1-14 January 2005
Installment #253---Visitor #Free Web Counter

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When we give talks around the country about our Ruby-throated Hummingbird studies at Hilton Pond Center, we're often asked about hummer migration--routes the birds follow, how long it takes, where they go, and what they do when they get there. Even though ruby-throats may be the commonest and most widely distributed of all 338 hummingbird species, science has surprisingly few answers to these basic questions. We know, of course, that each autumn nearly all ruby-throats leave their breeding grounds in southern Canada and the eastern half of the U.S. Most apparently fly across the Gulf of Mexico to the Yucatan Peninsula, but some may go overland through Mexico. We know generally they end up in Mexico or Central America as far south as northern Panama, but no one knows for sure if, for example, ruby-throats from New York stop in Nicaragua or those from Hilton Pond overwinter in Honduras. And even though more than 100,000 ruby-throats have been banded in North America in the past half-century, not a single one of them has been reported south of the Rio Grande River--so we really DON'T know where they go in fall migration. Lastly, almost no one has systematically studied ruby-throats on their wintering grounds to see if behavior in the tropics is similar to that on the breeding grounds.

All text & photos © Hilton Pond Center


With all this in mind, we didn't hesitate back in November 2002 when Holbrook Travel's Debbie Sturdivant asked if we'd like to organize an expedition to Costa Rica as part of Operation RubyThroat: The Hummingbird Project ( and The GLOBE Program. Because we wanted to involve classroom teachers in our Costa Rican hummingbird studies, we selected the week after Christmas 2004 as our trip date, knowing educators would still be on holiday during that time. (There's no sense going to Costa Rica during summer vacation to study ruby-throats; by then the birds are all up north to breed.) We advertised the trip on the Center's Web site and, to make the year-long recruitment story somewhat shorter, the concept was so popular we were able to put together TWO groups of teachers and citizen scientists. The first team flew to Costa Rica for eight days (26 December thru 2 January) and was replaced by another crew (2-9 January). These folks came from such diverse backgrounds as clinical psychologist, massage therapist, librarian, stock broker, teacher, wastewater expert--even a veteran bluebird bander--and from widespread parts of the U.S. including Montana, Michigan, Texas, the Carolinas, and several states in between. Some we met at Hummingbird Mornings programs or lectures we had given around the country, but for the most part we knew these folks only from E-mails in which they said they were zealous about gathering with strangers in Costa Rica to help unlock mysteries of hummingbird migration. In retrospect, we couldn't have hand-picked a better bunch of people to participate in the project.

Although we visited Costa Rica in February 2004 to get to know Holbrook and the mechanics of tropical travel, on that particular trip we went to Selva Verde on the Caribbean side of the country. Very few Ruby-throated Hummingbirds overwinter there, however, so our most recent foray was planned for northwestern Guanacaste Province--near the Nicaraguan border on the Pacific slope (see yellow region on map at right). Based on an extensive literature search and helpful communications from experienced birders and banders, we determined that Guanacaste hosts the largest Costa Rican populations of winter ruby-throats. This region, reminiscent of west Texas, is characterized by grassland, scrub, scattered trees, and patches of DRY forest rather than the RAIN forest usually associated with Costa Rica.

Since we'd never personally been to Guanacaste, the whole excursion was sort of a gamble; in large part we simply trusted the judgment of Ernesto Carman (left), a young but knowledgeable Costa Rican naturalist and Talamanca Hawk Watch counter who told us via E-mail he had observed ruby-throats in significant numbers among Aloe Vera plantations not far from Liberia, Guanacaste's capital, marked by X on map above. (Ernesto and his family run Finca Cristina, an environmentally friendly coffee farm that uses shade-grown techniques and recycles processing materials.)

Liberia has an international airport, so our field teams flew there and gathered at nearby Buena Vista Lodge (below right), an established 2,000-acre site known for its canopy tours, serpentarium, and horse-riding trails. The lodge--with rustic, comfortable rooms, spacious warm showers, and really great ethnic food--was base camp for all 16 days of the hummingbird expedition. Ernesto--who was born in Costa Rica 22 years ago to American parents, holds dual citizenship, is completely bilingual, assisted U.S. grad students in Guanacaste, and has a terrific personality--turned out to be the perfect expert guide for our hummingbird work.

