Sunday, July 31, 2011

Say's Phoebe

As we raced home from Olympia, most of our birding was restricted to Interstate rest areas. This Say's Phoebe was at an Interstate rest area in southern Montana.  This species breedings over much of western North America, even straying into Minnesota and eastern South Dakota.  Look for their nesting in abandoned prairie farm buildings. They prefer eating wasps and bees, but also sally forth to take a variety of other flying insects.

Saturday, July 30, 2011

Black-headed Grosbeak

Erika and I found this Black-headed Grosbeak singing in cottonwoods behind a Wyoming rest stop.  This grosbeak is the western counterpart of the eastern Rose-breasted Grosbeak. The two species hybridize where their ranges overlap in the Great Plains.


Males are monogamous and share nesting duties equally with their mates.  Both sexes sing, the males to establish territories, the females to retain communication with their mate and young.  According to Ortega and Hill (2010), "Occasionally, females sing full "male song, apparently to deceive mates about the presence of intruders and force greater nest attentiveness."


The male in this photograph is probably in its first breeding season.  Males do not molt into adult plumage until their second breeding season and this bird retains streaky flanks and does not have a completely black head.  Only first year birds that closely resemble the older males are able to hold territories and breed.  Males that look more like females suffer less aggression from breeding males.  Finally, bright plumage is correlated with testes size (Ortega and Hill 2010).

Friday, July 29, 2011

Common Buckeye

Erika and I stumbled upon this Common Buckeye as we strolled across River Bend Nature Area's Prairie Circle Trail in Faribault. Ordinarily the buckeye ranges across the southern United States, barely reaching southern Minnesota. They favor open habitats.

This distribution turns out to be more complicated. Buckeyes winter and then breed in the deep south. Subsequent generations migrate north. During some summers, successive generations over-shoot the normal range, even reaching southern Canada. In the fall these butterflies can make massive southward migrations.

Thursday, July 28, 2011

Veery

This Veery is in juvenal plumage, which it acquires after leaving the nest.  These thrushes retain this plumage for about two months, June through August. Next birds undergo a partial molt into basic (winter) plumage.  This molt involves most body feathers, but not flight feathers or scapulars.  Birds in basic plumage lack the speckles on their upperparts and their breast spots have a white background. I banded this bird on 25 July 2011 and assume that it likely hatched locally. Although I have also banded young Wood Thrushes, the Veery generally favors wetter, younger forests.

Wednesday, July 27, 2011

Bank Swallow

I was not the only dragonfly hunter in Rice County on the excruciating hot afternoon of 19 July 2011.  I am surprised by the throat speckles on both of these Bank Swallows (specially on the bird on the right). I have not seen this plumage illustrated in my field guides.  Both the National Geographic Guide and Sibley show juvenals with unspotted throats. Garrsion (1999), however, states that, in fresh juvenal plumage, the throat is often washed with buff and sometimes shows "faint, grayish brown spotting." In warn plumage, juvenals become very similar to the adults. In July, juvenal feathers begin to molt into prebasic (winter) plumage. This molt is suspended during fall migration and is then completed by November in the wintering grounds. Flight feathers are not molted until after migration (Garrsion 1999).  

Tuesday, July 26, 2011

White-faced Meadowhawk

Like the Band-winged Meadowhawk in my last post, this White-faced Meadowhawk is also trying to reduce heat stress.  His strategy is to throw his wings forward and down, thereby shielding his thorax from the sun's rays.  Because his transparent wings do not cast much of a shadow, this strategy may involve reflecting light from the body (Mead 2003).  The White-faced Meadowhawk is not new for my list, as I first found it when I began my dragonfly quest last August in Erika's garden.

