Wednesday, October 30, 2013

American Robin


More evidence of this year’s poor fall migration at the banding stations in Northfield: last year I banded 31 American Robins in October; this year only 7.  I do not have any definitive answers to this year’s poor migration except to mention that other people in parts of southern Minnesota have also complained of a lackluster showing of birds this fall. Realize that I am not saying anything about birds away from my banding stations—a few days ago Erika and I observed about 100 robins feeding on basswood trees at River Bend—but the birds sure are down in numbers in my yard in Northfield.

Monday, October 28, 2013

Australian Bush Turkey

Megapodes, or bush-turkeys, are found on the islands of southeast Asia and Australia. This Australian Bush-Turkey, as its name implies, is found in eastern Australia. This bird is odd looking—its tail appears to be stuck on sideways. The species originally inhabited coastal rainforest. Cutting of the rainforest has forced bush-turkies into disturbed areas and suburbs. These are omnivorous birds, they eat about anything, and are often found at landfills.

Megapodes (also known as mound-builders) share with some reptiles the curious behavior of building nesting mounds. They lay their eggs in big piles of leaves and earth; mounds can contain 4 tons of material and average 85 cm high (and up to 700 cm). By adding or taking leaves off these compost piles, they keep their eggs at an optimal temperature of about 33.3 degrees C.  The mounds can retain their heat for several weeks, not requiring attention from the birds.

Males are polygynous and build the mounds. Curiously, bush-turkeys occasionally use human compost piles, modifying them for their own use. Females are serially polyandrous (they stay with a single male for several weeks, but then move on to new mates). Several females may lay in one male’s mound. Males can have two active mounds, each containing up to 58 eggs, although only only up to 27 come from each female.

Most of this information is from The Handbook of the Birds of the World Alive, a web-based resource that I recently reviewed in this blog. I took this photograph in 1990 a city park in Port Macquarie, Australia, when our family toured after Erika and I presented a paper at an ornithological congress in New Zealand.

Saturday, October 26, 2013

Great (October) Egret

On a cold, gray 23 October 2013, John Holden and I were surprised to find a Great Egret approaching us along the shore of Circle Lake in Rice County. The end of October is a bit late for this egret in Minnesota, although birds are known to linger into November.
I quickly realized that this egret presented a photographic opportunity—a white bird against a smooth gray background and no horizon line or distracting sandbar or vegetation.
During the half hour we observed, the egret slowly strolled towards us. Every two or three minutes, the bird speared what appeared to be young bullfish, an abundant Minnesota catfish, inhabiting even muddy, shallow, or polluted waters of the state.
We did not think the egret was in any way impaired, escecially considering its apparent fishing success. When the bird finally flew, however, its legs seemed to dangle to the right and its muddy toes appeared to be oddly opened. While the bird foraged, however, nothing seemed to be amiss.

Thursday, October 24, 2013

Wood Duck

This photo is a left-over from last spring. I found these Wood Ducks in a small pond at the River Bend Nature Center near Faribault, Minnesota. Despite the trio here, two males and one female, Wood Ducks are monogamous. Males, however, do not take care of the eggs or young. Some males will mate with a second female after his first brood is fledged.

The male in the background is apparently beginning what is called a “Display Shake.” The male spreads his crest, extends and lowers his head, and exposes his white belly. The male in the foreground does not seem to be contesting the other male’s courtship. Aggression between Wood Ducks is short-lasting, with intruders quickly giving up (Hepp and Bellrose 1995).

Tuesday, October 22, 2013

Song Sparrow

Song Sparrows are perhaps “the most polytypic passerine in North America,” this sparrow occurs with more geographical variation than almost any other bird in the world (Arcese 2002). Ornithologists argue over the exact number, but some 38 races are recognized by the American Ornithologists’ Union. These subspecies, however, are not likely to be declared as full species—their mitochondrial DNA show little variation.

Here are three of my Song Sparrow photographs from across the United States—Arlington, Virginia (top), Aberdeen, South Dakota (middle), and near the Hearst Castle on the California coast (bottom). I am no expert on Song Sparrow races, and I lack comparative material. Nevertheless, here are my best guesses as to the subspecific identity of these birds. In any case, the purpose of this post is to point out the kinds of variation seen in Song Sparrows.

