Wednesday, January 30, 2013

Barn Owl

Although the Barn Owl is one of the most widespread of all owls and widely distributed of all land-birds (Marti et al. 2005), I never observed one in over 25 years in northeastern South Dakota. Occasionally I would get reports of these owls, but the birds invariably proved to be Great Horned Owls roosting in barns.

In the last century, despite often roosting in human-built structures, Barn Owls have declined in the upper Midwest. The species is now considered to be accidental in Minnesota. A number of factors have contributed to this situation.  First, grasslands, which the Barn Owls favor, have often been replaced by cropland or urban development. Second, you might think that a bird that roosts in barns and other out-buildings would not be in trouble--but these types of structures are slowly disappearing from the farmlands as barns collapse and large agribusinesses take over family farms.  Third, Barn Owls are often roadkill. In some areas, the building of major highways has caused the extinction of local Barn Owls.

I took this photograph of a young Barn Owl near Pierre, South Dakota. There Barn Owls are relatively common and can be seen if you know where to look. These young birds were in a burrow-nest in a cliff-side along the Missouri River. Near Pierre, I have also seen Barn Owls under local highway bridges and in structures on top of the Oahe Dam.  Where the owls are still common, populations depend on nesting sites (either human-made or natural) and high rodent populations.

Monday, January 28, 2013

Stripe-headed Sparrow

Stripe-headed Sparrows are common in the lowlands of southwestern Mexico south through Central America to Costa Rica. As you travel south, Stripe-headed Sparrows become larger and brighter. The song consists of "dry thin notes" and also a trill and a series of double notes. Flocks of family groups of up to 7 birds inhabit brushland (Wikipedia). This photo was taken when I was a teenager in Mexico in the 1960s.

Saturday, January 26, 2013

Lark Bunting

Some couples have "Their Song;" Erika and I have "Our Bird”—the Lark Bunting. An abundant bird, the sparrow is restricted to the American Great Plains grasslands. Erika and I first saw them when we met on a college camping trip across North Dakota and the Pacific Northwest. The photo was taken near Pierre, South Dakota. When we first moved to South Dakota, Lark Buntings could be seen in the Aberdeen area. After about a decade of relatively wet weather, however, these buntings appeared to retreat further west towards the Missouri River (as did Burrowing Owls).

Lark Buntings are unusual among sparrows in that males have a drab basic (winter) plumage and a bold alternate (breeding) one. During the winter in the southwest or northern Mexico, Lark Buntings are nomadic. In the spring, they slowly migrate north. Males arrive at breeding areas before females and establish compact territories. They nest on the ground, but the territories often include a plant to provide shade and from which they spiral up with stiff wing-beats while singing flight songs.

Thursday, January 24, 2013

Lava Gull

Although easy enough to see in the Galapagos Islands, Lava Gulls are among the rarest gulls. Population estimates run from 240 to 1200 birds. They are solitary nesters and lay their eggs near old lava flows on the islands. Presumably their gray plumage helps to conceal them while nesting. Like many gulls, they will eat almost anything from other species' eggs and nestlings, to fish and lizards (Wikipedia). As you can see in this photo of a gull hitching a ride between islands, Lava Gulls often associate with boats.

Although helped by the Galapagos Islands being an Ecuadorian National Park, Lava Gulls face a number of threats. They are occasionally caught on fishing hooks and fishermen have little love for these fish-eating birds. Also, like many Galapagos birds, they face threats from feral cats, rats, and dogs (BirdLife).

Tuesday, January 22, 2013

Spotted Towhee

Over the past couple of weeks, Jake Langeslag of Faribault enjoyed a Spotted Towhee at his bird feeder. Last week  Erika and I combined errands with a visit to the feeder. In a few minutes, the towhee obligingly made an appearance. I forgot to load the battery into my camera and took the photo above with Jake’s camera. I have previously posted about towhees. Both Spotted and Eastern Towhees stray north of their normal winter range and Spotted Towhees, which are western birds, are rare winter wanderers across the eastern United States.

Last spring, in the Canon River Wilderness Area of Rice County, I got excited when I found the Eastern Towhee in the lower photo—was it actually a Spotted Towhee? Sibley shows a white wing patch but not the white scapulars visible on my photo. The National Geographic Birds of North America, however, depicts the Eastern Towhee identical to my bird. One key to telling these two species apart is the spotted back of the Spotted Towhee.