Monday, July 25, 2011

Band-winged Meadowhawk

The Band-winged Meadowhawk in the upper photo is in an "obelisk position."  On hot days, to avoid overheating, dragonflies raise their abdomens towards the sun, thereby reducing the amount of their body surface being struck by solar radiation.  
Band-winged Meadowhawks are a widespread species, found across the northern United States and parts of southern Canada, but common locally only near ideal habitat.  According to Mead (2003), the nymphs are outcompeted by other dragonfly nymphs and are also heavily predated by fish.  Band-winged nymphs, therefore, are not well known. The nymphs were the goal of Scott King's recent expedition to an area in Dakota County where he often finds Band-winged Meadowhawks.  As you can see in the middle photograph, Scott was successful in his hunt.  To confirm his identification, Scott later raised a few of these nymphs to adult dragonflies.
Knowing that Band-winged Meadowhawks are relatively uncommon, Erika and I were surprised to find a second individual in Rice County at the River Bend Nature Center near Faribault, Minnesota.  This meadowhawk is in the bottom photograph.

Saturday, July 23, 2011

Common Wood-Nymph

Common Wood-Nymphs are found across most of the United States and southern Canada. Despite their name, they are not fond of woodlands. Look instead in meadows and grasslands. This July, Erika and I found numerous wood-nymphs flying erratically among the forbs in Carleton College's native prairie. I suspect the photograph above is of a female and the one below is male. Females are variable in the amount of yellow on their wings. Butterflies in the southeast show bright yellow wing patches; in the northeast and west, this yellow is subdued in females or absent in the males.

Friday, July 22, 2011

Great Crested Flycatcher: Anting or Sunning

On Tuesday, 19 July 2011, I was photographing dragonflies. My car thermometer read 97 degrees; the bank proclaimed 104--with record-breaking heat-index numbers for Minnesota. While I languidly scoped Odonata, a robin-sized bird flew out of a small woodlot and landed in a grassy, treeless hillside by the road. The bird plopped its belly onto the ground and spread its tail and wings.  Clearly this Great Crested Flycatcher was anting. 


Anting is a curious and unexplained phenomenon. Anting comes in two forms. Either birds pick up and rub ants on their feathers, and then eat the ants.  Alternatively, like the flycatcher in the top photo, they land on anthills and let the ants swam. The first form of anting leads researchers to hypothesize that anting is for food acquisition. Picking up the ants and getting them to discharge their folic acid may make the arthropods palatable.  Ants with their acid sacs surgically removed are not used by birds for anting.  A second hypothesis is that the acid from the ants controls feather mites, fungi, and/or bacteria, all of which can be harmful to feathers. Thirdly, the ants may prime feathers for molting or keep feathers from drying out.  


A final, fascinating hypothesis is that anting serves an autoerotic or intoxicating function.  Look at our flycatcher in the last photograph.  The wings and tail are spread, the body feathers are fuffed out, and its  beak is open.  Anting makes some birds shake and others unable to walk.  I am not sure what an erotically stimulated bird actually looks like, but my guess is that this Great Crested Flycatcher comes close.
UPDATE:  Pam quotes from About.com, "Many birds are observed sunning even on the hottest days, however, and it is believed that sunning can fulfill purposes other than just temperature regulation. Sunning can help birds convert compounds in their preening oil – secreted from a gland at the base of the tail – into vitamin D, which is essential for good health. If the birds have been in a birdbath, sunning can help their feathers dry more quickly. It is even believed that some birds sun themselves for pure enjoyment and relaxation, much the same way humans will sunbathe.


"The most important reason for sunning, however, is to maintain feather health. Sunning can dislodge feather parasites because the excess heat will encourage insects to move to other places in a bird's plumage. This will give the bird easier access to get rid of those parasites when preening, and birds are frequently seen preening immediately after sunning. It is essential to get rid of these parasites – the tiny insects that infect feathers can cause problems for a bird's flight, insulation and appearance, all of which can impact its survival."