The Virginia bird may be Melospiza melodia atlantica. This race is told by its gray-colored back with black streaks. Melsospiza melodia melodia, which is found across much of eastern North America, has a different-colored back. The back streaks are reddish-brown on a brown background, not on gray like the first bird. My South Dakota bird more or less fits this description and is the race expected in the state. Arcese et al. (2002), however, warns that these two subspecies are similar (although atlantica is limited to the far eastern US).

The California bird differs from the previous two. Note the black breast streaks—not brownish like on the other two birds. Notice, too, the bill, which appears to be longer and narrower than in either of the two previous photos. Finally, the bottom photo shows a bird with a brighter, reddish-brown back with black streaking—all characteristic of Melospiza melodia gouldii.

Again, these identifications are only guesses on my part. Arcese et al. (2002) summarize Song Sparrow variation by saying that, in general, darker birds breed in areas of high humidity, whereas pale races are found where humidity is lower. Northern birds tend to be large, while smaller subspecies are found in the southwest. (Note that in this post, I use the words race and subspecies interchangeably. The definition of both terms is a geographically identifiable population within a species’ range.)

Sunday, October 20, 2013

Ruby-crowned Kinglet

This male Ruby-crowned Kinglet’s crown is completely hidden. Kinglets are common migrants in our part of Minnesota. I include this photo due to the continued paucity of birds at my banding stations, continuing a trend begun last month. Head-on portraits are relatively uncommon—so much so that this photo might make a good quiz subject. I have posted previous photographs in which the ruby crown is not hidden.

Saturday, October 19, 2013

Hermit Thrush

The Hermit Thrush breeds in the Rocky Mountains and from Alaska across central Canada south to New England and Northern Minnesota, Wisconsin and Michigan. This thrush winters in the southern US and along the Pacific coast south to southern Mexico. This photo is of a migrant Hermit Thrush this October in the Carleton College Arboretum—the tiny buffy tips to the wing coverts indicate this individual was hatched this year. Older birds lack these spots.

Unlike other thrushes (e.g., Wood, Gray-cheeked, Swainson’s), Hermit Thrushes do not cross the Gulf of Mexico. This cold-hearty species arrives on its breeding grounds early in the spring and departs late in the fall. Hermit Thrushes usually migrate by night. Normally Hermits take off about 30 minutes after sunset. Most flights end about 40 minutes before sunrise. I often band Hermits very early or late in the day (Delinger et al. 2012).

Fall migrants prefer migrating in high-pressure weather systems, with clear skies and northerly winds. Curiously, Hermit Thrushes will fly into thunderstorms, “even if doing so results in a reversal of direction.” Each night, they maintain a constant direction (more or less south), changing headings depending on the position of each evening’s sunset, perhaps calibrating an internal magnetic compass (Delinger et al. 2012).

Friday, October 18, 2013

Cedar Waxwing

Cedar Waxwing numbers have increased during the past few decades. Pesticide use is ever more regulated. Furthermore, this species is ruled by fruit trees, which have become more abundant as farmlands turn back to forest and as urban trees mature. The dependance on fruit, a patchily distributed resource, results in waxwings traveling in flocks, to better find and harvest the fruit. Waxwings are nomadic, seldom returning to the same areas to nest, depending, instead, on abundance of local fruiting. (A waxing that I banded in Aberdeen, South Dakota on 24 January 1988, was caught on 11 November 1988 at the Carpenter Nature Center near Hastings, Minnesota.) Finally, waiting for fruit to ripen, waxwings breed late in the summer (Witmer et al. 1997).

Erika and I found this young waxwing—note the lack of much of a crest and its relatively ruffled plumage—feeding on grapes in the Carleton College Arboretum on 13 October 2013. Note also that it lacks the red wing spots often seen of both sexes and all ages of waxwings.

Thursday, October 17, 2013

Downy Woodpecker

On Sunday, Erika and I happened upon this Downy Woodpecker defying gravity, while pounding away on a dead tree stump. Apparently the bird is hanging by placing the tips of its claws into small holes in the wood.

Erika wondered why woodpeckers don’t suffer concussions and was sure the National Football League would really like to know. I turned to Erika and asked her to remind me not to get into the woodpecker line at the Reincarnation Center.

