Wednesday, February 27, 2013

Downy Woodpecker

This female Downy Woodpecker fed at our suet feeder. If you look closely, you may notice that this bird is banded on her left foot, so she is probably one of my local birds. I took this photo because the woodpecker, with her bill pointed skyward, seemed frozen at the feeder. I have noted this behavior when predators are nearby. Curiously this strategy is not mentioned in Jackson and Ouellet’s (2002) definitive account of this species.

As I write this post, I am surprised by this woodpecker’s white nape. Previously I posted rhapsodically on the beauty of female Downy Woodpeckers—compare the black nape on the nape of the woodpecker at this link with the white nape on the present bird. None of my field guides show woodpeckers from behind. Clearly my identification is correct, the bill of the bird on the present post is too small to belong to a Hairy Woodpecker (which my guides also show with a black nape).

Jackson and Ouellet’s (2002) list a number of hypotheses for the Downy’s plumage patterns. They do not mention the possibility that the two spots on the upper back may act as cryptic eye spots, making a predator think the woodpecker is facing it. To me, this Downy’s back looks a bit like a face. Another unmentioned possibility is that the white stripe down the back camouflages these small woodpeckers as they climb about snow-spattered trees.

P.S. I received the following comments from Jerry Jackson: "While working on my dissertation eons ago, I examined and measured about 6000 Downy Woodpeckers -- presumably about half of those were females.  There is considerable variation in the extent of white on the nape.  The complete band is relatively common and a characteristic that is also variable in Hairy Woodpeckers.  As an aside, in Hairy males, birds in eastern North America can have either a complete band of red or a red spot on each side of the nape.  In western North America, males seem to invariably have a solid red band across the nape -- and that band is wider (anterior-posterior) than in birds from the east. 

"I think your idea about the eyespots is on target.  I've been doing a lot of work with eyespots lately and certainly this was one of the first birds I had noted. The "freezing" and "sky-pointing" in response to the presence of a potential predator (or an alarm call given by another bird) is common. While I failed to mention it, I believe it is in the literature."

Monday, February 25, 2013

Scarlet Ibis

The top photo is of three Scarlet Ibis deep within the Caroni Swamp in Trinidad. The Scarlet Ibis is a perplexing species. Many ornithologists consider them to be only a color phase of the White Ibis. Interbreeding occurs in captivity, when captive individuals are released in each other’s range, and among wild birds in South America. Scarlet Ibis that are seen in Florida are often escaped from zoos or racetracks or the offspring of these escapees and wild White Ibis. In south Florida (where I took the lower photo of a White Ibis), if you are not careful when you look up, ibis can also be perplexing.

Saturday, February 23, 2013

Great Blue Heron

On this cold and snowy Minnesota day, I find myself dreaming about Florida. Audubon wrote that Florida birds were abundant and tame. Today the birds are less abundant, but they are often relatively tame—making Florida an an excellent photographic destination.

Great Blue Herons seem to have survived the onslaught of the 20th century despite plume hunters and widespread environmental degradation. One reason for their success is that heron rookeries are often located in areas that are difficult for predators to approach. They are also not picky eaters, preferring fish, but also consuming amphibians, rodents and other animals. Occasionally they even forage in fields, where unwary birders might mistake them for cranes.

Thursday, February 21, 2013

Black-billed Cuckoo

In an American folk songwe are told “the coo coo, she's a pretty bird...she never says coo-coo ‘till the fourth day July…” There may be some truth here—Black-billed Cuckoos time their nesting to correlate with caterpillar, particularly tent caterpillar, outbreaks. Cuckoos consume up to a dozen caterpillars per minute. Cuckoo stomachs often contain several hundred caterpillars, so many that the lining of their digestive tracts become coated with caterpillar spines. When the spines obstruct digestion, “the entire stomach lining is sloughed off and is regurgitated as a pellet” (Hughes 2001).
Black-billed Cuckoos declined during the 1900s, with severe drops in the 1980s and 1990s. Caterpillar outbreaks are now controlled with pesticides. These poisons are probably detrimental to both insects and birds. In any case, cuckoos are now rarely seen but singly. Older accounts report flocks of cuckoos “descending on caterpillar-laden trees and not departing until every insect was consumed” (Hughes 2001). These photos are from Rice County, Minnesota—the Black-billed Cuckoo from Dundas and the caterpillars from the Carleton Arboretum.

Tuesday, February 19, 2013

Piping Plover

Piping Plovers are "threatened and endangered" shorebirds. They breed along the northeastern Atlantic Coast and in the northern Great Plains and winter along the coast from the Carolinas to the Gulf Coast and West Indies. Censuses in 2001 found fewer than 3,000 breeding pairs (Elliott-Smith and Haig 2004). The species' survival depends on conservation management, including fencing off nests, restricting off-road vehicles on beaches and dunes, water-level management both above and below Great Plains dams, and predator control.