WEEK ONE: The Pioneers

We took four hummingbird feeders with us to Costa Rica in the hope of hanging two of them at the lodge and enticing ruby-throats to visit so we could catch them in traps like we do at Hilton Pond Center. This plan went awry the very first night, when high winds buffeted the feeders and sent them crashing to the ground. It seems that Buena Vista Lodge, which at 2,440 feet is about a third of the way up the west slope of Rincon de la Vieja volcano, is subject to winter gales that can reach 50 or 60mph, or more. Most days were mildly windy, but nights were marked by either constant high wind or periods of calm punctuated by gusts that suddenly roared in and departed like high-speed freight trains. Of all the things we encountered in Guanacaste, these zephyrs were the least expected, but we came to enjoy them as part of our international experience--especially since the wind also brought misty clouds that almost daily produced a spectacular rainbow or two (above left)--and even a rare black "moonbow" one night when the moon was full.

With two broken feeders and winds too strong to let us run mist nets at Buena Vista, we knew we weren't going to be catching any hummingbirds at the lodge. Thus, on 27 December--our first full day in Costa Rica--Group One (AKA "The Pioneers") boarded our travel bus and set off down the mountain toward the Aloe Vera fields and what we hoped would be a bonanza of Ruby-throated Hummingbirds.

In planning this trip last year, our greatest concern was that all our gung-ho helpers would gather in Costa Rica and be unable to find enough ruby-throats to study. Our anticipation grew that initial morning in Guanacaste as we got to the lowlands and left the bus to walk to the first of the Aloe Vera fields. We forded a stream, checked out ants living in hollow thorns on an Acacia tree, and listened as a trio of Rufous-naped Wrens (right)--looking and sounding like Carolina Wrens on steroids--sang noisily in the shady underbrush. As we looked up the trail, we could see a large clearing ahead--what our guide Ernesto knew was an aloe plantation where he had seen ruby-throats foraging in past years.

Our collective hearts pounded, but as we crested a hill overlooking vast acres of aloe, those quickening hearts nearly stopped beating entirely. In front of us were thousands upon thousands of Aloe Vera plants--potential nectar sources for hummingbirds--but not a single one was in bloom!

Actually, that's only a slight exaggeration. When we got over our initial shock and explored the rows and rows of aloes, we did find a flower stalk or two (left): Pendant yellow blossoms in a tubular shape that would fit a hummer's bill perfectly (below right). A couple of stalks wasn't enough, however, so spirits sank among some participants as they realized we appeared to be a month early for the aloe bloom and that things weren't unfolding as we had expected. Ever-optimistic and a chip off the old block, Billy Hilton III of Hickory NC--along for Week One as an assistant leader--quickly suggested we move to the perimeter of the aloe field where he spotted waist-high purple flowers standing above a weedy plot. Almost immediately a Ruby-throated Hummingbird zipped over, and then a Canivet's Emerald--a small dark green hummer formerly called Fork-taileed Emerald--paused to feed on the blooms. Our spirits rose, for at least we had seen a ruby-throat--even if they weren't going to be catchable in the aloe field.

Ernesto knew of another aloe plantation about a mile away, so we soon departed via bus to see if the second plot had more blooms. As we turned off the main highway between some wood-and-cinder block houses with tin roofs we encountered another impediment--a very dusty dirt road and rickety wooden bridge (below left) that didn't appeal in the slightest to Carlos Ruiz Visquez, our Week One bus driver. We had no choice but to disembark and navigate the rocky road on foot, and this turned out to be the best bit of serendipity on the whole trip. The closer we got to the bridge and the stream beneath, the more we could hear chittering and buzzing hummingbirds. When we looked skyward we were astounded to see more than a dozen ruby-throats foraging in a 30-foot-tall tree right beside the stream and just inside a barbed wire fence that once contained livestock.

Needless to say, we breathed a great sigh of relief in finding an active congregation of our study species, and we immediately began discussing how we might catch the tree-top hummers. Our conversation continued as we crossed the bridge and walked further up the road toward the second aloe plantation, which also turned out to be a dud with few blossoms in view. However, in the fence rows along the way we saw individual ruby-throats flitting about, so we became confident we had indeed found enough birds to capture, band, and observe. Maybe the hummingbird Pioneers from the U.S. could accomplish the mission after all.

