Tuesday, September 19, 2017

Claret Pondhawk


Claret Pondhawks (Erythemis mithroides) are rarely recorded in the lower Rio Grande Valley in Texas. This dragonfly is found across much of South America, with an isolated population in Central America (Mexico, Guatemala, and Honduras). At one time, the northern population was thought to be a different species. But subsequent study revealed that Claret Pondhawks are simply variable across their range (Paulson, per. com.).

Claret Pondhawks patrolled the Tárcoles ponds we visited on 3 July. This pondhawk and others we observed usually faced toward the pond centers—better to see prey and competitors. I am not sure to which population these Costa Rican pondhawks belong.

Monday, September 18, 2017

A Squadron of Pelicans and a Red-banded Gull

What do you call a flock of pelicans? Google suggests a squadron. Considering the smell of a pelican colony, I find that answer somewhat fishy. How about a whiff of pelicans? 14 September found Erika and me at nearby Circle Lake as we took photos of American White Pelicans. A few gulls, Franklin’s and Ring-billed, loafed in front of the pelicans. I noticed one sported red bands on its left leg. A post to the Minnesota Birding FaceBook group drew this response: "Todd Froberg Hi All, I'm a graduate student at the University of Minnesota working on this project. Thanks very much for the report on RBGUs with red bands. They are part of a University of Minnesota study on presence of non-pathogenic avian influenza in gulls. Birds were banded at 3 colonies and at various landfills in MN. We have had reports of gulls we banded as far as Lake Erie and Lake Michigan so far this late summer/fall. The bird in the photo was probably banded at the Rice county landfill. One aspect of the study is to learn about gull movement among different locations in the state, particularly in relation to poultry farms, so your reports and photos are of great help and interest. For more info, send questions/reports to Francie Cuthbert (cuthb001@umn.edu).”

Sunday, September 17, 2017

Shadow Darner

During the last week, a large, dull darner hovered over our water feature. Each time, I ran for my camera, only to have the dragonfly disappear. Friday, 15 September 2017, I caught an image. This observation is not my first for a Shadow Darner in the backyard. In an earlier post, I commented about this species’s cold tolerance.

The species deposits eggs into “wet, rotting wood of a floating log or a partially submerged log” (Mead). This day the darner behaved strangely. It repeatedly returned to the dry, mossy edge of our artificial pond and appeared to deposit her eggs along a crease along the pond wall, The eggs seemed to be placed deep into the mossy mat about four inches above the high waterline.

Saturday, September 16, 2017

Band-winged Dragonlet

Band-winged Dragonlets were fairly common along the Tárcoles ponds on 3 July 2017. This observation was not the first time we’ve seen this dragonfly. The first was in southern Texas on 18 March 2012. Judging by their numbers in Texas, Band-winged Dragonlets may be partially migratory. They are abundant in the tropics, from Argentina north into the United States (to Ohio, Georgia, and Florida). Look for them low in the grass or as they fly over ponds (Paulson).

Friday, September 15, 2017

Three-striped Dasher

These male (above) and female (below) Three-striped Dashers are from the Tárcoles district of Costa Rica. This dragonfly ranges from the southern tip of Texas to northern South America and from southern tip of Florida through the West Indies. They tend to perch in the shade, often with their wings drooped down. Their breeding biology is poorly known—males are found at or over water, while females stay further away. Pairs copulate in woodlands away from water (Paulson).

Thursday, September 14, 2017

Northern Jaçana

Almost every day during our Costa Rican trip, we saw at least a few new dragonflies (as to be expected on a dragonfly tour). Several days, however, were outstanding. The afternoon of 3 July was one of those mega-days. We explored two freshwater ponds in the Tárcoles District near the Pacific Ocean. The ponds were quite different, one surrounded by forest and the other beside a motel in the outskirts of the village of Tárcoles. I have combined these locations in my posts.

But first a bird—Northern Jaçanas greeted us at the motel pond. Everything about jaçanas is interesting. The cedilla hanging below the c in jaçana is often found in French and is pronounced like an “s” rather than a “k,” as in façade or garçon.

