recent genetic studies suggest that all Band-winged Meadowhawks constitute a wide-spread and variable species (Forbes 2009).

Thursday, October 16, 2014

Striped Meadowhawk

On 18 July 2014, as Erika and I drove from Missoula, Montana to our destination in Olympia, Washington, the sky quickly became hazier and darker from smoke from forest fires in Washington and British Columbia. The sky was so dark on the Idaho border that I took a photo of the sun in midmorning. The smoke over Spokane, Washington, was down-right apocalyptic—opaque reddish brown. Emails from family in Olympia warned that the Interstate passes were closed with no visibility and multi-car crashes blocking the highway. Thus we found ourselves in western Washington, heading south to Highway 12 and White Pass. Almost immediately the smoke cleared.

Potholes State Park just south of Moses Lake, is a great place to search for dragonflies. My ode-guru, Scott King, had mentioned the possibility of Striped Meadowhawks during our journey—and that is exactly what greeted us at the state park! This striped thorax is distinctive, at least for adults. Rarely do I know a dragonfly's identity the first time I see it.

Striped Meadowhawks range in western North America from British Columbia to the Soutwest, and east to the western Great Plains.  Males defend territories in weedy area and over grassy lawns.  More than other meadowhawks, they often perch in shrubs, and are usually found near water (Paulson 2009). The individuals we photographed were perhaps a quarter-mile from Potholes Reservoir.

Tuesday, October 14, 2014

Blue-headed vs. Cassin’s Vireos

This October I banded several Blue-headed Vireos. I have previously posted on this species. In 1997, genetic studies split the Solitary Vireo into Blue-headed, Cassin’s and Plumbeous vireos. Looking at this rather dully plumaged female, I wondered if a Cassin’s Vireo would be recognized if it wondered into Minnesota from the Pacific Northwest or from somewhere else in the far West.
Plumbeous Vireos, which nest in the southwestern Rocky Mountains, northeast to the Black Hills, are actually found closer to Minnesota than are Cassin’s. Plumbeous Vireos are much darker birds, with slate-gray sides. But Cassin’s Vireos could stray into Minnesota. I believe the bottom photo, which I took in southern Arizona in 1970, is a Cassin’s Vireo. Key field marks of a Blue-headed Vireo include: 1) the gray of the head sharply contrasts with the white sides of the throat; 2) the back of the is much brighter than most Cassin’s Vireos; and 3) Blue-headed Vireos are bright white below, unlike the dingier Cassin’s Vireo. My October birds, as expected, were all Blue-headed Vireos—but I remain vigilant.

Sunday, October 12, 2014

Four-spotted Skimmer

Not all the dragonflies that Erika and I found along the Madison River on 17 July 2014 were new to us. I quickly recognized this Four-spotted Skimmer. Clicking the link will take you a previous post on the species, which is found across much of North America and the northern Old World.

Saturday, October 11, 2014

Western Forktail

On 17 July 2014, Erika and I found another new odonate for us along the Madison River, Gallatin Co., Montana. The green thorax stripes and the blue-notched tip of the abdomen are indicative of the Western Forktail. Separating Eastern from Western Forktails can be nearly impossible in the field, but, fortunately, only the Western is found in western Montana—the Eastern venturing only to the Dakotas and eastern Montana, Wyoming, Colorado and New Mexico.

Males like this one are usually vastly outnumbered by their females. Similar to the Eastern Forktail, females need copulate only once, and then use one male’s sperm to fertilize their eggs. By fluttering their wings and curling their abdomens, the females, in fact, often repel males’ advances Paulson (2009).