That evening we gathered back at Buena Vista Lodge for one of several instructional talks about Operation RubyThroat and its goals; we also gave detailed instructions on how to age and sex Ruby-throated Hummingbirds we would be observing in the field. By week's end, all participants became certified in our hummingbird observation protocols and would be eligible to submit data to The GLOBE Program, either as individuals or on behalf of their students. Having acquired the proper permits from U.S. and Costa Rican authorities, we described some possible methods for trapping and netting the hummers observed near the bridge. Susan Beree of Rockport TX, a Week One participant who has been training to band hummingbirds under Brent Ortego, traveled south with one of Brent's Hall traps (above right)--a collapsible, carousel-shaped device with drop sides, and we had designed and brought from Hilton Pond Center a wire trap that folded up to fit into a large suitcase. (That metal trap--along with our banding tools, camera equipment, battery chargers, mist nets, and other paraphernalia caused quite a stir at various airline checkpoints during the trip, but ticket agents and baggage examiners alike were interested and understanding when we explained we were on a mission to band hummingbirds in Costa Rica.) After the evening lecture we assembled the traps and allowed folks to get extensive experience using the release mechanisms.

On the morning of 28 December the Pioneers ate an early breakfast--including the ever-present black beans and rice--and boarded our bus for another trip down the long and winding road to our study site. Upon arrival at the bridge, we noted that several ruby-throats were already active, and that a much-larger Green-breasted Mango hummingbird had joined the group. Our first task was to hang the wire trap in a low tree and then place a sugar water feeder inside; near this trap we also deployed a 2.5m x 6m mist net at ground level. Then we went to the main tree where the hummers were feeding and devised a pulley device that let us raise the Hall trap and feeder into the tree's top branches (above left). Each trap was kept open by a long, taut stretch of fishing line that, upon release, allowed the Hall trap curtain or wire trap door to descend and harmlessly capture a hummingbird. Under the watchful eye of the master bander, the Pioneers dispersed to vantage points from which they could hold the pullstrings and watch the traps and nets.

All morning our new-found Ruby-throated Hummingbirds ignored the traps and feeders and continued to visit flower clusters in the tree. Through binoculars we could see the tree's blossoms were quite tiny. Expert guide Ernesto climbed up and gathered a twig sample and brought it to ground level, where we found the blossoms measured only 2-3mm across (magnified at right). Most hadn't yet opened, and we marvelled that these miniscule blooms could make enough nectar to keep hummingbirds interested. Ernesto told us this tree was a Jocote, Spondias purpurea, grown frequently as a fence tree throughout Guanacaste Province. Our 30-foot specimen was relatively young with smooth gray bark; a few specimens nearby bore one-inch green fruits that eventually would ripen to red. These large-seeded fruits are harvested by the locals and eaten out-of-hand, even if still bitter and green; ripened, cooked fruits make an excellent jelly. Jocote--sometimes called "Purple Mombin" or "Spanish Plum"--is deciduous and flowers during the dry season when there are no leaves to obscure the blossoms. It was one of few tree species in bloom during our 16 days in Costa Rica. Not being fluent in Spanish, we originally confused this "Jocote" with "Pochote," a tree with fluffy white flowers that also attract several species of hummingbirds. Much larger than the Jocote, the Pochote is a canopy tree with heavy, conical spines on the trunk of mature specimens (below left).

Eventually, as we had hoped, several ruby-throats in the Jocote trees began investigating our two traps, but none seemed inclined to partake of the big red feeders within. Catching hummingbirds is like going fishing; some days you get one, and some days you don't, but the time spent waiting is made more enjoyable by all the things you can see. The Pioneers showed great patience and insatiable curiosity as they watched ruby-throats feed, preen, and interact, and we got to observe things like Squirrel Cuckoos and Orange-fronted Parakeets (below right). Although one ruby-throat occasionally chased another, there was no apparent territorial defense like we see at summer feeders back in the U.S. After several hours of sitting and watching, hummingbird activity slowed down considerably and at 11 a.m. the bus driver reminded us we needed to depart soon for the 90-minute trip back to Buena Vista Lodge for lunch. We took down the mist net and the traps but re-hung the feeders, thinking the Pochote tree hummers might start feeding on them in our absence.

The next day, 29 December, was a carbon copy of the 28th. Get up early, drive down the hill (stopping now and again for a quick look at a Turquoise-browed Motmot or Crested Caracara), get to the study site, deploy the net and traps, and sit back to wait. Same procedure, same result: Lots of ruby-throats observed, none captured, so again we went back up the hill for lunch. One thing we did learn was that the Hall trap, with its gauzy white sides, moved in the breeze and shined in the sun at treetop height. We suspected this distracted and maybe even scared the hummers, so we made a note to hang it low in the shade on the following day and to use the wire trap in the high position.

