House Sparrow

Digital photography has revolutionized my birding. I am excited even to take a picture of the lowly House (or English) Sparrow. They are despised and ignored by most birders and banders. Not only have these sparrows been introduced from England and Germany, they are ubiquitous (they have a nearly world-wide distribution) and take over nesting cavities of native species. Why were they introduced? I read that people wanted every bird mentioned in Shakespeare (or maybe birds of the Bible) to inhabit Central Park. In any case, the English tend to introduce British birds around the world.

House Sparrows prove to be interesting. The species demonstrates evolution at work. Since their introduction to Brooklyn in 1851 (and San Francisco in 1871, and Salt Lake City in 1873), House Sparrows have evolved! Today House Sparrows are smaller in the southern parts of North America and larger in the north. Furthermore, they have longer limbs in warm climates and shorter ones in cooler areas. (Similar size trends are noted for many species. Larger birds retain heat better than smaller ones since the larger ones have less of a surface to body mass ratio. And you would want shorter legs in cool climates to protect you from heat loss.)

Lowther and Cink (2006) also cite an 1898 study of House Sparrows after a Rhode Island ice-storm. Half of the 136 birds brought in to a lab died. Larger males survived more often than smaller ones. Females showed different survival patterns--average-sized females survived better than larger or smaller ones. This study is a clasic example of natural selection.

Michigan Lily

Today Erika and I rode our bicycles along the Sakatah Singing Hills State Trail.  Just west of Warsaw, we zipped by a few lilies in a marshy area below the trail-side.  In college I contemplated becoming a botany major, but a number of events conspired against that path. I remain, however, interested in wildflowers.  Over the years, I have taken a few wildflower photos (the flower photos are after all the birds), which you can see at:

http://picasaweb.google.com/danerika?showall=true#100

In any case, today's lilies struck me as small but intense orange, with their petals oddly reflexed towards the sky.  We stopped and peddled back to the flowers, Michigan Lilies, Lilium michiganense. They are found across much of the Midwest. This plant is threatened in Tennessee and endangered in New York.  In Minnesota, it has become uncommon due to conversion of wetlands to farmland and because of roadside maintenance destroying habitat (Moyle and Moyle, Northland Wildflowers, U MN Press 2001).

By the way, this lily's nomenclature is a bit confusing.  Moyle and Moyle call this flower the Turk's-cap Lily. The USDA plant database (http://plants.usda.gov), however, reserves this common name for Lilium superbum, a plant not known to occur in Minnesota.

Barn Swallow

Mid-July is upon us and we have the first sign of fall: Barn Swallows beginning to congregate on area power lines.  These swallows winter in Central and South America.  This species may be our only long-distance migrant that also breeds in its wintering grounds: Barn Swallows are known to nest in the austral summer in northern Argentina. These birds may be becoming southern residents and not making the return migration to North America.

Barn Swallows historically nested in caves, but now almost exclusively use human habitations.  This abundant species breeds across North America, Asia, and Europe, and its range is spreading along with human populations.

My source for most of this information is Brown, Charles R. and Mary Bomberger Brown. 1999. Barn Swallow (Hirundo rustica), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/species/452.

American Robin

The American Robin is the most abundant of the North American thrushes.  Robins are so numerous that many folks don't appreciate their beauty.  I banded this male robin (you can tell it is male because of its dark head--females have much grayer heads) on 6 April 2009 and recaptured it on 12 July 2010. Male robins are monogamous during the breeding season, but usually take different mates in subsequent years.

I am fascinated by robin subspecies.  Turdus migratorius migratorius, found across much of North America, is the most common robin and is the one found in Minnesota.  T. m. propinquus is larger and paler than our birds and lacks the large white spots on the outer tail feathers. This race is found in the western US from British Columbia and Montana, south into Mexico and the Great Plains.  Two subspecies of interest to Minnesotans are T. m. caurinus of the rain forests of western Washington north to southern Alaska and T. m. nigrideus of the damp coniferous forests of eastern Canada.  Both of these races are darker-backed than our birds and both might be expected to appear in Minnesota in the winter.  In the northland, many non-birders are surprised when they see robins in the winter.  But robins are not uncommon during the winter and I have noticed that they are usually much darker-backed than are our breeding birds.  For both of these races, spending the winter in Minnesota counts as a southern vacation!  Nevertheless, be warned, I am aware of no verified records of either subspecies from the state. (Three additional robin races exist, one the the southeast US and the other two in Mexico.)

Cedar Waxwings

The Cedar Waxwing is one of our two birds with yellow-tipped tails (the other is the Bohemian Waxwing).  The species is primarily a fruit-eater; waxwings have been known to become drunk on fermented berries.  If the berries are near a road, this can be fatal for the birds. We all know that being drunk on a highway is a poor strategy.

Waxwings derive their name from the red, wax-like tips to their secondaries.  You can see these structures in the photo above.  These are odd feather growths because they can be present on males or females. Older birds, however, tend to have more red tips than younger ones. The bird below is a male without the feather tips. You can tell it is a male because the black on its throat is more extensive than on a female (which sports only a very narrow line of black below the bill).

