Monday, June 30, 2014

Plains vs. Midland Clubtail


Scott King and I were unsuccessful in our search for snaketails on our expedition to the Cannon River Wilderness area last Tuesday. We did encounter two Midland Clubtails in a wheel position—the male above almost covering the female’s face as he guards her against fertilization by other males; the female collecting sperm from the male. Scott commented that clubtails usually were more desecrate and were not so often seen in reproductive mode. 
You may recall that a few posts ago I complained about how Midland Clubtains in our part of Minnesota are quite variable in their abdomen patterns. In our region, this diversity can make them difficult to separate from Plains Clubtails. Compare the Midland Clubtail (second photo) and the Plains Clubtail (third photo) that we also found on Tuesday. Scott patiently explained to me the critical differences between the two species. Note the underside of the third abdominal segment is white in the Plains Clubtail—it is usually yellow in the Midland, which tends to have narrower colored bands on the sides of its thorax. This last field mark is not so obvious in my photos.

Sunday, June 29, 2014

Cobra Clubtail

Compared to other local clubtails, the Cobra is very black. Note also the dark bar on the face. Several years ago, when I saw my first specimen, I wondered about the name. Not so when Scott King and I found this one on the road leading into the Cannon Valley Wilderness Area south of Northfield. When the dragonfly raised its abdomen, it did give the impression of a hooded snake.

Cobra Clubtails prefer sandy-bottomed streams with a slow to moderate current (Paulson 2011). The Cannon River in flood stage did not seem to deter these individuals.

Saturday, June 28, 2014

Inca Dove

Mueller and Mueller (2014) write, “During the day...[Inca Doves] alternate feeding, loafing, and sunning.” Last February, this Inca Dove, from just north of Edinburg, Texas, seems to be partaking in the latter two behaviors. Field marks for this species include the long tail and the scaly-looking body.

Inca Doves are found in the southwestern United State south to northern Central America. In the past 100 years, the species has spread both north and south. Originally birds of arid land, they have readily adapted to suburban habitats, taking advantage of water and bird feeders. See also my 2012 post on Inca Doves.

Friday, June 27, 2014

Common Ground-Dove

Apparently I have never posted anything about Common Ground-Doves. My previous photographs, taken in Florida and Texas, have not been stellar. This photo, taken this February at a feeder near Edinburg, Texas, is the best of the lot.

This dove is one of the smallest in North America. It is found across the southern United States through northern South America. It loves scrubland, but also is found in suburban habitats. Numbers of North American Common Ground-Doves are declining. Habitat loss to human development and fire suppression and resultant loss of early-succession habitat have been suggested as reasons for this drop in numbers (Bowman 2002).

Thursday, June 26, 2014

Emerald Spreadwing

On Tuesday, 14 July 2014, Scott King and I explored the River Bend Nature Center near Faribault, Minnesota. Scott pointed out an Emerald Spreadwing in the tall grass near a pond. This damselfly is common enough here, but one for which I had searched in vain.

This species has a wide distribution across northern North America, Asia, and Europe. It is not common in Britain, and where, until recently, it was thought to be extinct. There it is known as the Scarce Emerald Damselfly. No other damselfly has such a wide range. Here in the Upper Midwest, Emerald Spreadwings are found in temporary woodland ponds that lack predators. They have a life cycle with many stages. These emeralds overwinter as eggs, which are deposited into live stems of various marsh plants and into willows, sometimes high above the ground. Some eggs can withstand temperatures below -4 degrees F (DuBois 2005Paulson 2011).

Wednesday, June 25, 2014

Sedge Wren

I encountered a pair of Sedge Wrens on 22 June 2014 in the Carleton College arboretum. Sedge Wrens are found in the American Upper Midwest and also occurs in Central and South America. I have previously blogged about their curious North American breeding distribution—they have two breeding seasons in this region, one in May and June in the north, and a second in July through September further south.
Sedge Wrens inhabit ephemeral grasslands. Drought and flooding cause these changes. Human created grazing and harvesting add to the transitory nature of Sedge Wren breeding habitat. The result is high mortality and low site tenactiy among the wrens (Herkert et al. 2001).

