Friday, December 30, 2011

Eastern Screech-Owl

This Eastern Screech-Owl basked in the sun on a very cold winter morning in Aberdeen, South Dakota. The photograph reminds me of Jubba the Hutt in the Star Wars movie. One criticism of George Lucas's science fiction films is that most of his creatures show Earth-like symmetry. Although an eel-like creature lurks here or there, his creatures usually have one head, two arms, and two legs. Because far-away galaxies undoubtedly support different genetic codes and evolutionary histories, their fauna will prove vastly, perhaps unimaginably, different from our own.

Wednesday, December 28, 2011

Great Horned Owl

Although large, Great Horned Owls can be surprisingly cryptic. This owl was on a nest in a relatively small tree, amazingly over a parking lot in the Everglades National Park in Florida. A park ranger pointed the bird out to me, and I showed it to others. I did not expect a nesting owl among the traffic and tourists.

Here in Minnesota, Great Horned Owls are early breeders. They begin to lay eggs by mid-February, with young hatching in April or May. Despite Minnesota's harsh weather, this early nesting allows hatching during peak rodent populations in the spring. I am not always happy to see these owls, as I am told that Great Horned Owls in Minnesota displace Barred Owls.

Sunday, December 25, 2011

White-faced Nunbird

Christmas Day has me thinking about birds named after the heiarchy of the Catholic Church--the first birds to come to mind are cardinals, Red Bishops, and Prothonotary Warblers; monklets and nunlets are out there too--and there are others. This White-faced Nunbird is found in Central and South America. This photo is from Ecuador. Nunbirds eat a variety of prey--insects and other arthropods, and even frogs and lizards, as well as various fruits. They dig nesting tunnels beneath the jungle floor. They are classified as puffbirds, a neotropical bird family. The Handbook of the Birds of the World classifies puffbirds in the order, Galbuliformes (which they share with another tropical family, jacamars), and considers them to be remotely related to woodpeckers, barbets, or motmots.

Wednesday, December 21, 2011

Townsend's Solitaire

On Tuesday, Erika and I read on the MOU listserv that a Townsend's Solitaire was discovered at the Carpenter Nature Center in Washington Co., Minnesota, along the St. Croix River just north of its confluence with the Mississippi. This thrush's range is normally in the mountains of western North America. Often their fall migration only involves moving to lower elevations in the winter. Other individuals may be sedentary. Canadian birds tend to migrate further than more southern ones. Nevertheless, some birds regularly winter across the dakotas and other plains states, where they often prefer cedar trees. Since the 1970s, Townsend's Solitaires have been seen in increasing numbers in Minnesota. The further east you travel, the more infrequent Solitaires become. The normal eastern limit of their wintering range is unclear (Bowen 1997).

Because these solitaires maintain winter territories, they are often relatively easy to see. They often perch high in cedars and give beautiful warbling songs (link with permission of Thayer Birding Software). These two photographs are of the same individual bird. The image below appears much browner than the gray one above, which looks much more typical. This variability, due to the soft December sunlight, is one reason identifying birds from photographs can sometimes be tricky.

Monday, December 19, 2011

Sharp-shinned Hawk

John H. and I censused this hawk during last Saturday's Christmas Bird Count. The hawk's small bill, uniform gray crown, lack of whitish on the nape, and relatively uniform length of tail feathers all point to Sharp-shinned Hawk. The bird tamely sat high in a tree in residential Northfield. As many of you know, the bird count began on Christmas Day 1900 by a group of Audubon Society members who thought they would count, rather than shoot, birds during the holidays. Counts are held across the country (and now the world) and comprise a 15 mile diameter around a central spot. Counts are managed through the Audubon Society and cost $5.00 for participants. More information, including locations of counts near you, can be found at http://birds.audubon.org/about-christmas-bird-count.

Friday, December 16, 2011

Free Advice from 50 years of Birding

I began birding in the fall of 1960. Do I have any advice for young birders? You betcha! Keep a detailed notebook with dates and precise locations of where you find birds. These days you might want to include numbers of individuals seen, in case you one day contribute records to eBird. Don't just include life birds or new birds for the year, but all the birds you see. I suggest a notebook like the
bound sketchbooks available at many art stores. After 50 years, you may be lucky enough to have equally-sized books across your bookshelf.

