Wednesday, April 28, 2010

Long-billed Curlew

Like other birders and banders, I haven't been seeing much for the past week.  I have banded no birds for the past three days. Perhaps we are being fooled by our lovely April weather.  The migrants, however, seem to know better than to return to Minnesota before May.  I checked my records from last year and found that banding did not pick up until the first of May. The plant store assures us that the average last frost for the Twin Cities is in mid-May!

So I find my thoughts drifting to Long-billed Curlews.  When we taught outdoor education classes, we introduced our students to predictive morphology.  By knowing the shape of a bird's bill, you might be able to predict its feeding habits.  The longer the bill, especially among shorebirds, the deeper it should probe.  The Long-billed Curlew does, indeed, probe deeply in the ocean mudflats where it winters.
But what does it do with that bill where it breeds in dry Mid-West?  From my reading, I do not think too much is known about their summer food habits.  My colleague Doug Backlund of South Dakota discovered that Long-billed Curlews insert their bills down wolf spider burrows in search of juicy arachnids.  Here is a link to an interesting website that Doug made (http://pie.midco.net/dougback/curlew.htm).  I also read that Long-billed Curlews use their bills to flip cow pies in order to expose  invertebrate prey!
For that matter, what do sleeping Long-billed Curlews do with all that bill?  Above is a curlew, sound asleep, balanced on one leg.  Its bill is nestled in there somewhere!  Both photos are from Morro Bay, California.

The probing and cow pie information is from: Dugger, Bruce D. and Katie M. Dugger. 2002. Long-billed Curlew (Numenius americanus), 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/628

Friday, April 23, 2010

Dwarf Trout Lilly


The last glacier stopped about 10,000 years ago just west of Northfield.  During this stressful time, a population of White Trout Lilies, Erythronium albidum (right photo), mutated into the Dwarf Trout Lily, Erythronium propullans (left photo). Dwarf Trout Lilies no longer reproduce sexually.  Instead they spout from single underground stems.  Their flowers are smaller (dime-sized) and usually fewer petaled (4-5 pedals vs. 6 on the White Trout Lily). 

If you want to see a Dwarf Trout Lily, the flowers are obviously much smaller than those of the much more common White Trout Lily.  If you are in doubt, the plant is probably the White Trout Lily.  The plant is a rare and endangered species, found only in Rice, Goodhue, and Steele counties of Minnesota.  These photos were taken in Nerstrand Big Woods State Park near Northfield.

Why don't more plants and animals give up sex?  Sex sounds like a pain in the neck.  You have to brush your teeth, comb your hair, get flowers at the florist, be relatively civil.  Some suggest that sex is more fun, but few have tried asexual reproduction, so I'm not sure how they could know for sure.  Evolutionary biologists suggest that sex creates more genetic variation, the stuff that evolution works on, and so sexually reproducing populations have the potential to evolve quickly and successfully.

See also http://www.fws.gov/midwest/endangered/plants/dwarftro.html
files.dnr.state.mn.us/natural_resources/ets/dwarf_trout_lily.pdf

Spotted Sandpiper

Most of my female friends rolled their eyes when I told them about bright male White-throated Sparrows' propensity for promiscuity and about male bluebirds taking on extra mates.  In case you were beginning to think that males are only good for collecting multiple mates,  consider the Spotted Sandpiper.

Pairs of Solitary Sandpipers court, and males will chase after females.  Females also fight over males.  Females often begin building nests, although often the males finish the job. After the females lay their eggs, males suffer a ten-fold decrease in testosterone levels, and have high levels of proclatin.  These hormones leave the males in a domestic mood, and they brood the eggs until the young hatch and are on their own. (Females will occasionally lay their eggs in other Spotted Sandpiper's nests, the young of these nests being raised by unrelated males.)

Upon laying their eggs, the females usually mate with a second male, and abandon their first mates.  If the females help with incubating, brooding, or nest guarding at all, it is with her second mate.  Occasionally females take on a third mate, abandoning the second.  One result of all these multiple matings is that, unlike in more traditional birds, few males lack a brood.  Furthermore, the sex ratio often gets skewed so that many populations of Spotted Sandpipers have more males than females.

I am not sure what is up with the Spotted Sandpiper "yawn" in the photo above.  Perhaps more likely it is regurgitating arthropod exoskeletons from its gullet.  Females, however, do perform a choking display when courting males. (I did not, however, see any other nearby Spotted Sandpipers when I took this photo at Sand Lake National Wildlife Refuge in South Dakota.)