Flocks of Cedar Waxwings are often found in cedar (and other fruit) trees.  I did not expect to find these birds on a barbed wire fence at the Dennison Water Treatment ponds near Northfield.  Their unkempt, long crests also surprised me.  Usually waxwings have handsome, slick plumage.

Dakota County Common Loon

Susan P. mentioned that she found an adult and young Common Loon at Kingsley Lake near Lakeville, Dakota Co., and that the birds could probably be photographed.  Because loons are my favorite birds,  Erika and I were not long in searching.  We immediately found the birds along the southwest corner of the lake. The adult gave several clear and piercing yodels as we approached.

I did not know that Common Loons nest this far south in Minnesota.  Janssen, in his book, Birds in Minnesota, indicates that Dakota Co. is the southern limit to their nesting range.  Non-breeding loons are found south of their nesting range.  Historically, loons may have bred as far south as the Iowa border.

If you look for these loons, watch your toes.  The lake is guarded by this aggressive snapping turtle.  If you look closely, a leech is riding the turtle's back. Perhaps the turtle is one reason there is only one young loon. 

More perils await both loon parent and young, since their main wintering area in the Gulf of Mexico is awash in spilled oil.  These birds are probably doomed unless they are fortunate enough to winter, as some loons do, along the Atlantic coast.

Recaptures and Chickadee Tails 2

In my recent post about ageing birds by tail feather wear, I compared a Black-capped Chickadee to a Northern Cardinal.  Today I banded an adult female chickadee, and I thought comparing two tails from the same species made more sense. The worn tail on the left is from the adult chickadee, while the pointed tail feathers on the right is from the young bird.

I also recently recaptured three birds from last year--two House Wrens: one banded on 11 May 2009, recaptured on 28 June 2010; the other banded on 19 May 2009 and retrapped on 8 July 2010.  A Chipping Sparrow caught today, 8 July 2010, was banded exactly one year ago.

Speaking of Cloacae

Roxie Laybourne, who spent her career at the National Museum in Washington, was one of my mentors.  Among her claims to fame was that she was the only person who could identify the sex of a living Whooping Crane.

Whooping Crane sex is important.  The Fish and Wildlife Service took eggs from wild nests in Canada and hatched them in Maryland.  They bred these birds to build a captive flock, thereby assuring survival of the species in case anything happens to the wild birds (oil spills, late season hurricanes?). 

The problem is that Whooping Cranes form life-long pair bonds.  If you accidentally try to mate two males, they may form a homosexual pair bond, and you have just wasted two very valuable birds.  Roxie developed a machine, basically an ophthalmoscope with tweezers, to peer into a Whooping Crane's vent and into the cloaca (see last post).  Male birds have two testes, but females normally have but one ovary.  Thus, the male cloaca has five internal openings (two sexual ducts, two urinary ducts, and the digestive tract); the female has four (only one sexual duct).  By counting those openings, Roxie knew the sex of those birds.  (Of course, the cranes were not crazy about having their cloacae examined.  Wildlife technicians caught the captive birds and placed them in special straight jackets before Roxie went to work.)

Cloacal Protuberances

I last posted about some of the ways banders identify a bird's age.  Often both sexes of birds are similar.  The photo below is of one of these species, the Chipping Sparrow. In the photo, the bird is on its back, with the tail going towards the upper right and the belly feathers moved out of the way. 

 

When breeding, most male birds have a swollen cloacal protuberance, the structure in the center of the photograph.  A female's cloaca is, by comparison, never so swollen. Structurally, the cloacal protuberance is not a penis.  The swollen cloaca is also not a cloacal phallus (an organ of ducks and ratities), which I wrote about in my 2 April 2010 post.

The cloaca is a chamber into which empty the digestive tract (the anus empties into the cloaca; the exit of the cloaca is called the vent), sexual ducts, and urinary tubes.  Cloaca comes from the Latin for sewer.  Male birds get the job done with a cloacal "kiss," with little or no penetration of the female. I will have more to write about cloacae (I assume cloacae is the plural of cloaca) in my next post.

Tail Tip Tales

The Black-capped Chickadees, as evidenced by my banding 12 recently fledged young, have fledged their first broods.  Many young birds look very similar to adults, and discerning the ages can be difficult.  One method of aging birds is by the ossification of their skulls.  Young birds have almost transparent "windows" in their skulls.  These windows become ossified and opaque as the bird ages. Observing the relative ossification of bird skulls, however, requires practice and experience.

Tail tips also give a clue to age.  Look at the tips of this recently fledged Black-capped Chickadee's tail. The tips of the tail feathers are pointed and unworn.  These are relatively new feathers, grown as the bird molted from its nestling feathers (juvenile) to its current basic (winter) plumage.

Compare the shape of those tail tips to those of an adult female Northern Cardinal.  The adult bird does not molt all its tail feathers at once--the molt into winter plumage takes weeks and does not occur until after the breeding season is finished.  Thus the adult feathers are squarish (not pointed like in the chickadee) and relatively worn.