Saturday, April 30, 2016

White-throated Sparrow

White-throated Sparrows are abundant spring and fall transients through southern Minnesota. The following paragraphs are from my free, on-line ornithology course:

White-throated Sparrows winter in the southeastern US, breeding across Canada and parts of the northern United States. During early spring, birds store large amounts of fat as an energy source during migration. Reproductive development occurs during spring. Following June breeding, gonads regress and remain small until next spring. These events (fattening and gonad size increase) and migratory restlessness and orientation towards north or south are all affected by prolactin from the pituitary and corticosteroids from the Adrenal cortex.

A. H. Meier injected corticosteroids into White-throated Sparrows at time zero. Prolactin given at 12 hours results in: rise of fat stores, rise in gonad size, rise in migratory restlessness and a rise in locomotor activity towards north (= spring migrant). Prolactin given at 4 hours results in arise in fat stores, rise in migratory restlessness, no gonad increase, and an orientation to south (= fall migrant). Prolactin at 8 hours decreases fat stores, decreases locomotor activity, and decreases gonad weight (= winter bird).

This does not explain how the bird knows which way is north or South.

Friday, April 29, 2016

Yellow-headed Blackbird

John Holden and I photographed this Yellow-headed Blackbird at Dakota County’s 180th Street Marsh on 27 April 2016. Minnesota and Wisconsin are about as far east as this western species breeds. I have written about this species before, including in June 2014.

Males winter further north than do females. The males migrate one to two weeks before the females. The center of their wintering range is throughout the Mexican Central Plateau, but they are also abundant in the winter in southern Texas and New Mexico. Scattered winter records exist elsewhere, even in Minnesota. The species has been seen in Europe, though these vagrants may be escapes from captivity (Fraga 2016).

Thursday, April 28, 2016

Red-winged Blackbird

On 20 April 2016, one of the most curious birds that John Holden and I saw at Dakota County’s 180th Street Marsh was one of the most common. Red-winged Blackbird are abundant. Males sang atop many of the cattails. Among them was a female bird that was apparently defending territory.

Ornithologists are not sure if female Red-wings hold territories. Males are famously polygamous and females are aggressive towards each other. Some researchers maintain that females hold sub-territories within the male territory. But these sub-territories seem to overlap, and singing females do not usually drive away intruders. The status of a female within a male’s territory depends on several factors, including how long she has been mated and her distance from her nest (Yasukawa and Searcy 1995).

Tuesday, April 26, 2016

Tufted Titmouse

We found this titmouse at the Ray Roberts Lake State Park near Denton, Texas, on 17 March 2016. Tufted Titmice are abundant across most of eastern North America, but less so in the north. Their range, however, is expanding northward. This change may be due to global warming and/or increased use of bird feeders by birders.

The titmouse’s song, “peter-peter-peter-peter” is a dominant sound in most forested areas of the southeast. Titmice are a “nuclear species” in mixed flocks of forest birds. The other species follow the titmice, which often know where food supplies lie or where feeders exist.  Titmice also aggressively mob predators, thus alerting the other birds of danger (Ritchison et al. 2015).

Monday, April 25, 2016

Bleeding Heart

About 20 species of Dicentra, Bleeding Heart, a poppy, are found around the world. Cultivated Bleeding Heart originally grew in Asia. Now the plant is introduced around the world. A popular garden plant, Bleeding Hearts require minimal care. To keep them from taking over her garden, Erika must cut and weed these perennials. Ants disperse Bleeding Hearts. Ants collect lipids found on Bleeding Heart seeds. The arthropods take the seeds to their burrows, where ants eat the lipids, but do not damage the seeds. The plants also attract hummingbirds, which are their main pollinators.

Bleeding Hearts should be handled with care. They are poisonous, causing rashes in some people and sometimes killing cattle. Deer avoid Dicentra. No species of Dicentra should be ingested. Indigenous Bleeding Hearts were used by settlers and Native Peoples for the treatment of sprains, bruises, and insect bites. The plant is eaten, however, by some butterfly larvae, snails, and aphids (Softscholls.com; Buzzle).

Sunday, April 24, 2016

Large-flowered Bellwort

Large-flowered Bellwort are found across much of eastern North America, including almost all of Minnesota. Formerly classified as lilies, they are now placed in the closely related family Colchicaceae.

They are common in woodland areas, and are marching up the edge of Erika’s garden. Because we do not remember planting them, these bellworts may be wild volunteers. Other gardeners report that this species can remain dormant for many years, often reappearing after European Buckthorn is eradicated. According to a reader comment in Dave’s Garden website, “Roots, shoots and leaves were used for food by early settlers. In early medicine, it was used as a general stomach remedy, [and] a poultice for wounds and skin inflammations. A concoction from the roots was used for canker sores.”

Saturday, April 23, 2016

Blue-winged Teal

Also from Wednesday’s jaunt to Dakota County’s 180th Street Marsh was a close encounter with a Blue-winged Teal. Whenever I see drake Blue-wings, I am reminded of my seventh-grade teacher, John Trott, who introduced me to birds. He also sparked my interest in reading. He asked my parents if he could give me “The Big Sky,” a rather raunchy novel (at least for a 1960s grade-schooler) about fur trappers in the Dakotas. I never imagined a book could be so cool. In the book, our doomed hero falls in love with a Blackfoot woman with eyes the shape of the moons on a teal’s face.

For more information about Blue-winged Teal, see my post of 5 May 2012.

Friday, April 22, 2016

Vesper Sparrow

Two Wednesday’s ago, John Holden and I found a flock of about a half-dozen Vesper Sparrows. The birds fed along the roadside near Circle Lake here in Rice County. Vesper Sparrows are abundant field birds here in Northfield, and I have posted on the species in this blog. Field marks include the dark cheeks, which contrast with the white eye ring. Especially in flight, the white outer tail feathers are apparent. Not so evident in this photo is the Vesper Sparrow’s chestnut shoulder. Early ornithologists referred to the bird as the Bay-winged Sparrow.

Thursday, April 21, 2016

Pied-billed Grebe

On Wednesday, John Holden and I were lured to the 180th Street Marsh in nearby Dakota County. We were disappointed in the lack of diversity we discovered. But we enjoyed the few birds we did see, like this adult Pied-billed Grebe.

Pied-billed Grebes are opportunistic feeders. They prefer crayfish, but also consume other invertebrates, frogs, and fish. Most of this prey is taken by diving. Dives last about 12 seconds, as the grebe zig-zags after its submerged quarry.  Grebes also occasionally forage off the surface of aquatic vegetation (Muller and Storer 1999).

For more information on this species, see my 8 October 2010 post in this blog.

Wednesday, April 20, 2016

Lesser Scaup

One key to separating Lesser from Greater Scaup is their head shape. Greater Scaup have relatively round head profiles, while Lessers heads have taller hind crowns. Sibley writes, “differences in head shape are easily seen on sleeping birds…Scaup  are often more easily identified when sleeping than when awake.” No doubt that this Texas duck from last March is a Lesser Scaup.