Monday, January 21, 2013

Swallow-tailed Gull

Swallow-tailed Gulls breed in Ecuador's Galapagos Islands and Columbia's Malpela Island. After breeding, this gull migrates widely along the Humboldt Current, from Peru to Panama. This photo was taken in the Galapagos, where breeding pairs, like many of the island's birds, are remarkably tame.

They eat squid and fish. Unique among gulls is this species' nocturnal feeding. The hypothesis is that Swallow-tailed Gulls have been driven into the night by frigatebirds, that are infamous for harassing and stealing prey from gulls. For whatever the reasons for their love of night, the result is that Swallow-tailed Gulls' eyes are larger in size and volume than any other gull (The Pacific Wildlife Foundation). This gull lacks a melatonin rhythm.  At night, diurnal gulls have high melatonin levels, which make vertebrates sleepy. Wikipedia warns, however, that we do not know if this relative lack of melatonin is the cause or an effect of the Swallow-tailed Gull's nocturnal habits.

Saturday, January 19, 2013

Silver Gull

I once considered keeping a life list of birds seen at the movies or television. The rule was that the show could not be about the bird in question. The bird's appearance had to be unintended. One of the birds on my movie/tv list was a Silver Gull, one of the most common Australian gulls. One flew behind racing sloops at the America's Cup at Perth, Australia. The species earned a place on my regular life list when I found this gull as we both strolled on the promenade in front of the Sydney Opera.

This gull's age can be judged by the intensity of the red on their bills--the brighter the red, the older the bird (Wikipedia). I assume this bird is relatively young. Obviously this gull has adapted to urban environments. They scavenge and thus thrive at malls and garbage dumps. At least twice, Silver Gulls have been seen in North America (in New Jersey and New York) but these birds are assumed to be escapes from captivity. Normally the species is restricted to Australia and New Caledonia.

Thursday, January 17, 2013

Book Review: Dragonflies and Damselflies of Texas

The full title of this book is Dragonflies and Damselflies of Texas and the South-Central United States. This area includes Texas, Louisiana, Oklahoma, and New Mexico. Thus the book covers a huge region often visited by dragonfliers and birders.

This audience for this book is probably folks who are not rank beginners. The book includes color photographs of almost all the species. The photographs, however, are relatively small and do not have arrows or text pointing out salient field marks. Most disconcertingly, the photos only indicate the location where the photo was taken and does not direct the reader to the appropriate pages for species accounts in the text. The computer-enhanced illustrations in Abbotts' Damselflies of Texas are far superior. But the damselfly book does not cover dragonflies and is limited to Texas.

The text is well-written and organized. Unlike many other dragonfly books, keys to the species, genera, and families help the reader note the critical field marks of each species. The accounts include size, regional and general distribution, flight season, identification, similar species, habitat, a short discussion, and references. Clear maps, showing counties where each species has been found, accompany each account. One assumes some of the blank spaces are simply unstudied counties. Also illustrated are odonate backends (often critical for correct species identification).

The introduction is short, only 14 pages, but covers a great deal of information. Habitat and zoogeography are discussed and are important, since the range accounts often refer to the biotic provinces of the region. Odonate life history and seasonality are covered. A few paragraphs on photographing odonates conclude that you should bring with your equipment "a healthy dose of patience."  Finally the introduction presents detailed drawings of various aspects of anatomy.

The book ends with a checklist of species and an extensive bibliography. The bibliography is to be expected in a book directed at professionals needing to identify odonates.  Indeed, Abbott occasionally refers to "this study found," which indicates the origin of the book may have been a dissertation or other scholarly work. Nevertheless, one of Abbott's goals is to pass along "as much natural history and other biological information about each species as possible."

The book covers 263 species, making somewhat more manageable than Paulson's Dragonflies and Damselflies of the West, with its 348 species. The keys to the species make Dragonflies and Damselflies of Texas indispensable for the dragonfly enthusiast.

Tuesday, January 15, 2013

eBirdGM—Inserting Maps into eBird

This app is found on BirdVenture.  It enables you to embed Google Maps into your eBird lists. Go to BrdVenture to use the app. This would be helpful like when you see uncommon birds (like my very early Red Crossbills last summer in Dakota County) and you want to lead others to the location.