Tuesday, June 24, 2014

Yellow-throated Warbler

These photographs are not the most stellar of a Yellow-throated Warbler, but do show why colonial ornithologist Mark Catesby (1682-1749) called it the Yellow-throated Creeper. This and two other Yellow-throated Warblers worked their way through the high canopy of trees around the gift shop parking lot at Whitewater State Park in southeastern Minnesota on 21 June 2014. Little is known about Yellow-throated Warbler breeding biology because of its treetop habitat.

About a half-dozen records have been reported in Minnesota this year for this denizen of the American Southeast. For unknown reasons, this warbler’s range shrunk in the early 1900s. Now the breeding range is again expanding north (McKay and Hall 2012).

Monday, June 23, 2014

Henslow’s Sparrow

This Henslow’s Sparrow, which Erika and I found in Carleton College’s restored prairie on 20 June 2014. This bird is a bit odd, since Henslow’s Sparrows are supposed to have ochre-washed breasts. Nevertheless, the wing color and the sides of the face are what you would expect of a Henslow’s. The bird was also singing a perfect rendition of a Henslow’s Sparrow’s song, described in Herket et al. (2002) as a “feeble hiccup.”
Henslow’s Sparrows have declined during the last 50 years. In the last 30 years, populations have declined by about 7.5% annually, the biggest drop for any grassland bird in North America (Herket et al. 2002). The loss and degradation of our native prairies seems to be responsible. It is remarkable and heartwarming that Henslow’s Sparrows have returned to the Carleton prairie. Restoration of this tallgrass prairie began in 1978. Plants are usually from local sources and maintained by regular controlled burns. Seeds from these forbs are being used to restore other Minnesota prairies. Carleton’s goal is an 140-acre grassland.
P.S.: Doug Johnson writes "You mentioned that Henslow's have been declining dramatically. That was true until CRP took hold. Now BBS indices have about returned to early levels. What HAS happened is that they shifted their range from eastern prairies to midwestern grasslands, largely I believe due to CRP.(http://www.fwspubs.org/doi/suppl/10.3996/nafa.79.0001/suppl_file/appendix+a.pdf) Hate to see what will happen as CRP continues to fade from the landscape.”

Sunday, June 22, 2014

Pelicans and Cormorant

On 18 May 2014, John Holden and I encountered a Double-crested Cormorant that seemed to be conducting a chorus of silent American White Pelicans. All but the pelican on the far left appeared to be following the gaze of their conductor. “Why do cormorants hold their wings out like that?” asked John. Like many a professor, I answered and then verified my reply later. Turns out that cormorants have relativelty little preening oil with which to water-proof their feathers. To keep dry, cormorants have to hang their feathers out to dry. Allaboutbirds.com continues, “though this seems like a problem for a bird that spends its life in water, wet feathers probably make it easier for cormorants to hunt underwater with agility and speed.”
The pelicans, who were really not paying much attention to the cormorant, performed various maintenance behaviors. It looks like a pelican has to be an adept acrobat to scratch its neck, all the while standing on one leg and not falling forward from the weight of its bill. The horn on the White Pelican’s bill, by the way, is present only during breeding season. The horn is present on both sexes and is shed after egg laying. As I have written previously, the exact function of the horn is unknown.

Saturday, June 21, 2014

Midland Clubtail

I photographed these Midland Clubtails on 8 June 2014 in the Carleton College arboretum.  I indicated in my last post that I have been finding clubtail identification to be challenging. For one thing, Midland Clubtails in our part of Minnesota tend to be quite variable—our population is in a blend zone between a western and eastern subspecies, Gomphus fraternus fraternus and Gomphus fraternus manitobanus. Most our our Midland Clubtails have a yellow triangle on the top of their 8th abdominal segment. The 9th segment is variably marked, sometimes strongly yellow, other times dusky, and can be totally black.
Another key for identification is the thin yellow or green line across the sides of their thorax. I have previously blogged about Midland Clubtails. This species is a voracious predator that often consumes other dragonflies. This clubtail often perches on sandy trails and roads.

