Thursday, May 31, 2012

Ladder-backed and Nuttall's Woodpeckers

Also at the Bentson State Park bird feeders was the Ladder-backed Woodpecker (above), a common bird of the southwest. This "zebra-backed" woodpecker is quite similar to the Nuttall's Woodpecker (below) found in the oak woodlands California.  Fortunately for birders trying to identify them, the two species' ranges barely overlap. (In the limited area of overlap, the two species have been known to hybridize.)

In my photos, the Ladder-backed Woodpecker is a male and the Nuttall's is a female--hence the red on the Ladder-back's head, which is not present on the female Nuttall's. Only one of the field marks mentioned by Sibley to separate these woodpeckers is evident in my photographs. Note the upper back on these birds. On the Ladder-backed Woodpecker, the upper back is whitish with thin black stripes. In the Nuttall's Woodpecker, in a photograph from the California coast, the upper back is solid black. Sibley's suggestion that the feathers behind the bill (the lores) are white in the Ladder-backed and buffy on the Nuttall's are not born out by my photos.
Despite both species' being common within their respective ranges, neither woodpecker has been well-studied by ornithologists. With few exceptions, observations on the breeding biology of both birds tend to be "incidental and superficial" (Lowther 2000, 2001).

Wednesday, May 30, 2012

Golden-fronted Woodpecker

Bentson State Park is another location birders visit in Texas' Lower Rio Grand Valley. For us the disadvantage of this park was their admission fee; our senior Federal passes did not allow us free access to state parks. We visited Bentson twice and listed a few different birds. One is the Golden-fronted Woodpecker, a tropical American species that ranges north through Texas to Oklahoma.

Not only does this woodpecker look similar to Red-bellied Woodpecker, the two species hybridize. Golden-fronted Woodpeckers have expanded northward. Apparently hybridization occurs where contact between the two species is recent (Husak and Maxwell 1998). Surprisingly, neither the interbreeding, nor this woodpeckers' biology in general, has been well-studied by ornithologists.

Tuesday, May 29, 2012

Spring Migration

As stalwart readers of this blog are aware, I have been taking a series of bird portraits with the subjects facing the camera. While perhaps not the best photographs for identification purposes, they do present novel views of plumage patterns. A good example is on this Ovenbird, with the malar stripes continuing past the bill and bordering the orange crown; or this Yellow-rumped Warbler, glaring at me earlier this spring.
Banding has been extremely slow this spring. Although I observed several mixed flocks of migrating warblers, none were near my nets. I find myself already looking forward to the fall migration. In any event, both these photos were taken in Northfield, Minnesota, during May 2012.

Monday, May 28, 2012

Black-necked Stilt

Black-necked Stilts, although looking a bit like circus clowns on bright pink stilts, are nonetheless graceful shorebirds found in southern and western North America. They are vagrants to Minnesota and the Dakotas. We found them nesting near Aberdeen, South Dakota, but I am unaware of Minnesota breeding records.

Stilts eat brine flies. Stilts are often found in shallow and temporary ponds with emergent vegetation. The problem is that this habitat often collects agricultural contaminants. These birds are particularly susceptible to selenium, which causes embryo deformities (Robinson et al. 1999).

In March, Erika and I found small flocks of Back-necked Stilts at the Santa Ana National Wildlife Refuge. To my amazement, my dragonfly expert Scott King looked at this photo and asked about the damselfly. "Is the damselfly in the tip of the bird's beak, or is it on the branch behind?" I never saw it, not in the field or in the photograph. Look closely! The odonate is on the branch behind the beak. This episode demonstrates that proficiency in finding and identifying dragonflies (and birds) takes years of practice.

Sunday, May 27, 2012

Odonate Additions

On Friday at the University of Minnesota Landscape Arboretum, Erika and I found two unfamiliar dragonflies. Oddly, I already had photographs of both, except that previous photos were all of females. This season's odonates are males. The top critter is a Horned Clubtail, a species I first found in the Carleton Arboretum and blogged about on 20 September 2011. I needed assistance identifying the clubtail because this species' tail is not clubbed, but rather has widely branched cerci, the spines at the end of the abdomen. Thanks, as always, to Scott King for his help.
The second photo is of a Dot-tailed Whiteface. I found this species in Dakota County and made a post on 6 October 2011. On Friday, a male flew up from a duckweek-filled pond and, in midair, attached himself to a female. In a fraction of a second, the pair assumed a "Wheel Position." The two Whitefaces, now in tandem, landed back on the pond.