Although we spent most mornings on our sun-baked study site trying to capture hummingbirds, we elected to pass the afternoons in cooler temperatures back at Buena Vista Lodge. There trip participants were free to explore the lodge's 2,000 acres and miles of trails, and to discover flora and fauna new to them. Folks got to see everything from Coatimundis to Cane Toads to Mantled Howler Monkeys and even took a chance on handling a massive--and scratchy--male Rhinoceros Beetle found one night along the trail (above left). Almost every evening we gathered at the El Mirador lookout, a terrific place to watch the sunset and get mellow before supper and our evening presentations.

During our first two days of running traps and one net, the Pioneers noted that when hummers departed Jocote flowers they often flew east at tree-top height. Determined as we were to capture some of these high flyers, on 30 December we asked Ernesto to wield his machete to topple a tall, straight sapling we lashed to the top of the bus and took down to our study site at the bridge. There we used the pole to erect--with considerable effort--a 2.5m x 12m mist net near the top of the Pochote tree and gained confidence when it immediately captured one of the Tennessee Warblers that seemed to be everywhere. As illustrated in the photo above, this high net became much less effective as the sun rose in the sky and made the netting too visible; nonetheless, during morning it was shaded enough to capture such birds as an adult Green-breasted Mango hummingbird and a Philadelphia Vireo, shown together (below) in a phenomenal size comparison.

After examining and releasing these non-ruby-throats from the high net on 30 December, we also deployed our two traps and a low net as the Pioneers took their observation stations. at 7:45 a.m. Susan Beree volunteered to hold the string on the Hall trap she had brought from Texas.

You'll recollect that we had been leaving feeders in the trees after taking down the traps at the end of each field day. Since sugar water levels were usually lower the next morning when we reported to the study site, we were certain at least some of our local hummers became acquainted with artificial feeders as a food source; we were not surprised that ruby-throats paid more attention to the feeder/trap apparatus while we were watching. What did surprise us that morning was how quickly things began to happen.

At 7:50 a Cinnamon Hummingbird zipped through the study site toward the low-hanging Hall trap but never got there; it was intercepted instead by the 6m net erected nearby. Expert guide Ernesto, who has considerable experience handling tropical hummingbirds, quickly extricated this boisterous red-billed bird from the net and brought it to the master bander's portable work table (above right & below left). There we examined the bird and prepared to take a series of photographs but got distracted at 7:59 a.m. when a watcher called to Susan Beree that a Ruby-throated Hummingbird was approaching her Hall trap; after a hasty picture or two we released the Cinnamon. Meanwhile, ever-vigilant Ms. Beree had an eye on the ruby-throat and her trap, and she was quick to release the string when the hummer entered to feed. Susan was more emotional than one might imagine and the master bander/trip leader was both elated and relieved, for we now had caught our first Ruby-throated Hummingbird in Costa Rica!

It was easy for the master bander to remove the hummer from the Hall trap--the bird simply sat inside as we grabbed it gently and placed in a soft lingerie bag used to hold our captures temporarily. After showing this prize catch to all the Pioneers, we got down to the business of ageing, sexing, measuring, and banding what was for us a very special Ruby-throated Hummingbird. Based on the heavy green streaking and five red feathers on its throat, we knew it had to be a "hatch-year" male, i.e., one that hatched in 2004 somewhere in the U.S. or Canada. This bird looked very much like young male ruby-throats we had banded the preceding August and September at Hilton Pond Center, but there was one major difference: It was molting its primaries, the long flight feathers on the end of the wing. During their first winter ruby-throats replace all their wing feathers with new ones, but since this occurs in the tropics we had never seen the phenomenon back at Hilton Pond in South Carolina.

After banding and then photographing the first hummingbird for posterity, we hardly had time to reflect on the subject of wing molt because Susan Beree--obviously on a roll--had swapped with another Pioneer and was monitoring the wire trap in the top of the Jocote tree. At 8:17 a.m. she released the string and the door dropped shut behind our second ruby-throat capture. The crew lowered the trap with our jury-rigged pulley apparatus and Ernesto retrieved the bird (below), bringing it to the banding table for processing. We barely had time to run the trap back up into the tree when Ann McAllister, our clinical psychologist from Pine Lake GA, caught ruby-throat number three at 8:23 a.m. and then number four at 8:36 a.m. Things were happening so fast that when we caught a fifth hummer in the high mist net at 9:03 a.m., the master bander asked the Pioneers to stop trapping until all the birds in hand were measured, banded, and safely released.

