Wednesday, October 31, 2012

Green Heron

Here are a few Green Heron photos I found filed in various folders in my computer. The first, taken last May, is from Lake Byllesby in Dakota County; the second is from the University of Minnesota Landscape Arboretum; the third is from the Old Highway 77 Bridge near MSP Airport. The last two photos were taken several years ago.
Green Herons are among the few birds that use tools. They occasionally make fishing lures! They lay bait to attract fish—bread crumbs, mayflies, worms, pieces of sticks, and even feathers. Baiting works best for adults and birds that use live bait (Davis and Kuslan 1994). When not fishing with bait, Green Herons are opportunistic feeders. The previously cited authors list dozens of prey species, ranging from insects, spiders, amphibians and fish. Fish, however, are favored. The authors conclude, "Will exploit a superabundant resource, e.g., grasshoppers in California...and frogs in New York.” Add to that statement, frogs in Minnesota!

Monday, October 29, 2012

White-eyed Vireo

Due to their tangled, brushy habitat, White-eyed Vireos, like the one in the top photo from the Aransas National Wildlife Refuge in Florida, are often easier to hear than to see. Although their songs are complex and variable, if you know the call, this vireo can be easily recognized (call used with permission of Thayer Birding Software). The bottom photo is of a White-eyed Vireo in the Black Hills of South Dakota. The White-eyed Vireo is rare anywhere in the state, and this photo was the first record of the species in far western South Dakota.

Even where they are common, populations of White-eyed Vireos depend on dense scrublands. A problem is that such habitat is rarely protected. These vireos are also heavily parasitized by cowbirds. Almost half of all vireo nests contain cowbird eggs and, when they do, the young White-eyed Vireos do not survive (Hopp et al. 1995).

Saturday, October 27, 2012

Sharp-tailed Grouse

Once found across much of central and northern North America, Sharp-tailed Grouse were formerly more common in northern Minnesota and across South Dakota. They prefer grasslands and mixed-shrub habitats, and now depend also on croplands. Despite their decline, these grouse are still hunted. This decline continues despite some stabilization from grasslands planted through the Conservation Reserve Program.

Like many grouse, the Sharp-tailed dances at leks, where a few males dance and father most of the upcoming generation. The males, however, take no part in further parenting duties. The dances are spectacular and were the inspiration for many Native American pow-wow dances (Connelly et al. 1998). This photo was taken several years ago in western South Dakota.

Thursday, October 25, 2012

White-tailed Ptarmigan

The smallest North American grouse is the White-tailed Ptarmigan. This bird inhabits alpine areas at or above treeline from western Alaska and western Canada south through Rocky Mountain peaks to Colorado and New Mexico. Ptarmigans exhibit a host of cold-weather adaptations. They are white in the winter and brown in the summer, thereby matching the ground color. This May bird in Colorado is blotchy, going into its brown summer plumage. Ptarmigan flocks roost in snowbanks, which remain around freezing even when the weather outside is far colder. Ptarmigan are also famous for their feathered, snowshoe-like toes. When predators (or birders) approach, rather than flying, ptarmigan tend to crouch, walk away or even hide under rocks. I only found this ptarmigan by hearing it and knowing the bird must be nearby.

Tuesday, October 23, 2012

Greater Sage-Grouse

I enjoyed a short, but glorious, career as an ecotour guide. Unfortunately I never figured out how to charge enough money to come home with any cash in my pocket. On one trip my clients and I enjoyed a charmed tour of South Dakota's Black Hills. One of our target birds was North America's largest grouse, the Greater Sage-Grouse.

I assured my clients that seeing sage-grouse required knowing the precise location of leks and having the grouse as your only goal. Leks are sites where males perform a strutting display to impress females. Often only a few of the best dancers will breed with most of the females. Males take no further part in raising the young (Schroeder et al. 1999).

Not an hour later, as we drove north through Wyoming grasslands, I was asked, "What were THOSE birds?" Along the roadside grazed over a dozen sage-grouse. This grouse favors sagebrush prairies of western North America. I once picked up sage-grouse guano and found that the guano smells like sage. Because of loss of habitat due to cultivation, burning, overgrazing and eradication of sagebush, sage-grouse populations have drastically declined.

Because of differences in size, behavior, genetics, and plumage, the Gunnison Sage-Grouse is now considered to be a distinct species. Unlike the relatively wide-ranging Greater Sage-Grouse, the Gunnison grouse is only found in restricted areas of Colorado and Utah.