The first photo is of a winter-plumaged bird, probably a female, taken on Sanibel Island, Florida.  The second is of a male breeding bird taken near Aberdeen South Dakota. You could guess that the second bird is from the Great Plains, since, unlike Atlantic breeders, inland Piping Plovers have a complete neck band. The two populations are recognized as being of different subspecies.

Sunday, February 17, 2013

Chestnut-backed Chickadee

Chestnut-backed Chickadees are found along the west coasts of North America, from Alaska to southern California. Evolutionary studies suggest, although their crowns are black, they are closely related to Boreal Chickadees (Dahlsten et al. 2002). Although seeds and other plant materials are consumed, these chickadees specialize on insects and arthropods. They are particularly fond of insects on Douglas Firs. This photo was taken in Lacey, Washington.

Friday, February 15, 2013

Short-eared Owl

I flushed this Short-eared Owl along the shore of Sand Lake National Wildlife Refuge’s Mud Lake (in South Dakota). As the owl flew away, I noted the long wings that result in a bouncy, “butterfly-like” flight profile as seen in the second photo. Short-eared Owls hunt by day and in night. In North America, however, habitat loss has been attributed to declining numbers of this ground-nesting owl over the past several decades (Wiggins et al. 2006).
Short-eared Owls are widely distributed across the world. They even inhabit the Galapagos and Hawaii in the middle of the Pacific Ocean. In the United States, the species inhabits open country like grasslands and marshes. The owl’s numbers are controlled by vole and other mouse population dynamics—when voles are abundant, Short-eared Owls are often common. The last photo is of a bunch of tourists watching a Short-eared Owl in the Galapagos, where the owls hunt seabirds nesting in lava flows. (The relatively tame owl is in the lower right corner of the photograph).

Wednesday, February 13, 2013

Boreal Chickadee

After finding the Boreal Owl of the last post, Erika and I searched for Boreal Chickadees. These birds are restricted to the boreal forests of Canada and the northern-most United States (and, unlike the owl, not found south through the Rocky Mountains). Like other chickadees, the Boreal is territorial during the breeding season, but forms flocks when not breeding.

The species tends to be tame and will visit bird-feeders, such as within the Zak-Sim Bog in northern Minnesota, where we found this bird. During the winter, they consume seeds, fruits, and hibernating insects and/or their eggs and pupae. In the summer, they are opportunistic and omnivorous, seeking out insects and spiders, fruit and birch and conifer seeds (Ficken et al. 1996).

Monday, February 11, 2013

Boreal Owl

Boreal Owls inhabit spruce forests from Alaska and across Canada to the Atlantic. Scattered populations are also found in the Rocky Mountains, from the Pacific Northwest to northern New Mexico. The owls are also found across Siberia to northern Europe. In Minnesota, as in other areas of the United States, they are restricted to the far north.
They show irruptive cycles in Minnesota. They very rarely breed in the state, and then usually only after invasion years. These influxes appear to be caused by cycles in vole populations and or heavy snow cover. Females (which are the larger of the sexes) tend to wander further than do males. Males may remain in breeding territories to guard their nest-holes. Many Minnesota birders predicted a Boreal Owl invasion would occur this winter. All was quiet on state listservs until about three weeks ago, when dozens of owls began to be reported along Lake Superior north of Duluth.
Friday morning Erika and I slowly drove up the North Shore from Duluth to Two Harbors. Lake effect snow fell. We drove very slowly as we searched for owls. The problem was that, never having seen a Boreal Owl, we had a poor search image. We expected a bigger bird than a saw-whet owl, but, in fact, Boreals are only marginally larger birds. Some female saw-whets are as large as some small male Boreals. We also did not know where to look for them--deep within the spruces? On the tree tops? We saw nothing all the way up the lake, enjoyed lunch, and headed back towards Duluth. We were not optimistic.
We took a back road before coming out to the highway. We were warned in a listserv posting by local birder Sparky Stensaas "Note that looking for parked cars, birders, and photographers...is just as effective as looking for tiny owls!" At the highway, I looked right--nothing. I looked left, to see a line of about a half-dozen cars parked on the side of the highway. "Birders!" identified Erika, "I see scopes!" We pulled up and asked "Do you have an owl?" "Yes, right in front of us, at the tip of the closest spruce bough!" We photographed this bird for about ten minutes. The owl appeared to be actively searching for prey, as the bird repeatedly looked to the left and right.

