Monday, April 30, 2012

Great-tailed Grackle

Great-tailed Grackles spread from Mexico into the United States and Canada during the 1900s. Urbanization and agricultural irrigation seem to have contributed to the species' spread. Until the 1960s, Great-tailed and Boat-tailed grackles were thought to be the same species. Now they are considered to be distinct. For one thing, Boat-tailed Grackles in Florida and the Gulf Coast, like the one in the lower photo, have dark eyes. Great-tailed Grackles, like the one above from Rockport, Texas, have yellow eyes. (Boat-tailed Grackles outside the areas of overlap, like along the Atlantic Coast, also have yellow eyes.) Great-tailed Grackles are found in prairies, agricultural areas, and towns; Boat-tailed Grackles prefer marshy areas (Johnson and Peer 2001).

Great-tailed Grackles are polygynous. Social bonds are "ephemeral;" females (and males) may switch mates within or between breeding seasons. Males defend small territories containing trees in which females nest. One reason for this pattern may be that males suffer relatively hight mortality rates, resulting in more females in the population (Johnson and Peer 2001).

Sunday, April 29, 2012

Black-bellied Whistling-Duck

Black-bellied Whistling-Ducks were a highlight of our early March stop in Rockport, Texas. Erika and I were driving through town in the evening, when unfamiliar birds began swooping down and landing a few blocks away. At first glance, I thought they might be ibis. These migrants from Mexico probably returned to eastern Texas a few days before we discovered them. As you can see below, they were attracted by a woman feeding massive bags of grain in her backyard.

You can tell my age because I call these birds Tree-Ducks. (Don't be surprised when I say a Northern Harrier is a Marsh Hawk.) These ducks nest in tree cavities and nest boxes. They form life-long pairs. Often they lay eggs in other whistling-duck nests (Dale and Thompson 2001). With so many whistling-ducks nearby, we had no trouble hearing their loud, whistled "pe-che-che-ne" calls.

During our Texas travels, we looked in vain for the other North American whistling-duck, the Fulvous. We read reports on eBird of south Texas Fulvous Whistling-Duck sightings, but the ducks kept a step ahead of us.

Saturday, April 28, 2012

Sora

Erika and I also saw a single Sora in the marsh near the Virginia Rail along the Old Highway 77 Bridge at the Minnesota Valley National Wildlife Refuge. A quick look at the bills of these two rails suggests that they partition their feeding habitats. Obviously the Virgina Rail's long bill (see last blog post) is more efficient at probing deep into the mud, while the Sora is probably restricted to shallower prey. Both rails feed on invertebrates and plant seeds.

This Sora photo was taken in South Dakota. The bird we saw on Tuesday was barely visible. Despite the difficulty in seeing a Sora, the species is abundant in North American marshes. Even if hard to see, their loud whinnies are often heard (link curtesy Thayer Birding Software). Despite their being a game bird in many states, the main threat to Soras is wetland destruction. The etimology of the word Sora is unknown but presumed to be derived from a Native American language (Words for Birds: a Lexicon of North American Birds).

Friday, April 27, 2012

Virginia Rail

Reading reports of several species we lack for our eBird list on the MOU listserv, Erika and I drove on Tuesday to the Old Highway 77 Bridge in the Minnesota River Valley National Wildlife Refuge. We strolled out to the end of an elevated walkway that leds to an observation point in the marsh along the edge of the Minnesota River. At the observation deck, several birders patiently tallied birds. "Virginia Rail!" exclaimed one of our companions. "Where?" we asked in unison. "Right behind that first clump of reeds" came the reply. (How nice sharp eyesight would be again...) You can see the Virginia Rail feeding in the marsh in the center of the photo above. Look for its orange-red bill. Sometimes the ripples of water made as it walked across puddles located this secretive bird.
Finally the rail walked across an open area. When given a choice, the bird remained in the shade and walked into the densest of cattails. The rail can remain in the reeds because the body is laterally compressed. In other words, the rail is narrow. Rails also have flexible vertebrae so they can make their way around the stalks. Virginia Rails are fairly common in Minnesota marshes, but are more often heard than seen. They also often respond to taped calls, as did the Virginia Rail in the lower photo (from South Dakota). Some birders disapprove of playing tapes, so curtesy usually demands you ask for an OK if you and to try to attract rails. Rails do not always respond. The rail in the top two photos were found without the aid of a tape.
Virginia Rails are monogamous. They often build dummy nests in their territories. Young leave the nest immediately upon hatching, though both parents continue to care for them. Virginia Rails are so secure in their wetland tangles that they are able to undergo two annual molts. Their late summer molt leaves them flightless, as they lose their wing and tail feathers simultaneously (Conway 1995). Even when they are not molting, Virginia Rails usually run from danger.

