Texas Shorebirds in April

The Gulf Coast provides many accessible site for watching shorebirds, so I thought I'd share some photos from our recent trip to Florida (Tarpon Springs) and East Texas (Bolivar Peninsula). Have written about these species at some length in the past, so today I'll stick with pictures. Many of the birds are in transition from winter (basic) to breeding (alternate) plumage.

Ruddy Turnstone - Arenaria interpres - Breeding

Dunlin - Calidris alpina - Winter

Western Sandpiper - Calidris mauri - Breeding. Blurry Sanderling in background.

Sanderling - Callidris alba - Molting into breeding plumage.

Texas - Terns in Context

Recently mentioned that the Black Tern is one of the smallest of the terns, but I didn't really place that in context. A photo from Rollover Pass on the Bolivar Peninsula may give you a better idea. Here 3 small molting Black Terns are in the center, dwarfed by 3 large Royal Terns to the right with their orange bills, and 2 medium-sized Sandwich Terns on the left, with yellow-tipped black bills. The Royal Tern at 20" is almost as large as the 21" Caspian Tern.

At Bolivar Flats the Black Terns were seen with the slightly smaller Least Terns. I thoughtlessly tried to frame the Black Terns by themselves, but did find the 2 small tern species together. The bill of the Least is yellow in breeding plumage, with a touch of black at the tip. No other terns seen in the U.S. have yellow bills.

Terns were once grouped with the Gulls in the family Laridae but DNA analysis convinced the taxonomists to give terns their own family, Sternidae. There are about 44 species of birds in the tern family, including 5 species with the name noddy.

We did get to see a few distant Gull-billed Terns on the Bolivar Peninsula along Yacht Basin Road, a new species for us. They have relatively longer legs that most terns, as well as thick black bills, and are not usually seen along the shore with other terns.

American Alligator - Alligator mississippiensis

During our April visit to east Texas we stopped several times at the Anahuac National Wildlife Refuge, not far from High Island. The highlight there is a great loop drive around "Shoveler Pond", not unlike the drive around the Colusa National Wildlife refuge in the Sacramento Valley. At Anahuac visitors are permitted to walk along the levees. As we rounded a bend on the route we spotted this imposing beast sunning along the shore. I got out of the car to take a photo, but kept my distance. Viewing and photographing through a scope certainly lowered any stress.

The American Alligator shown above was about 9 feet long, perhaps a male. They increase in size with age, and can reach 15+' in length and a weight of 1,000 pounds! Pretty common in fresh water habitats of Florida and other gulf coast states. The bulge below the mandible is a feature that varied from minute to minute, perhaps helpful with thermoregulation. A friend wrote that the sense prey from receptors on floor of the mouth, so maybe this one was checking the air the way a snake extrudes its tongue.

Black Tern - Chlidonias niger

The timing of our Texas birding trip in early April preceded the peak of spring migration for the songbirds and others, but we did get to see a strong pulse of Black Terns passing through, with many present at both Rollover Pass and Bolivar Flats. Most birds we saw were in the middle of their pre-alternate molt, presenting interesting mixtures of black and white. This one apparently has a long way to go....

The birds at Bolivar Flats (a sanctuary managed by Houston Audubon) were pretty oblivious to our presence, so we had prolonged opportunity for viewing. This second bird has developed more black, but still far from the beautiful sleek finery it will obtain over the next month.

The Black Tern is a small tern, less that 10" long including those long wings. Compare to the Least Tern, 9" long. Overcast sky added to the pleasing monochromatic composition. 

Last shot shows one of the birds stretching. The black "band" is simply the tips of the secondaries on the trailing edge of the right wing. 

All birds we saw were simply resting on the beach or shoreline. Our only previous experience with the Black Tern was on a Rich Stallcup outing to Moonglow Dairy about 10 years ago, where we watched several of them flying like swallows over a marshy area and deftly snatching insects from the water's surface.

Wilson's Plover

One reason I like plovers is that they are pretty tolerant of humans, so they can be closely observed and photographed. On our Texas trip in May we observed 7 species in the family Charadriidae, which includes the plovers, sand-plovers, lapwings, and dotterels. One of the best spots was Rollover Pass, where we watched Wilson's Plover, Charadrius wilsonia. In the shot below the duller female Wilson's is on the left, the male with the rufous eyebrow and wide breastband is in the center, and the slightly larger Dunlin is on the right. The long thick bill quickly separates Wilson's from otherCharadrius plovers.