Thursday, July 21, 2011

American Rubyspot

On Saturday Scott King also introduced me to a third broad-winged damselfly--the American Rubyspot.  (The  broad-wings are a family of damselflies that includes the jewelwings.) These gorgeous creatures are down-right tropical, ranging from Central America, across almost all of the United States, and on into northeastern Canada.  Like the jewelwings, look for American Rubyspots along creeks and rivers.  We found this rubyspot in Dakota County where Chub Creek meets the Cannon River.


Female rubyspots submerge when laying eggs on creek vegetation.  As they lay their eggs, the females are often guarded by their males from above (Bugguide.net).  While we watched, Scott and I witnessed some interesting rubyspot behavior, which I will share with you in a future post.

Wednesday, July 20, 2011

River Jewelwing

On 16 July 2011, I tagged along with Scott King as he searched for meadowhawk nymphs. Heath Creek, which runs just south of Highway 19, harbored hundreds of Ebony Jewelwings--a species I wrote about last June.  Among the Ebony Jewel wings, and closer to the creek surface, hunted River Jewelwings.  The males of these large damselflies are easily identified by their black wing tips.  The species is common along waterways from the northern United States to southern Canada.


Male River Jewelwings actively court their females.  The male flutters back and forth in front of perched females.  After mating, the female backs down an aquatic plant until she is about a foot under water. She then lays her eggs on the plant stem.  After hatching, the young take up to three years to mature (Idaho State University).

Tuesday, July 19, 2011

Midland Clubtail

Midland Clubtails visited Erika's garden in late May and early July.  This individual warmed itself on the side of our home.  They are known to feed on other dragonflies, including Twelve-spotted Skimmers, which had become common in the garden.  Our fast-running water feature may also have attracted this dragonfly.  One diagnostic field mark is the small yellow spot on the upper side of the end of the abdomen.  This species is found in northeastern North America west to South Dakota and western Manitoba. 

Monday, July 18, 2011

Cliff Swallow

Cliff Swallows construct large colonies of mud nests under bridges, culverts, steep cliffs, and under building eaves. The birds in the first photograph were under the Highway 19 bridge in Cannon Falls.

I banded over 500 Cliff Swallows in Aberdeen, South Dakota. They nested under bridges along a creek that ran through town. I found that they moved from bridge to bridge during the summer. I also caught them in Aberdeen in subsequent years, although not often under the bridges where I first banded them.

In
The Birds of South Dakota, Dave Swanson, Jef Palmer and I cited a Cliff Swallow banded on 14 June 1937 near Sioux Falls, South Dakota that was recovered in West Virginia 16 July 1937. Cliff Swallows breed across most of North America (including Canada and Mexico). They winter from southern Brazil to central Argentina. Do our birds regularly head east before heading to their wintering grounds?

Cliff Swallows are socially monogamous but geneticaly polygamous. That's to say, only one male and one female use a given nest. But both sexes mate with other birds besides their mates. Copulation often occur within the nest. Extra-pair copulations often occur at mud holes where Cliff Swallows collect nesting material. One of these rapes appears to be happening to the right in the photograph below (taken at Sand Lake National Wildlife Refuge near Aberdeen). Males often attack their mate when she returns from mud holes, and forces copulation with her.
According to Brown and Brown (1995), "This may reflect sperm competition...a male's probable defense against extra-pair copulations" that are so frequent at the mud sites. Nevertheless, studies have shown that about half of Cliff Swallow nestlings in any given nest are not related to at least one of the parents. Sometimes the young are related to neither parent!  Females are known to lay in or carry eggs to other, usually nearby nests (
Brown and Brown 1995).  Females that practice this behavior to continue to raise the remaining eggs in their own nests.

Sunday, July 17, 2011

Question Mark

On the underside of the wing in the lower photograph,  do you see the small, white question mark that gives this butterfly its name?  Appropriately, this critter's scientific name is Polygonia interrogationis. Question Mark caterpillars eat, among other vegetation, American Elms, Hackberries, and nettles. Adults consume rotting fruit, tree sap, carrion, animal waste, milkweed, and asters (Ohio History Central).  My Question Mark fed among the fine sand settled in cracks on the street.