Most field guides do not show Virginia Rails with bright bills like these. I assume this bright color indicates the rails are courtshiping. Usually to locate rails, you must listen for their grunting duets.  This recording is courtesy of Thayer Birding Software, Birds of North America for Windows, Gold Edition. (Mac versions are also available.)

Thursday, April 26, 2012

Laughing Gull

Even if you forgo the Whooping Crane tour boats, Rockport, Texas, is great for birding. Our hotel was within walking distance of the Rockport Beach Park. This proximity saved us from an entry fee charged to automobiles. We enjoyed birding here during our last visit several years ago in January. In April the Laughing Gull nesting area, which also contained a few nesting Black Skimmers, was in full swing.
We witnessed many gull behaviors that we previously only read about in behavior textbooks. Laughing Gulls turn aggressive when they see black heads and white eye rings. This reaction makes it hard to attract a mate. So the gulls use a display called Facing-Away. Birds face each other, but turn their heads to one side. This way they do not see each others' black faces or white eye rings. Only gradually is a pair able to face one another, but they often have to fluff their head feathers so that the heads appear less black.
The Hunched Posture is another appeasement display. At the same time, the females give a low "mew" or "croon." The females show this posture during courtship and just before copulation. By pulling their heads into their body plumage, the females appear smaller and more compact. From this posture, females often solicit courtship feeding (Burger 1996).

Wednesday, April 25, 2012

Horned vs. Eared Grebe

On 21 April 2012. Erika and I photographed this rather handsome Horned Grebe on Cannon Lake in Rice County, Minnesota. This observation was not the first of the year, as we already listed in near the Oregon Coast during our April road-trip (second photo). The Oregon bird is well on its way to molting into breeding plumage
Birders sometimes have trouble telling Horned and Eared Grebes apart. In breeding plumage, the Horned Grebe's neck and breast are reddish-brown. Note the Eared Grebe below (from South Dakota). The Eared Grebe's breast is black. In winter plumage, the two species are more difficult to identify. Note the crested top knot on the Eared Grebe's head. This profile is usually sufficient to identify the species. Also note the red eyes in both species. Apparently many diving waterfowl have red eyes. This color becomes invisible under a few feet of water, thus prey are less likely to see the divers' attack.

Tuesday, April 24, 2012

Whooping Crane

Our plan, after leaving the Golden-cheeked Warblers of Fort Hood, was to spend a couple of days exploring Austin, Texas. But Austin was hosting thousands of tourists for their South-by-Southwest music and film festival, so Erika and I headed for two days at Rockport.

Along the way we visited the Aransas National Wildlife Refuge, famous for its wintering Whooping Cranes. On a previous visit we had ridden on one of the tourist birding boats, the best way to see the cranes (see my blog post of 6 July 2010). (If you have never seen Whooping Cranes, we recommend the tour boat. Many years ago we visited Aransas and missed the cranes since we could not afford the tour.) Aside from our success with the cranes, we were somewhat disappointed in the refuge, which was dry after suffering several years of record-breaking drought.

Despite our bypassing the boat tour, we were successful in seeing cranes. We found three cranes that grazed in the marsh near a refuge crane observation deck. As we walked along a nature trail, we came very close to this solo crane, apparently practicing its dancing moves.

Notice that our crane is not banded. Apparently the wild flock has not been banded since 1988. Only older birds remain among banded birds. The International Crane Foundation, however, continues to band Whooping Cranes released from their propagation flock. Thus the sighting of banded Whoopers gives observers some indication of their origin.

Monday, April 23, 2012

Lesser Goldfinch

Lesser Goldfinches are found in much of the western United States, from Oregon east to Colorado and Texas, and south into Central and South America. Two subspecies are known: western males (lower photo) are green-backed; eastern males (upper photo) are strikingly black and yellow. An isolated population of western birds also exists in the Hot Springs city park in South Dakota. The species is most common in California (I took the lower photo in San Diego) and Texas (The upper photo is from the Lady Bird Johnson Wildflower Center in Austin). Lesser Goldfinches are less common and sporadic elsewhere in the country (Watt and Willoughby 1999).

The Lady Bird Johnson Wildflower Center is an interesting destination for those interested in flora and/or birds. Our visit in early April was a bit early in the season for most of the flowers. We were delighted to discover that University of Minnesota Landscape Arboretum members are granted reciprocal entry fees, thus admission was waived after we presented our Arboretum membership card.