Kurt Meade (Dragonflies of the North Woods) writes, "mating is usually initiated by the male who, with the grace of a professional wrestler," curves his abdomen forward, and attaches the end to the back of the female's head. This behavior is to assure no other males visit his mate. The female then obtains sperm by attaching the end of her abdomen to his sexual organ. Sperm transfer is accomplished only after he purges other males' sperm from her genital opening. Meade concludes, "the time needed to complete fertilization ranges from 15 seconds to well over an hour."

Saturday, May 26, 2012

Chalk-fronted Corporal

Yesterday Erika and I chased dragonflies at the University of Minnesota Landscape Arboretum. We found one new for us, a Chalk-fronted Corporal. (Presumably the name "corporal" comes from the stripes on the thorax.) This species, found across southern Canada, dropping down through California and also the northeastern United States, can be very common. They breed in bogs and woodland ponds--you may note by the leaves in this photo that our corporal was in a forested area. They tend to lay in wait for mosquitos and blackflies. Chalk-fronts tend to be aggressive species. Males will guard their females after copulation. After depositing her eggs in standing water, the females often fly into nearby woods (Dragonflies of the North Woods; Dragonflies and Damselflies of the East).

Thursday, May 24, 2012

Northern Mockingbird

Erika took this photograph of a Northern Mockingbird at Santa Ana National Wildlife Refuge near Mission, Texas. Mockingbirds are found throughout the United States and most of Mexico. Although they are becoming less common in southern parts of their range, mockingbirds have been increasing in the north. They are occasionally reported from Minnesota, the Dakotas, and even southern Canada.

Their spread northward is attributed to increasing suburbs and secondary habitats. Mockingbirds will eat almost any fruit or arthropod. Both male and female mockingbirds sing. Males often sing over 150 distinct song types, which change and increase as birds age (Farnsworth et al. 2011). They imitate other bird songs and even non-avian species. I have heard mockingbirds imitate the sounds of passing trains. One explanation is that, as mockingbirds are omnivores, their varied repertoire discourages competition from other birds in the neighborhood.

Wednesday, May 23, 2012

Long-billed Thrasher

Long-billed Thrashers were common at Santa Ana National Wildife Refuge near Mission Texas. The species ranges from southern Texas through eastern Mexico. In Texas, it is most abundant in the Rio Grand Valley, where the bird has suffered from habitat destruction. Long-billed Thrashers (above) are similar to Brown Thrashers (below). This similarity has led ornithologists to assume that the two species also share similar behaviors, and thus the Long-billed Thrasher remains poorly studied (Tweit 1997).

Differences between the two species include the amount of white at the base of the lower mandible--all dark in the Long-billed Thrasher, half whitish or yellowish in the Brown. Long-billed Thrashers tend to have darker backs than do Brown Thrashers. Notice the unstreaked undertail feathers on the Long-billed Thrasher. Finally, Long-billed Thrashers have blacker streaking on their underparts than do Brown Thrashers. The Brown Thrasher in the lower photo was taken near Dundas, Minnesota.

Tuesday, May 22, 2012

Hooded Merganser

Although male Hooded Mergansers are stunning, hens are ducks with unruly coiffures. Erika and I encountered this bird in early May along the Cannon River near Northfield. Breeding across most of Minnesota, our bird may have been a migrant or a summer resident. In any event, females pick and maintain nesting cavities. They readily use nest boxes. These sites are often selected the season previous to their use. Drakes abandon their mates as the hens begin incubation, which lasts for about a month. Once hatched, the young remain in the nest for only a day (Dugger et al. 2009).

Monday, May 21, 2012

Sapsucker on a Wire

On 7 May 2012, John H. and I were birding near Dundas, Minnesota. I heard the the unmistakable, persistent, call of a Red-breasted Nuthatch. To show off to John my prodigious ability to recognize bird calls (and secretly affirm my identification), I played a screech-owl tape from my phone. Up flew this Yellow-bellied Sapsucker, and landing on an overhead telephone wire--an odd pose for a woodpecker. Not far behind, the nuthatch flew into a nearby spruce, thus keeping my bird call recognition reputation intact.
The nuthatch is probably a migrant in Rice County. This species breeds in northeastern Minnesota. Birds in Minnesota lists breeding records south to the Twin Cities, which are a couple of counties north of us. The sapsucker breeds across most of Minnesota, although it is more common the farther north you travel.