We knew that woodpecker neck muscles are relatively thick and help avoid brain injuries. I have previously blogged about woodpecker nictitating membranes, which keep woodpecker eyes from popping out when the bird pecks. A bit of Internet research came up with a 2011 article in Science China: Life Sciences. Compared to Mongolian Sky Larks, Great Spotted Woodpeckers have a thick, spongy skull.  This structure shields the woodpecker’s brain from g-forces 1,000 times that of gravity; humans do poorly when subjected to g-forces as low as 46 times gravity (Livescience.com).

Furthermore, woodpecker beaks are also relatively spongy, which may absorb the impact while the bird drills, diverting the shock away from the brain. This adaptation is sort of like indentations in automobile chassis that buffer the cabin from head-on collisions—although the last time I noticed, the car chassis did not retain its original structure after the crash.

Tuesday, October 15, 2013

Android Birding Investment

I am not sure about the relative advantages of the iPhone and Android mobile phone platforms. All I know is that iPhones are more often used by relatively wealthy, older Americans, whereas Androids are favored by younger, poorer, and often foreign users. My understanding is that Android apps tend to be free, but pay their developers through advertisements. Android apps may also be more difficult and more expensive to develop due to the plethora of different Android operating systems. I like my Droid because of its five-inch screen and consequent larger key board.

For birders, one of the advantages of the iPhone is an app called BirdsEye. You can find what birds species are being seen near your location (via eBird). You can find the locations of specific birds. You can set the app to search from 1 to 50 km from your exact location. (The photo above shows Bald Eagles near an observer in Denver). If you use eBird, BirdsEye can show you the locations of bird that you need for your various lists (life, year, county, or even big day). You can quickly locate birding hotspots. Abundance graphs show what birds are most likely to be seen in your location. You can access lists and locations of notable sightings. Most birds have photos and sound recordings, and you can connect to Wikipedia and Flickr (if you are within Internet range). You can read more about this exciting app at the BirdsEye home page.

The BirdsEye folks are developing BirdsEye for the Android. They have come up with an interesting way to fund this development, by giving birders the opportunity to pre-purchase this app for their Android phones. To date, they have raised $33,000 of the $45,000 they need to complete the project. For $20 you will be put on a waiting list for the new app when it finally hits the market. I look forward to the ability to find birds with my cell phone rather than having to do research with eBird from my home or hotel room. Here is a link to pre-purchase BirdsEye.

I have no financial ties to BirdsEye—not even a free app in return for this post; I have already made my pre-purchase. Note that BirdLog is a different app from BirdsEye. BirdLog allows you to enter data into eBird on both iPhone or Android phones.

Sunday, October 13, 2013

Yellow-rumped (Myrtle) Warbler

I previously blogged about Myrtle and Audubon’s warblers and the dangers of lumping them in one species (the Yellow-rumped Warbler). Last week I banded the bird in this photo. Despite the buffy-yellowish sides of the throat, this is clearly a Myrtle Warbler. Note the line that continues from the back of the throat and continues half-way around the dark cheek patches. This line is lacking in an Audubon’s Warbler, which also lacks much of a supercilliary stripe. Thus Audubon’s Warblers (which also have a white eye ring) have a much more hooded appearance. The Myrtle Warbler breeds across northern Canada and some of the northern-most states in our country. The Audubon’s breeds in the Pacific Northwest and northern Rockies of both countries. Myrtle Warblers breed and are common migrants in Minnesota. Audubon’s Warblers are rare vagrants to our state.

One of these days Myrtle and Audubon’s warblers may once again be considered to be separate species. They only have a narrow band of hybridization in British Columbia and Alberta. This band is generally less than 200 kilometers, and genes from each race do not spread far from the area of hybridization. Away from this band, the two groups’ DNA differ “well below the average distance between species, but typical of some closely related species pairs” (Hunt and Flaspohler 1998). These ornithologists conclude that “further work on the complex may be appropriate."

Saturday, October 12, 2013

Monarch on Blue Giant Hyssop

I have blogged about Monarch Butterflies—this individual perched atop a Blue Giant Hyssop in the Carleton College Arboretum last Sunday. This mint is a summer-bloomer, usually lasting into September. October nectar must be quite attractive butterflies. This wildflower brings in bees. People are also attracted, since the flower makes for licorice-flavored teas and jellies. Blue Giant Hyssops are found in north-central and northern North America. Thanks to Nancy Braker of the arboretum for identification help.