The hummer in the mist net was retrieved by Elaida Villanueva Mayorga, a Costa Rican Indian who--like Ernesto--had worked at the Talamanca Hawk Watch and had considerable experience mistnetting hummers and other bird species on her reservation. Elaida and Oscar Zuniga Meza (a second-year forestry student from San Jose) were able to participate in Week One activities thanks to full scholarships from Holbrook travel and Operation RubyThroat. These two native Costa Ricans brought an important local perspective to our hummingbird work and provided a people-to-people connection that was truly Neotropical.

To say that all the Pioneers were jubilant about our sudden shift in capture results on 30 December would be an understatement. In one morning we had caught and banded five Ruby-throated Hummingbirds--two juvenile males and three females of unknown age--so we knew we wouldn't be going back to the States with no banded birds to our credit. Those first birds will be remembered forever by everyone involved in Week One, as will their sixth bird--another female--caught in the wire trap on 31 December by Yvonne Michel, an outdoorswoman and Sierra Club activist from Charleston SC. Six birds spread over their first six days in Costa Rica was an acceptable average for the Pioneers (above), and a pretty good start on our ruby-throat study in the tropics. We deeply appreciate the work of the Pioneers--who joined us on our very first banding expedition on Ruby-throated Hummingbird wintering grounds. Those not yet mentioned include Erv Davis (retired school principal & bluebird bander, Charlo MT), Cheryl Garnant (medical massage therapist, Myrtle Beach SC), Susan Hilton (trip co-leader & guidance counselor, York SC), Amy Mullenhoff (bank quality consultant, Charlotte NC), Suzanne Parsons (5th grade teacher, Charlotte NC), Betsy Russell (school librarian, Columbia SC), and Lisa Schuermann (stock broker, Charlotte NC).

One of the most pleasant aspects of our mornings on the study site was the interest shown by adults and children who lived in the neighboring community. Amy Mullenhoff (one of our Hummingbird Morning recruits whose favorite phrase in Spanish was "Hi, I'm Amy. What's your name?") was our principal cheerleader. She and the other Pioneers made many new friends in Guanacaste--as did their successors during Week Two--and we were pleased to share our learning experience with inquisitive and pleasant young ticos like five-year-old Joey and his big brother Joshua (above left); Joey (again at right) was with us every day in the field over the whole time we were in Guanacaste. On our final full day at the lodge we took a break from hummingbirds and took a horseback ride up the volcano and through the forest to Buena Vista's on-site spa, where we reflected on the the Pioneers' accomplishments while enjoying a steam lodge, mud bath, and heated pools. Not a bad day to end Week One.

WEEK TWO: Second Wave

On 2 January, as Carlos the bus driver took Week One's Pioneers over the mountains to the airport in San Jose, Ernesto and trip leader Hilton stayed behind to link up with Guillermo (AKA "Whiskers"), the new bus driver (in photo with Carlos below left)--and to greet the Week Two "Second Wave" as they flew into Liberia to replace the first crew. Since the Pioneers had laid considerable ground work, the Second Wave was able to hit the ground running at the study site, so we were pleased but not surprised that on their first full morning (3 January 2005) they managed to trap THREE Ruby-throated Hummingbirds. The first two were young males now classified as "Second-Year" birds because they hatched sometime the previous year (2004). They were caught one after another--8:35 and 8:40 a.m.--in the Pochote tree high trap by Bruce Moorman. (We met Bruce, a semi-retired wastewater treatment specialist from Ypsilanti MI, last summer during our Hummingbird Mornings presentations at Land Between the Lakes, Kentucky, where he immediately committed to the Costa Rican expedition.) Then, at 9:35 a.m. an adult male ruby-throat hit the low mist net--our first ruby-throat in Costa Rica with a full red gorget.