I do not have good records for those first birds I listed. At the time, checking the species off on the life list in my Peterson field guide seemed sufficient. Beginning in 1961, I have a date and location for each of my over 2,000 life birds. The one exception is from a month in Spain where I recorded the location of my new birds, but not the date. What was I thinking?? In any case, once I saw a bird, I did not record it again. Later I kept year lists, but without dates or locations. I now regret both practices. I wish checklists came with a place to check birds and a space for location.

For the last 20 years, I have kept daily diaries--either in daily calendar books or in those drawing books. These records vary in their usefulness. For example, if one day I drove from South Dakota to Minnesota, I seldom noted the exact location where I saw a particular species. EBird is going to change my laziness! Furthermore, eBird will also automatically update my county lists. Meanwhile, I am entering my old records into eBird (at least those records for which I have data). A final piece of advice--backup your eBird records onto your hard drive. There is no guarantee that eBird will last for the next 50 years!

Now if I can just remember when I photographed this wind-blown, female Northern Cardinal....

Wednesday, December 14, 2011

Western vs. Clark's Grebes

Western Grebes (the top photograph) are locally common in the summer in western Minnesota; Clark's Grebes are also found in the western part of the state, but are rare. (The ratio of the two species in the eastern Dakotas is about 100 Westerns to one Clark's.) I usually see several Western Grebes in Rice County, but, to date, never a Clark's. (These photographs were taken at Sand Lake National Wildlife Refuge in northeastern South Dakota.)

At least four field marks can be used to separate these two grebes. 1) The Clark's Grebe's bill is brighter yellow than the Western's. 2) The Clark's Grebe's eye is surrounded by white, the Western's is surrounded by black. 3) The Clark's Grebes flanks and back tend to be much paler than those of the Western. 4) Clark's Grebes' calls usually have one syllable, while Westerns have two notes. Be forewarned, however, that these grebes are variable in color and plumage, and some can be very difficult to identify. Furthermore, the two species occasionally interbreed, creating intermediate hybrids.

Until recently these two species were considered to be color morphs of a single species. Both grebes perform identical, complex courtship displays. So why are they now thought to be distinct? Western and Clark's Grebes prefer not to breed with each other. In the Dakotas, male Westerns apparently interbreed with Clark's only out of desperation late in the season after they are unable to find an appropriate female. Although DNA sequences are similar in the two species, the differences are of equal magnitude as other closely related species. The difference in the number call call notes is apparently critical in keeping Western and Clark's Grebes reproductively isolated (Storer and Nuechterlein 1992).

Monday, December 12, 2011

Mallard

The Mallard is the most abundant North American Duck. Despite being heavily hunted, Mallard populations remain relatively constant. This species' success "reflects its adaptability to varied habitats, its hardiness in cold climates, its catholic food tastes, and its tolerance of human activities" (Drilling et al. 2002). John H. and I found a large Mallard flock basking in the sun in a parking lot near Hastings, Minnesota.  Although the day was cold (below 20 degrees F), and a nearby pond was frozen over, open water flowed in the vicinity.

Saturday, December 10, 2011

American Tree Sparrow

Birding the other day in the snow and cold near Circle Lake in Rice County, I came upon a flock of about a dozen American Tree Sparrows. Having seen little else during the trip, I wondered how this hardy winter visitor survives the cold. Typically individual songbirds can withstand colder weather in the winter than they can in the summer. A zero degree day in July will kill them. Small birds can also increase their metabolic rates by breaking down internal organ weight. By these and other behaviors, our small winter residents are not usually challenged by Minnesota winters. 

Thursday, December 8, 2011

Gray-winged Trumpeter

In 1976, I took this Gray-winged Trumpeter photograph deep in the Ecuadorian jungle, south of the Napo River. I was doing bird surveys for a proposed national park. We were in an unnamed village of Waorani, an only recently contacted tribe. These people kept pet trumpeters as snake alarms. When Gray-winged Trumpeters discover snakes, the birds make a loud, distinctive, crane-like call given only in the presence of snakes. Other trumpeters join in the ruckus. Trumpeters will eat small snakes, but just alert the village to the presence of larger ones.

