THIS WEEK at HILTON POND
15-21 February 2010
Installment #464---Visitor #msn live graphics

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COSTA RICA PORTFOLIO 2010:
FLORA, FAUNA & HABITATS OF GUANACASTE PROVINCE

Each winter through Operation RubyThroat we depart Hilton Pond Center and meet up in Costa Rica with one or more groups of citizen scientists from the U.S. and Canada, with the intent of learning as much as we can about Ruby-throated Hummingbirds (RTHU) on their wintering grounds in Guanacaste Province. The expeditions, organized through Holbrook Travel, always include Ernesto Carman Jr.--a tico who in the early part of this decade discovered concentrations of ruby-throats in Aloe Vera plantations around Liberia. Ernesto has been our knowledgeable, dependable, and industrious in-country guide, interpreter, and friend ever since, and this year he brought along Elaida Villanueva Mayorga--his new bride and a young tica quite familiar with our hummingbird research. Ela, Ernesto, and Operation RubyThroat trip leader Bill Hilton Jr.--known as the "Omega Group"--traveled to Guanacaste a week early and stayed another several days after the six-member "20-Tenners" crew departed. During the full three-week span the collective efforts of everyone involved helped us make new discoveries about RTHU winter behavior, summarized in last week's photo essay. Our current "This Week at Hilton Pond" installment is a portfolio of people, places, and things we encountered in far-away Costa Rica in January-February 2010, so please scroll down for a look at what we experienced.

All text & photos © Hilton Pond Center



All text & photos © Hilton Pond Center

Our primary reason for being in Guanacaste Province, Costa Rica was, of course, to observe, capture, and band Ruby-throated Hummingbirds on their wintering grounds. Most years we use mist nets to snare hummers, but in 2010 we decided to also try a few Dawkins traps baited with sugar water feeders (above); the traps worked very well catching ruby-throats last fall at Hilton Pond Center, so Ernesto hung one of these contraptions on the perimeter of commercial aloe fields belonging to Pelón (formerly Carrington Labs' Finca Sabila). Meanwhile, Ela watched for hummers in surrounding trees. Unfortunately, strong winds around Liberia blew the traps around so much they were ineffective.


All text & photos © Hilton Pond Center

Numerous Neotropical migrants besides Ruby-throated Hummingbirds frequent Pelón's aloe fields in Guanacaste--including adult male Baltimore Orioles (above). Tennessee Warblers, Baltimore and Orchard Orioles, and several NON-migratory hummers also find aloe flowers to be a rich source of carbohydrates. The close-up image of an immature (second-year) female Baltimore Oriole (below) shows her sharply pointed bill that is adapted for, among other things, taking nectar from short, tubular flowers. (This bill--as we know from painful experience--can also puncture the bander's skin if an in-hand oriole starts pecking like a woodpecker!)

All text & photos © Hilton Pond Center


All text & photos © Hilton Pond Center

One of the first Ruby-throated Hummingbirds we netted at Pelón this year was a "young" female (above). We called her a second-year bird that must have hatched in 2009; this determination was made because new body feathers she was bringing in were much darker and better-formed than the pale, brown-edged ones she acquired last year as a nestling. Differentiating immatures from adults among male RTHU is easy; it may be next-to-impossible to age most females conclusively using plumage characteristics.


All text & photos © Hilton Pond Center

Beneath the banding table at Pelón we found this interesting artifact--a lump of hard soil with numerous circular openings. We're guessing this is the mud nest of some wasp species and that the holes are exits through which a new generation of insects emerged after spending egg, larval, and pupal stages therein. (NOTE: As with other unidentified organisms on this page, if you think you know specifically what's depicted in a photo, please send a note to INFO.)


All text & photos © Hilton Pond Center

Even though our main effort in the field in Costa Rica was to band Ruby-throated Hummingbirds, we also devoted considerable time to looking at local flora--especially flowers visited by RTHU. The 1.5"-diameter purple blossom above, which we believe is one of the Butterfly-Peas (Clitoria sp.), was growing among our net lanes at Pelón. We don't think it is a hummingbird flower, although some peas are. (NOTE: Our next installment of "This Week at Hilton Pond" will be the third and final one about our 2010 Costa Rica expedition. It will include photos and a full discussion of Neotropical plants visited--and possibly pollinated by--Ruby-throated Hummingbirds.)


