Yellow-bellied Flycatcher

The 2013 banding season continues to be slow and late in Northfield. Yesterday, 9 September, I caught my first Yellow-bellied Flycatcher. These flycatchers have a short breeding season. In Minnesota, the first fall migrants can be seen in July. This year is not the first that I missed the early migrants—I banded my first fall Yellow-bellied Flycatcher in 2011 on 7 September. I find capturing the true colors of this bird to be most difficult. This photo comes closer than most, but is a tad brownish. The birds actually show a muted tropical greenish on their upperparts.

Golden-winged Warbler

On Sunday I banded this Golden-winged Warbler. This warbler is so beautiful that I can not resist sharing this image with you, despite having done so a few times in the past. Indeed, I took a very similar photograph last spring. Previously I have discussed the possibility that there is good reason that this warbler looks somewhat like a Black-capped Chickadee. I have also described the genetics of this species’ hybridization with Blue-winged Warblers.

Golden-winged Warblers have been declining for the last 40 years at a rate of 2.8% per year. The species no longer breeds in part or all of Georgia, South Carolina, Virginia, Massachusetts, Connecticut, Rhode Island, Vermont, New Hampshire, Indiana, Illinois, and Ohio; the species is listed as threatened in Canada and a “species of management concern” in the United States (Confer et al. 2001). On the bright side, Golden-winged Warblers are increasing and spreading northwest across Canada.

What’s happening? The secondary habitat in which they breed is disappearing in the East, where old fields are once again becoming forests and where people destroy wetlands. Loss of habitat in their wintering grounds may also work against the species. Golden-winged and Blue-winged warblers also hybridize. The hybrids apparently have reduced fitness, and they drop out of the populations within 50 years of initial contact; they are replaced by Blue-winged Warblers. Furthermore, Golden-winged Warblers may be particularly prone to parasitism by Brown-headed Cowbirds. Remedies suggested to combat this decline include burning nesting areas to keep fields in a state of early succession, planting aspen in the northern parts of the range, control of cowbirds, and even killing Blue-winged Warblers in areas of overlap (Handbook of Birds of the World Alive).

American Golden-Plover

On Saturday noon I drove 40 miles south to Steele County, where state birding listservs reported a huge flock of American Golden-Plovers. After several miles’ searching, I found the promised field filled with a flock of about 800 birds. In this first photo, some plovers are loitering in front of the first pond, but about 100 more are feeding behind the water.

The next photo gives you an impression of the huge number of birds as the flock was spooked by a Northern Harrier and an over-flight by a Peregrine Falcon. I was not able to get all the flying birds into my photo frame.

A few birds flew closer to me. In the final photo, note that the under-wings are white, not black. These white axillars are one of the field marks of golden-plovers. These birds are browner above than the much grayer-backed Black-bellied Plover. Few retrain the black bellies of breeding golden-plovers, although a few are black speckled. Note the bird on the far left in the bottom photo.

Such a large flock like this one is uncommon in Minnesota in the fall. American Golden-Plovers have an elliptical migratory pattern. They usually fly off the Atlantic Coast, often nonstop from James Bay to South America (some go all the way to Tierra del Fuego). In the spring, they return through the central United States.

Some birds, especially juveniles and a few adults do make their fall migration through the Great Plains, while fewer still work their way down the Pacific Coast. The fall migration is lengthy—juveniles depart their arctic breeding grounds (along with unsuccessful breeders) much earlier than do breeding adults. In fact, the first birds arrive in South America long before the last birds leave the tundra (Johnson and Connors 2010).

Tennessee Warbler

This portrait is of this season’s first Tennessee Warbler, an abundant migrant in our area. I have posted on the species many times before—search for these posts by entering “Tennessee Warbler” in the “Search this Blog” box on the right hand column of this blog.

I happened upon an Internet site that may be of interest to photographers and birders—Birding Across America. Although somewhat redundant to the Minnesota Ornithologists’ Union’s home page and to the rare species photographs on eBird (and to eBird, itself), this site, nevertheless, gives photographers another opportunity to post their work. Presumably the site also alerts birders to locations for searching for birds as well as species being seen across the country.

Northern Gannet

I thought I blogged about the Northern Gannets that Erika and I saw during our January 2004 Florida trip. Perhaps because I was on a rocking ferry from Cape Hatteras to the mainland of Virginia and the resultant somewhat blurry photos, I didn’t get around to the post.

Gannets are, nevertheless, wonderful birds. They only breed in 32 colonies on cliffs in northern Europe to Quebec and Newfoundland. Only six of these colonies are in North America. Our gannets winter off the Atlantic and Gulf coasts.

They make spectacular dives for the fish and squid. They plunge from heights of up to 40 meters, achieving speeds over 100 km/hr, before hitting the water, penetrating up to 5 meters, and sometimes swimming 15 meters further down. Often gannets feed in flocks of hundreds. When I taught ornithology, I always wished to share this sight with my students, but I never found anything on the Internet. Lately I located this video of a single gannet diving.

