Monday, October 16, 2017

Squirrel Cuckoo

5 July 2017 proved to be interesting. The day began with our usual 6 AM bird walk. Dragonfly chasers are much more laid back than birders. Dragonflies don’t fly until much later in the morning. Erika quickly spotted a Squirrel Cuckoo foraging high in the trees above the river at the Villa Lapas Hotel.

Squirrel Cuckoos are common from Mexico south through most of tropical South America. Across this range, the species is highly variable, with 14 races described. Some of these populations are probably distinct species. These cuckoos are found in a variety of forest habitats, gliding from tree to tree. 

Sunday, October 15, 2017

Muscovy Duck

Strange ducks perched on the trees along the Rio Tarcoles—Muscovy Ducks. Wild Muscovy Ducks range from Mexico south Argentina. Some may wander into the United States. The problem is that feral Muscovy Ducks have been introduced around the world, sort of like chickens and pigeons. Birds in Texas and Florida are probably escaped domestic individuals. One result is that the feral birds are highly variable in plumage and probably should not be counted on birders’ lists.

Muscovy Ducks appeared to be fairly common in Costa Rica. Many roosted in riverside trees as we returned to the dock in the gathering dusk. Across their range, their numbers appear to be somewhat variable. Often populations suffer from over-hunting, egg collecting, and hybridization with domestic populations (Handbook of Birds of the World). 

Saturday, October 14, 2017

Double-striped Thick-knee

“Once more bend in the river,” exclaimed our Tarcoles River boat tour captain, “and we will find thick-knees!” In the gathering dusk, sat two Double-striped Thick-knees, birds I very much wanted to see. Thick-knees are thought to be most closely related to plovers. Ten thick-knee species are found around the world. Erika and I saw Peruvian Thick-knees in Peru, a Bush Thick-knee in Australia, and, in my youth in Somalia, my brother and I listed Water Thick-knees, which we jokingly called Zombie Birds. Double-striped Thick-knees have an odd distribution—Veracruz, the Pacific Coast of Central America, and scattered areas of Venezuela and other locals in northern South America.

Thick-knees are crepuscular or nocturnal feeders. They eat insects, worms, mollusks and occasionally lizards and small rodents. Mexicans sometimes keep them around ranches, "where species is held to be a useful controller of insect pests and is kept on patios and in corrals of country houses” (Handbook of Birds ot the World).

Friday, October 13, 2017

Great Blue Heron

Most North American herons and egrets are found in Costa Rica, so I suppose I should not have been surprised to see this Great Blue Heron along the Rio Tarcoles on 4 July 2017. Although they are winter visitors to most of Central and Northern South America, they are year-round residents in Costa Rica. 

Thursday, October 12, 2017

Banded Garden Spider

Last Monday, this Banded Garden Spider guarded the green-beans at our CSA farm (Community Supported Agricultcure). This view is the bottom side of the spider. This is actually the second species of garden spider (Argiope) we have seen at the farm, the first being a Black-and-Yellow Garden Spider.

Banded Garden Spiders are widely introduced around the world. They prefer fields and prairies. They hang upside-down in their webs, waiting for flying or jumping insects to become entangled. Males die soon after mating. Females last until the end of Autumn. Females lay eggs sacs, each containing about a thousand eggs (Bugguide).

Wednesday, October 11, 2017

Wood Stork

Wood Storks loitered along Costa Rica’s Rio Tarcoles on 4 July 2017. Despite their wide range—the southeast United States south along both coasts of Mexico and Central America and continuing south through most of eastern Amazonia—local population show little variation and all belong to a single race. To my disappointment, this species is the only stork we observed during our journey. (I was hoping to find Jabirus, but they remained elusive.) I have posted more information about Wood Storks elsewhere in my blog.

Tuesday, October 10, 2017

Golden-mantled Howler Monkey

A Golden-mantled Howler Monkey watched as our boat headed up the Rio Tarcoles on 4 July. At first glance, this primate may not seem too pleased with our intrusion. This impression may not be accurate. This species of howler, found from Mexico to the western coasts of Colombia and Ecador, eats more leaves than others (up to just more than 50% of its diet). Leaves are hard to digest, resulting in the monkey’s spending most of their days resting and sleeping.

Golden-mantled Howler Monkeys have a wide variety of sounds, but are most famous for their howls. They sound almost like a low, loud, but distant wind. They can be heard for several kilometers. The sounds are amplified by the monkeys’ hollow hyoid bone, which is near the vocal cords. The calls allow the monkey’s to maintain their sedentary life style. The sounds also allow monkeys to locate each other without risking aggressive confrontations (Wikipedia). This source also reports, “the mantled howler is usually indifferent to the presence of humans. However, when it is disturbed by people, it often express its irritation by urinating or defecating on them. It can accurately hit its observers despite being high in the trees.”

Monday, October 9, 2017

Southern Lapwing

Southern Lapwings are found in much of South America, from Tierra del Fuego north into Nicaragua. Their range has been expanding northward (Costa Rica—1993; Nicaragua—2009; Mexico 1996). Records even exist for Florida and Maryland, although these may be escaped captives (Handbook of Birds of the World). Most of these northern records are of vagrants, but the species now breeds in Costa Rica.

We spied this Southern Lapwing along the shore of the Rio Tarcoles on 4 July. After we left the mangrove swamp, we motored upstream in search of Double-striped Thick-Knees. I very much wanted to see a thick-knee, and the captain of our launch was convinced we would see them upriver.

Sunday, October 8, 2017

Boat-billed Heron

Boat-billed Herons inhabit swamps from the coasts of central Mexico south through most of the Amazon Basin. Because they tend to feed at night—note the large eyes—these herons can be illusive. They use their out-sized bill to scoop up prey—fish, crustaceans, insects and amphibians. The herons walk along with their bills half submerged in the water. The bill is thrust forward when prey is encountered (Handbook of Birds of the World). We saw several during our Tarcoles, Costa Rica, mangrove swamp tour on 4 July 2017.

Saturday, October 7, 2017

Mangrove Warbler

Yellow Warbler systematics are complex and confusing. Across their range from Alaska and northern Canada through Mexico, Central America, and the West Indies, and including islands out in the eastern Pacific, at least 43 races have been described. These races sort out into some five groups, which often overlap in plumage coloration. Those with chestnut heads, like this one we saw on our 4 July mangrove tour, once were considered to be a separate species—the Mangrove Warbler. Now they are thought to be a race of Yellow Warbler.