Sunday, January 25, 2015

Semipalmated Plover

Cleaning up unpublished posts for last year’s blogs, I came upon this photo of two Semipalmated Plovers. These shorebirds are common but, as you will notice, they are sometimes hard to see. This cryptic nature and the birds’ tendency to migrate in more dispersed flocks than other shorebirds, make estimating global populations difficult (Nol and Blanken 1999).

Unlike some other shorebirds, Semipalmated Plovers are monogamous and both male and female care of their eggs and precocial young. The species breeds from Alaska across Arctic Canada. They winter from our southern and eastern coasts all the way to the tips of Argentina and Chile. A few are even encountered within continental South America.

This photo was taken on 13 May 2014 in Rice County, Minnesota. I have previously blogged on this species.

Friday, January 23, 2015

Guira Cuckoo

The Guira Cuckoo inhabits savannas and pastures of southern Brazil, eastern Bolivia and northern Argentina. These cuckoos are found in flocks of up to 20 individuals. The species is generally common and, with deforestation, has been expanding its range. They  eat arthropods, frogs, lizards, and snakes as well as the juvenal birds and bird eggs.

Guria Cuckoos are thought to be closely related to anis. Molecular studies of cuckoo systematics, however, leave ornithologists somewhat at a loss. Cuckoos appear to have no close living relatives among other bird families (Handbook of Birds of the World—Alive).

Wednesday, January 21, 2015

Pine Grosbeak

Over the weekend, aside from these Pine Grosbeaks, Erika and I saw very few birds in northern Minnesota’s Zax-Sim Bog, usually an excellent place to list a variety of otherwise hard to find species.

Pine Grosbeaks breed across Canada, south through the Rocky Mountains. Typically unwary, three female grosbeaks fed on roadside berry bushes and on gravel in the middle of our snowy road. These grosbeaks irrupt into the eastern United States, but less frequently than other winter finches, and seldom reach as far south. Rocky Mountain populations do not wander more than a few miles from their breeding habitat (Adkisson 1999).

Although Pine Grosbeaks might be expected, during exceptional flights, to reach southern Minnesota, Erika and I have not seen them in Northfield. We have seen them previously in the bog, and, over the years, I have banded a few in Aberdeen, South Dakota.

Monday, January 19, 2015

Common Eider (Pacific)

On Friday, Erika and I finally drove up to Duluth, Minnesota, to search for the Common Eider that has been seen since 10 November 2014. The bird was within a large flock of Mallards, Black Ducks, and even a few Pintails. Despite its different-shaped bill and pale color, the bird could be difficult to spot among the other ducks. (When first reported, there were two individual eiders in the area, representing the first winter records for the species in St. Louis County.)

Last November I posted a photo of one of the Atlantic races of the Common Eider and concluded, as have most observers, that the Duluth bird is a Pacific race. The distance between the eye and the back extensions of the bill is much greater in the Duluth bird than in the Atlantic one (fide Ken Able). The extensions are more pointed in the Duluth bird. Finally, the Duluth bird is much paler brown. Sibley suggests that birds of the western Arctic are so distinct from other Common Eiders that they “seem to be good candidates for splitting."

One may be surprised that an inhabitant of the north Pacific would show up on Lake Superior. Perhaps not coincidently, a huge low-pressure storm, the most intense ever reported in the region, blew up the Pacific and into the Bering Sea and Alaska. Barometric pressure reached near record lows and winds approaching 100 mph. The low pressure area spun clockwise, bringing warm weather to Alaska, but pulling frigid Arctic air into the continental United States, including Minnesota (Accuweather.com). This weather system may also be responsible for pushing Pacific Common Eiders to our region (fide Peder Svingen and Matt Dufort).

Friday, January 16, 2015

Limber Honeysuckle

This Limber Honeysuckle flower was photographed during one of Erika and my summer cycling trips in Rice County, Minnesota. The leaves are opposite and the uppermost pair are perfoliate. The plant grows in open woods and woodland edges. It will develop red berries.  The flowers attract hummingbirds and bumblebees.

