Monday, February 27, 2012

House Sparrow

Looking through my bird photographs, I was surprised I lack the ubiquitous female House Sparrow. Last summer I set about to remedy this situation, but I failed to obtain a good photo. The closest I got was this male, molting into Basic Plumage.

The plumages of juvenal male and female House Sparrows are similar as they leave their nests. But soon thereafter they begin a post-juvenal molt. As time progresses, their bibs, due to feather wear, become more extensive. The bib on the bird in the photograph indicates this House Sparrow is a first-year male.

House Sparrow numbers have been declining in North America. The Breeding Bird Survey indicates declines of almost 3% a year in most regions. One reason for this trend may be that House Sparrows thrived when we humans depended on horses to get around. (They fed on grain, both before and after it passed through livestock.) But with the advent of automobiles, the sparrows shifted to more rural environments. Lowther and Cink (2006) explain that "changes in farming practices in the 1960s--towards larger farms and greater degree of monoculture crops--have probably contributed to a general decline in continental populations of House Sparrows...." (I have previously posted an account of the introduction and subsequent evolution of House Sparrows.)

Saturday, February 25, 2012

Red-tailed Hawk

On Saturday, 11 February 2012, Erika and I discovered two Red-tailed Hawks bouncing through our back woods. They chased each other this was and that, dropping to the ground and flying into the trees. What was this behavior--courtship? Aggression? We are not sure. Courtship usually involves aerial maneuvers. Territories are defended, even during the winter, but, as you can see, our birds perched in close proximity. Usually aggressive interactions, which are rare in winter, also include aerial fights and attacks with wings and talons open (Preston and Beane 2009).

Thursday, February 23, 2012

Evening Grosbeak

After seeing these handsome birds in Montana, I blogged about Evening Grosbeaks in my post of 29 June 2011. This species also breeds in northeastern Minnesota, but is not seen every year. Winter bird feeders are the best places to look for them. Elsewhere in its range, Evening Grosbeaks, tied to Box Elder seed and Spruce Budworm abundance, tend to show a two year cycle.

The top photo of a female was taken this February during our recent trip to Sax-Zim Bog. The lower one was taken several years ago, near the bog. The ice on the bottom male's crown indicates that the winter the photograph was taken was more typically cold (-38 degrees F) than the abnormally warm winter of 2012.

Tuesday, February 21, 2012

Varied Thrush

The Varied Thrush is found along the west coast of North America from Alaska to southern California. Northern birds leap-frog over southern ones during migration, wintering further south than more southern breeders, which may be fairly sedentary. Every two to five years, populations irrupt, and Varied Thrushes occur in very low numbers across North America.

Erika and I drove over to a backyard in Hastings, Minnesota, on Sunday afternoon to see a Varied Thrush that has attracted a plethora of birders during the past few months. Remarkably tame, but difficult to photograph, the thrush roosted deep within the lower branches of a spruce. This location is somewhat consistent with the bird's breeding habitat--dark, wet northwest rainforests where it prefers old-growth and avoids fragmented tracts (Luke 2000).

Sunday, February 19, 2012

Snowy Owl

This winter witnessed one of the largest Snowy Owl invasions in recent memory. But seeing a Snowy took a whimsical road trip to Dodge County, Minnesota, on 17 February 2012 (thanks to a MOU listserv posting by Ken Vail), and eagle-eyed Erika to spot one. Snowy Owls prefer open country. Be wary of reports of Snowy Owls from forests--these owls may well be pale Canadian Great Horned Owls. I have seen Snowy Owls perch in small trees, but they prefer telephone poles or, like the one we found, on the ground in open fields.

The epicenter of this season's invasion seems to be the eastern Dakotas, but owls are also being reported from elsewhere in the Midwest (where they have reached Texas), the Pacific Northwest, and the northern Atlantic Coast (south to New Jersey and Pennsylvania). One Snowy Owl even made it to Hawaii! (Most of the data and the quote in this post are from an eBird article, interesting reading for anyone.)

When Erika and I lived in South Dakota, we could find a few Snowy Owls most winters. But larger invasions occurred more or less on seven-year cycles. Snowy Owl populations are dependent on Arctic lemmings. If a Snowy Owl does not see a lemming, the female does not even ovulate! Last summer was probably very productive for Snowy Owls in their Arctic breeding grounds. Lemming populations must have subsequently crashed, driving the owls south. The eBird folks speculate that, given the areas of winter concentration, "the source for these birds was presumably the central Arctic, or central-western Arctic. But without data from the breeding grounds, this connection is hard to make and even harder to prove." Few, if any, owls reaching the United States survive to return to their breeding grounds. Winter food sources are scarce here. Most owls are emaciated. The owls also suffer collisions with our abundant cars and power-lines. With fewer owls in the Arctic next season, lemming populations will rebound, and the cycle will renew.