Despite their great success at catching three hummers on their first field day in Costa Rica, the Second Wave caught no birds on 4 January and spent 5 January on a trip to Santa Rosa National Park and a Pacific Ocean beach nearby. There we watched Brown Pelicans dive and a Mangrove Black Hawk eating a coconut. We also spotted a four-foot-long male iguana-like Ctenosaur lizard (above)--with a one-inch tick in its ear!--and marveled at an amazing colony of Stingless Bees (left) guarding and navigating a five-inch waxy tunnel that led to their honey hoard.

To and from our Santa Rosa trip we saw occasional Ruby-throated Hummingbirds sitting on phone lines or zipping across the road, which we took as a sign that we needed to work even harder to catch birds back at the study site. On 6 January we deployed the wire trap in the Jocote tree (below right) and two nets near the bridge--the Hall trap had gone back home to Texas--but sent Ernesto with a second crew to erect two low mist nets at Site B, near the Aloe Vera field about a half-mile away. This strategy paid off nicely, and we ended up catching three birds at the first site and two more at the second. These included another adult male (9:25 a.m.), plus four females that we elected to call "After-Hatch-Year" birds because we couldn't determine a more exact age; they were caught at 9:00, 10:14, 10:25, and 10:27 a.m.

Friday, 7 January was to be our last day in the field, so the Second Wave went all-out setting two traps and two nets at the primary site and four nets at the site near the aloe field. This extended effort went almost for naught, but we did manage net one last female ruby-throat at Site B, bringing our total catch for eight field days spread over two weeks to 15 Ruby-throated Hummingbirds banded and released. Although by some standards this wasn't a lot of birds, it was a worthwhile effort and the first attempt we know of to systematically catch, band, and observe ruby-throats on their Costa Rican wintering grounds.

It's worth mentioning that all 15 Ruby-throated hummingbirds we banded also were marked with temporary blue dye on their neck feathers (see female below left). We did this for four main reasons: 1) to avoid re-trapping birds that were already banded; 2) to help us estimate the number of ruby-throats at our study site; 3) to facilitate behavioral observations and, 4) to allow for the possibility that someone might just see one of our Costa Rican birds on the migration north in Spring 2005. Of these, the latter is least likely because the dye will disappear over the next month or so as the color fades or the hummers molt before migrating. Interestingly, on our last field day--7 January--we could see 12-13 ruby-throats feeding simultaneously in our favorite Pochote tree, but only two were color-marked. From this we concluded that Guanacaste RTHUs might not be site-specific foragers and that they may wander about on the wintering grounds looking for food.

Second Wave participants were first to observe that one of our banded young male ruby-throats--distinguishable by his color mark and the pattern of his incomplete red gorget--actually defended the feeder high in the Jocote tree; he didn't feed there himself after capture, but he did prevent other hummers from exploring or entering the trap in which the feeder hung. This observation was initially made by Peggy Spiegel (a veteran birder from Rockville MD, standing above right) and Patsy Davis (4th grade teacher, Newnan GA, seated on bridge) and may be the first verifiable instance of any sort of "territorial defense" among wintering ruby-throats in Costa Rica.

The remaining Second Wave participants (all shown above) included Jim & Sue Brownell (retired engineer and full-time mom, respectively, from Hickory NC, with Jim celebrating his 78th birthday with us on our last day in Costa Rica), Rebecca Chandler (retired psychiatric and hospice social worker, Pawley's Island SC), Amy McDowell (5th grade teacher, Temple GA, shown below right on horseback), and Peggy Preusch (doctoral student in science education, Rockville MD). Joining these North Americans and receiving full scholarships from Holbrook Travel and Operation RubyThroat were Costa Rican natives Mariela Cruz (high school biology/ecology teacher from San Jose) and Silvia Monge (nature center educator). Again, having these two ticas in the group helped us in many ways; we're especially hopeful that Mariela's students will begin submitting winter observational data through Operation RubyThroat AND connect with North American students who observe breeding season behavior in the U.S. and Canada.

In addition to helping us band hummingbirds, the Pioneers and the Second Wave got an in-depth look at Guanacaste natural history. For example, the first week we recorded 66 bird species--96 during Week Two--and observed a wide variety of plants and animals endemic to Central America. Both weeks involved hot, sweaty work on the study site but provided plenty of time to have a true "Neotropical experience" that included conversations with our Costa Rican participants, visits to the central plaza in downtown Liberia, and that long-awaited horseback ride and mud bath at the volcanic hot springs on Rincon de la Vieja (below).