Sunday, May 20, 2012

Least Grebe

Least Grebes are found from southern Texas to Argentina. In March 2012, Erika and I found them to be relatively common at the Santa Ana National Wildlife Refuge, although other birders commented that their numbers vary markedly from year to year. Because Texas was just coming out of several years of draught, perhaps grebe numbers were concentrated in areas with ponds. Least Grebes are the least studied North American grebe (Storer 2011).

Saturday, May 19, 2012

Mostly Lesser Yellowlegs

During a field trip in late April to Lake Byllesby in Dakota County south of Minneapolis, I found a number of sandpipers. Most were Lesser Yellowlegs, told by their yellow legs, relatively short bills, and streamlined bodies. Look closely at the first two photographs. In the top one, at the back, is a longer-billed Greater Yellowlegs. In the middle photo, on the far left, the bulkier body of a Greater Yellowlegs is apparent.

One of the sandpipers is quite different. Look at the bird in the foreground in the first photo. The back is more cleanly spotted than on any of the yellowlegs. A clear white ring surrounds the eye. Last, but not least, the legs are greenish rather than yellow--all field marks of a Solitary Sandpiper.

The eye ring is not fool-proof. In the last photo you can see that Lesser Yellowlegs also show white eye rings. The legs, however, are yellow and the back not cleanly spotted. This last photo was taken at the Minnesota Valley National Wildlife Refuge.

Sandpiper bills are used to illustrate ecological partitioning. Species with relatively long bills can specialize in prey deeply buried in the mud, while those with shorter bills go after invertebrates at respectively shallower depths. (Obviously those with longer legs can also forage in deeper water.)

Friday, May 18, 2012

Couch's and Tropical Kingbirds

Our recent stay in south Texas resolved a complicated birding conundrum for me. In 1964 I visited the Santa Ana National Wildlife Refuge and listed a Tropical Kingbird. At that time that identification was the only one possible. Turns out that a second species, the Couch's Kingbird, was described in 1853, but was considered to be just a race of the Tropical Kingbird since 1874. Like many young birders, I was unaware of bird races when I made my initial ID.

In 1966 ornithologists split the Tropical Kingbird into two species, the Tropical, found in southern Arizona and elsewhere in South America, and the Couch's Kingbird, found in southern Texas south into northern Central America. In the 1980s, because of their ranges, I was able to add Couch's Kingbird to my life list.
The reason for this split was that each species has a distinctive call. This year, when we entered the Santa Ana Refuge, we clearly heard Couch's Kingbirds. Their call reminded me of the "Beer" part of the Olive-sided Flycatcher (see last post). It was good to finally REALLY see a Couch's Kingbird. (We saw many Tropical Kingbirds during our research in Peru and Ecuador.)

The situation is more complicated. In the 1990s, Tropical Kingbirds began breeding in southern Texas. During our March 2012 visit, Erika and I found a Tropical Kingbird near the National Butterfly Center near Mission. The bird clearly had a different call from the Santa Ana birds. Thus I added the Tropical Kingbird to my United States list.
In this post, the first two photographs are of different Couch's Kingbirds at Santa Ana National Wildlife Refuge. The final photo is of the Tropical Kingbird we saw and heard near the National Butterfly Center. Although the species overlap in habitat, notice that the two Couch's Kingbirds are surrounded by woodland, whereas the Tropical is in the open on a telephone wire. Sources for this account include Brush (1999) and Stoffer and Chesser (1998). The song links in this post are used with permission from Thayer's Birds of North America DVD Gold Edition V5.5.

Wednesday, May 16, 2012

Olive-sided Flycatcher

A flycatcher with dusky, vest-like sides and a relatively large bill is likely an Olive-sided Flycatcher. Look for this bird perched on top of tall, bare tree branches. Its song, "Whip-three-beers" is easily recognized and often appreciated by thirsty northwoods hikers and canoeists. This species breeds in forests across Canada and the northernmost United States, south through the Rocky Mountains.