Friday, October 11, 2013

Winter Wren

The diminutive, somber-plumaged Winter Wren, like this one I banded this week, is awash in scientific controversy. I previously blogged about Winter Wrens currently being considered three species—the eastern Winter Wren and the western Pacific Wren, plus another species in the Old World.

In Europe and Asia, at least 44 races are described. DNA research indicates that, in the Old World, at least four groups exist, possibly containing several distinct species. The groups reside in Europe, eastern Asia, Nepal, and in the Caucasus. The potential, new species within these groups are said to be cryptic—you can only identify them with a DNA laboratory in your field vest.

Winter Wren races have different habitat preferences. North American birds breed in coniferous, boreal old-growth forests. Clear-cutting and forest fragmentation have reduced the numbers of North American Winter Wrens. European Winter Wrens breed in deciduous woodlands and in urban parks and gardens. In North Africa, these wrens are limited to forested streams at elevations of 1200 to 1800 meters. In the Himalayas, they are found to 4575 meters (Handbook of the Birds of the World Alive).

All this is confusing enough, but DNA work also indicates that Winter Wrens are more closely related to Cistothorus, a genus of Old World warblers, than they are to other wrens—even other wrens that currently share the Winter Wren’s genus, Troglodytes. Many ornithologists now argue, using both DNA evidence and other morphological data, that Winter Wrens should put in a separate genus, Nannus (Hejl et al. 2002). I do not believe, however, that anyone is suggesting that these birds are not wrens.

Finally, DNA studies suggest that wrens, traditionally listed near dippers and mimc thrushes, are actually closer to treecreepers, gnatcatchers, and nuthatches. I don’t know about you, but all this confusion finds me beginning to recite Shakespeare ("a rose by any other name would smell as sweet").

Thursday, October 10, 2013

Syrphid Fly and Wasp Warning

Erika and I had a bad September. Underground Paper Wasps, 10,000 of them, built their nest under our peony bush. Erika was stung three times, I, twice. We didn’t do anything to deserve this viscous attack—we were just standing in the garden. I swelled up, but did not go into anaphylactic shock like I did the last time I was stung. Erika ended up in the emergency room of the Northfield Hospital as she broke out in hives, lost her vision, and passed out. One thing that saved us was our taking two Benadryl right after being stung.

So, in the past few weeks, we have not been outside much. Only now, after dispatching the wasps, have we ventured into the garden. I took a few meadowhawk photos on Tuesday. I gasped upon seeing this bee—had the wasps returned? No, this creature turns out to be a fly, probably an American Hover Fly, famous for mimicking bees and wasps. This look-alike strategy is called Batesian Mimicry, since the fly is harmless to humans.

But hover flies are not harmless to aphids, often the scourge of gardeners and farmers. The larval flies eat aphids and scale insects. Researchers are trying to use hover flies as a biological control of the smaller pests. The adults feed on nectar and pollen. The maggots require aphid meals to complete their development—they are “aphidophagous”—a new word I learned while writing this blog. Releasing hover fly larvae into fields quickly reduces aphid infestations or even eliminates the aphids (University of California).

Wednesday, October 9, 2013

American Goldfinch

The chickadee I wrote about in my last post was not the only species feasting on aster seeds last Sunday. A couple of American Goldfinches also gorged themselves on seeds, although not quite as acrobatically as the chickadees. Because of its jet-black wings, I assume this bird is a male. The otherwise drab plumage suggests an immature. See my blog post of February 2010 for more information on aging and sexing goldfinches.

Tuesday, October 8, 2013

Black-capped Chickadee

One of the advantages of photography and blogging is the joy of seeing and sharing images of even very common birds. This Black-capped Chickadee is a good example. Many birders barely pay attention to this abundant species. On Sunday, Erika and I stood in the Carleton College Arboretum wondering why we were not seeing many migrants. Just next to us, a chickadee flew up and briefly fed on aster seeds. The bird flew off, but repeatedly returned to the same seed-heads. Apparently the bird was intent on consuming every seed, regardless of the acrobatics necessary for this mission,

Sunday, October 6, 2013

Prairie Falcon

Prairie Falcons breed across much of the western United States, Baja California, north-central Mexico and barely extending into southestern Canada. They fill in non-breeding areas in the winter, moving east into the Dakotas south to central Texas—perhaps as far east as western Minnesota. Their narrow “mustache” stripes and black “armpits,” visible on flying birds, are keys to identification. This photograph was taken in central South Dakota.