My source for this blog entry is: Oring, Lewis W., Elizabeth M. Gray and J. Michael Reed. 1997. Spotted Sandpiper (Actitis macularius), 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/289

Tuesday, April 20, 2010

Zygodactyle Toes

When I wrote my recent post on Brown Creeper toes, I was surprised I did not have a decent photo of zygodactyle woodpecker toes (two toes forward, two toes back).  I have been on the lookout for woodpecker toes ever since.  Today, 19 April, I banded this Red-bellied Woodpecker and got a toe photo, as well as a demonstration that the Red-bellied Woodpecker does, indeed, have a red belly.
I also retrapped two Song Sparrows today.  One was banded on 5 April 2010, and the other on 8 April 2008.

Monday, April 19, 2010

Eastern Bluebird Eggs

Today, 19 April 2010, we found our first Eastern Bluebird eggs of the season: one nest with two eggs, and a second one with seven.
My bluebird box-building friends tell me they often have best success when they place two houses in close proximity, separating these by at least 1000 feet from the next houses.  J.H., however, has enjoyed success by placing single boxes near telephone wires. 

At an AOU (American Ornithologists' Union) meeting in Seattle I heard about a study that showed male Eastern Bluebirds with access to more than two boxes were able to attract more than one female.  As nesting locations were at a premium, the female bluebirds had better success raising young if they were attached to a wealthy real estate magnate, even if they had to share his attentions with other females.  When a male's territory was plastered with nesting boxes, however, the females began bickering with each other and, consequently, their nesting success dropped.  Apparently there are limits to polygamy, even among wealthy bluebirds!

Saturday, April 17, 2010

Field Sparrow

For the past two years, I have banded birds at two locations--my home in Northfield at the edge of a city park, and a large tract of land along the Cannon River near Dundas.  The second site includes a large fen-like wetland.
Each spring and summer at the Dundas site, I have heard many Field Sparrows singing from all the open areas near my nets.  Yesterday I finally banded the elusive Field Sparrow, my 94th species banded at both banding stations.  In 2008 and 2009, I banded 3135 individual birds at the two sites.  I am finding interesting differences between the two sites, differences that I will share with you as my study and my blogging continue.

Wednesday, April 14, 2010

White-throated Sparrows

I  enjoy blogging because I am learning new things about birds as I write.  I always knew that White-throated Sparrows come in bright and dusky morphs (the photo above is of a bright bird, the one below is a dusky one).  You might be tempted to say that the bright birds are males and the dusky ones are females, but the only way to tell the sexes apart is by wing length or, in the breeding season, by cloacal condition.

Researchers have found that each morph usually breeds with its opposite type (dull males mate with bright females and visa versa).  The two morphs have different chromosome arrangements.  Compared with dull males, bright males are more aggressive, more territorial, and more "apt to seek matings outside the pair bond." Dusky females, on the other hand, provide more parental care than bright females. No other bird, even those with distinct morphs, share such complicated genetic, plumage, and behavioral differences.
These photos were taken last year at the University of Minnesota Landscape Arboretum.  My source for the information is: Falls, J. B. and J. G. Kopachena. 1994. White-throated Sparrow (Zonotrichia albicollis), 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/128
These photos are from this year's banding, with a bright bird on the left, and a dusky one on the right.  Finally, on a light note, White-throated Sparrows in the United States sing "Poor Sam Peabody, Peabody, Peabody" but, upon entering Canada, sing "Oh sweet Canada, Canada, Canada!" W.S. writes, "I thought the Minnesota White-throated Sparrows, in contrast to the New England birds, sing, 'Poor Sven, Peterson, Peterson, Peterson.'"

Tuesday, April 13, 2010

Ruby-crowned Kinglet


Lots of Ruby-crowned Kinglets in our woods this morning.  They can be identified by their small size, the nervous flicking their wings while they forage, and, in the spring, a loud, high, musical warble of clear notes--but probably not by the males' ruby crowns (which, as you can see, are usually hidden).

This winter I liked the white background in the bird portraits I took in front of snow drifts.  This is my first photo using a white foam mat for background.  Perhaps I've lost something by not having a natural background, but I am still impressed with the photo.  I will keep trying this spring.  I am disappointed not to have captured a reflection in the kinglet's eye, despite my having used the camera's flash.