Olive-sided Flycatchers migrate from the northern forests to Central and South America. We saw this early migrant south of Faribault, Minnesota, during our Rice County Big Day census. We tallied 121 species, well short of the county record of over 140 in a single day. Despite this failure, we enjoyed seeing many new birds for the year and, of course, excellent companionship.

The song link used in this post is with permission from Thayer's Birds of North America DVD Gold Edition V5.5

Tuesday, May 15, 2012

Eastern Kingbird

This past week, Eastern Kingbirds returned to breed in Minnesota. They nest in most of eastern North America, and also across much of the northwest.  Erika and I often saw this species in the winter in the Amazon jungle. Unlike in the summer, wintering birds form large flocks. Seeing these kingbirds reminded us of home.

Eastern Kingbirds raise three to four young, but only one clutch per year. The thought is that procuring flying insects is energetically expensive and relatively difficult. The birds have a particularly hard time feeding large broods during wet, cool summers. Furthermore, the parents care of their young for three to five weeks, thus curtailing any time for a second brood (Murphy 1996). The fledglings at the bottom of this post are from South Dakota; I saw the bird above during Saturday's Rice Co. Big Day attempt. I will report on our census in a subsequent post.

Monday, May 14, 2012

Band-winged Dragonlet

After Harlingen, Texas, we spent three days in the Rio Grand Valley, with our headquarters at Mission.  Our favorite birding area was the Santa Ana National Wildlife Refuge. This refuge is large and diverse. With our Federal Senior Pass, admission was free (unlike various state and county parks). We made three visits to the refuge and saw different birds each time.

One of my favorite critters, however, was not a bird, but this Band-winged Dragonlet. What a wonderful name! Our odonate chasing was crippled by our malfunctioning camera. The dragonlet often spends time in forests, which is where we found this one. I am not sure of this individual's sex, as dragonlets come as males (or females) or as andromorph females. Andromorphs look like males and may thereby avoid being harassed by amorous males.

Band-winged Dragonlets may be partially migratory. They are known from Argentina north into the United States (to Ohio, Georgia, and Florida) (Dragonflies and Damselflies of the West).

Sunday, May 13, 2012

White-throated Sparrow

One of the all too infrequent thrills of bird banding is when one of "your" birds is encountered in a distant location.  A White-throated Sparrow that I banded near Dundas, Minnesota, on 3 May 2007 was recovered in Montichello, Arkansas on 20 March 2012.  Since the bird was at least in its second year when banded, the age when recovered was at least six years, a respectable age for a sparrow. The record age for a banded White-throated Sparrow is just under 15 years (Bird Banding Laboratory). The sparrow photos in this post are both from the Dundas station and taken this spring.

Friday, May 11, 2012

Spiny Baskettail

Thanks to Scott K. for help in identifying this Spiny Baskettail, potentially a new record for Rice County, Minnesota!  Two were in Erika's garden yesterday afternoon. They flew about waist-high across the grassy yard and perched on lilies and garden posts. They prefer open areas near water at woodland edges, habitat that describes Erika's garden. This baskettail is a northern species, found from New England and the Appalachians northwest to northern Alberta and British Columba, then south to northern California along the Pacific states. Identification hinges on the clear hind wings and the downward-pointing spine at the base of the final segment.

Two good dragonfly sources are: Dragonflies of the North Woods and Dragonflies and Damselflies of the East.

Thursday, May 10, 2012

Neotropic Cormorant

The Minnesota bird listservs have been buzzing about a possible Neotropic Cormorant in Minnesota.  This small cormorant is often recognized by the white band behind its bill, visible in this photo that Erika and I took this spring near Rockport, Texas. This species ranges throughout South and Middle America, north to Texas, Oklahoma, Arkansas, Louisiana, New Mexico and Arizona. It wanders further north, even to Saskatchewan and Pennsylvania. Neotropic Cormorants inhabit a variety of habitats and are tolerant of many human activities. They have, nevertheless, not been extensively studied by ornithologists (Telfair and Morrison 2005).