Sunday, April 22, 2012

Cattle Egret

For the past several days Cattle Egrets have been reported from a pasture west of Faribault in Rice County. Although both Great Blue Herons and Great Egrets are occasionally seen in fields, none of our native herons and egrets use dry pasture land as their primary habitat. Cattle Egrets feed in close association with livestock. They feed on arthropods that the cattle disturb. They do not eat ticks from livestock.

Cattle Egrets began spreading across the world in the late 1800s. They first appeared in North America in the 1950s and, in the ensuing 40 years, have become common in most of the United States, Central and South America (Telfair 2006). Their range expansion continues even today. In Minnesota, the species is considered to be rare but regular (MOU). The species is even more common in South Dakota. The reasons for the Cattle Egret's success are probably multiple, but certainly include the bird's preference for pasturelands.

The photograph above is of the Rice County Cattle Egret in breeding plumage. (In Great Britain, the species is called the Buff-backed Heron.) The white, fall bird below is from South Dakota. This bird clearly possesses binocular vision, a trait that is probably handy for chasing grasshoppers across cattle pastures. The large black structure behind the egret is a cow's leg.

Saturday, April 21, 2012

Variegated Meadowhawk

On September 16, 2011, in my blog I mentioned that Variegated Meadowhawks tend to be immature in the fall migration and adults in the spring. Indeed, I hardly recognized this gorgeous adult (on 20 April 2012), my first Minnesota odonate of the spring, as being the same species as the fall individual. The two yellow spots on this dragonfly's thorax and the boldly patterned abdomen are clues to its identity.

Variegated Meadowhawks flycatch from perches or from the ground. During migration, they are also found in treetops. Migrants appear in Minnesota in early spring, well before any local emergence is possible (Dragonflies and Damselflies of the East).

Friday, April 20, 2012

California Towhee

One of the most common birds in coastal California, found from Oregon to the tip of Baja California, California Towhees adapt to urbanization and are found in many yards and gardens. They can be hard to photograph, since they feed in low vegetation and brushlands. This individual posed for us at the Kate Sessions Park in San Diego.

The drab California Towhee has a colorful taxonomic history. They were once considered to be a race of the Brown Towhee, a common bird of much of our Southwest and Mexico. DNA technology demonstrated that the two populations are not closely related. Ornithologists now recognize two species, the California and Canyon towhees.

Thursday, April 19, 2012

Audubon's vs. Myrtle Warblers

Males of eastern and western races of Yellow-rumped Warblers look radically different. Eastern birds, called Myrtle Warblers, breed in the forests of Alaska east across Canada into New England, New York, and the Appalachians. Western birds breed in the Pacific Northwest and adjacent Canada, south through the Rockies to our Southwest. They breed east to the Black Hills of South Dakota. In these photos, the top is of an Audubon's Warbler at the Kate Sessions Park in San Diego; the bottom is a Myrtle Warbler in Pierre, South Dakota

Despite their differences, the two races hybridize in the southern Canadian Rockies. In fact, they both are very similar aside from the plumage of the males--behavior, habitat, and song are all similar. The area where they interbreed is very narrow--less than 200 km. One theory is that the two species came into contact as forests grew higher into mountain passes after the last glacial retreat some 10,000 years ago (Hunt and Flaspohler 1998). These authors cryptically comment that the narrowness of the hybrid zone may warrant further study of just how
Audubon's and Myrtle warblers are related.

Wednesday, April 18, 2012

Cassin's Kingbird

The Kate Sessions Park seemed an unlikely location for the birding adventure we enjoyed. Nestled in the San Diego urban sprawl, the park seemed poorly maintained and was full of joggers and dog-walkers. Another bird we found as we stepped out of our car was a Cassin's Kingbird. Erika immediately proclaimed, "That is NOT a Western Kingbird. Look at the white band at the end of the tail! Look at the gray breast! Look at the white malar stripe!"
The Cassin's Kingbird's range is a bit odd with most birds found in Mexico, but also New Mexico, Arizona, eastern Colorado and even southwestern South Dakota, as well as coastal California. Over most of the northern parts of its range, this flycatcher is migratory. In the United States, however, some coastal populations (in Orange and San Diego counties) are year-round residents (Tweit and Tweit 2000). This species is named for John Cassin, an ornithologist who lived in the 1800s.

Cassin's Kingbirds are often noisy and conspicuous. Our bird in the Kate Sessions Park was relatively tame. But the species can have restricted habitat and is hard to find in South Dakota.

