Thursday, May 21, 2015

Prothonotary Warbler

If you visit Rockport, Texas, as we did last March, an interesting (and unlikely-looking) site to visit is the Demo Bird Garden and Wetlands Pool maintained by the city and the Texas Department of Transportation. A short boardwalk winds across several ponds and through a small woodland patch. We had stopped here on previous visits during draught, but knew the location had potential in a wet year.

This year, one of the first birds we found was this Prothonotary Warbler, found in Southeastern swamps and even venturing into southern Minnesota. Despite the bird’s being common, this photo is my first of the species. This warbler is named after prothonotaries, yellow-robed papal clerks in the Vatican. Prothonotaries are our only warbler that breeds in tree cavities, often using holes made by Downy Woodpeckers.

My mentor, John Trott, told the story of how a Prothonotary Warbler resulted in the allegation of Alger Hiss's being a communist spy. Petit (1999) retells the tale. Briefly, a man named Whittaker Chambers accused Hiss of being a spy. Hiss claimed not to know Chambers. Chambers countered that the two men did know each other, and that Hiss, a birder, told Chambers than he had seen a Prothonotary Warbler along the Potomac River. Hiss independently told the House UnAmerican Activities Committee about seeing the warbler, confirming his lying about not knowing Chambers. This discovery was partially responsible for the political rise of one of the committee members, Richard Nixon.

Wednesday, May 20, 2015

Field Sparrow

Field Sparrows are common in brushy fields, but tend to avoid urban and suburban habitats. Consequently, these sparrows have declined in numbers. This year I heard a Field Sparrow before I banded one—presumably the individual I heard. The song is an accelerating series of whistles that end in a trill. The species is common across the eastern United States and southern Canada.

Tuesday, May 19, 2015

Black-bellied Whistling-Duck

Erika and I have seen Black-bellied Whistling-Ducks during previous visits to Rockport, Texas, but they seemed down-right abundant in mid-March. This observation is perhaps not too surprising, since, unlike sedentary Latin American populations, northern birds are migratory. Our previous trips were earlier in the year.

I usually call whistling-ducks by an older name, tree-ducks. Black-bellied Tree-Ducks are more arboreal than other whistling-ducks, and often nest in tree cavities or duck boxes. This species appears to be moving northward from its haunts in Texas, Louisiana, Arkansas, Florida, and Arizona, with recent records from South Dakota, Minnesota, Ontario and elsewhere.

Monday, May 18, 2015

Black-throated Green Warbler

On Saturday, 15 May 2015, I banded a gorgeous Black-throated Green Warbler in Northfield, Rice Co., Minnesota. At the time, I noticed the black post-auricular spot.  I also was aware of faint black streaks on the bird’s back. After researching the afore-mentioned spot, I slowly concluded that this warbler is probably a hybrid between a Black-throated  Green and Townsend’s warbler. Black-throated Green and Townsend’s warblers hybridize in the limited area where their ranges overlap in central British Columbia (Toews et al. 2011).

Here is why I thought this bird was odd:

1) The black post-auricular spot started my unease with my initial identification. Most field guides don’t show this mark. A few photos on the Web of birds identified as Black-throated Green Warblers do show similar dark spots. The stripes on the sides of this bird’s face, however, are darker than expected on a typical Black-throated Green Warbler.

2) In the field, I noticed the faint black streaks on this bird’s back. A Black-throated Green Warbler’s back should be completely unstreaked. Male Townsend’s Warbler’s have dark-streaked backs.

3) After reaching the conclusion that my bird might be a hybrid, I returned to my photographs and found the photo below. Although a pure Townsend’s Warbler should have a black crown, unlike the green one on a Back-throated Green, notice the black feathers along the upper edge of this bird’s yellow supercilliary stripe.

I should have stopped my research there. But, instead, I continued on to Stephenson and Whittle’s definitive book, The Warbler Guide. There I found photos of Black-throated Green Warblers showing all the field marks I have discussed. They write that the back has little or no streaking (the emphasis is mine). Several photos show black post-auricular spots, and a couple of them show black-lined, yellow supercilliary stripes. Well, “easy come, easy go” is all I have to say.  I just had hybrids on the brain after my apparent hybrid between an Audubon’s and Myrtle warbler.

Sunday, May 17, 2015

Brown Pelican

Brown Pelicans are common around Rockport, Texas. Their aerial dives into the water are entertaining. Laughing Gulls, hoping the steal or scavange the pelican’s catch, often accompany the pelicans.