Wednesday, May 9, 2012

Sedge Wren

On Tuesday, Erika and I made a quick stop at the River Bend Nature Area near Faribault, Minnesota. We heard a Sedge Wren's familiar call coming from the swampy field next to the parking lot. A moment's spishing brought this curious wren up close. In July 2010, I blogged about a lot of Sedge Wren biology and included a link to the bird's call. Looking back at those earlier photos makes me chuckle over the improvement in my bird photography, the result in evolution of camera equipment rather than photographic skill. On our winter trip this year, I managed to fall on top of my camera. (I was chasing Green Jays). Even though Erika replaced my shattered lens, I do not recommend this as a strategy for updating equipment. A conundrum is that, with a larger lens, I tend to take photos of more distant birds. The results are not necessarily better photographs.

Tuesday, May 8, 2012

Plain Chachalaca

The Plain Chachalaca is found from the Lower Rio Grande Valley south through the lowlands of eastern Mexico into Central America. Despite their superficial resemblance to turkeys, chachalacas are more closely related to Australian megapodes. They are placed in the family Cracidae, which includes a number of other large gamebirds (guans and curassows). Unlike most other Gracidae, Plain Chachalacas prefer scrubland and forest edge rather than the deep forest. Thus these chachalacas are less prone to be threatened by tropical deforestation. Urban sprawl and large-scale agriculture, however, do threaten the species.

Chachalacas are named after their raucous dawn choruses. Erika and I found Plain Chachalacas in almost every refuge we visited in south Texas. The photo above was taken at the Laguna Atascosa National Wildlife Refuge. Most of the refuges in this region maintain bird-feeders, which make visits particularly rewarding for birders.

Monday, May 7, 2012

White-tipped Dove

Another south Texas specialty Erika and I found at Laguna Atascosa National Wildlife Refuge was the White-fronted Dove. Found across much of South America and Mexico, this dove is terrestrial. The species usually forages alone or in pairs and is is more often heard than seen.  This dove favors heavy vegetation, typically flying only short distances. Despite being a relatively common gamebird across its range, ornithologists know relatively little about White-fronted Dove biology (Hogan 1999). They are nonmigratory residents in Texas.

Sunday, May 6, 2012

Palm Warbler

Although Palm Warblers are common migrants in our part of Minnesota, my only decent photograph was of the winter-plumaged bird in the first photo. I encountered that individual in downtown Key West in February 2011. (Palm Warblers were first found in Hispaniola, which accounts for their name.) Actually Palm Warblers breed in bogs and fens and enjoy one of the more northern breeding ranges of all warblers. Spring-plumaged birds are a whole lot brighter than those in winter plumage, as you can see in the next photographs. I banded this bird, my first for Minnesota, in Northfield on Friday. (I banded a few Palm Warblers in South Dakota, but never photographed one.)
Palm Warblers are recognized by their chestnut caps, yellow throats and under-tail coverts, and habitual tail bobbing. Two races are recognized and are fairly easily identifiable in the field. The Yellow Palm Warbler of eastern Canada and New England has completely yellow underparts. The Western Palm Warbler, which breeds west of Ottawa and uncommonly in Minnesota's Arrowhead, lack yellow across their mid-breasts.
The Western Palm Warbler is the race expected during migration in Minnesota and, as you can easily tell in my photographs, that is exactly what I banded in Northfield. Apparently the two races interbreed where their ranges meet. Wilson (1996) warns, however, that evidence for this intrebreeding is based on very few specimens and that "studies on the interactions of the two subspecies are needed."

Identifying the races of Palm Warblers may be more difficult than some books suggest. Chris Wood, of the Cornell Laboratory of Ornithology, writes "There is alarge amount of variation in both Western and Yellow Palm Warblers and the extent of yellow on the underparts is particularly variable in spring. A fair number of Western Palm Warblers are [extensively] yellow below. I would look more at the color of the nape and wings, which would be more strongly olive in Yellow Palm Warbler. The back of the auricular should be more yellowish, or at the very least a bit more olive. Yellow Palms also should show... extensive chestnut streaking on the sides of the breast ..."

Saturday, May 5, 2012

Name that Duck!