The directions from BirdVenture are simple:
  1. Go to Google Maps
  2. Zoom in on your precise location (or search for it)
  3. Right-click exactly at that spot, and select "What's Here?"
  4. Copy the Latitude-Longitude coordinates that appear in the search box
Then click the “Get Code” button and you should generate some code to paste into eBird.
Go to eBird.  Click on the Add Details button in your bird list.  Paste in the code that you copied from eBirdGM.  Save the file.  The map should appear on your list.

Sunday, January 13, 2013

Biographical eBird Map (eBird LifeMap)

This frigid, icy weekend my get-up-and-go got-up-and-went (to more or less quote from an American folk song), and I found myself bird-surfing the WEB. I stumbled upon the eBird LifeMap. This app converts your eBird data to a Google map, connecting your locations by date of observation with red lines. The result is a birding travel log. I will provide you with a link to this WEB site at the end of this post.

I assume you are familiar with eBird. Last year I entered almost all my bird records into eBird, beginning from 1960 when I was a 13-year-old. The records fall into three categories: life list records, miscellaneous birding lists, and current eBird submissions. The compilation of these 35,053 records can be seen in this first map.
Life-list records tend to give you the cleanest trip routes. But the routes are not always precise. Note the jags across the map of North Dakota. Erika and I drove staight across the state in 1968. I think what is happening here is that birds were seen on the same day but the computer has no way of knowing which species was seen first. A larger anomaly is the red line heading north out of the Galapagos Islands on the World map. You can only fly into the Galapagos from Ecuador. What happened here is that I left the islands, spent the night in Quito, and then returned home. The next new bird I saw was several months later in South Dakota. Thus a straight line exists between the Galapagos and South Dakota. The overall map, although not completely accurate, does give a satisfying representation of my birding career. A more practicable use for these maps might be to spot date or location errors in your eBird reporting.
The final map depicts my birding in the Minneapolis Metro Area. This map includes a year or so of almost daily eBird submissions (and no life birds). Clearly Northfield is my center of operations. The odd, comet-tail patterns at the top of the map are due to 20-years of commutes into the Twin Cites from South Dakota for birding and culture. Another possible cause of these patterns is that some of those early lists are of county birds rather than of specific locations. 
You can build your own eBird LifeMap by following the instructions at the Birdventures website.  This process is relatively simple but geared to the PC computer. Because I own a Mac, I had a bit of trouble. I e-mailed developer Zachary DeBruine for help, and was amazed by his prompt and patient responses. (You do not have to use all your eBird records. You could use, for example, the records from one summer’s travels and generate a map of those trips.)

The eBird LifeMap is not the only eBird mapping app available from Birdventures. In my next post I will review their eBird GM app that allows you to embed Google Maps directly into eBird files.

Friday, January 11, 2013

Baltimore vs. Bullock’s Orioles

While reviewing my blog, I am surprised how little I have had to say about Baltimore or Bullock’s orioles. These species are common across North America, with the Baltimore (above from Minnesota) breeding in the East, and the Bullock’s (below from Arizona) in the West. Across the Great Plains, where their ranges overlap, the two species interbreed—even though, as you can see in these photos, the two populations look quite different.  In 1983, citing this hybridization, ornithologists merged the two populations into a single species, the Northern Oriole.

Much to the delight of North American bird listers, the merge of the Baltimore and Bullock’s orioles only lasted a little over a decade.  During this time a number of discoveries were made. The zone of hybridization between the two species is relatively narrow, only some 150 to 200 miles wide. Hybrids are only very rarely found outside this zone and pure types are often observed, even in the zone’s center. Ornithologists concluded that, although lots of hybrids can be found within the stable hybrid zone, gene flow is restricted across the zone.  Perhaps hybrids are formed only where the appropriate mates are not easily encountered. Furthermore, because of the hybridization, ornithologists have always assumed the two species are closely related. To their surprise, a number of biochemical studies indicate Baltimore and Bullock’s orioles are not each other’s closest relative. Baltimore Orioles are more closely related to Altamira Orioles, while Bullock’s are closest to Streaked-backed Orioles (Rising and Flood 1998).

Wednesday, January 9, 2013

Pectoral Sandpiper

Like Least Sandpipers, Pectoral Sandpipers have yellowish legs. But Pectorals are much larger shorebirds than Leasts and are not as dark-backed. Identification, however, could be muddled by the large size difference between male and female Pectorals. Males are almost 30% larger than females. The sharp line of demarcation between the dark breast and white belly is is an excellent field mark.

