Treefrog in the Garden

This tree-frog in Erika’s rose bush is may be a Gray Treefrog. The problem is that Gary Treefrogs can not be told from Cope’s Treefrogs, except by call.  But even the call is similar. The Gray’s call is slower than the Cope’s. This one was silent. Grays also have twice the chromosomes as Cope’s—no help here. Both species venture into urban areas.

Gray Treefrogs spend the winter partially frozen under leaf litter.  This frog’s liver coverts glycogen into glycerol, which prevents ice formation in their tissues. Some of their organs can also tolerate ice crystals. Some tropical treefrogs are among the most poisonous of animals. Skin secretions from Gray Treefrogs can be very painful if you get the secretions in your eyes, nose, or open sores (Savannah River Ecology Lab).

Swainson’s Hawk

A poor photo of a good bird in Rice County—a Swainson’s Hawk. This individual was first reported by Gerry Hoesktra, who saw it on several occasions this summer. After several previous searches, John Holden and I finally found it on Wednesday. It flew from telephone wires next to the road to a perch high in a distant oak. 

Over the years, I have seen a few in the county. This raptor is western, breeding in the Great Plains, from southern Canada to northern Mexico. Western Minnesota is normally as far east as this species breeds. Swainson’s Hawks winter in Argentina.  They form flocks during migration, a flight over 10,000 km each direction. An incredible 845,000 individuals have been censused during the fall migration over Veracruz, Mexico (Bechard et al. 2010). Although Swainson’s Hawks eat mammals, birds, and reptiles, perhaps one reason for these seasonal movements is their fondness for grasshoppers, dragonflies, and caterpillars—all abundant in the Great Plains and the Argentine pampas.

Review: Birds of Peru App.

Birds of Peru App. Birds in the Hand, LLC. Version 1. 929 MB.  Requires iOS 9.0 or later.  Compatible with iPhone,  iPad, and iPad touch.

Peru, with over 1800 bird species, is a fantastic country for birders. In 2007, Princeton University Press published Birds of Peru by Schulenberg et al.  A second edition appeared in 2010. Princeton also sells a non-interactive digital edition. The Birds in the Hand app, which I am reviewing here, is an interactive version of the second edition.

Why buy the app if you already own the book? The number one reason is the inclusion of songs for 1510 Peruvian birds. These recordings are a treasure trove for birders. The plates and maps for each species are large and excellent. Thirteen of the world’s most famous bird artists contributed full-color portraits.

The app’s organization is straightforward. A menu bar takes you to a list of Peruvian bird families. The family list links to a species list that includes thumbnails of the birds of Peru. The effective use of these lists depends on the user’s familiarity with tropical bird families. The app includes options for filtering the list by the color, size, and habitat of what you are trying to identify. The result is a list of possible birds. You can even filter the list by the general region of Peru that you are visiting. Future editions will include a “nearby” option, showing what birds are found in your GPS area.

Other links on the menu bar take you to written discussions of field marks and habitats and to large range maps. Another link takes you to bird songs. Having separate links seems a bit clunky. Too bad the links are not next to the species’ plates. Perhaps there could be a thumbnail map next to each bird’s picture. As it is, the reader has to leave the plate to get written text or maps. A final link takes you to your life list, which you must manually enter (a shame you can’t import your eBird data).

Comparing similar species is hard since there is only one species per page. Instead you must depend on the tiny thumbnail portraits in the table of contents. Brief descriptions of field marks, perhaps linked to the descriptive texts, could be included with the large portraits. Once you know what you are looking for, searching can be expedited by using four-letter codes.

This app costs $34.99 at the iTunes Store.  Princeton’s non-interactive digital book costs $26.71 at Amazon. The paperback book is $28.12 at Amazon. Some may think that the digital price is high, but, when you consider the up-front development cost, the price seems reasonable.  The songs and the filtering capabilities of the app are worth the cost of the app. Nevertheless, a hard-copy book, for me, is easier for comparing species. Traditional books do not need recharging at the end of the day. Both formats are essential for anyone interested in the birds of Peru.

(I took this photo of a White-plumed Antbird in Peru in 1972.)

American Rubyspot

A male American Rubyspot flashing his red wings. On Sunday, Erika and I stood on a bridge in the Lyman Lakes area of the Carleton College campus. I told Erika, “three years ago, I saw American Rubyspots at this exact location.” As soon as I uttered these words, we discovered a single rubyspot perched on a twig in the middle of the creek. The damselfly made repeated forays from his perch, aways quickly returning. This behavior allowed me to take several in-flight photographs, of which, this picture is the best.

In a previous post, I wrote "The male rubyspot’s red wing spots grow larger over time, and are largest on dominant males. Paulson suggests that these spots actually decrease the most dominant male’s hunting success.” In my older post is a photograph of a male with less gaudy spots.