Friday, June 20, 2014

Horned Clubtail

I have spent the summer trying relatively unsuccessfully to learn how to identify clubtails. Scott King verifies that these two photographs are Horned Clubtails. My research indicates that Horned Clubtails can be identified by their dark-topped 8th abdominal segment in combination with the yellow spot on the top of the 9th segment. Horned Clubtails have horns, one of which I think is visible in the upper photo, along side of the right eye and behind the antenna. Finally Horned Clubtails have a yellowish plate on the top of their head, a plate that is often notched. Males, like in the lower photo, lack distinct clubs at the end of their abdomens. All this sounds easy enough, but among the Horned Clubtails, I have encounted dozens of Plains Clubtails, which I will discuss in my next post.

I have posted on Horned Clubtails before and I do not have much to add to that previous account. Horned Clubtails are often found near water. Males perch on bare ground, rocks, waterside leaves, and lily pads. When disturbed, both sexes often seek refuge in nearby forest treetops.

Thursday, June 19, 2014

White-tipped Dove

Last February, Erika and I enjoyed a parade of birds at our Edinburg, Texas, friend’s bird feeder. White-tipped Doves are found north from the Amazon Basin north through Central America, both coasts of Mexico, and just reaching southern Texas. I previously blogged on this species, from our last Texas trip.

Texas White-tipped Dove populations seem to be in decline. Ornithologists are at a loss to explain this trend. The species is hunted, but a more likely cause is that only about 5% of mesquite forests remain in south Texas. (Our friends are protecting the mesquite forests on their land.) These doves, on the other hand, do breed in suburban settings and citrus orchards. Thus the downward trend in White-winged Dove numbers needs further study (Kelly 1999).

Wednesday, June 18, 2014

Dickcissel

John Holden and I took photos of this Dickcissel at the Great Western Industrial Park near Randolph, Minnesota, on June 11, 2014. I have blogged about this species on several occasions, such as in June 2010. This Dickcissel seemed inordinately beautiful, with its streaked back and yellow crown.
Dickcissels are abundant breeders in grasslands of the upper midwest of North America. They are, however, nomadic and their occurrence is erratic and unpredictable. Unlike so many of our other prairie birds, dickcissels appear able to adapt to the destruction of our native grasslands. They tolerate disturbed habitat and even thrive in some farmlands (Temple 2002). Dickcissels winter in huge numbers in Venezuela, where they can cause tremendous damage to cropland.

Tuesday, June 17, 2014

Grasshopper Sparrow

A week ago, John Holden and I found two Grasshopper Sparrows in Randolph, Minnesota’s Great Western Industrial Park. We easily took photographs of both birds. Grasshopper Sparrows range widely across the eastern and midwestern United States, but have suffered declining populations due to habitat loss. Such is undoubtedly the future of this population that resides in a grassland actively being developed for industry.
Because they are ground-feeders, Grasshopper Sparrows prefer intermediate grassland—drier areas in tall-grass prairies and lusher short-grass lands. The raised wing in the last photo is a territorial display (Vickery 1996). Note that the left wing is raised while the right remains at rest.

Monday, June 16, 2014

Blinded Sphinx Moth

Sometimes the bird net contains non-avian surprises, like this Blinded Sphinx Moth I found last Monday. Bugs and butterflies are often difficult to extract from the net, but this moth flew off after being photographed.

Bugguide.net speculates on the origin of this moth’s name. “Blinded" comes from the small blue hindwing “eye” spots that lack central black spots. Without a “pupil,” the moth must be blind.

The range of the Blinded Sphinx Moth includes most of the United States and southern Canada.  Butterflies and moths.org continues that they are found in deciduous woodlands and suburbs. Adults do not feed, but lay eggs that become fully-grown caterpillars. These caterpillars pupate and overwinter in underground chambers. Although rare at the edges of its range, the species is thought to be overall secure.

Sunday, June 15, 2014

Eastern Kingbird

On 15 May 2014, Gerry Hoekstra and I discovered a large flock of Eastern Kingbirds in a field in Carver County, Minnesota. I tend to think of kingbirds as solitary creatures, seldom seen beyond pairs. But when Erika and I studied in Ecuador in the winter, we often saw large flocks. Judging by the numbers I saw this year—Gerry and I conservatively counted 16 in one field—I suspect kingbirds make their northward migration in flocks.