In the summer, male Question Marks often lay in wait for females on tree trunks.  Some avoid the winter by migrating, others by hibernating. The are found across most of the eastern United States, spilling over into southern Canada and northern Mexico.

Saturday, July 16, 2011

Eastern Forktail

Along with about a half-dozen other Odonata species, I encountered male and female Eastern Forktails along a small pond in the Carleton College Arboretum on 5 June. Forktails get their name from tiny projections at the end of the males' abdomens (first photo). The abdomen tends to be black with a brilliant, neon-blue tip. Females are more variable. Sometimes they look like males, but usually they are orange and black-striped, as in the second photo.

Eastern Forktails are among the first damselflies of the year and fly until the first fall frosts. They are common near water and, like those in these photos, are usually found low in shoreline vegetation. They are found across eastern and central North America.

Friday, July 15, 2011

Blue-gray Gnatcatcher

On 11 July 2011, John H. and I banded a female Blue-gray Gnatcatcher (first two photographs). Despite gnatcatchers' being common in most of the eastern and southwestern United States, this individual was a first for our Dundas banding site. Previously in Northfield I banded the male in this post's last photo.

Gnatcatchers
are monogamous. The males assist in most aspects of breeding, including the building of intricate lichen and spider-web supported nests, incubation, and the care of the young. Populations have grown over the past 25 years, increasing towards the north (Ellison 1992). They are an early migrant, their buzzy calls often indicating their presence, but become difficult of see once trees have leafed.

"Just what is a gnatcatcher?" asked John.

"Good question," I replied. "Early ornithologists thought they were Old World Flycatchers (Muscicapidae) or even in the mockingbird family (Mimidae). Then they were given their own family, the Sylviidae. In 1904, they were moved to the family Polioptilidae. By 1934 they moved into the chickadee family, Paridae. Later still they were again classified as Old World Warblers (a redefined Muscicapidae). Recent DNA studies indicate that gnatcatchers are most closely related to wrens (Troglodytidae). DNA folks argue whether gnatcatchers might be creepers (Certhiidae) or actual wrens. Clearly more research is needed. Today the American Ornithologists' Union calls them Polioptilidae; The Birds of North America (A publication of the AOU), Sylviidae; and The Handbook of Birds of the World labels them Polioptilidae."

John raised his eye-brow at me and passed me another cup of coffee.

Thursday, July 14, 2011

Colorado Potato Beetle

A bucket of Colorado Potato Beetles (and larvae) is bad news.  These beetles can devastate potato, tomato and eggplant crops.  The beetle originated in the Southwest and Mexico and spread across the country in the 1880s.  Now they are also found across Europe and Asia.

In four or five weeks, females can lay over 500 eggs.  Potato Beetles mature in three weeks from hatching, and three generations can occur in a single year.  They can quickly defoliate their favored crops.

Populations were controlled by DDT until the 1950s, but the beetles became resistant to this and subsequent pesticides.  Farmers have experimented with natural controls like a ground beetle and a fungus with mixed results. Natural controls also are dangerous since their effects on other aspects of the environment are often unexpected.

About.com gives the following advice if you encounter Colorado Potato Beetles in your garden: crush eggs by hand (you will find these yellow masses on the underside of leaves), hand pick adults and larvae (drop them in a bucket of soapy water), use a barrier around young seedlings to keep beetles off, plant crops that mature early, and weed the garden before spring beetles emerge (the beetles will feed on a variety of weeds if their favored crops are absent). The bucket of beetles in my photograph is from our CSA (Community Supported Agriculture) farm near Northfield.

Wednesday, July 13, 2011

Northwestern Crow

Another perplexing bird of the Pacific Northwest is the Northwestern Crow. This small crow historically was restricted to the tidewater from Alaska to Puget Sound. Deforestation has resulted in the Northwestern Crow's expanding its range, meeting up and hybridizing with American Crows moving into cleared lands from the east. It is a common bird in coastal, agricultural, and urban landscapes. (The last photo in this post is of a Northwestern Crow perched on the back of a pickup truck parked at a fast food parking lot.)


