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.

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.

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.

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).

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.)

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.

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).

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.

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.

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.