Forster’s vs Common Tern

I took the first photo at Chincoteague National Wildlife Refuge on 28 March. In the field, due to the white windows in the upper wing, I identified it as a Forster’s Tern. But when the file came out of my camera, I was less sure. The bill and feet seemed too red. On the other hand, I think I see a white leading edge to the outer tail feather—a Forster’s Tern field mark.

On 18 May, back in Minnesota, at Lake Byllesby, I saw three terns that were clearly Common. Look at the gray underparts that contrast with its white cheeks. Moreover, the outer edge of the outer primary appears to be black—clearly a Common Tern. I also became a whole lot more confident of my previous Forster’s Tern identification.

Spot-winged Glider

On 15 July 2016, Erika and I walked in the Carleton College arboretum. We are quite a sight. Erika gets further and further ahead, as I squeak at birds and try to focus my camera on dragonflies. This situation is good, because she can spot dragonflies for me.

On this day, Erika stopped and pointed, “Come quick, there is a dragonfly hanging in the grass on the side of the path.” When I finally saw the dragonfly, I knew it was different. Look at the red eyes and the robust abdomen. I started at the baskettails, but quickly honed in on gliders. I have seen Wandering Gliders in the arboretum. But this glider did not look quite right. For one thing, its sides are brownish, not yellow.This photo proves that Spot-winged Gliders’ wing spots are not always visible. They adorn the base of the hind wings. I tried to maneuver to get a back-side view, but the glider quickly flew.

Spot-winged Gliders are found from Canada to Argentina.  In Minnesota, they are migratory. They winter in the south and appear here in summer. The larvae develop in only five weeks, before departing to warmer climates (Mead). Our record is the first for Dakota County (and a first for us, for that matter). A couple of records do exist from next-door Rice County.

Black-shouldered Spinyleg

Erika and I came face-to-face with this Black-shouldered Spinyleg on 2 July 2016 in the Carpenter Nature Center (Washington County, Minnesota). I have only seen this species once before, in nearby Afton State Park on 19 August 2011. Because of the broad, dark bands on the sides of the thorax, I was fairly confident in my identification. The dragonfly flew and landed several times, always facing towards us, before it flew into the woods. In fact, later this same day, we saw another spinyleg at the state park.

This spinyleg is an immature. They become more dusky as they age. The spines on the legs, for which this dragonfly is named, are barely visible in this photo. Minnesota is on the western edge of the Black-shouldered Spinyleg’s eastern North American range.

Canada Warbler

Male Canada Warblers are among the most beautiful birds. I banded this one last May. These birds breed across most of Canada, southeast into Minnesota, Wisconsin and the northeastern United States, south through the Alleghenies to Georgia. They winter in Northern South America. We saw them in October and November in the Peruvian and Ecuadorian jungles.

Canada Warblers appear to be in trouble. Their population is often declining by more than 2 percent each year. Lumbering and loss of forested wetlands contribute to this problem. A glimmer of hope is that this species can breed, if enough trees remain in fragmented forests. But the warblers’ survival depends on vigilant habitat management (Reitsma et al. 2010).

Azalea sawfly

This May, a herd of Azalea Sawflies defoliated, but did not kill, Erika’s azaleas. I base my identification by their food choice. Actually two species of Azalea Sawflies exist. Although they are in different genera, they are so similar in the larval stage that they defy identification. The larvae develop into stingless wasps.

Azalea Sawflies feed until only the leaf’s mid-vein remains. Fortunately only one generation of sawflies appears per year. Aside from squashing them between your thumb and forefinger, by the time the larvae are as large as the one in my photo, there is not much you can do. Younger larvae do most of the damage. Soapy sprays can be used but, since you need a direct hit, tend not to be very effective. The remaining alternative is to use commercial insecticides (University of Minnesota Extension Office). (We used the thumb and forefinger technique.)

Powdered Dancer

Last week, on 12 July 2016, Erika and I encountered hundreds of dancers along a trail in the Carpenter Nature Center in nearby Washington County. I first identified them as Blue-fronted Dancers, but I was not completely sure. Later in the week, Facebook proved its worth when another contributor’s photo was corrected from Blue-fronted to Powdered Dancer. My photos are also Powdered Dancers. 

The first two photos are of andromorphs. These females look similar to males, but lack blue abdomen tips. The sutures between their blue thorax plates are wider than those of Blue-fronted Dancers. Elsewhere in this blog, I wrote that the apparent advantage for a female looking like a male is that competing males are less likely to hassle these females.

This third photo is of an immature male. Note its blue abdomen tip and the broad, pale stripe along the side of its thorax. In the field, I actually identified this individual correctly as a Powdered Dancer.

These last two photos are of female Powdered Dancers. The black lines on the thorax are too wide to be other species. These damselflies also lack dark sides to the ends of their abdomens. Thanks to Ed Lam for assisting me through Facebook with these identifications. Of course, I am ultimately responsible for the IDs made on this blog page.