All text & photos © Hilton Pond Center

Members of the Tyrant Flycatcher Family (Tyrannidae) abound in Costa Rica, and a bunch of them are yellow-breasted. Western Kingbird and Tropical Kingbird are quite similar, but the latter--depicted above and below--has a darker back and a MUCH heavier bill. Flycatchers are among those birds with well-developed "rictal bristles"--stiff, hair-like feathers that project from the base of the bill. Some folks believe these structures funnel insects into a bird's gape; we think they also may serve to protect an avian predator's eyes while it's trying to swallow a squirmy beetle or bug.

All text & photos © Hilton Pond Center


All text & photos © Hilton Pond Center

Iguanas are everywhere in Costa Rica but--despite the appearance of the jade-colored youngster above--in Guanacaste Province the Green Iguana, Iguana iguana, is virtually absent. Instead we find lots of Black Iguanas, Ctenosaura similis. Ctenosaurs start out green (above) and gradually become brown; older males (below) develop short dorsal spines and a big dewlap, the loose fold of skin on the throat. These heavy-bodied big lizards--up to five feet long--are amazingly agile, especially in trees where they spend a great deal of time sunning.

We photographed this adult male Ctenosaur (above) on a sun-drenched boardwalk in late afternoon at Palo Verde National Park south of Liberia. He was almost oblivious to us--and apparently to the surprising number of ticks that were attached in his ear (at right in the close-up photo below) and elsewhere on his body. Some of these ectoparasites were quite distended with blood, while others were still small and at the "seed tick" stage. We counted five ear ticks and at least a half-dozen more scattered about. (In the photo above there are even two more ticks among the dorsal spines.)

All text & photos © Hilton Pond Center


All text & photos © Hilton Pond Center

Palo Verde National Park, visited by the Omega Group before the 20-Tenners arrived, is a vast 32,000-acre protected wetland along the Tempisque River at the north end of the Bay of Nicoya. In midwinter much of the water dries up and local farmers are permitted to graze horses and cattle (above) that, in turn, keep cattails from taking over the marsh. Receding waters also tend to concentrate huge flocks of waterfowl and wading birds, including Black-bellied Whistling Ducks (above and below).

All text & photos © Hilton Pond Center

Along with the whistling ducks in the photo above are two Black-necked Stilts (at right), an adult Jaçana (lower left) and an immature Jaçana (above left). We also saw, among other waders, several Tricolored Herons, Little Blue Herons, Snowy Egrets, Limpkins, Roseate Spoonbills, Great Egrets, and--of course--Cattle Egrets.

All text & photos © Hilton Pond Center

It's hard to tell just how many Black-bellied Whistling Ducks are standing around in the Palo Verde wetlands until a Peregrine Falcon buzzes through. When that happens, enormous flocks of ducks lift skyward (above) and wheel around for several minutes before settling back down in the marsh. Anyone care to count?


All text & photos © Hilton Pond Center

Palo Verde National Park is so-called because it is home to a common tropical tree bearing that name. Parkinsonia aculeata (formerly Cercidium sp.), the Mexican Palo Verde. Palo verde literally means "green stick," appropriate because this plant can photosynthesize through its chlorophyll-laden trunk. Found widely from the southern U.S. into Central America, it is the state tree of Arizona.

All text & photos © Hilton Pond Center

The Mexican Palo Verde has big clusters of yellow flowers (above) that branch from among thorny stems and leaves with hard little knobs along their margins. It is drought-tolerant and a perfect plant for arid Guanacaste (AND Arizona).

All text & photos © Hilton Pond Center


All text & photos © Hilton Pond Center

By far the biggest reptile in Palo Verde National Park is the American Crocodile, Crocodylus acutus (above). Adult males can grow to 13 feet in length and weigh more than 800 pounds--a creature to be treated with caution and respect. The individual in the photo above was an immature only about three feet long, but we could tell from the glint in its pale eye it would probably take a nip out of us if we wandered too close.