Trumpeters have proven almost impossible to breed in zoos. Even the Waorani raise their pets from wild-collected eggs. The young birds imprint on their human foster-parents and will call loudly when strangers approach, thus acting like a watch-dog. Most ornithologists agree that these ancient, grouse-like birds are not grouse or quail, but closely related to cranes and Limpkins (Handbook of Birds of the World, Vol. 3).

Wednesday, December 7, 2011

Bobolink

Most birds exhibit countershading. They are dark above and pale below. This pattern flattens their profiles and shades their pale underparts. The color of their surroundings may also reflect on the underparts, further camouflaging the birds. Predators find countershaded birds to be very hard to see. Then why do male Bobolinks show reverse countershading? Most likely this reversal makes Bobolinks highly visible to females in their grassland habitat. The advantages of being extremely visible to potential mates must outweigh the dangers of predators. Additionally, predators may follow males and miss seeing breeding females.

Monday, December 5, 2011

Northern vs. Loggerhead Shrike

Northern and Loggerhead Shrikes can be difficult for beginners to identify. Kim Eckert, in his A Birder's Guide to Minnesota, wisely writes, "a shrike in Minnesota May through September is 'always' a Loggerhead; a shrike November through February almost always a Northern." (Kim's guide is an excellent source for learning how to identify birds.) In this post, the first two photographs are first-year Northern Shrikes, the last, taken in Florida, is an adult Loggerhead.
One problem is that one really needs to be familiar with both species to easily identify them. Beginners are often misled by field guides that suggest that identification is easy, and, consequently, Northern Shrikes are sometimes misidentified as Loggerheads in the winter. Northern Shrikes are bigger than Loggerheads. Northerns have larger, more strongly hooked bills. Some of the less reliable marks mentioned in books include the Northern's narrower black mask that usually does not continue in front of their eye (or continue above the bill), and the Northern's more strongly barred underparts. Both these field marks can be difficult to see in the field. Note, for example, the Northern Shrike in the second photo in this post.
Northern Shrikes are uncommon but widespread winter visitors to Minnesota. Loggerheads are rare and local in the summer. Loggerhead Shrike populations across North America have seriously declined in recent decades. The reasons for this trend are unclear, but probably include widespread spraying of biocides, clearing farm trees and shrubs, and an unfortunate tendency to be hit by automobiles. Predation by house cats, competition with kestrels, and historic persecution by people add to the Loggerhead Shrike's woes (Yosef 1996).

Saturday, December 3, 2011

Blue-winged Teal

The Blue-winged Teal photograph above is one of my favorite photographs taken several years ago from a blind in Pierre, South Dakota. The teal below are from Rice County this spring (27 April 2011) when I was trying to photograph duck pairs. Blue-wing Teal are early migrants to Minnesota. They form pairs in the late winter or during spring migration. Nest failure can be over 90%--mostly due to mammalian predators. Blue-winged Teal numbers, however, depend on prairie wetland conditions. In dry years, populations fall. In wet years numbers can double (Rohwer et al. 2002).

Thursday, December 1, 2011

Gadwall

These two photos, both taken on Cannon Lake near Faribault, Minnesota (27 July 2008 above and 17 March 2009 below) just about cover Gadwall identification. In all plumages, their white wing patches are usually diagnostic--if you can see them. The gray-sided males show black under tail coverts. Erika calls them "Black-assed Ducks." In the first photos, the female, looking a lot like a small female Mallard, might be hard to identify. (Indeed, the duck in the upper left of the lower photo is a Mallard.)

Gadwalls are monogamous. Pairs form as early as November on their wintering grounds in the southern United States and the Mexican coast. Nesting in dense vegetation and often on islands, Gadwalls enjoy high reproductive success. As with many other ducks, pairs break up during incubation, when males join molting flocks. After incubation, the females rear their young in larger lakes. The young are independent ten weeks after hatching (Leschack et. al 1997).