Sunday, October 21, 2012

Northern and Wattled Jaçana

Jaçanas are fascinating. They are a pan-tropical bird family (found in most of the world's tropical areas). The c-cedillia in the spelling of jaçana is usually replaced with a c in English. The c-cedillia also appears in the French words garçon and façade. The point here is that jaçana should be pronounced with a soft c. Jaçanas are also called Lily-trotters or Jesus Birds. These names derive from the Jaçanas' ability to seemingly walk on water--their long toes allow them to walk on waterlilies and other floating aquatic vegetation.

Two species of jaçana inhabit the New World. The Northern Jaçana is found from northern Mexico south to Panama. In the 1960s, I took the top photo near Acapulco, Mexico. The bottom photo is of a Wattled Jaçana from Pucallpa, Peru. This species is found from Panama through much of tropical South America. When I took these photos, the two birds were thought to be one species. Hybrids were reported from Panama, where the two populations overlap. Individuals formerly thought to be hybrids, however, prove to be immature Wattled Jaçanas. Thus I added two birds to my lifelist without revisiting the tropics.

Jaçanas once bred in south Texas, but now only occasional juveniles are found there. I am not sure why the breeding birds have retreated to Mexico. Jaçanas have odd breeding behavior. One female may breed simultaneously with up to four males. The males attend to all the "home" duties (nest building, incubating, and raising the young). Females defend territories (that include the males' nests) against other females and intruders. In order for this polyandry to occur, the females must have rich territories. In poorer territories, the males are spaced further apart, and thus their nests are harder for the females to defend; the females then tend to take on fewer mates (Jenni and Mace 1999).

Friday, October 19, 2012

Cinnamon and Blue-winged Teal

I took this photograph of a male Cinnamon Teal (in the foreground) and male Blue-winged Teal (in the background) at the Santa Ana Refuge in south Texas this March. Genetic studies suggest that these two ducks "evolved recently and rapidly" (Gammonley 2012). They are so closely related that these two species often hybridize. The actual frequency of this interbreeding is unknown, since only male hybrids are easily recognizable, the females being quite similar. Cinnamon Teal breed in western North America and are also found through South America. Blue-winged Teal breed across northern and central North America.

Tuesday, October 16, 2012

Blue Jay

In 2010 I blogged about how adult Blue Jays have black linings to the inside of their upper mandibles. Since that post, I have not caught many jays, but I have kept my eye out for a young jay. Finally this October I met with success. Note the whitish color inside the upper bill--one mark of a young Blue Jay.

Monday, October 15, 2012

American Robin


These two photos are of young American Robins that I banded this fall. The top bird seems to be in odd plumage, with its chestnut eye ring, supercilliary stripe, and throat. Normally robins look more like the bottom robin, with a white eye ring and throat. A cursory review of my field guides and banding references fails to come up with an explanation for the chestnut bird.

Even more curious has been the relative lack of robins at my banding stations in Northfield. This spring (April through June) I only banded 7 robins. In July and August I banded none--no adults, no speckled fledglings! September and October has welcomed a plethora of migrating thrushes, with 55 robins banded so far.

I can not explain this summer's lack of robins. According the the University of Wisconsin, however, robins are West Nile Virus' "Super Spreader." University researchers conclude that robins are "more important to the spread of West Nile in the Northeast and Midwest than any other host." This year's West Nile Virus season has been intense. Scientific American suggests that West Nile Virus is responsible for the leveling off of once-growing robin populations. Perhaps our local robins were adversely affected.

Saturday, October 13, 2012

Chuck-will's Widow

A breeding bird of the southeastern United States, the Chuck-will's Widow has been expanding its range north and west. The Oahe Dam, upstream from Pierre, South Dakota, must be about as far north and west as this species can be found. Chuck-will's Widows were first found breeding on the ground in a large grove of cottonwoods in 2000. For the next several years, if birders knew exactly where to search, they were often successful. This nocturnal bird was also found in the same area for several years in the 1980s, but nesting was not confirmed (Tallman et al. 2002).

This species is most active at dawn and dusk. Chuck-will's Widows (and nighthawks) are goatsuckers. Folk traditions often believed mistakenly that these birds suck goat's milk. Although primarily insectivorous, Chuck-will's Widows do occasionally take small birds, bats, and frogs (Straight and Cooper 2012). They usually feed while flying low to the ground or under street lights. Their name derives from their call (thanks to Thayer Birding Software for permission to use this file).