Sunday, April 11, 2010

Brown Creeper Toes

Brown Creepers are common but easily overlooked Minnesota birds.  I have banded 18 of them since the end of March. Because they are drab and poke around tree trunks, Erika refers to them as tree lice.  Sibley calls them "tree huggers." They are woodpecker wannabes; they have stiff woodpecker-like tails, but their toes are like songbirds--three toes forward, one back.  DNA studies suggest creepers are most closely related to nuthatches and gnatcatchers.
On the other hand, woodpeckers, like the Pileated, have two toes forward and two toes back (see the lower toes on the next photograph.) If you want to impress your significant other, you can tell him/her that songbird toes are anisodactyl, whereas woodpeckers are zygodactyl.
Exceptions among the woodpeckers are the Three-toed and Black-backed woodpeckers.  They have three toes (two forward, one back).  Curiously, despite this morphological difference, these two woodpeckers have recently been lumped into the same genus as Hairy and Downy Woodpeckers, which have typical woodpecker toes. Note the toes of this Black-backed Woodpecker.
I think it is a bit unkind for Erika to say that Brown Creepers are Tree Lice.  Brown Creepers actually have lovely, chestnut and white-speckled rumps (seldom seem except when the creeper is in hand.)

Friday, April 9, 2010

Black-capped Chickadee Nest

For the past few days, a pair of Black-capped Chickadees have been flying in and out of a hole in a relatively small ash tree.  Chickadees used this same cavity last year.  This year, as I took photographs, I was pleased to note that at least one of the pair is banded--not too surprising, since the nest is within several feet of my bird net.
As I watched, the chickadees entered the hole and, within a few seconds, emerged carrying what appears to be chunks of rotten wood.  The bird in this photo is splattered with tiny wood chips.
Both chickadees carried away the rotten wood as they flew from the nest.  I assume this activity represents April "house" cleaning in preparation for the 2010 breeding season.  I am somewhat surprised that the birds did not choose a more vertical nest entrance.  Surely this upward-facing hole must get wet during storms!

Monday, April 5, 2010

Hepatica and Song Sparrow

Hepatica exploded through the leaf litter.  Many other spring ephemorals, if not actually flowering, are spouting.  They were joined by a Song Sparrow at the banding station;  I have been hearing their cheerful calls for a few days.  Other birds banded include Ruby-crowned Kinglet and Yellow-rumped Warbler.  Spring is at hand.

Saturday, April 3, 2010

Tenacious Bloodroot

Today a tenacious Bloodroot poked out of the stone edging of our front walk.  The third of April seems inordinately early for this spring wildflower to appear--even more striking, since the flower emerged from stones covering plastic lining.  How do Bloodroot propagate?  Did a seed germinate above the plastic lining?  Or did a long dormant root punch its way out from below?  In either case, I imagine yesterday's record-setting warmth was magnified by both pebbles and plastic.

S. H. replies: This is from a wikipedia article, not necessarily the most accurate source, but interesting anyhow. Bloodroot is one of many plants whose seeds are spread by ants, a process called myrmecochory. The seeds have a fleshy organ called an elaiosome that attracts ants. The ants take the seeds to their nest, where they eat the elaiosomes, and put the seeds in their nest debris, where they are protected until they germinate. They also get the added bonus of growing in a medium made richer by the ant nest debris.

Friday, April 2, 2010

Mallard Copulation

Last year a Mallard pair used our water feature in the early spring.  The pair retired elsewhere to nest (or at least went their separate ways) later in the summer.  Today, an early April evening, we were delighted when a pair strolled up our brick entryway, copulated, and fed in the water.

If you look closely at this male's vent, you might notice a pink, slightly curly structure.  Since I have assisted Federal duck banders, I was aware that ducks and ratities (flightless birds like ostriches and emus) are the only birds with penises. (All other birds get the job done with a cloacal "kiss," with little or no penetration.) Tonight I discovered that I am mistaken, instead of a true penis, ducks and ratites  have an erectile cloacal phallus.  Sperm are deposited in the male duck's cloaca and travel down the outside of the phallus.  In mammals, of course, sperm travel through the penis's interior in the urethra.  Thus the two structures are not homologous.

You learn something new every day; in this case from Cornell Laboratory's Handbook of Bird Biology.