Local ornithologists will tell you that, as a result of this hybridization, now no such thing as a Northwestern Crow exists. They will wink at listers who check small Northwestern Crows, ignore intermediate birds, and identify larger crows as American Crows. If you want to list a Northwestern Crow, the bird must be small and next to the ocean.  They are about 10% smaller than American Crows, have smaller feet, faster wing-beats, and a lower pitched voice (Verbeek and Butler 1999). These authors warn, "A small crow seen in coastal Oregon is not necessarily a Northwestern Crow; it is more likely to be a small subspecies of American Crow, Corvus brachyrhynchos hesperis." They continue, "Successive editions of the American Ornithologists’ Union Check-list have listed Northwestern Crow as a full species (1910), a subspecies of American Crow (1931), and a full species (1957, 1983, 1998)." Not even ornithologists have been consistent, and many now once again consider the two to be subspecies.
I found the bird above in the tidewater of the Olympia harbor.  When I first spied this individual, I thought it was a large grackle!  I was surprised this by this juvenile bird's blue-gray eye--but young Northwestern and American crows are reported to sport this color eye. Finally, Northwestern Crows store food that they capture during low tide.  They retrieve it later, usually during the next high tide.

Tuesday, July 12, 2011

Western Gull

Western Gulls are encountered along the west coast of the United States and Baja California.  They are easily identified--a white bodied, pink-legged, dark-backed gull along the Pacific Coast is a Western Gull.

Western Gulls are, never-the-less, perplexing. Despite their being easy to see, they have a relatively small population size--only about 40,000 pairs nest at fewer than 200 colony sites within their range (Pierotti and Annett 1995). According to these authors, this gull is threatened by El Nino oscillations, oil spills, and pesticides.

In Puget Sound, Western Gulls hybridize with Glaucous-winged Gulls (see photo below), which breed from the Sound on north to Alaska. As many of 75% of birds in Puget Sound are hybrids, often called Puget Sound or Olympic gulls. The northern 300 kilometers of the Western Gull's range is a hybrid zone (Pierotti and Annett 1995). Local birders only identify birds at the extremes of the resulting variation. With such a great amount of genetic flow between Western and Glaucous-winged gulls, I wonder why they are not classified as races of a single species.

Monday, July 11, 2011

California Gull

During our June visit to Olympia, Washington, my family took me to the ocean.  Birding on the seashore  is normally rewarding.  Our expedition was an exception--we listed only a few birds.  One of these birds was this California Gull.

California Gulls breed in scattered locations from the Prairie Provinces of Canada south through the northern arid West and northwest Great Plains.  These gulls winter along the Pacific coasts of the United States and Mexico, often fairly far out at sea.  Off Washington, first year birds are often encountered further from the shore than are adults.  One hypothesis for this distribution is that the young are forced further out by competition with adults.   Nonbreeding individuals, like the bird in my photograph, are often found along these coasts in the summer.

The California Gull in this photograph is somewhat oddly plumaged. This species takes three years to reach adult plumage.  First-year birds have dusky brown bodies, blue-gray legs, and pale bills with black tips.  Third-year birds are generally white with gray backs, black wings, and yellow legs.  Second-year birds are variable in plumage and leg color.  This California Gull appears to be a second-cycle bird that has retained the gray legs but is molting into adult plumage.  Note the black band and red spot on the bill, both field marks of a third-cycle individual.  Other adult characters include the red eye-ring and dark eye.  A photograph of a very similarly plumaged California Gull with gray legs is found in Howell and Dunn (2007).  Identification using many other field guides, however, would be difficult.  I think I have mentioned in previous posts that gull identification can be vexing.