Eastern Kingbirds are normally the only kingbird in eastern North America. Their range, however, extends across the continent to the Pacific Coast. In the northland, they catch flying insects, the lack of which can limit their reproduction in cool, wet weather (Murphy 1996). In South America, however, they also eat fruit.

Thursday, June 12, 2014

Blue-gray Gnatcatcher

In May, I found this female Blue-gray Gnatcatcher in Rice County's Cannon River Wilderness Area. Luckily gnatcatchers are fairly early migrants in Minnesota, because the birds become relatively hard to see after the trees leaf out in the spring. Often the only indication of their presence are their high-pitched calls. Our gnatcatcher is found across much of North America, south through Central America. Other species are found in the American Southwest and in Latin America. Ours is the only truly migratory species. In the past 25 years, gnatcatchers have expanded northward (Kershner and Ellison 2012),

Tuesday, June 10, 2014

Yellow-headed Blackbird

The last year or two, I have found Yellow-headed Blackbirds more frequently in eastern Minnesota. This bird was perched on the side of a road in Dakota County in May. These blackbirds prefer deep-water cattail marshes and are found in much of western North America.

Yellow-headed Blackbirds are polygynous, often with up to 16 females in a harem. Productive lakes have more females than poorer ones, and more females per male. Unfortunately, what with my new-found interest in odonates, productive marshes are usually defined by high rates of dragonfly emergence. In the winter, these blackbirds eat grain.

Males defend their territories against other males and usually do not breed until after their second year. Females defend small areas around their grouped nests. Females, however, will copulate with “any observed male,” usually those males with adjoining territories when the female's mate is absent (Twedt and Crawford 1995).

Monday, June 9, 2014

Purple Martin

On 4 June 2014, John Holden came upon a pair Purple Martins on a dirt road in the village of Warsaw, Minnesota. This behavior is reported for this largest of North American swallows. Tarof and Brown (2013) write that martins use fine bits of gravel to help digest insect exoskeletons. Martins do not feed in flocks, but often in pairs—the result of mating-guarding by the males.

Martins consume dragon and damselflies as well other arthropods. such as beetles, bugs, flies, grasshoppers, butterflies and moths (and their caterpillars), wasps and bees, and even termites. I have previously written about martin diets. Tarof and Brown report that no credible data exist that Purple Martins eat mosquitos, despite the popular belief to the contrary. For one thing, martins tend to feed high in the air (sometimes up to 450 feet), whereas mosquitos stay near the ground.

I also wrote about Purple Martin range. Since that post, some fascinating research with geolocators has appeared, as reported in the Forest Lake Times. Here you can find maps of routes taken by two Minnesota Purple Martins to the Brazilian Amazon Basin. One bird flew over the Gulf of Mexico and down through Central and South America and returned by the same route. The other took the same path north in the spring, but, during the fall migration, visited the length of Cuba before continuing to Brazil.

Sunday, June 8, 2014

Four-spotted Skimmer

Another dragonfly I encountered during my expeditions to the Carleton College arboretum is this Four-spotted Skimmer. Males and females are often not distinguishable in the field (at least by humans). See my previous post on this species. Paulson writes that the males of this species are highly territorial, but tolerate “satellite” individuals.  These individuals are non-mating, subordinate males.

Four -spotted Skimmers are found across much of North America, all the way to Alaska. They are also found across the Old World, from Great Britain to Japan. Four-spotted Chasers, as they are known in England, are migratory in Europe, but such behavior is unrecorded in the New World.

Saturday, June 7, 2014

Dot-tailed Whiteface

For the past two days I have been searching the Carleton College arboretum for a snaketail, a kind of dragonfly, but without success. I have seen about a half-dozen other species of odes, including this lovely male Dot-tailed Whiteface. Summer seems to have finally arrived. The basis for this name should be patently obvious from this photo.

In most of the northern United States and in southern Canada, this species is the most frequently encountered white-face. I have blogged about it before. According to Paulson, Dot-tailed Whitefaces keep fixed territories, but do not defend them aggressively. Other males can fly through a territory, but are not chased unless they come relatively close to the territory owner.