Friday, February 17, 2012

Common Raven

Ravens, the largest of all passerines, is a common bird of northern Minnesota. It is amazing, however, how big crows can appear when you are searching for your first raven! Ravens differ from crows in their larger size and wedge-shaped tails. As you can see in the first photo, ravens' central tail feathers are longer than the outer ones. The calls of ravens differ from those of crows--crows say "caw, caw," while ravens give a guttural "wonk, wonk."

The omnivorous Common Raven, found in North America, Europe, Asia, and North Africa, is one of the most widespread birds in the world. Now accidental in the prairies of the Great Plains, they were also abundant there in the days of American Bison and wolves. Now Ravens are found in wilderness areas, and are now reestablishing itself in eastern forests and urban areas of the eastern United States. The first photo was taken in the Sax-Zim Bog of northern Minnesota; the second from St. Jon in western Arizona.
According to Boarman and Heinrich (1999), ravens are part of Native American folklore. Many peoples "revere ravens as being the creator of earth, moon, sun, and stars, but also regard it a trickster and cheater. Poets and authors of Western cultures have often used the raven to symbolize death, danger, and wisdom."

Wednesday, February 15, 2012

Gray Jay

Because Gray Jays are found across North America's northern forests, they were once known as Canada Jays. Their range, however, drops into northern New England, Wisconsin, Minnesota, the northern Rocky Mountains, and the Pacific Coast of the United States. Others name this jay Camp Robber, as the bird readily raids campsites for food scraps, even off picnic tables.

Gray Jays thrive in frigid northlands. They nest in late winter. Eggs are incubated at temperatures of -30 degrees C! They do not even attempt a second brood in the seemingly more benign weather in May. Instead they rely on hoarded cashes of food glued to the undersides of tree bark and lichens. The Gray Jay's salivary glands are enlarged, thus the bird has plenty of spit to use as glue!

In these years of climate warming, Gray Jay numbers are declining at the southern end of their range. Ornithologists speculate that this trend is caused by their food cashes thawing and rotting and, thus, not being available during their late winter breeding season (Strickland and Ouellet 2011).

Notice the white feather shafts on the Gray Jay's back in the bottom photograph. These streaks are present only in Gray Jays in British Columbia south to northern California. Until at least 1931, these birds were thought to be a separate species, the Oregon Jay. The photograph was taken at Crater Lake National Park in southern Oregon.

Monday, February 13, 2012

Pine Grosbeak

This weekend two friends and I spent the weekend searching northern Minnesota's Sax-Zim Bog. This wild area, northwest of Duluth, is named for two small towns and is famous among birders as a good location Northern Hawk Owls and Great Gray Owls. A host of other infrequently seen birds inhabit the area.

We first found Pine Grosbeaks. A photograph of the male is above, a female below. These are large finches with small heads. They breed across the coniferous forests of northern Canada, south into the Rocky Mountains of the United States. They are annual winter visitors to northern Minnesota, but some years they are more common than others. Only during exceptional winters are they seen in southern Minnesota. Annual numbers fluctuate less dramatically than do many other winter finches. In fact, western populations apparently do not fluctuate or migrate (Adkisson 1999). Pine Grosbeaks feed on many tree buds and are often found at bird feeders.

Friday, February 10, 2012

Little Blue Heron

The Little Blue Heron inhabits the southern United States and even wanders occasionally into southern Canada. This is a common, but often overlooked, heron. This species lacks the long plumes of other herons and egrets and, thus, populations were never decimated by the plume hunters of the 1800s.

Like the Reddish Egret, Little Blue Herons come in all-white and all-dark plumages. This dimorphism, however, is different. Little Blue Herons are unique among herons in that these plumages are correlated with the age of the bird. Young are white, older birds are dark. A white young bird molting into its dark adult plumage is sometimes called a Calico Heron.

The first photo was taken in the Corkscrew Swamp Sanctuary run by the Audubon Society. At any price, Corkscrew is a must-see location for birders visiting Florida--Audubon members are offered admission discounts. The young bird below was photographed in the Everglades National Park, another hotspot for birders.

Thursday, February 9, 2012

BirdsEye Bird Log

I discovered a wonderful Android App called BirdsEye Bird Log. The purpose of this app is to produce field checklists and submit them directly from your smart phone to eBird. The app appears to be both intuitive and easy to use.

The most awesome aspect of the app is the ability to enter your location. The Bird Log displays an eBird Google map showing public hotspots and previous personal locations. A tap of your finger, and your location is on your bird list. If you are at a new location, the map shows your exact location. One click enters the new location on to the list complete with location description. If the location description does not suit you, it is easily edited. You can even enter your location from a moving car, though I hope you are not driving at the same time!

Entering birds to the list is easy. As you start entering bird names, the app gives you a list of species choices. This process is even easier for folks who know bird banding alpha codes, as the app accepts these shortcuts. Numbers of individuals observed is also easy to enter. Click on the appropriate box and a numeric keypad appears.