Friday, October 12, 2012

Common Nighthawk

Nighthawk numbers are falling. The birds are considered to be imperiled in most of New England. Declines of about 50% are reported from Canada, where the species is listed as Threatened. Pesticides and habitat destruction are the most likely causes. Another factor may be that architects no longer favor flat gravel city roofs. Nighthawks often nest on such roofs, as well as on the ground on gravel beaches, outcrops, and burned-over woodlands. A nest is not made, the eggs being laid directly on the ground (Brigham et al. 2011). These authors further comment that the name nighthawk is "inappropriate...because it is most active at dawn and dusk, not night, and...not related to the hawks."

This photo was taken several years ago near Pierre, South Dakota. Although I was on the lookout in Minnesota, and although birders in the state reported seeing many nighthawks, I did not seen a Common Nighthawk this year.

Wednesday, October 10, 2012

Double-crested Cormorant

The often maligned Double-crested Cormorant is, never-the-less, a handsome bird. The photo was taken several years ago at Sand Lake National Wildlife Refuge in northeastern South Dakota. All four toes are webbed, making the cormorants systematically allied (at least traditionally) with the pelicans in the order Pelicaniformes.

Cormorants are often accused of taking excessive numbers of gamefish. Add to that accusation great increases in cormorant numbers, and you have the ingredients for political (i.e. state's rights) debates. Cormorants are opportunistic feeders--they take whatever fish are most abundant and easily caught. These fish are rarely top of the food chain species prized by fishermen. Only when gamefish are stocked and abundant do they constitute a large percentage of a cormorant's diet. Although cormorants are protected species and their economic affects on fisheries are not precisely known, permits have been issued in a few states to cull their numbers (Hatch and Weselch 1999).

Tuesday, October 9, 2012

White-winged Dove

Erika took this White-winged Dove's photo near Fort Hood, Texas. Before the 1980s, this species ranged only as far north as southern regions of Texas, New Mexico, Arizona and California. Since then, it has spread north, with breeding birds found in Oklahoma. Now vagrants are seen almost annually by birders in Minnesota and the Dakotas. The reasons for this expansion include increasing agriculture and the planting of ornamental trees across the Great Plains (Schwertner et al. 2002).

Monday, October 8, 2012

Lincoln's Sparrow

Ornithologists consider the Lincoln's Sparrow to be one the the most elusive of North American birds (Ammon 1995). This bird nesst in boggy willow swamps of the far North. During migration and winter, Lincoln's Sparrows skulk through brush piles, like this one in the Carleton College Upper Arboretum. I have previously blogged about this sparrow, which can be recognized by the fine stripes on its tan-washed breast.

Saturday, October 6, 2012

Patriotic Mockingbird

I have a few photographs left over from my series of blog posts I shared with you from last March's road-trip across the western United States. The first is a patriotic Northern Mockingbird singing atop a flag pole at the The Flower Fields of Carlsbad, California. Farnsworth et al. (2011) write that both sexes of mockingbirds sing. Repertoire's often contain over 150 song types. This repertoire changes and increases as the bird ages. Mockingbirds mimic other birds, non-avian species and even mechanical sounds. I have heard mockingbirds in Washington, DC, imitate trains, complete with whistles and high-pitched squeals. Why so much mimicry? Mockingbirds defend territory against multiple species. A large repertoire may also communicate fit genes. Such a playlist may also indicate the knowledge and fitness that often accompany old age.

Note on the upper right column of this blog, my dragonfly book is offered at a 20% discount until 23 October 2012. Click the book graphic. Enter the word "FANS" when you checkout of the Blurb site.

Friday, October 5, 2012

Hermit Thrush

October has brought Hermit Thrushes to the banding station. These thrushes are common migrants in our area, one of the first to appear in the spring and a relatively late in the fall. I have previously blogged on the species. One reason for this migration pattern is that this species is our only small thrush that spends the winter in the United States (although some go as far south as Central America). A few even attempt to winter in southern Minnesota. Fruits and arthropods comprise its diet.

Wednesday, October 3, 2012

Book Review: Bird Watcher's Bible




This fascinating book is aimed at beginning to intermediate birders. It would make a great holiday gift for a young person just beginning to show interest in birds. While not quite the "complete treasury" of "science, know-how, beauty, and lore" as hubristically noted on the cover, the book does present a competent, well-written, and entertaining introduction to birding. 

The color photographs in this book will inspire would-be birders to take to the field. Two especially caught my eye. A Black Skimmer, in silhouette only, leaving a trail of splashing water behind its elongated lower mandible, is exquisite. Another stunner is a close-up of a Peregrine Falcon carrying a still-alive Willet. 