Northern Jaçanas range from coastal Mexico south to Panama. Occasionally they stray into eastern Texas. Note the yellow spurs, outgrowths of their wrist (carpometacarpus) bones. These are displayed during courtship. These structures are not unique to jaçanas, some plovers also have them.

Female jaçanas are larger than their males and their sex roles are reversed. Males build the nest, incubate, and bood their young. Females rarely brood the chicks. The females mate simultaneously with up to four males. The females defend their mates' nests against other females and other male jaçanas. This polyandry occurs in rich habitat. In poorer habitat, male territories tend to be larger, the result being their females may mate with fewer or just one male (Birds of North America).

Tuesday, September 12, 2017

Lemon-tipped Helicopter

As I recall, Netta Smith saw a Lemon-tipped Helicopter (Mecistogaster ornata) first thing at Carara National Park, but nobody else saw it. After our lunch, she found it again. Photographing Lemon-tipped helicopters, as these damselflies row lazily through the air, is nearly impossible. No structure is visible to the camera’s autofocus. I took this photo with manual focus.

These elegant odes are sometimes called Ornate Helicopters or Yellow-tipped Helicopters—no official common names exist for most Costa Rican dragonflies. They range in tropical woodlands from Mexico to northwestern Argentina. Like the Blue-winged Helicopter, these dragonflies are web-spider specialists. Apparently the yellow wing spots distract the spiders before they are captured. Lemon-tipped Helicopters also eat insects trapped in spider webs. These damselflies lay their eggs in water-filled holes in trees (ICN Red List).

Monday, September 11, 2017

Blue-eyed Setwing


Back at the tour bus for a picnic lunch on 3 July at Carara National Park. With our bee allergies, picnicking can be a bit dicey. We ate quickly and searched the parking area for more dragonflies. This Blue-eyed Setwing (Dythemis nigra) perched at the forest edge. The species is known from northeastern Mexico (almost to the United States) south through most of Brazil. This habitat is typical for the species. Males perch on dry stems and survey their territories (Benoit.Guillon).

Sunday, September 10, 2017

White-whiskered Puffbird

Also attending the army ant swarm on 3 July at Carara National Park was a male White-wiskered Puffbird. Puffbirds are neotropical birds related to Jacamars and, more distantly, to woodpeckers. The White-wiskered Puffbird inhabits forests from southeastern Mexico to Ecuador. Males are more rufous than females. Puffbirds perch quietly, occasionally capturing insects, frogs, or lizards. White-wiskered Puffbirds are known to join mixed species flocks around army ant swarms (Cornell).

Saturday, September 9, 2017

Bicolored vs White-cheeked Antbirds

Bicolored Antbirds are common across their range. This bird is an obligate army ant follower. As the ants move through the forest, they stampede a host of invertebrates in front of the swarm. Army ant followers pick off the stampeding invertebrates, leaving the army ants alone. Bicolored Antbirds also take small frogs and lizards.
Two disjunct populations exist—one from Honduras south to northern Colombia and western Ecuador; the other in upper Amazonia, from southeast Colombia to north-central Peru. Erika and I worked with Bicolored Antbirds in Ecuador. I am surprised I have not shared a photo of the Ecuadorian bird with this blog. Note the bird in the second photo. Unlike the Costa Rican bird in the first photo, the Amazonian bird is white below the eye; behind the eye is black, not brown; the upper-parts are richer chestnut; and the calls are different. Genetic studies show that the two populations are not closely related.

eBird, presumably following the American Ornithological Society, now classifies my Ecuadorian bird as the White-cheeked Antbird (Gymnopithys leucaspis) and the Costa Rican one as the Bicolored Antbird (Gymnopithys bicolor). When we saw our Costa Rican bird at the furthest point of our jungle hike on 3 July at a bridge over a small river, we had no idea we were adding a life bird to our lists. One thing for sure, the ground was swarming with ants!