Breeding birds prefer dry habitat and nest along cliffs and buttes. They prey upon ground squirrels and birds. In the winter, they favor Horned Larks and Western Meadowlarks. Being basically a desert bird, Prairie Falcons avoided the onslaught of DTT and other pesticides better than did many other raptors. Now the birds face "agricultural encroachment, livestock-grazing, energy development activities, off-road vehicle use, and military training” (Steenhof 1998).

Saturday, October 5, 2013

Northern Harrier

Northern Harriers breed in the north half of North America and winter south to northern South America. Although they are common, I find them hard to photograph—perched birds usually fly before I get my camera focused, and taking pictures of flying birds is always a challenge. This photo was taken during a snowy spring in South Dakota.

Harriers are reognized by their long wings and tails; the gray males are smaller than the brown females. Both sexes show white rumps. They often fly near the ground over fields—their primary prey are voles (although I have also seen them take small birds, and harriers do take a wide variety of other prey). One reason for flying low is that, unlike other hawks, harriers rely on auditory, as well as visual, cues to find their prey,

Northern Harriers are intimately tied to their vole prey, so much so that Frances Hammerstrom wrote a book called “Harrier, Hawk of the Marshes: The Hawk That is Ruled by a Mouse.” When vole numbers are down, few harriers are seen; when vole populations expand, harriers become common. But the story does not stop there—males are often bigamous, especially when mouse populations are high. During abundant vole seasons, some males have up to five mates. The females incubate and brood their young, while the males provide most of the food for both their mates and young (Smith et al. 1011).

Friday, October 4, 2013

Wilson’s Snipe

On Wednesday morning, John Holden and I birded the Great Western Industrial Park near Randolph, Minnesota. The park is being developed in beautiful prairieland and, in any season, is a great place to look for birds. You would think that people with foresight would build their park in a cornfield rather than in lovely, pond-studded grassland.

One highlight of the visit was this Wilson’s Snipe. This species breeds across Canada and the northern United States, wintering southward all the way through South America. Despite being common within its range, relatively little is known about its biology. The snipe’s marshy habitat, camouflaged coloration, and because it usually forages at dawn and dusk, all combine to make the species difficult to study.

This species is variably named the Common or Wilson’s snipe. What you call it depends if you consider our species to be the same as the Old World's Common Snipe. These days ornithologists treat the Wilson’s Snipe as a distinct species from the Common—their breeding displays, when they dive while making a winnowing sound with their outer tail feathers, are different. They also look slightly different.

Some snipe trivia from Mueller (1999): the word “snipe” is derived from “snite,” meaning “snout”—a reference to their long bills. As do other sandpipers, the bill has sensory pits near the tip, so snipes can detect their prey under their muddy, marshy habitat. Finally, snipe eyes are set relatively far back on their head—they are able to see right and left, but also to the rear—even when their bills are probing the mud, they can watch for predators from behind.

Wednesday, October 2, 2013

Red-breasted Nuthatch

October brought this fall season's first Red-breasted Nuthatch to the banding station. I last banded one of these nuthatches on 7 June. I have previously lectured on the dangers of misinterpreting Red-breasted Nuthatch summer records. In Minnesota, the species breeds in the Northeast, south to Minneapolis/St. Paul. Nevertheless, by October, this nomadic invader from the northwoods is a harbinger of the winter to come.

Tuesday, October 1, 2013

Amber-winged Spreadwing

Because every record is vetted by experts, not just the rare ones, Odonata Central is more rigorous than eBird. Of course, birds are better known by citizen scientists than are dragonflies—and far more bird records are submitted to eBird than dragonfly records go to Odonata Central.

My record of an Amber-winged Spreadwing took a long time to be vetted. I submitted the record from Erika’s garden on 7 August 2013 and it was not vetted until 20 September. I assumed that the script-like thorax markings and the brown-banded abdomen were diagnostic. The wings are not particularly honey-colored, but Paulson writes that this color is not always obvious. No other spreadwing has dark bands across bright yellow sides, although admittedly, the sides of my damselfly are not particularly bright.

Odonata Central shows this species’ range to be northeastern North America, west to Minnesota, Iowa, and Missouri. Only four records come from southeastern Minnesota; mine is the second from Rice County. The species is to be expected near a variety of wetlands.