Friday, September 23, 2016

Rainbow Bluet

On 24 June 2016, I walked around Carleton College’s Lyman Lakes. By accident, I discovered a pair of Rainbow Bluets, one of the more striking damselflies. I noticed them on the side of a Yellow Water-Lily. I took the photo think it would be a pretty photo of ordinary, unidentifiable bluets. I checked the photo focus out on my camera screen, I immediately knew these were a male and female Rainbow Bluet in tandem. The male clasps the back of the female’s neck to guard her from competing males.
In the first photo I noticed another species of bluet behind the lily stem. This damselfly turns out to be a Stream Bluet. Too bad its head is hidden. Male Stream Bluets have one of the terminal abdomen segments entirely blue, They have only thin, blue bands across the abdomen, which is mostly black.  Unlike similar bluets, the thorax is blue with black stripes (DuBois). Stream Bluets are one of the most common damselflies across their range.

Thursday, September 22, 2016

Coral Hairstreak

This spring, I found a Coral Hairstreak in the Koester Prairie (Prairie Creek Wildlife Management Area). This grassland is fairly pristine. Males perch and wait for females. Their eggs overwinter. Adults feed on a variety of flowers. Caterpillars consume Wild Cherry, plum, chokecherry and Butterfly Weed. The species is found across much of North America.

Tuesday, September 20, 2016

Black Saddlebags


Black Saddlebags are most often seen flying high overhead. This summer I have found two perched. The first was at Carleton College’s Lyman Lakes. The second was along the Cannon Valley Trail. The latter forayed out and repeatedly returned to a solitary, high twig. I was ready on one of its returns. Note that it has its legs down, but has not quite landed. Paulson writes that Black Saddlebags are highly migratory. They appear in the north in summer, and their young return south in the fall.

Monday, September 19, 2016

Ring-necked Pheasant

I took this Ring-necked Pheasant photo on 29 April 2016. I was in Rice County, near a game-bird farm. This species often escapes captivity. To survive, pheasants need dense winter cover and diverse farming practices. Agriculture with large monocultures and clean farming practices do not tend to support pheasants. Early mowing takes out many pheasant nests (Giudice and Ratti 2001).

Sunday, September 18, 2016

Cobra Clubtail


Cobra Clubtails are identified by their broad, black-topped tail tips. The second to last yellow spots at the end of their abdomens is smaller than the last one. Finally, the dorsal side of their addoments have small, yellow spots, making the tails look relatively dark. 

Each of the five years that I have been paying attention to dragonflies has been different. Until this year, I rarely found Cobra Clubtails. This year they seemed to be everywhere, even in Erika’s garden. This abundance seems a bit odd to me. My reference guides all report that Cobra Clubtails are usually seen near rapid streams. Such habitat is in short supply here in Rice County.

Saturday, September 17, 2016

Book Sale

All formats of my dragonfly book are on sale through 21 September 2016. Use code VIP20. eBooks are already inexpensive at $9.99 before the sale. The more expensive traditional formats also qualify for the sale. Check it out at http://www.blurb.com/b/6845664-dancing-dragonflies-and-damselflies

Friday, September 16, 2016

Bobolink

Bobolinks are blackbirds.  They breed across the northern United States and southern Canada and winter in Bolivia, Paraguay and Argentina. They make an annual round-trip of about over 12420 miles. Renfrew et al. (2015) report a ten-year old, banded male that “presumably made this trip annually, a total distance equal to traveling 5 times around the earth at the equator!”

Bobolink numbers have decreased during the last 50 years. Factors contributing to this decline include hayland mowing, grazing, shooting and trapping (especially in their wintering and migratory ranges), and pesticides. Bobolinks are, nevertheless, relatively easy to find in Minnesota in the summer. These birds were in the Prairie Creek Wildlife Management Area—Koester Prairie Unit on 14 May 2016. I have blogged about Bobolinks in several previous posts, including in December 2011.

Thursday, September 15, 2016

Common Yellowthroat


Common Yellowthroats love marshes and weedy fields. Adult males are easy to identify. Females and young males are much more difficult. Usually these drab birds show some brown on the crown and yellowish-green tails.

I believe the first photo is of a female bird. It strongly responded when Erika and I made spishing sounds in the Carleton College arboretum on 2 August. The bird appeared to be defending a breeding territory.

I discovered the yellowthroats in the second photo on 16 August at the Dennison Sewage Treatment facility. These two birds are much brighter yellow and appear to show small black flecks on their faces. These field marks add up to immature males.

Common Yellowthroats are common across most of North America, south into Mexico. They were one of the first American species described by European ornithologists. Because of their wide, but somewhat fragmented range, many races of yellowthroats have been recognized. As their genetics are studied, some may prove to be distinct species.

Wednesday, September 14, 2016

Review: The Second Nebraska Breeding Bird Atlas

The Second Nebraska Breeding Bird Atlas. Wayne J. Mollhoff. Bulletin of the University of Nebraska State Museum. Volume 29. 2016. $30.00 softbound.

This book gives the results of Nebraska’s second breeding bird survey. The first census was conducted in 1989. This book, a 30-year update, is essential reading for anyone remotely interested in Nebraska’s breeding birds. The book consists of accounts, one page for each species, for each of the state’s 225 breeding bird species.

A 29-page introduction describes the methods used for the two atlas projects. Nebraska’s ecology and climate are also covered. A short discussion of changes of breeding bird distribution concludes this introduction. Finally, there is a page or two on how to interpret the species accounts.

Each account consists of a short description of the status of each species. These paragraphs include habitat and distributional notes. Comments are included on population trends, along with data from Breeding Bird Surveys. Two charts follow, one describing habitat use and the other, patch size.

Aside from the perennial problem of the variability of identification abilities by observers, two weaknesses stand out. First, patch size is the estimated size of the habitat in which birds were found breeding. Mollhoff admits that patch size is an odd concept. Reporters differ in their ability to estimate patch sizes. Often observers did not report patch sizes. The other “weakness” is that many more observers participated in the second survey. The result is that one does not know if population increases are the result of actual increases or an artifact of having more observers. To his credit, Mollhoff points out this problem where it occurs.

Each account concludes with two distribution maps, one for the first Atlas, the other for the current survey. These maps are invariably fascinating. They allow the reader quick access to distributions and to geographical trends. The blocks with breeding birds are indicated by a red dot. The result is a flat representation of occurrence, but not a display of relative abundance.

The book ends with 10 appendices. These statistically compare the two atlas surveys and present county-by-county analyses. Atlas blocks are described, species at risk are listed, and potential additional species are discussed. Finally Mollhoff presents acknowledgments, references, and a checklist of Nebraska’s breeding birds.

Tuesday, September 13, 2016

Turkey Vulture

On 24 August 2016, John Holden and I drove by two large, black birds. I declared them to be young Turkey Vultures. These vultures begin life covered by fuzzy, white down. A bit of this fuzz remains around the back of this bird’s head and ear. For several months, young have black heads. In the fall, the head begins to turn pinkish. Adult coloration is attained late in their second year.

Turkey Vultures accumulate pesticides in their tissues They are shot or trapped, either accidentally or on purpose. They may succumb to lead poisoning eating animals that have been shot. Like this bird, vultures often scavenge for roadkill along highways. This behavior makes them liable to collisions with automobiles or to electrocution from power lines. Turkey Vultures are the number one cause of damage and fatalities in military aircraft bird strikes. Despite all these perils, these vultures are tolerant of humans and adaptable in diet and nesting sites. Populations are thought to be stable or increasing (Kirk and Mossman 1998).