Tuesday, April 17, 2012

American Avocet

Yesterday Gene B. reported an American Avocet at Circle Lake in Rice County, Minnesota. Unable to give chase until noon today, I thought my chances of finding the bird were slim.

The avocet uses its long, upturned bill to feed on invertebrates. Because of the bill's extreme sensitivity, the avocet can capture invisible prey in murky water. Avocets generally nest west of Minnesota--only a few breeding records exist for western part of our state. The species specializes in temporary wetlands. In many areas, avocet numbers have declined with increases of human use of scarce water resources. Avocets have also suffered from poisoning by selenium from contaminated irrigation drain water (Robinson et al. 1997).

Monday, April 16, 2012

White and Dwarf Trout-lilies

One of the thrills of living in Minnesota is the blooming of the spring ephemerals. These April wildflowers bloom before the tree leaves shade the forest floor. On Sunday Erika and I found the Big Woods State Park awash in trout-lilies. We found both the abundant White Trout-lily (lower right) and the rare Dwarf Trout-lily (lower left). As its name implies, the Dwarf Trout-lily's flower, hardly larger than a dime, is far smaller than the normal species. The Dwarf Trout-lily is restricted to several east-central Minnesota counties. I have previously blogged on these two species and speculated on how the dwarf species evolved.
Princeton University Press recently published a new book, Spring Wildflowers of the Northeast. I recommend it for those interested in wildflowers. Many of the species of that region are also found in Minnesota. From the book, I learned that Trout-lilies contain an antibiotic called tulipalin A, which can cause allergic skin reactions. Native uses of the plant, however, include, after lengthy preparation, consuming trout-lily bulbs (both as a winter staple, but also as an emeitc). Perhaps due to the antibiotic, crushed leaves were also used as a poultice for skin sores.

Sunday, April 15, 2012

Bushtit

Like the Wrentit, Bushtits enjoy a confusing taxonomy. At first these common, non-migratory western birds were thought to be in chickadee and titmouse family, Paridae. Furthermore, Bushtits with black or plain ear auriculars (ear coverts) were thought to be distinct species (named Black-eared and Plain bushtits, depending on the color). Ornithologists discovered that ear color was polymorphic, some birds out of the same nests had black ears and others plain-colored ones. The farther south you travel, the more you encounter black-eared birds. Males are more often black-eared than are females. Almost all northern birds, like the one in my photo from the Kate Sessions Park in San Diego, are plain-eared.

DNA research makes the surprising conclusion that Bushtits are the sole representative in the New World of an Old World family, Long-tailed Tits, Aegithalidae. Long-tailed Tits have only recently been moved from the Paridae (titmice, etc.) into Aegithalidae.

Whatever their evolutionary history might be, Bushtits are easy to find in the west. They can form large flocks and often move about with other species.  We found this Bushtit in the company of the Wrentits of the previous post.They prefer oak, pine, and coastal shrub-lands. Their feeding behavior is often similar to chickadees. Bushtits are also interesting because they will often help other pairs raise young--these helpers can be male, female, juvenile, or adult. The helpers are not necessarily related to the nesting pair they assist. But, to complicate matters, Bushtits of both sexes may take on multiple mates (Sloane 2001).

Saturday, April 14, 2012

Wrentit

I was delighted to find Wrentits when we recently visited the Kate Sessions Park near San Diego, California. Note the blur of the Wrentit's long tail in my photograph.

Just what is a Wrentit? When I first listed this species many years ago in northern California, ornithologists considered Wrentits to be in their own family, Chamaeidae. Now confusion reigns. Look in The Sibley Guide to Birds, and you find Wrentits to be the only North American member of a large (and diverse) family of Old World birds called Babblers, Timaliidae. Look in the National Geographic Field Guide to the Birds of North America, Sixth Edition, and Wrentits are placed in another Old World family, the Sylviidae. My usual ultimate source for such taxonomic questions, the Handbook of the Birds of the World, Volume 12: Picathartes to Tits and Chickadees, has Wrentits both ways!  They reside with the Babblers, but the authors write that recent DNA studies indicate that many Babblers, including Wrentits, are actually Sylviidae, while other Babblers need to be reclassified. If this discussion sounds confusing, that is because it is.

In any case, Wrentits are common residents along the Pacific Coast of North America, from Oregon south to northern Baja California. The species is usually found in dense brushland. Wrentits form life-long, monogamous pairs and remain in their territories, for up to 12 years. Males and females incubate their eggs, remain in vocal contact with each other, and mutually preen (Geupel and Ballard 2002).