Native American uses for Limber Honeysuckle included as a cathartic, menstrual difficulties, kidney stones, diuretic, flu drug, emetic drug, and variously as a love or anti-love potion (wildflower.org). The hollow stems were also used as straws and in pipes.

Tuesday, January 13, 2015

Red-shouldered Hawk

On Tuesday, the Red-shouldered Hawk reappeared at our Dundas, Minnesota, banding site. The raptor had been absent since 19 November. Of course, it is a guess that this individual is the same as the previous bird. If it is the same, then its bloody breast feathers are nicely cleaned. Another interesting difference is that the small birds at the bird feeders, and especially the Blue Jays, repeatedly mobbed the hawk. The jays sometimes struck the hawk’s back.
In November the small birds paid little attention to the hawk. We assumed that the hawk’s preference for small mammals made it little threat. Perhaps the hawk’s diet has shifted during this long, cold winter. Several hypotheses exist for why small birds mob predators.  Mobbing alerts nearby birds of the nearby predator. The hawk probably has trouble keying in on a single mobber, thus there may be safety in numbers. Mobbing may also drive a dangerous predator away. The Red-shouldered Hawk was clearly bothered by the jays. Note, in the center photo, the hawk peering skyward, watching for the jays. Finally the hawk flew off southward.

Sunday, January 11, 2015

Roadside Hawk

Roadside Hawks are quite common from eastern Mexico south to northern Argentina. Often they are the most common hawk in their range. Ornithologists have described at least eleven races of this species. The photograph, taken in northern Argentina, appears to be Rupornis magnirostris saturatus, which is found from Bolivia through north-central Argentina.

The Handbook of Birds—Alive describes Roadside Hawks as being “very catholic” in their prey selection. These hawks take almost anything, mainly insects, reptiles, birds and small mammals. They are known to follow army ant swarms and eat insects trying to flee from the ants. They also hunt along the edges of grass fires, where they occasionally get singed. On the other hand, they are occasionally eaten by boa constrictors!

Thursday, January 8, 2015

Why Are Grebe Eyes Red?

This Eared Grebe certainly sports bright red eyes. The photo was taken of a breeding bird at Sand Lake National Wildlife Refuge many years ago.

Why are loon and many grebe eyes red? I remember reading in one of my loon books that, because red is filtered out of water after a depth of 15 feet, the eye would be indistinct to prey. This camouflage may be important, if prey key on eyes of predators. Many creatures make use of an opposite phenomenon—butterflies and moths, for example, often show eye spot patterns on their wings, thus dissuading potential predators, who in turn, do not wish to become prey themselves.

One problem with this hypothesis is that young loons and most young grebes have dark eyes. Other grebes do not even have red eyes, as is the case with many other diving waterfowl. Perhaps red eyes are used to attract mates. That sort of answer is a stock fall-back reply to unanswerable evolutionary questions. A third alternative is that red eyes allow divers to see more clearly under water. The answer many be a combination of all three hypotheses.

Tuesday, January 6, 2015

Snow Bunting

Yesterday, I drove John Holden to see the Snowy Owls photographed in the last two posts. The morning was gorgeous but, at -10 degrees Fahrenheit and with a wind chill probably around -20, temperatures were unpleasant. The good news is that we had no problem finding one; the bad news was, to our surprise, the owl was perched on the ground right next to the road and quickly flew.

Twice during the morning we happened upon large flocks of Snow Buntings. We wondered how the buntings handled extreme weather. These Snow Buntings voraciously consumed weed seeds. The species roosts in open areas in small impressions in the snow. When temperatures drop below 20 degrees F, they block the wind by perching behind snowdrifts. They are not known, however, to huddle in tight-knit groups. During blizzards, buntings get covered with snow and, during extreme conditions (like when temperatures drop below -30 degrees), they burrow into the snow (Montgomerie and Lyon 2011).

Sunday, January 4, 2015

Snowy Owl 2

Yesterday I took Erika to see the New Year’s Day Snowy Owl. I believe this individual is not the same bird we saw on Thursday—the back and breast seem to be definitely heavier barred. Nevertheless, both individuals appear to be males (see previous post). Although somewhat closer to the road than the first bird, both were in the same quarter-section. This photo is also greatly enlarged.