All text & photos © Hilton Pond Center

After a week of preliminary work by the Omega Group, our six 20-Tenners flew in from various parts of the U.S.; first stop leaving the airport was the Laurel House (above), a fine open-air restaurant that served our crew their first traditional Costa Rican meal.


All text & photos © Hilton Pond Center

The Ruby-throated Hummingbird is by far the most common trochilid we encounter in Guanacaste--really nice considering it IS our target species. We capture other hummer species occasionally, including the red-billed, rusty-breasted Cinnamon Hummingbird (above). This species--a bit larger than a RTHU--is sexually monomorphic, with males and females looking alike. (The immature bird in the photo above had malformed bill tips that were slightly crossed.)


All text & photos © Hilton Pond Center

Costa Rica is home to about a hundred species of snakes, but we seldom see any of them on our trips to Guanacaste; this is partly because many of them are nocturnal. On one of their first nights at Buena Vista Lodge the 20-Tenners encountered the snake above slithering around on concrete outside the dining hall. We took several flash photos and then had to distract the night watchman who wanted to cut off the hapless animal's head. We're happy we could shoo the snake--as yet unidentified--into nearby vegetation where it was not seen again, even though the watchman went after it with a spotlight and a machete. It's hard to tell from the photo, but this 18" serpent had vertical-slit pupils and appeared from a wide section of its body to have eaten recently. (If you know this snake's identity, please send a note to INFO.)


All text & photos © Hilton Pond Center

In much of Central America, vultures are like pigeons in a city park in the U.S.--almost fearless of people and sometimes getting underfoot as they hop awkwardly toward refuse and dead animals along the street or trail. We almost tripped over the Turkey Vulture above while it was intent on eviscerating the carcass of a Cane Toad flattened by a passing vehicle. The vulture flew up onto a low-hanging branch and stared at us intently until we departed and left it alone with its lunch. Note the bird's head appears red because that's the color of the vulture's cranial skin; young Turkey Vultures have gray head skin. The bird's legs also are red-skinned, but they appear discolored in the photo because of dried fecal material. Vultures may defecate on their legs to help keep the animal cool through evaporation and/or to help kill bacteria from the vulture's decomposing prey.


All text & photos © Hilton Pond Center

One of the fun aspects of traveling to faraway places is thinking and talking about neat things you've seen. At the end of each day, the 20-Tenners gathered at Mirador (above) to watch the sunset and compile field notes and birding checklists that would provide a permanent record of the trip.


All text & photos © Hilton Pond Center

And speaking of featherless heads on birds, this close-up (above) of the face of a male White-winged Dove shows a bare patch of cyan skin that surrounds an eye with a blood-red iris. Note also the iridescent feathers and blue-black spot on the neck. (The female dove will be somewhat paler.)


All text & photos © Hilton Pond Center

One afternoon during their nine days in Guanacste we took the 20-Tenners to Santa Rosa National Park, where they got to see the tropical DRY forest--an endangered habitat usually ignored by visitors to Costa Rica. The dry forest includes both deciduous and evergreen trees, shrubs, and vines and is home to some animals not found elsewhere. One bird NOT unique to the dry forest is the White-throated Magpie-Jay, a big 19" corvid that looks like a wildly crested Blue Jay on steroids. What IS unusual about the jays at Santa Rosa is some are further adorned with color bands on their legs (above)--bands applied at least seven years ago by researchers studying behavioral ecology. Each bird is identifiable through binoculars or spotting scope--without recapture--because of its unique combination of colors.


All text & photos © Hilton Pond Center

Birds aren't the only animals marked with color bands at Santa Rosa, as we learned when we entered an old hacienda that was the site of a famous battle in 1856. Clinging to high wooden walls in several rooms were three species of bats, and some of these had plastic bands attached to their wings. Many bats worldwide are threatened or endangered by habitat loss, insecticides, and disease, so researchers are interested in how well these aerial insect (or fruit or nectar) eaters are doing in Guanacaste. (Let us know if you can identify this bat species by sending an e-mail to INFO.)