Sunday, July 10, 2011

Widow Skimmer

While on an unsuccessful search for nesting Sandhill Cranes just south of Northfield, John H. and I found Widow Skimmers in a wet meadow.  The female is pictured above, the male below.  Erika and I have since discovered this dragonfly within the city of Northfield.  The species is found across most of North America, although not in the Rocky Mountains.   Look for this species near permanent wetlands. Mead (2003) advises that the Widow Skimmer's wing pattern "is not matched by any other species."

Saturday, July 9, 2011

Northern Pearly-eye

Northern Pearly-eyes are another resident of the eastern United States and parts of adjacent Canada.  They tend to be common in shady areas of deciduous forests.  Note that the tip of the antenna, visible protruding from behind an inconvenient leaf, is basally black. Adults feed on tree sap, dung, mud, and carrion (Marrone 2002). Erika found this one flying low along the Cannon Bike Trail on 3 July 2011.  

Friday, July 8, 2011

Silvery Checkerspot

During our recent Cannon Bike Trail ride, Erika and I discovered a pair of Silvery Checkerspots.  They flew low and perched on the ground.  The species is common across most of the eastern United States. Silvery Checkerspots are attracted to composite flowers and their caterpillars can skeletonize the leaves of their host plants.  Adults also visit variety of flowers, including clovers, dandelions, milkweed, and Canada Thistle (Marrone 2002).

Thursday, July 7, 2011

Pigeon Guillemot

From Alaska to California, Pigeon Guillemots are found along rocky coasts, where they dig nesting tunnels. They are a year-round resident in Puget Sound.  I have previously seen them at the Bremerton Ferry; only before it was Christmas and the birds were in their gray and white winter plumage.  Like the Pelagic Cormorant, Pigeon Guillemots feed inshore. They dive to the seabed where they consume bottom-dwelling invertebrates and fish (Ewins 1993). The black line through their white wing patch is a key to identification.  Occasionally their bright red feet can also be seen.

Wednesday, July 6, 2011

Pelagic Cormorant

We arrived at our destination, Olympia, Washington, and, the next day, drove to Seattle. We avoided car-clogged I-5 by taking the ferry from Bremerton to Seattle. Although photography was challenging from the rocking, vibrating ferry, I was able to add a few species to the birds covered in this blog.

The first bird is the Pelagic Cormorant, a common species of the north Pacific.  It ranges from the Arctic to Baja California and to southern China.  Despite its name, the Pelagic Cormorant prefers inshore marine waters, making Puget Sound a perfect place to look for them.  Although not always evident, these small cormorants, especially in flight, usually show white flank spots.  The white plumes in the bird above are indicative of breeding plumage.

Pelagic Cormorants tend to be more solitary than other cormorants. They feed by swimming under water and feeding on fish (which they grab with their bills, rather than spearing) and benthic invertebrates. Like all cormorants, these birds are at risk of oils spills, ocean pollution, and being tangled in fishing nets (Hobson 1997; All About Birds).

Monday, July 4, 2011

Western Fox Snake


I am not used to tripping on really big snakes in Minnesota.  Despite the 3rd of July crowds along the Cannon River Bike Trail in Goodhue Co., this Western Fox Snake slithered across the bike trail in front of us.  Despite their size, these serpents are harmless to people.  They range from 3 to 5 feet in length--ours was somewhere between those extremes. We identified it by its relatively plain-colored head.
Fox Snakes inhabit southern Minnesota (and also in Michigan, Wisconsin, Illinois, and Iowa) in moist woodlands, prairies, meadows and rocky outcroppings near rivers.  They are often nocturnal during the summer.  When handled, they are usually passive, though often release a musky smell from scent glands at the base of the tail.  This odor smells like a Red Fox, hence the snake's name.  If cornered and unable to flee, Fox Snakes can vibrate their tails and also strike at their attackers.  Unfortunately, this behavior leads to misidentifications that often result in the snakes' being killed by humans.  These snakes usually consume rodents, often killing them by constriction. Fox Snakes are active between April and October.  In winter they hibernate in rocky crevices.