Saturday, February 9, 2013

Pronghorn Antelope

Pronghorns are not true antelopes, but examples of convergent evolution, wherein unrelated animals evolve in response to similar habitats so as to resemble one another. Rather than being an antelope of the Old World, the Pronghorn is the only surviving member of the family Antilocapridae (Wikipedia). Pronghorns are found in the Great Plains of southern Canada south into northern Mexico. Pronghorns rarely seen in western Minnesota are likely to be wanderers from South Dakotan herds. This photo was taken north of Fort Pierre along the western shore of the Missouri River.

In our region, Pronghorns become more common the further west you travel. Your chances increase when you cross the Missouri River in South Dakota and you can usually see them by the time you cross into Wyoming. In the 1920s, presumably due to overhunting, Pronghorn populations declined to about 13,000. They have now rebounded to about a million, and, in fact, may outnumber people in Wyoming (Wikipedia). East River populations in South Dakota were decimated (and perhaps extirpated) by blizzards in the late 1800s and 1940s. The animals have been reintroduced to these regions, but suffer from competition from livestock, sheep diseases, and prairie fragmentation.

Thursday, February 7, 2013

Pileated Woodpecker

On Tuesday my fellow Northfield blogger Penelope posted and included a video about seeing a Pileated Woodpecker near her home in town. Low and behold, the next day a female Pileated landed at our far suet feeder. Thanks to Penny for sending the bird to our house! We’ve seen them there in previous years, but this was the first for this winter. Its appearance explains the continual, mysterious lack of suet at the feeder. 
I have previously posted about this woodpecker. For a photo of a male, see my post of 6 November 2010.  Note the male’s red forehead and red malar stripe, both of which are basically black in this female. On 5 November 2009, I posted a humorous gif of a Pileated doing damage to your’s truly, the Ace Bander. Finally, on 27  December 2010, I photographed a Pileated Woodpecker feeder on a natural food source, Hackberry tree berries.

Tuesday, February 5, 2013

Bell’s Vireo

Bell’s Vireos are found in the central Great Plains and the southwestern United States. Although rare and local in southeastern Minnesota (Eckert), these vireos are common in South Dakota along and west of the Missouri River. Throughout their range, Bell’s Vireos are indicative of healthy, brushy, riparian habitats with dense undergrowth. Unfortunately precisely this sort of habitat is often cleared in “beautification” areas in state parks and other areas. Bell’s Vireos are also heavily parasitized by cowbirds. California declared this vireo to be Endangered in 1986.

The Bell’s Vireo was discovered by Audubon, who named it after John Bell, a friend and companion on Audubon’s 1843 expedition to the Missouri River (Kus et al. 2010). This photograph was taken near Fort Pierre, South Dakota (along the Missouri River) after it was attracted by a tape of its call.

Sunday, February 3, 2013

Long-eared Owl

Long-eared Owls breed across much of northern North America, where they inhabit "open and sparesely forested habitats" (Marks et al. 1994). They nest in trees and use other species' abandoned nests. Less frequently they nest in tree cavities or on the ground. They can be difficult to locate, and thus their winter range is less precisely known, with some owls being resident and others wandering south into Mexico. Populations of these owls are known to fluctuate, depending on vole populations.

Although nesting in forested areas, Long-eared Owls hunt at night over open habitats. During the day they often roost communally, in flocks of two to 100. On my first weekend in South Dakota, I found a roost of a dozen at a state park near Aberdeen. Erika and I occasionally found Long-eared Owls in the conifers of our residential backyard in Aberdeen (although I never banded one). Another good place to look for this owl is in the cedar draws along the Missouri River. This adult and fledgling Long-eared Owl were in a nest in a small deciduous forest downstream from the Oahe Dam near Pierre, South Dakota.

Friday, February 1, 2013

Red Eft

Red Efts (sometimes called Red-spotted Newts) are salamanders that are found across much of eastern North America. This photo is from Pennsylvania, and I have seen them in the Boundary Waters Canoe Area of northeastern Minnesota. This species usually has three life stages—aquatic larvae, terrestrial juveniles (efts), and aquatic adults.  The efts lose their gills and usually remain on land for up to three years. In times of drought, efts can live, although not reproduce, “indefinetly,” while they await the return of rains (herpadventures).

The eft’s color ranges from red, brownish, or, as in this case, bright orange. Bright colors in animals often warn predators that the bright creature is poisonous.  In the case of the Red Eft, the skin secretes toxic substances. The bright spots are even retained by the aquatic adults, which otherwise become yellowish-green. Aquatic newts, therefore, are not consumed by fish and terrestrial efts may be avoided by jays and other birds. I do not believe this venom affects people, although, before rubbing your eyes, it might be a good idea to wash your hands after handing a Red Eft.