Friday, April 13, 2012

White-fronted Goose

The Greater White-fronted Goose is an opportunistic vegetarian, consuming both terrestrial and aquatic plants. This individual appeared to be feeding on green algae in a pond just east of the Northfield, Minnesota, golf course. Although this goose appears early in the spring in Minnesota, they linger through most of May. Thus a mid-April occurrence is not noteworthy. Thanks to Gerry H. for alerting me to the location of this bird.

Thursday, April 12, 2012

Yellow-bellied Sapsucker

Back in Northfield after our month-long road-trip, we are slowly getting our routines reestablished. We cleaned and turned on the water feature. Banding nets are reopened. Today we banded this lovely male Yellow-bellied Sapsucker. The woodpecker flew to a tree near the water feature and then we caught it low in the net as the bird came in for water. This behavior is somewhat surprising. Walters et al. (2002) surmise that sapsuckers usually get all their water from their sap wells. Our bird, however, was clearly intending to drink from the water feature.

Wednesday, April 11, 2012

eBirding California Thrashers

As many of you know, one of the delights of eBird is that this website allows viewers to discover where birds are seen across the country and the world. When we were in San Diego, I typed into eBird California Thrasher and California Gnatcatcher, two species I have never seen. To my surprise, both these species, along with Wrentits, which I only listed once before, (plus Bushtits, which have previously avoided my camera lens), were all recently seen at a park only a few miles from our hotel!

The next day we visited the Kate Sessions Park, a relatively small, dry brushland between La Jolla and San Diego. We never would have stopped at this park were it not for eBird. We quickly found all our target species and photographed all but the shy gnatcatcher. The photo above is of the California Thrasher. Perhaps our largest thrasher, this species is found only in the chaparral of coastal California and adjacent northern Baja California. Commercial development and house cats are both contributing to the decline in this species' populations. Although they do sing from bushtops, as in my photo, California Thrashers often prefer heavy cover.

Tuesday, April 10, 2012

Golden-cheeked Warbler

Erika and I are just back from a month-long road-trip to Seattle to meet a new Granddaughter.  Somehow I convinced Erika that southern Texas and California were along our route. In a normal, snowy winter this itinerary may have made some sense. We had a good time, nevertheless, and did a lot of birding. In the process, I put the new Birdseye Bird Log phone app through its paces. We often found that we missed birds if we were too busy entering records into our phone. Thus we often found ourselves using the app to establish our exact location. Later we entered empty lists to eBird and filled them in with our computer later the same evening.

One of our first stops was to visit our neighbor, Sim, who, for the past two years, has been working with Golden-cheeked Warblers and Black-headed Vireos at Fort Hood, Texas. We arrived on 11 April, a week too early for the vireo, but, as you can see, we did find the warbler.

The Golden-cheeked Warbler is the only Texas breeding bird that nests nowhere else. Although rare and endangered, it is locally common in juniper-oak woodlands of central Texas. By early summer, it leaves for its wintering grounds in southern Mexico and Central America. The species is threatened by its restricted range and the ever-growing human population and consequent clearing of its Texas habitat (Ladd and Glass 1999).

Sunday, April 8, 2012

Wilson's Plover

The Wilson's Plover is restricted to southeastern coastal areas of the United States, Mexico, and Central America. We found several on Sanibel Island in late February 2010. This date was early for this species, a migrant from the south. Wilson's Plovers suffer from beach development and disturbance. This species is recognized by its short, thick, black bill.

Wednesday, April 4, 2012

Sandwich Tern

In North America, the Sandwich Tern is a "common but local" resident of the Gulf and southeastern Atlantic coasts. The species also occurs in Eurasia, and was first described in 1787 from the village of Sandwich in Kent, England. Sandwich Terns always breed in colonies with other species of gulls or terns. These other species are invariably more aggressive than the Sandwich Terns. Apparently Sandwich Terns "parasitize" the more aggressive species for protection against predators. An open question is why the aggressive species allow such parasitism (Shealer 1999). In any event, this photograph was taken of a Sandwich Tern along the Florida coast of Sanibel Island.

Monday, April 2, 2012

Ruddy Turnstone

Ruddy Turnstones are another common coastal shorebird that migrate over Minnesota to the High Arctic. Like the Sanderling in the last post, these photos were taken in Florida a couple of years ago. Even in their relatively dull basic plumage, turnstones are striking when they fly. Note the turnstone's slightly upturned bill--evident in the lower photo. Turnstones flip pebbles and other beach detritus in search of just about anything edible--invertebrates, small fish, human garbage, and even other birds' eggs (Nettleship 2000).