Erika says that someone ought to write a field guide to Dabbling Ducks dabbling.  For these birds, if you guessed Blue-winged Teal, you would be correct.  These are prairie-breeding ducks. Populations depend on prairie pothole conditions, with low cycles corresponding with drought and wetland drainage. Blue-winged Teal also suffer very high predation rates--often over 90% of nests fail--by raccoons, fox, and coyotes. Nevertheless, since hitting a 40-year low in 1990, Blue-winged Teal numbers more than doubled (Rohwer et al. 2002).

Although males do not help with incubation or care of the young, in the spring they vigorously defend territories picked by the females. In the summer, males molt earlier than the females, and afterward head south without their mates and, by mid-August, arrive at their Gulf Coast wintering areas. This pair of Blue-winged Teal fed in a small pond near the Old Highway 77 Bridge in the Minnesota Valley National Wildlife Refuge near Minneapolis. I was surprised by the male's iridescent purple head coloration.

Friday, May 4, 2012

Green-winged Teal

Green-winged Teal are common, small dabbling ducks. Being a dabbler, they feed by tipping their bottons into the air in shallow waters on invertebrates and grass and sedge seeds. Unlike diving ducks that must run along the water surface, dabblers can take to the air in a single bound. Green-winged Teal differ from other dabblers in that they are one of the few that do not primarily breed in the prairie pothole region of north-central North America. Instead most breed in northern Canada and Alaska. Due to the remoteness of the breeding areas, Green-winged Teal numbers are high, and may be increasing (Johnson 1995). This teal is monogamous during the breeding season, although males will attempt extra-pair copulations. I photographed this handsome drake in late April at the Old Highway 77 Bridge in the Minnesota River Valley National Wildlife Refuge.

Thursday, May 3, 2012

Green Jay

The suite of Texas bird specialties we found at Laguna Atascosa National Wildlife Refuge surprised me. I thought you had to be right on the Rio Grande to see them. The first of these birds was the Green Jay, found just north of the Rio Grande south through South America to Peru and Bolivia. As I ran about in chasing jays, Erika took these photographs.

South Texas Green Jay flocks contain related nonbreeding birds. Flocks contain a breeding pair, the current year's young, and jays from the previous year. What is unusual is that these nonbreeders do not help at the nests, as do many other birds. They do, however, provide territorial defense for the breeding pair. The birds from the previous year are run out of the flock when the current year's nestlings fledge. Oddly, Green Jays in Colombia do help their parents raise the current year's young. This difference may be the result of less abundant food resources in Colombia (Gayou 1995).

Wednesday, May 2, 2012

Tree Swallow

Tree Swallows are lovely, early migrants to Minnesota. I have previously blogged on this swallows on 20 April 2011 and 11 August 2011. Because they compete with Eastern Bluebirds for nesting holes, the swallows are sometimes maligned by bluebird enthusiasts. If you favor bluebirds over Tree Swallows, you have a number of options. Keep your bluebird boxes widely separated. Bluebirds defend larger territories than do swallows. Too many boxes increase swallow/bluebird aggressive encounters. Bluebirds often are the victors when there are not too many swallows in bluebirds' habitat.

Surprisingly another solution is to pair bluebird houses. Swallows will drive out close-by swallows, but they often ignore nearby bluebirds. Even back-to-back boxes will work. Nevertheless, the houses for bluebirds should still be widely (300 feet) separated. These bluebird facts are from Chris Gates and his website that makes for interesting reading. This year my friend Penny has been having a great time running a bluebird trail--check out her website.

Tuesday, May 1, 2012

Greater Roadrunner

Erika picked the next stop of our road-trip, the Laguna Atascosa National Wildlife Refuge northeast of Harlingen, Texas. I knew little about this refuge except that Aplomado Falcons have been released there in an attempt to reestablish them in the United States. I was not expecting the diversity of species we found near the refuge headquarters. The first hint of this entertaining birding was our welcome by a pair of roadrunners at the refuge gate.

I have previously posted on roadrunners, terrestrial cuckoos found across the southwestern United States, from coast to coast (and south into central Mexico). Greater Roadrunners are monogamous, maintain long-term pair bonds, and mutually defend territories. Every spring pairs renew their bond through elaborate courtship desplays involving a lot of male dancing, including his bringing nesting material and food items to his mate (Hughes 2011),

As seen in the bottom photo, adults have prominent erectile crests and dark blue skin around their eyes. The orange postorbital apteria (the skin between the feather tracts) is usually not visible.