Hummingbird Wing

My hummingbird feeder is at the edge of the woods. The feeder is infrequently and only briefly in the sun. On Thursday, when I saw this Ruby-throated Hummingbird, with its wings blurred and backlit in the sunlight, I ran for my camera.

Researching the Internet gives you a lot of different numbers for how fast hummingbird wings beat. Wikipedia’s data seem similar to other sources—hovering, typical hummers flap their wings about 50 to 80 times per second. While hovering, the wings make a figure-8 pattern. Unlike large insects that generate lift equally with their up and down strokes, hummingbirds generate about 75% of their lift during the downstroke, and 25% on the upstroke. Furthermore, the downstroke uses less energy than does the upstroke.

Tricolored Heron

Frederick (2013) writes that the Tricolored Heron suffered from the millinery slaughter of North American herons and egrets in the 1880s, but was a collateral victim as mixed colonies were destroyed. Populations have rebounded along with egrets and herons. Now populations are again declining as a result of coastal habitat destruction. Erika and I found this Tricolored Heron underneath the headquarters of the Ding Darling National Wildlife Refuge on Sanibel Island.

Swallow-tailed Kite

Erika and I were surprised by the numbers of Swallow-tailed Kites that we saw during March's Florida trip. This kite was one of several we saw at Sanibel Island.

In almost ten years of birding in Louisiana, we never saw this raptor. Meyer (1995) suggests the relative ease of seeing this species in Florida masks its scarcity. It is easily seen in the few places it nests. Hundreds of kites, which gather from great distances, can been seen in communal roosting sites. In the 1880s, Swallow-tailed Kites were found from Minnesota and South Dakota across much of the eastern United States. Now they are restricted to swamps of the extreme southeast, from South Carolina to extreme eastern Texas.

The species is occasionally reported in its previous range—in September 2007, in Mitchell, South Dakota, I saw one feasting on flocks of migrating dragonflies. Flying insects, in fact, make up most of this hawk’s diet. Only when breeding does it consume a variety of vertebrate prey—small frogs, lizards, birds and snakes, which are taken from treetops and swamp vegetation.

Scarlet Skimmer

During one of our unsuccessful searches last March for the Gray Kingbird in the Ding Darling National Wildlife Refuge, I spied this red skimmer. Erika was some distance ahead of me, as is usual, due to my photographing miscellaneous birds and odes. “Better come back here and look at this one,” I called. “Gosh, that’s a beautiful dragonfly,” replied Erika.

Scarlet Skimmers are North America’s only introduced odonate.  In the Lower 48 States, they are only found in south Florida. They are native and widespread in southern Asia, from the Middle East to China and Japan, through the Philippines and northern Australia. The species was first discovered in Florida in the 1970s, and has since been found in Cuba, Jamaica, Hispaniola. Puerto Rico, and Hawaii. I do not know who introduced them to the New World, nor do I know why. The larvae, however, are eaten in parts of China (Wikipedia). BugGuide.com, however, claims the introductions were accidental.

Striped Mud Turtle

I believe this creature that I photographed last March in the Bailey Tract of the Ding Darling National Wildlife Refuge is a Striped Mud Turtle. The yellow head stripes are just barely visible. The species is found throughout most of Florida and up the Atlantic coastal plain to southeastern Virginia. These turtles inhabit swamps and canals. Striped Mud Turtles are odd in that the females nest in the fall, unlike other species that breed in the spring or summer (Savannah River Ecology Lab).

I was surprised as I worked on this photo for presentation for my blog. Do you see the damselfly on the turtle’s back? I never saw the damsel when I took the photograph. Greatly enlarging the photo does not give a definite identification, but the damsel may well be an Eastern Forktail.

Wood Thrush

Among four Swainson’s Thrushes I banded Friday evening, I was surprised to find a Wood Thrush. This thrush is common enough in area woodlands, but I do not catch many in the small forest behind our home. Our forest patch must be too small to support resident Wood Thrushes. This young bird must be a migrant—unfortunately, in our woods, I do not hear the loud, flute-like calls during the breeding season.

Because Wood Thrushes are intolerant to forest fragmentation, both in their eastern North American breeding territory and in their Central American wintering range. they have become increasingly uncommon since the 1970s (Evans et al. 2011). Habitat destruction in North America leaves this species vulnerable to nest parasitism by cowbirds and, in both North and South America, cutting of forests forces Wood Thrushes into secondary habitats where they become more exposed to various predators.

Florida Cooter

In the Bailey Tract of the Ding Darling National Wildlife Refuge, Erika and I found two turtles basking in the sun. I believe they are Florida Cooters, which are known to be social turtles, often basking in groups (Savannah River Ecology lab). The species is found throughout the southeastern coastal plain, from Mississippi to Virginia. Three races across this range may, in fact, be distinct species. In any event, they are omnivorous. Females prefer aquatic plants, while males prefer aquatic invertebrates.

Willet

Three Willets loafing on the Sanibel Island beach last March—all three appear to be asleep, or at least they have their eyes closed. Nobody has quantified the daily time budgets of Willets —such a study might make a nice Master’s degree. Willets are known to roost at high tide and they rest communally when not breeding (Lowther et al 2001).

Due to the advent of molecular genetics studies, these days avian systematics is in a state of flux. Willets, for example, used to reside in their own genus, Catoptrophorus, a Latinized version of the Greek for mirror-bearing—referring to the striking white wing stripes visible on flying Willets. Genetic research concludes that these birds are, in fact, members of the genus Tringa (along with Solitary Sandpipers and the yellowlegs).

Sandwich Tern

Sandwich Terns are named after the town from which they were first described in 1987. They are found across much of Europe, the southeastern Atlantic coast and Gulf Coasts of the United States, and the Caribbean and Atlantic coasts of South America. Three races are recognized. Those found in Europe and North America are quite similar. South American birds have yellow bills and some ornithologists think that they are a distinct species—Cayenne Terns. North American birds were formerly known as Cabot’s Terns, but one does not see that name very often in modern literature.

This Sandwich Tern gazed upon Erika and me along the Sanibel Island, Florida, beach last March. We also listed this species on our previous trip to the area in 2012.

Green Heron

Fortunately, John Holden and I were wearing our hats when we spied this Green Heron in Rice County, Minnesota, last Wednesday. This little heron goes by many names, including “Shite-polk,” due to its habit of defecating as it flies from its perch.

Green Herons have other names too, including Green-backed, Striated, and Little Green heron, due to ornithologists’ confusion about the species' systematics. This situation is not surprising. The birds’ range is huge—North and South America, Africa, and Asia. At least 33 races are recognized, and scientists argue that some are, in fact, distinct species. For example, Martinez-Vilalta et al. (2014) consider all these populations to be subsets of a single species, the Green-backed Heron. Davis and Kushlan (1994) follow the current American Ornithologists’ Union edict that the North American population is a distinct species, the Green Heron, distinct from South America’s Striated Heron. This unlikely conclusion leaves the South American birds more closely related to Old World populations than to North American birds.

When Erika and I visited the Galapagos Islands, we saw Lava Herons, like the one in the photo below. This population looks like very dark Green Herons. These birds may be another species in the Green Heron complex. Most ornithologists, however, consider them to be a dark morph of the South American birds. They are variable in color—this one is a bit paler than most—and no significant genetic differences have been found between Galapagos and mainland Striated Herons.