Tuesday, September 1, 2015

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.

Monday, August 31, 2015

Sea Cucumber

A sea cucumber on the Sanibel Island beach last March; not a plant—but a starfish with its arms connected by flesh. Sea cucumbers are close to Erika and my hearts. When we were in college, Erika spent a summer taking marine biology at Santa Barbara, while I studied birds at LSU. I returned to California just in time to participate in her biology class’s culminating feast, wherein the students ate the marine life they had been studying.

Sea cucumber recipe: spread salt over animal’s body until the echinoderm eviserates its digestive tract (an escape strategy for sea cucumbers in the wild). Cut the creature into tire-shaped pieces.  Marinate in vinegar for several hours, and, voila, its ready.

When it came to sea cucumber, Erika promised me, “If taste it, so will I.” I chewed, and chewed—the poor creature tasted like salty rubber—but Erika reneged on her promise and, to this day, has never experienced the delight of sea cucumber salad.

Saturday, August 29, 2015

Lesser Black-backed Gull

Especially during the last 25 years, Lesser Black-backed Gulls are now regular visitors to eastern North America—and the range is expanding. This gull is common across Europe. Almost all seen in North America are the race that breeds in Iceland, Britain, and western Europe—as you can see in this photo from Sanibel Island in March, the back is much lighter than the wing tips. The yellow legs are a good field mark for the species; similar gulls have pinkish or yellowish legs.

Friday, August 28, 2015

Black-necked Stilt

Black-necked Stilts have long, red legs—not that you can tell from these photos from Sanibel Island last March. Stilts feed in shallow water of various depths, but do not like getting their breasts wet. They consume a wide variety of aquatic insects and even crayfish, small fish and frogs (Robinson et al. 1999). These authors describe three feeding methods—Pecking, Plunging, and Snatching. Clearly the bird in the bottom photo is Plunging. Some studies have shown that flocks of stilts have higher foraging success than solitary birds.

Thursday, August 27, 2015

Zebra Heliconian and White Peacock

Last March, Erika and I found two easily identifiable, tropical butterflies on the Bailey Tract of the Ding Darling National Wildlife Refuge.

The Zebra Heliconian is found from South America north into Florida and southern Texas. The butterfly strays north to New Mexico, Nebraska, and South Carolina. Larvae feed on poisonous passion vines, rendering the butterflies poisonous to predators and the adult’s striking pattern further advertises their noxiousness (Brock and Kaufman).

Helionians also have a bizarre mating habit—upon mating, males present females with a cyanide-laced spermatophore, a “nuptual gift" containing sperm.  The cyanide does not kill the female or the embryos, but does make them distasteful, if not poisonous, to predators. The spermatophore also changes the female’s odor, making her less attractive to other males (Wikipedia).

White Peacocks have a similar range to the heliconian, but may more wides wonder into the central United States. Male White Peacocks hold 15-meter territories containing host plants and aggressively defend them against other insects and male peacock butterflies (Wikipedia). Host plants include Water Hyssop, Green Shrimp Plant, and Frogfuit.

Tuesday, August 25, 2015

Lance-tipped Darner

Because they dart this way and that and seldom land in reach of my camera lens, darners are hard to photograph. As we tended Erika’s garden on 23 August, this female Lance-tipped Darner flew up and landed between Erika and me. The yellow rose and the red hibiscus make for a great background!

On the dragonfly, note that the thoracic stripes widen dorsally and that the face lacks a black cross-line. The species is found across the northern United States and southern Canada. Lance-tipped Darners feed as they fly close to the ground, often into the evenings (Meade).

Sunday, August 23, 2015

FOY Fall Warblers

Fall migrants appear in central Minnesota during the last week of August. Last spring was a miserable migration for my banding and birding—hopefully problem was that the weather was just so good last spring that the migrants flew right over Northfield, without bothering to stop. This week I have caught up by listing two FOY warblers. FOY is birder lingo for First of Year.

Both the Blackburnian (above) and the Chestnut-sided warblers (below) are considered to be common in Minnesota (Eckert 2002). They are among the many warblers I missed seeing this spring, and are thus FOY for my year list. I have linked both species’ names in this paragraph to previous accounts in this blog. The links also give you images of these species in spring plumage.

Saturday, August 22, 2015

Black-bellied Plover and Ruddy Turnstone

We often saw Black-bellied Plovers and Ruddy Turnstones running on the Sanibel Island beach last March. Both species were in molt, with the turnstone further along than the plover. A breeding plover, as its name suggests, will have black underparts. Both species undergo an incomplete Definitive Prealternate molt to take them into breeding plumage. Among plovers, males undergo a more extensive molt than do the females. The sexes of turnstone undergo a much more similar molt. This Black-bellied Plover has a way to go to achieve breeding plumage. Turnstones are in breeding plumage in late April through mid May (Paulson 1995; Nettleship 2000). The turnstone in my photo is much closer to breeding plumage than is the plover.

Friday, August 21, 2015

Marl Pennant

Erika and I became aware of Marl Pennants during one of our later March visits to the Bailey Tract on Sanibel Island. We met another dragonfly enthusiast in the field and we owe our identification to that gentleman. This species is found along Atlantic and Gulf coastal areas, across Mexico, and south through the Caribbean  to Belize and Venezuela (Paulson 2011). They are found in brackish and fresh water and often perch, like this one, on the tips of vegetation. The dark “W” marking is a good field mark of the species. Marl is a calcium carbonate or lime-rich mud; it is unclear if this substance is critical for this dragonfly.

Thursday, August 20, 2015

Fish Crow

Fish Crows used to only be found in tidewater areas of the southeastern United States. They have adapted to scavenging human trash and were common around Sanibel Island, Florida. I have posted previously that these small crows are expanding northward, even as far as St. Louis and southern Ontario.

I suspect they will one day become common in Minnesota—the trick will be documenting their occurrence. Small, female American Crows are almost identical to Fish Crows. Young American Crows are smaller than adults. The only reliable difference between these two crows are their calls, and even these sounds can be confusing. “The Fish Crow sounds like an American Crow with a bad cold” writes McGowan (2001). The trouble is that so do begging young American Crows—subordinate adults give similar nasal begging calls when young are not around. Theoretically American Crows never give a double-noted “Uh-uh” call, which ends abruptly with no “higher-pitched gobbling notes” at the end. If you hear such calls, try to record them on your cell phone (assuming you have one handy).