Here's a better shot of the male. The pink legs also set it apart from other plovers.

The plovers are usually grouped with the large family Scolopacidae, the Sandpipers. It was interesting to read in Sibley's Guide to Birdlife & Behavior that the plover family may be more closely related to the Gulls and Terns than to the sandpipers!

The list of plovers we encountered in Texas included Black-bellied, American Golden, Piping, Semipalmated, Snowy and Wilson's Plovers, along with the Killdeer.

Some past plover photos.

Upland Sandpiper - Bartramia longicauda

During our 6 day visit to Texas in April we concentrated on sites known for birding diversity and good viewing. For us that meant Bolivar Flats and the Houston Audubon Society's preserves at High Island. On the morning of April 8th we decided to explore the local backroads in search of the Upland Sandpiper, a species we have never seen. Our search grid included the area south of I-10, west of route 124, and north of White's Ranch Road (rte 1985). Tired without success to find some flooded fields for shorebirds, but mostly looked for grassland habitats preferred by the Upland SP.

Driving slowly on Fairview Road we spotted a few medium sized shorebirds foraging in the grass near the roadside, and watched them as they flew into a nearby field. There we followed a loose flock of 10+ Uplands as they searched for invertebrates. Often we saw only their heads, but occasionally a few provided a decent view, although at some distance.

Their big eyes contributed to the choice of their old name, the Upland Plover, although it was recognized that they belonged in the sandpiper family rather than with the plovers (see below for taxonomy). Their small rounded heads have been described as "pigeon-like".

Their long necks are like those of larger sandpipers, but since they don't forage on mudflats they don't need long bills like their curlew cousins.

Taxonomy, from Birds of North America Online,  #580, C. Houston and D. Bowen:

Related Species

Although it is placed in a monotypic genus, Bartramia longicauda could be considered a small curlew (Numenius spp.) with a short, straight bill; the two genera are sisters (see Sibley and Monroe 1990, Thomas et al. 2004, Baker et al. 2007). The curlew radiation lies squarely within the family Scolopacidae, the shorebirds, where it appears to be basal to a radiation that includes many of the familiar genera in the family (Baker et al. 2007), such as Limosa (the godwits), Gallinago (the snipes), Calidris (the “peeps” and stints), and Tringa(the shanks).

The Upland Sandpipers spend 8 months of the year "wintering" in grassy fields of South America, where of course it is "summer" down there. They migrate north through the central and eastern US. Populations have declined in the past because of hunting (said to be very tasty) and habitat loss.

Black Spreadwing - Lestes stultus

Damselflies are tough for a beginner like me, as the difference in the species are often subtle. Identification best performed by examination of a specimen "in hand", but sometimes a digi-scoped view gets me close enough to see some subtle features.

Most damselfly species rest with their wings folded near the body, but the Spreadwings (family Lestidae) usually perch or hang with wings in an open position. Here is what I believe is a male Black Spreadwing, Lestes stultus, one of many seen at Nagasawa Community Park in Santa Rosa, California. Photos are from a visit on May 10, 2016.

The male above has started to briefly fold the wings. The sexual appendages at the end of the abdomen are curved inward, with the cerci above framing a window showing the the club-shaped paraprocts below. Here the paraprocts are reflecting white, but in fact are black. Note the black panel near the ends of the wings, the pterostigma, here with a narrow white border.

 

This was the only time I saw this spreadwing with the wings folded, albeit briefly. The head and thorax have a hint of purple iridescence.

A crop of another view shows a bit more detail in the appendages:

Many of the 20+ Black Spreadwings gathered near a small ponded area in the center of the swale, most either in tandem or in the wheel position, as here. The abdomen segments near the end of the male are flexed sharply forward, allowing him to grasp the female just behind the head in an area that I believe is called the prothorax. The female's entire abdomen is curled forward to complete the wheel (or "ring"), allowing her to receive the sperm stored in secondary genitalia of the male on the undersurface of segment 2.

Cropped view of the male grasping the female, showing how the appendages have spread apart to firmly grasp the prothorax.