Gannets suffer “fishing accidents,” being tangled in nets, and persecution by fishermen. Despite their limited breeding locations and high adult mortality rates, Northern Gannet populations are increasing at a rate of about three percent each year (Mobray 2002).

Differential Grasshopper

Assuming the salient field marks of this arthropod are the herringbone chevrons running up its hind legs, this must be a Differential Grasshopper. The species is common in southern Minnesota and most of the United States (except the East Coast and the Northwest.

Dave Bartkey and his family pointed this one out to me at the River Bend Nature Center near Faribault, Minnesota. As you can see, this critter was depositing egg pods containing dozens of eggs between the bricks at an outdoor viewing area. Each pod contains up to 200 eggs, which hatch in the late spring. The young nymphs become adults in a month or two. Usually one generation is hatched each year. The species is not migratory and overwinter in the egg stage in Minnesota.

These grasshoppers can be a significant crop pest. They eat most plants, but prefer grasses, ragweed, sunflowers and Prickly Lettuce. The young feed on grains, alfalfa and hay; adults consume corn, cotton, and fruit crops. Often large swarms attack fields (Wikipedia).

Midland Clubtail

Earlier this season, I took this photo of a Midland Clubtail devouring a hapless butterfly. This species is a strong flier, able to chase down other flying invertebrates, including other dragonflies. They breed in fast-moving, clean streams in the northeastern United States, north and west to southeastern Canada and Manitoba. This individual hunted in the Carleton College Arboretum. See also my post of 16 June 2013.

American Rubyspot

On Saturday, I found four American Rubyspot damselflies along the creek that feeds into Carleton College’s Lyman Lakes. Identity should be no problem here, although these damselflies, even the male above, were not as gorgeous as the first rubyspots I saw in 2011. Photographing a flying rubyspot proved to be difficult. The damselfly suddenly darted over the stream, but usually returning to its original perch. Notice that this male’s abdomen is wounded, perhaps from an encounter with a hungry bird. Purple Martins, other swallows, and flycatchers all find dragonflies to be tasty morsels.

I was so intent on catching the rubyspot in air, that I never saw the Eastern Forktail fly by in the upper right-hand corner of the center photo. Only when I got home behind my computer did I see the forktail. The male rubyspot’s red wing spots grow larger over time, and are largest on dominant males. Paulson suggests that these spots actually decrease the most dominant male’s hunting success.

The last picture is of a female American Rubyspot. These damselflies do not have courtship displays.  Dominant males simply seize approaching females (Paulson). Males may briefly guard their mates, but only copulate once with any individual female, who may mate with a second male.

Marsh Wren

Reviewing my blog, I am surprised to find no entries for Marsh Wrens. The species an abundant breeder in many cattail marshes across northern North America. They winter further south and into most of Mexico. They are usually easily brought forth by an observer who makes spishing or squeaking sounds.

The Marsh Wren’s song is described by Petersonas “reedy and gurgling, running into a guttural rattle.” Thayer Birding Softwarekindly allowed me to link you to this sound file. Erika and I have always compared this song to popcorn popping in the marsh. After extensive study, ornithologists discovered that Marsh Wrens learn up to 200 song types. They sing almost nonstop, day and night.

Why so many songs? Marsh Wrens are polygynous. In any given population of wrens, about half the males mate with two or more females. The males also build dummy nests—sometimes up to six besides the one actually used by one of their mates. They may be advertising their fitness by displaying their variety of songs and showing off their real estate. 

Birders noticed that eastern and western Marsh Wrens differ. Western birds sing up to four times the number of songs than do eastern ones. The songs of the western birds are less liquid than eastern birds, the western ones being harsher, more complex and variable. Western males are more likely to be polygynous than eastern wrens. Kroodsma and Verner (1997) predict that these two populations will be split by ornithologists into two species, the Eastern Marsh-Wren and the Western Marsh-Wren. The first photo in this blog is an eastern Marsh Wren banded in Aberdeen, South Dakota. The last photo is a western bird, taken in Olympia, Washington.

Tule Bluet maintenance

With some help from Scott King, I believe these damselflies are Tule Bluets. The male below shows the typical field marks for the species—a small, black spot on top of the first abdominal segment coupled with most of the remaining segments showing more black than blue. Female Tule Bluets show fewer field marks, and may not be identifiable in the field. The female bluet in the upper photos, however, looks close enough to a Tule pattern to be that species—plus this damselfly was in the vicinity of the male below.

The female bluet showed intriguing behavior. As she perched on a dead branch, she wagged her abdomen up and down.  Then she lowered it, as seen in these first two photos. Apparently she used her hind legs to rub off a bit of irritating spider web.  Look carefully for the web strand connecting the tip of the damsels abdomen to the side of the twig. These photos were taken in August at Circle Lake in Rice County, Minnesota.