Saturday, April 19, 2014

Caspian Tern

Except for Antarctica, Caspian Terns are found around the world. In North America they breed along our coasts and in the interior of the United States and the prairie provinces. Their colonies are adversely affected by changes in water levels, competition with gulls, predators and people. Caspian Terns will often desert their colonies when they are disturbed. Nevertheless, North American populations have increased. In Europe and Africa, however, this tern has declined and is now absent from many parts of the Old World (Cuthbert and Wires 1999).

This Caspian Tern flew overhead as Erika and I explored the South Padre Island Birding and Nature Center on 20 February 2014. These terns subsist almost entirely on fish. They forage with their bills pointing downward. When they find fish, they hover, and then dive, usually completely under water.

Friday, April 18, 2014

Common Gallinule

The birds at the South Padre Island Birding and Nature Center were so tame that I wondered if they were captive. These gallinules appeared to be adorned with red leg bands. This color proves to be a good field mark on any closely observed breeding Common Gallinule. Common Gallinules look like ducks but are actually rails. Note the long, unwebbed toes. This species has had a recent, rocky systematic history. Not so long ago, the ornithologists merged North American Common Gallinules with nearly identical European Common Moorhens, and the resulting species was named Common Moorhen. Now the name has reverted to Common Gallinule, due to differences in calls, bill structure, and DNA.

Common Gallinules are found across much of eastern North America, Mexico, and Central and South America. In many areas they are considered to be game-birds. Bannor and Kiviat (2002) note that the effects of hunting pressure on gallinules is unknown, as are environmental interactions between these birds and other marsh-loveing inhabitants such as muskrats. Wetland pollution and destruction also are threats. The aforementioned authors also relate the story told in Hawaiian mythology that the gallinule’s forehead was scorched red while the bird brought fire to the Hawaiian people.

Thursday, April 17, 2014

Tricolored Heron

We left Atascosa National Wildlife Refuge and drove over to South Padre Island, on the Texas coast. Erika and I had never visited South Padre, and, upon arriving, we figured out why—nothing but high-rise condos and hotels as far as the eye could see. The visit was rescued, however, by my remembering Kirk Mona, a Minneapolis blogger whom I follow, and his post from last January and his account of the South Padre Island Birding and Nature Center. This center charges admission to walk through their small marshland on an elevated boardwalk. Kirk wrote that “there were birds everywhere.” He is right. Most of the birds were tame and easily photographed. Actually the experience was a little like going to a birding Disneyland. I was slightly put off by the zoo-like experience.

Our first bird was this Tricolored Heron. in the 1950s, this species was probably the most common North American heron. Its population was not decimated by the plume-hunters of the previous century. Unfortunately, now Tricolored Herons are declining, often dramatically, throughout their southeastern North American Range. The species depends on estuaries and other coastal areas—habitat that is rapidly being lost to draining, development, and pollution (Frederick 2013).

Wednesday, April 16, 2014

Falcons, Songbirds, and Seriemas

We did not stay at Laguna Atascosa National Wildlife Refuge for very long on 20 February. It was noon, a bad time to look for birds, windy, drought-stricken, and we had plans to visit South Padre Island. We did take a quick drive over to Osprey Lookout, guarded by this spectacular Crested Caracara.
Caracaras are falcons that look like hawks but act like vultures. They share a common ancestor with typical falcons, like the American Kestrel we found later in our trip in New Mexico. More distantly related are forest and Laughing falcons (Morrison and Dwyer 2012). I took this photograph of a Laughing Falcon, in the early 1960s, in Veracruz, Mexico. I have also seen this species in Peru.
Much of the birding world is all a-twitter at the recent discovery that falcons are not closely related to hawks, but are another example of convergent evolution. Their closest relatives appear to be parrots and songbirds. The American Ornithologists’ Union and the newest Sibley guide now place falcons and parrots between the woodpeckers and songbirds (ABA).

The story gets stranger. Genetic evidence suggests that another family of birds, Seriemas, are also closely allied with falcons, parrots and passerines (BirdsEye Birding). Seriemas are odd, South American birds that were thought to be related to cranes. I photographed the Red-legged Seriema in the last photo in northern Argentina in the mid-1960s.