The photo below really should be credited to both of us. Erika found a pelican sleeping on a pier. The bill is completely hidden in the back feathers. “Take a photo, Dan,” Erika said, “that is certainly a Kodak moment!” Notice the half-open eye. Birds (and some aquatic mammals) are able to sleep with one eye open and half of their brains awake. The ability, termed “unihemispheric sleep” allows them to sleep, while, at the same time, be alert for predators (Mascetti and Vallortigara 2001).

Saturday, May 16, 2015

Yellow-headed Blackbird

I have posted a number of times on the Yellow-headed Blackbirds of Dakota County’s 180th Street marsh. See, for example, a posting from last June. When John Holden and I listed this blackbird once again last Wednesday, I could not resist posting yet two more photos of this dragonfly-eating omnivore.

Friday, May 15, 2015

American Pipit

American Pipits breed across the Canadian Arctic, most of Alaska, and south through Rocky Mountain tundra into the United States. They winter in the southern United States, Mexico, and northern Central America. In Minnesota, they are uncommon spring and common fall migrants (Eckert). Last Wednesday, John Holden and I found this pipit at the 180th Street Marsh in Dakota County.

American Pipits vary in the amount of breast streaking. Non-breeding birds tend to be much heavier streaked than birds in breeding plumage. See my 2012 post, showing a heavily streaked bird I photographed near La Jolla, California. In that post, I commented that American Pipits used to be named Water Pipits, when our birds were considered to be races of European birds. Our birds received new nomenclature when ornithologists decided our birds are not races of the European pipits, but a species of their own.
Four races of American Pipit are currently recognized—one breeds above treeline, from northern Alaska to Newfoundland; a second breeds from Alaska south through the Rockies to Oregon; and a third breeds further south in the Rockies of the United States. The fourth race of the American Pipit, the Asian Pipit, breeds in eastern Siberia and winters from northern India to Japan. They only accidentally wander into the New World. Asian Pipits show a number of subtle plumage differences, and have pink legs (Hendricks and Verbeek 1012). In his field guide, Sibley illustrates an Asian Pipit.

I think the American Pipit is poorly named. To call the Siberian birds “American” seems absurd. It makes as much sense as naming the whole species “Siberian Pipits.” Buff-bellied Pipit, occasionally used at the subspecies level, might be a better species name.

Thursday, May 14, 2015

Whooping Crane

One reason to visit Rockport, Texas. is that the town is close to where the world’s wild Whooping Cranes winter. This crane is one of the rarest birds in North America. Over 250 birds compose the wild flock (USFWS). The best way to see the birds is to take a boat tour from Rockport, as Erika and I did in 2010. But boat trips cost money, and a visit to the Aransas National Wildlife Refuge will likely meet with success. In recent years, we have discovered Goose Island State Park, just across the bridge north of Rockport. The photo above was taken last March in Goose Island, near the The Big Tree.

The Texas cranes are vulnerable to pollution, competition with people for water, and natural disasters such as hurricanes. By releasing captive birds, biologists have attempted to establish secondary flocks of Whooping Cranes. Programs along the Rocky Mountains and in Florida have be abandoned. Birds raised and Wisconsin and taught to migrate to Florida suffer repeated nest failures. A new release, to reestablish a nonmigratory Louisiana population, began in 2010.

The birds in my photograph appear to be a family group of two adults and one young. Whooping Cranes care for their young for up to a year, and young birds learn their migration routes by following their parents. Usually only one hatchling survives their two-egg clutches. Taking single eggs for propagation programs, therefore, does not affect the wild population. Wild birds may live to be 25 years old; captive birds can live over 40 years. They do not mate until they are three or four years old (in the wild) or as old as eleven in captivity (Urbanek and Lewis 2015).

Wednesday, May 13, 2015

Herring Gull

This Herring Gull image is the last of three photos Erika and I took in Rockport, Texas, last March of bathing birds. Herring Gulls often bathe while resting on water, ducking their bodies under water and then shaking their feathers. After bathing, these gulls will often preen (Pierotti and Good 1994). You might not think that a gull would get dirty enough to need a bath. The behavior probably both cleans and helps control feather parasites such as mites.

Tuesday, May 12, 2015

Eastern Forktail

On 7 May, I encountered this damselfly on a path along the Minnesota River Valley National Wildlife Refuge’s Bass Ponds. In the field, I identified it as an Eastern Forktail, one of the most abundant forktails in most of its range. Back home, I was less sure.  With its chestnut thoracic stripe and pale, emerald tail, I could not find anything quite like it in my guides. My ode guru, Scott King, confirmed my initial identification—this young female is acquiring the blue pruinosity of an adult. I have posted an entry showing photos of both young and old individuals.

Damselflies sure can be frustrating to identify. You can have males, young females, old females, and andromorphs—females that look like males. How is a fellow supposed to remember all that?