Friday, June 6, 2014

Cedar Waxwing

I’ve been on the lookout for a Cedar Waxwing with red waxy tips to its secondary feathers, and this May I caught one. The bird in the photo looks a bit strange because I have photoshopped my hand away. Both sexes of waxwings have these red tips, which may serve as a status signal in mate selection. Older birds have more red tips than younger ones. Birds tend to pick mates with a similar number of waxy wing tips. The red tips were once thought to protect the feathers from wear as waxwings frolic in cedars, but this hypothesis is no longer supported by most ornithologists.
After taking a photo of the spread wing, I held the bird further away to include an image of the waxwing’s yellow tail band. To my surprise, when I developed the picture, I noticed some of the tail feathers also have red tips. I can find no mention of this plumage trait in Witmer et al. 1997, although a photo in their account shows a tail with much less distinct red tail feather tips. 

Waxwings with orange-banded tails were first observed in North America in the early 1960s and are becoming increasingly common. (See my first-ever post in this blog.) Apparently this orange color is due to the waxwings’ eating Morrow’s Honeysuckle, an introduced plant that has now become fairly common. The honeysuckle contains rhodoxantin pigments, which, if eaten at critical times of feather growth, change the color of the tail band. 
P.S. Roger Everhart directed me to this link: http://www.birdvancouver.com/blog_spring_2014.html.

Thursday, June 5, 2014

Curve-billed (Plateau) Thrasher

Next up at the Edinburg, Texas, bird feeder on 21 February 2014, was a Curve-billed Thrasher. This species probes in the ground litter for insects and seeds. It also consumes berries and cactus fruit. Curve-billed Thrashers are tolerant of a range of habitats and seems to coexist with people. Just how this thrasher will survive the extreme development of the Texas brush country, however, remains to be seen (Tweit 1996).

Curved-billed Thrashers in the Arizona Sonoran Desert and northwestern Mexico may be a different species from those in the Chihuahuan Desert, Texas, and central Mexico. The two populations do not overlap and their mitochondrial DNA differs. Among other field marks, eastern birds have light breasts, which make their spotting more distinct. Western birds have grayer breasts, with resultant less distinct spots. Western birds also have less distinct wing-bars. Compare this Texas bird with one I took in 2012 in southern Arizona. For the time being, the two populations are considered to be subspecies. But the question of splitting Curve-billed Thrasher into an eastern Plateau Thrasher and a western Palmer's Thrasher is currently on the agenda of the American Ornithologists' Union's checklist committee.

Tuesday, June 3, 2014

Wilson’s Phalarope/Lesser Yellowlegs

Last winter, Scott King and I made a deal. If I showed him a Lesser Yellowlegs, he would find a dragonfly I need for my list. I feel a little guilty about this deal, since I knew I’d be fairly safe in finding the yellowlegs. These three Lesser Yellowlegs strolled behind a female Wilson’s Phalarope this May at the Great Western Industrial Park near Randolph, Minnesota.

The phalarope is less common than the yellowlegs. I have previously posted on the species. Most birders know of their reversal of sex roles. Female phalaropes are larger and more brightly plumaged than their males. The females often mate with more than one male. The male provides all parental care of the young.

Lesser Yellowlegs’ breeding cycle is less well known to birders, but is also interesting. Males court females and both parents incubate their eggs. Both sexes vigorously defend their territories and care for their precocial young. Females, however, tend to migrate from their breeding areas before their young can fly, leaving the males to become the sole defenders of the chicks (Tibbitts and Moskoff 2014).

Monday, June 2, 2014

Virginia Rail

On 28 May 2014, John Holden and I checked out Swan Lake in nearby Nicollet County, Minnesota.  We listened for the Virginia Rail “grunt” call. Check it out if you have the Sibley Bird app on either your Android or iPhone. Out of the cattails, strolled two Virginia’s Rails. Note the long toes of the bird in the first photo.
These small rails are lovely creatures. One of our rails circled, fed, and occasionally grunted at us. The rails give back-and-forth, grunting duets during courtship. These are specialized calls used in pair bonding. 
Male Virginia Rails are larger than the females, but can not otherwise be told apart in the field. Virginia Rails are dietary generalists, eating much of what comes their way—invertebrates, small fish, and seeds.
In the last photo, the rail seemed to stick its tongue out at us. I am not sure what the object is toward the end of the tongue—an ant?  Or just some dirt?