Tuesday, April 15, 2014

Great-tailed Grackle

Great-tailed Grackles also fed at Laguna Atascosa refuge during our February visit. I have previously blogged about this species’ northern expansion, beginning in southern Texas in the early 1900s and continuing by century’s end across much of the central United States, including Minnesota, and even at least three Canadian provinces.

Great-tailed Grackles are fairly omnivorous. Their diet is composed mainly of plant material in the winter; arthropods and other animals in the summer. They are reported to kill small birds, but to leave them uneaten (Johnson and Peer 2001). These authors provide an extensive list of food items, but do not mention fruit, such as the grackle below appears to be devouring. I assume Great-tailed Grackles limit their fruit consumption to bird feeders and that they do not normally attack orchards.

Sunday, April 13, 2014

Olive Sparrow

The National Wildlife Refuges and many of the State Parks in Texas feed birds and build viewing blinds. At Laguna Atascosa refuge we got great views of an Olive Sparrow. This sparrow forages on or near the ground in dense cover. As a result, little is known about Olive Sparrow biology.

This species was a new one for my USA list. I previously listed one in Mexico. Although a common resident from southern Texas south through Costa Rica, Olive Sparrows have large gaps in their range. Many ornithologists believe, among at least 9 races currently recognized, perhaps as many as three species exist—the Texas Sparrow, found in Texas and eastern Mexico, the Yucatan Sparrow, found in the Yucatan Peninsula through Belize and Guatemala, and the Pacific Sparrow, found along the west coast of Mexico. These potential species differ in size and color (Brush 2013).

Saturday, April 12, 2014

Common Loon

As I have written before, loons are among my favorite birds. I was delighted on Wednesday when Penny H. alerted me to a loon at a small pond in suburban Northfield. Common Loons, like the bird in the second photo, search for their prey by swimming while holding their heads under water .
Common Loons usually avoid foraging in deeper parts of lakes. They prefer lake edges between 50 and 150 meters from shore and in areas less than 5 meters deep. Here they find their preferred prey, common at these depths, fish generally smaller than 15 centimeters (Evers et al. 2010).

Friday, April 11, 2014

Dark-eyed Junco

Here is an oddly-plumaged Slate-colored Junco we banded last Monday near Northfield, Minnesota. I do not recall ever handling a junco with such odd facial markings. The bird is clearly in molt—note the feather sheaths on its ear coverts. Are the pale gray supercilliary marks winter feathers not yet molted into dark adult plumage? What about the odd necklace running across its upper breast? That this bird is the Slate-colored form of a Dark-eyed Junco is evident by the sharp angle formed by the edge of its white belly.

Thursday, April 10, 2014

Fox Sparrow

Weckstein et al. (2002) wrote "When John James Audubon found a Fox Sparrow for the first time on its breeding grounds in southern Labrador in 1834, he had no idea that he was looking at one of North America’s most geographically variable birds, with 18 subspecies divided into 3 or 4 distinct groups…”  I have posted a number of times on this species’ taxonomy—use the search box to the right of the posts to pursue this information.

Because of the cold winter, our Texas travels, and other mitigating events, only this week did I get my banding nets set up. We were happy to band three Fox Sparrows, a Song Sparrow, and about a dozen Slate-colored Juncos.

Wednesday, April 9, 2014

Plain Chachalaca

Feeding along with the Green Jays at Laguna Atascosa National Wildlife Refuge were flocks of Plain Chachalacas.  These large birds are in the same order, Galliformes, as turkeys, but they do not seem otherwise closely related. They are assigned to a separate family, Cracidae. In fact, some evidence exists that they are most closely related to Bush Turkeys. Some ornithologists go as far as to assign the Cracidae and the Bush Turkeys to their own order, Craciformes, separate from turkeys, grouse, pheasants and quail (Handbook of the Birds of the World—Alive). In any event, chachalacas are primarily South American species, with only the Plain Chachalaca barely ranging north of the Rio Grande.