The book is edited by Jonathan Alderfer and contains seven chapters written by several authors. The paragraphs that follow give an extremely brief and non-comprehensive review of some of what is covered in these chapters.

Chapter 1, "The Anatomy of a Bird," by Kimball Garrett, gives a superficial discussion of avian anatomy and physiology. For example, two bird skeletons are illustrated but none of the bones are labeled. The book is full of odd lists. The list in this chapter is the completely subjective "Top 12 birds with the Best Plumage." How can you limit the world's most beautiful birds to 12?

Chapter 2, "Birds through the Ages," is by Catherine Herbert Howell. She takes us from ancient Egypt and aboriginal America to the mid-1900s. Along the way we meet such subjects as a pet Starling that mimicked Mozart's music and a pigeon that won a medal in World War Two.

Chapter 3, "The Life of A Bird," is by Kimball Garrett and discusses avian development and ecology. Included in this chapter are descriptions of the "top 10 amazing bird nests." Courtship and eggs are also discussed, as are birds that have adapted to the human landscape.

Chapter 4, "Science Discovers the Bird," also by Catherine Howell, talks about paleontology, banding and tracking, and human commercial use of birds. Another of those lists names the top 10 most common bird blogs. My blog is not listed (sniff). Art as science is an odd discussion that takes the reader through Peterson but omits any living bird artist. This book includes an abundance of antique bird illustrations. A few of these golden-oldies are fine, but such numbers supplant space that could have been used to showcase more modern artists. Finally a few current avian studies are recounted in "Breaking News."

Chapter 5 is called "To be a Birder." Curiously the author is not cited. Two pages are devoted to National Geographic's Birds of North America. Had this really been a birder's Bible, other current field guides would have also been highlighted. Optics and birding hotspots are described. A sort of out of place chart of bird body parts is also included here.

Chapter 6, by Scott Weidensaul, briefly discusses the mechanics of flight and migration. You can read about flyways, weather and fallouts, as well as banding and telemetry. As you might guess, there is a list of the "top 10 long-distance migration champs."

Chapter 7, again without author citation is about attracting birds. Beginning birders will learn about "food and feeder basics," bird houses (complete with a martin house design), attracting hummingbirds and bluebirds, and even a list of the "top 10 birds that live in bird houses." Water features are mentioned, followed by pages on landscaping in the Northeast, Southeast, Northwest, Southwest, but not in the Midwest.  The Chapter includes a discussion of Citizen Science.

Finally comes Scott Weidensaul's "Birdographies."  This list is relatively poorly illustrated and includes a paragraph about each of Scott's favorite birds. The book ends with a short list of further reading. I'll end this review by asking my readers to guess the 10 top-grossing films about birds.  Hint: The Big Year is not among them. The answer is in yet another list in this book.

Tuesday, October 2, 2012

Black Meadowhawk

On Monday, Scott King alerted us that Black Meadowhawks were flying at Lake Byllesby Regional Park in Dakota County. Erika and I met Scott at the park. "This meadowhawk is a northern species," explained Scott, "and is only rarely found this far south." He guessed that these dragonflies already bred further north and were pushed south by drought and October winds. Lake Byllesby provides the spring-fed ponds this species prefers, but, as you can see in the lower photo, not necessarily a safe haven. We witnessed a Leopard Frog leap into the air and narrowly miss a passing Black Meadowhawk.

The first of these photos shows a male Black Meadowhawk, the second a female. This species normally ranges from Alaska to eastern Canada. It drops south through the Rocky Mountains and also into northern Minnesota, Wisconsin and New England.  It is also found all across northern Eurasia (Paulson 2011)Mead (2003) cautions that, although large migrations of Black Meadowhawk have occurred off the coast of Ireland, such movements are unreported from North America.

Monday, October 1, 2012

Philadelphia Vireo

This last week I banded a single Philadelphia Vireo. I have previously posted about separating Philadelphia and Warbling vireos. Moskoff and Robinson (2011) suggest that Philadelphia Vireos are also often confused with Red-eyed Vireos, both due to similar plumage and calls.

An ecological rule states that no two species can occupy the same niche, which is to say they can't exploit the same habitat in the same way. Philadelphia and Red-eyed Vireos come close to breaking that law. Philadelphia Vireos actively defend their territories against Red-eyes--in dense populations the two species may actually fight each other.  Philadelphia Vireos may avoid competition by utilizing areas not exploited by Red-eyes. The Philadelphia Vireo, although usually an inhabitant for younger forests, often forages higher in old-growth forests than does its competitor (Moskoff and Robinson 2011).