Pectoral Sandpipers breed across the central and western Canadian Arctic tundra all the way into Siberia. They winter in southern South America, the Siberian populations migrating east or across the Great Circle route over the Arctic Ocean to the New World. These later routes result in distances of over 30,000 km, among the longest for any avian migrant. For her dissertation, Erika studied the trematode parasites of Pectoral Sandpipers as these shorebirds made their intercontinental migrations.

Male Pectoral Sandpipers are either polygynous or promiscuous. In any case, males court any female that lands within his territory and males often leave nesting areas before the young hatch. Males associate with females only long enough for courtship and copulation.

Pectoral Sandpipers are relatively common, but numbers are greatly reduced from the late 1800s, when they occurred in “enormous” numbers. Although this shorebird suffered from intense market hunting, habitat loss may also contribute to their decline. Much of the information in this post was gleaned from Holmes and Pitelka (1998).

Monday, January 7, 2013

Least Sandpiper

Least Sandpipers breed across northern North America from Alaska to Nova Scotia. They winter in the southern United States south through central South America. Although they are common migrants across most of the United States, eastern populations may make flights up to 4000 km over the Atlantic Ocean from New England to northern South America (Nebel and Cooper 2008).

This sandpiper is recognized by its small size, dark brown back, and yellowish or (as in this case) greenish legs. Most, if not all, other small New World sandpipers (peeps) have black legs. Observers should beware of much larger shorebirds that also sport yellowish legs, including Wilson’s Phalaropes, Pectoral Sandpipers, and, of course, the yellowlegs. Least Sandpipers foraging in mud may have their leg color hidden. This least Sandpiper was photographed near Aberdeen, South Dakota.

Saturday, January 5, 2013

Herring Gull

Erika and I had visions of finding rare gulls during our New Year’s Day drive to Prescott, Wisconsin. But we were able to hallucinate none, finding only Herring Gulls. Rarer gulls such as Thayer’s or Icelands would show little or no black on the underwing tips (see my January 2012 blog). Other species would show darker backs than the gray-backed individuals we observed.

Herring Gulls are perhaps the most common gulls in many parts of North America. Breeding from Alaska to New England, northern Minnesota, and the East Coast, the species winters widely across much of the United States and Central America. In the 1800s, Herring Gulls were almost driven to extinction by plume hunters and egg collectors. Thanks to protective laws, and the Herring Gull’s love of garbage dumps, by the 1960s, numbers fully recovered (Pierotti and Good 1994).

Thursday, January 3, 2013

Lesser Scaup

To jump start our 2013 birdlist, on New Year’s Day, Erika and I drove over to Prescott, Wisconsin, on the opposite shore from Dakota Co., Minnesota. We saw nothing unusual, but not for the lack of trying. Perhaps our “best” bird were these ducks, which I presume to be Lesser Scaup. In the first two photos of the same male, you can see that the head is not round, but somewhat crested—usually a fairly reliable field mark for Lesser Scaup. In the first photo, note that only the underwing over the secondary feathers is white. I think a Greater Scaup would have the white extending onto the primary feathers.
In my experience, Lesser Scaup are have duskier sides than Greaters. The third photo is of a female that hung close by the male. In all three photos, the black nail at the tip of the bill is small and relatively inconspicuous. I have previously discussed scaup identification problems in my blog last April. Lesser Scaup winter further north than Greaters, which prefer more open and salt water, and are usually encountered in the winter in coastal habitats (Sibley). Janssen considers the Lesser Scaup to be a winter straggler in Minnesota, but indicates the Lesser is more likely to be encountered in the winter than is the Greater. Unfortunately for my 2013 Minnesota bird list, these ducks swam well within Wisconsin waters.

Tuesday, January 1, 2013

Common Redpoll and 2012 Banding Report

Common Redpolls have discovered the banding station. We banded six in December and look forward to many more with the new year. Redpolls are an irruptive species whose abundance is tied to seed production by arctic trees like spruce and birch. When these seed crops fail, redpolls invade the northern United States.

During their first and second years, male and female Common Redpolls can not be told apart by plumage. Only after their second year do males become rosy-breasted--see my previous post for a photo of one of these older males.

With the New Year, I have updated my banding summaries for my Dundas and Northfield banding stations. To see this list, click on the appropriate tab at the top of this blog page. Basically 2012 saw similar banding results as in 2011. These results may be a bit deceptive, since, as stalwart readers of this blog are aware, Erika and I travelled during most of last March.