Finally, entering appropriate eBird data is easy. Then click "submit" and your list is sent to eBird. If you need to edit the list, editing can later be done from your home computer.

The program can be found on the Android Market and costs $9.99. As far as apps go, this price is perhaps high. But proceeds support Cornell's eBird and further product development. I think it is worth every penny. Gone are the days of searching for pen and bird list. Also gone is wondering were the heck I am! Go to the market and just search for Birdseye. Be sure to read the product description. You can not use your android to search for birds on ebird. Not yet, but product development is heading in that direction.

Wednesday, February 8, 2012

Reddish Egret

Reddish Egrets are found along our Gulf Coast states. Nearly brought to extinction by plume hunters in the 1800s, this egret is still relatively uncommon. Only about 2000 pairs inhabit the United States (Lowther and Paul 2002). Others are found in Mexico and the Caribbean.

As you can see in these photos, this egret is dimorphic--it comes in dark and white morphs. Most birds in our country are dark, like in the first photo, taken in Lovers Key State Park on the Florida Gulf coast. Only rarely are white morphs found in the United States, like the one below from Ding Darling National Wildlife Refuge on Sanibel Island, Florida. Curiously, in the Bahamas and Greater Antilles, white birds are more common than dark ones. A couple of other of our egrets and herons display dark and white morphs. The reasons for these difference are not understood. Presumably the colors confer advantages to each type of bird under different environmental conditions.

In any event, as they feed, Reddish Egrets flamboyantly dance with their wings held out. Probably this behavior startles the small fish upon which they feed. Other herons hold out their wings, casting shadows that are attractive to small fish--something similar may be happening here. Finally, casting shadows may help the egret find minnows by reducing the sun's glare off the water.

Monday, February 6, 2012

Hybrid American Black Ducks

On Sunday, Gerry H. and I searched for Black Ducks along the Cannon River in Faribault, Minnesota. In the photo above, the bird in the background is a fairly typical female Mallard. The middle duck is likewise also a Mallard. The bird in front, however, has a dark bill with an olive tip,typical of the American Black Duck. On the other hand, its tail feathers are broadly edge white, as you would expect on a Mallard. I suspect this bird is a hybrid Mallard and Black Duck.

Ornithologists once predicted the demise of the American Black Duck due to hybridization, as Mallards expanded out of the Grteat Plains into the eastern range of the Black Duck. This expansion was the result of habitat change and game farm releases in the east. Recently, however, Black Duck populations have increased. The two species prefer breeding true. Nevertheless, about 13% of harvested ducks are hybrids. The situation is confounded in that the offspring of hybrids breeding with non-hybirds are often look identical to either Mallards or Black Ducks, depending on with which species the hybrid mates (Longcore et al. 2000).

As you can see in the bottom photograph, the facial pattern on these hybrids is also odd. I find nothing identical in any of my field guides. Note also the hen Wood Duck behind the hybrid. Wood Ducks do not usually winter in this part of Minnesota.

Saturday, February 4, 2012

Orchids

Residents and visitors to Saint Paul or Minneapolis, Minnesota, should not miss the Como Park Conservatory. This monster green house contains a myriad of tropical plants and occasional great exhibitions. Erika and I are fond of orchids. Although we can understand becoming passionately involved in orchid growing, we are not orchid growers. The photographs were taken during last weekend's St. Paul Winter Carnival's orchid show. I was not able to gather identifications of these flowers and welcome any input from my readers.
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Thursday, February 2, 2012

Eurasian Collared-Dove

Eurasian Collared-Doves are an invasive species sweeping across North America. Individual birds tend to exhibit long-distance dispersal. In North America, however, the situation is confused by multiple local releases.

Originally this species was found only in India and Myanmar. In the 1600s, they expanded, either naturally or with human assistance, to Turkey. The range expanded again through Asia, in the 1800s, and Europe in the 1900s. In the mid-1970s, 50 Eurasian Collared-Doves escaped and were purposefully released from a Bahamian bird dealer. To save doves from a volcanic eruption in 1976, others were released from the island of Guadeloupe in the West Indies. Soon afterwards, collared-doves appeared in south Florida. By the late 1980s, they were established in the southeast United States. Both by natural dispersal and with the help of many releases (both on purpose and accidental) by private dove breeders, collared-doves have spread across the continent.

Whatever the actual origin of North American populations, little or nothing can stop them now. You should look for them near human habitation. In the midwest, they often inhabit areas near grain storage areas. In more urban areas, they are attracted to bird feeders. Collared-Doves can even survive Canadian winters. Disease may cull some dense populations, but "it seems highly likely that the Eurasian Collared-Dove will become a widespread, permanent member of the North American avifauna" (Romagosa 2002).

The first photograph is this post is from Key West, Florida, in 2011. The second, taken several years ago, is part of a flock of 80 birds near a grain elevator and cattle feedlot in Fort Pierre, South Dakota.