From 26 December 2004 through 9 January 2005 two successive groups of U.S. teachers and citizen scientists visited northwestern Guanacaste Province, Costa Rica in what may be the first reported systematic attempt to observe and band Ruby-throated Hummingbirds, Archilochus colubris, on wintering grounds in that country. The research and expedition venture was conducted as part of Operation RubyThroat: The Hummingbird Project, an education outreach initiative of Hilton Pond Center for Piedmont Natural History in York SC. Research was conducted under the approval of U.S. and Costa Rican authorities using bands issued by the U.S. Bird Banding Laboratory. All banding was done by trip leader Bill Hilton Jr. (master bander #21558).

Pull-string traps (baited with sugar water feeders) and 25mm mesh mist nets in various lengths were deployed at several sites near Liberia CR. Of the 15 Ruby-throated Hummingbirds (RTHUs) captured and banded 30 December 2004 through 7 January 2005, two were fully gorgeted adult males hatched prior to 2004 (above right), four were partially gorgetted young males from 2004, and nine were plain-throated females of undetermined ages. All birds showed significant molt in their remiges (wing feathers), with most retaining 3 or 4 outer primaries that were somewhat faded and worn; inner primaries and primary covert feathers showed varying degrees of replacement, and heavy rectrix (tail feather) wear was evident in nearly all females and young males. The four young males had varying degrees of dark streaking on their throats and had only 4-6 metallic red feathers in their gorgets. All measurements (wing chord, tail length, culmen, and weight) were similar to those in birds of the same ages and sexes in the U.S.; none of the birds showed any furcular fat accumulation. One female had a malformed lower bill (above left), perhaps due to injury or fungal infection.

RTHUs at the primary study site and elsewhere showed strong preference for Jocote trees, Spondia purpurea, which were leafless but in full bloom during the period. RTHUs foraged in lesser numbers on other herbaceous, viny, or woody plants, especially bright red Turk's Cap, Malvaviscus palmanus (above right); plus yellow-orange Shrub Verbena, Lantana camara, and an unidentified vervain-like purple-blue flower (below), possibly Blue Porterweed, Stachytarpheta jamaicensis. Cultivated fields of yellow-flowered Aloe, Aloe vera, an anticipated hummingbird food source around Liberia, were not in full bloom during the study period, but ruby-throats were seen foraging high up in white-flowering Pochote trees, Bombacopsis quinata

RTHUs were far more common than we had expected, although very few adult males with full red gorgets were observed at the main study site or elsewhere. We encountered RTHUs throughout northwestern Guanacaste in groups at Pochote trees and frequently as individuals on highway rights-of-way, in fence rows, and along open trails from 100m to 750m altitude--especially where the were patches of nectar-bearing plants mentioned above. Migrant RTHUs far outnumbered all resident hummingbirds, which included Cinnamon Hummingbirds, Steely-vented Hummingbirds (left), Green-breasted Mangos, Canivet's Emeralds (formerly Fork-tailed), and noticeably long-billed Plain-capped Starthroats (below). We witnessed no dominance by larger resident hummingbirds over RTHUs but did observe an apparent territorial defense in which a young male RTHU repeatedly kept others of his species from visiting a sugar water feeder hanging inside a trap. This observation was facilitated because each banded RTHU was also marked with temporary blue dye on its neck; this dye is expected to fade or be molted off within a month or two, but the possibility remains that observers in the U.S. or Canada may see blue color-marked RTHUs from Costa Rica during northward migration in Spring 2005.

Although Guanacaste is frequently described as "marginal hummingbird habitat," it actually may be an optimal place for wintering RTHUs. Food sources seem adequate, and competition from non-migrant hummingbird species appears minimal. Our banding work would have been facilitated by a permanent hummingbird feeding station at which RTHUs might concentrate, but we were not able to find such a site. Strong winds during the mid-winter dry season in Guanacaste make running mist nets less effective; late November or late February might provide better conditions for deploying nets.


We wish to acknowledge the help of Debbie Sturdivant and other Holbrook Travel representatives for handling travel arrangements; Paulo Valerio for organizing in-country activities and recruiting native Costa Rican participants; expert guide Ernesto Carman for his natural history skills, boundless energy, and language interpretation; Leica USA for a very fine Ultravid 10x42 BR binocular graciously loaned to the vision-impaired trip leader; subscribers to HumNet, BirdChat, Ornith-L, and other listservs for sharing their RTHU observations from Costa Rica; Avinet (Mary Beth & Sam Sumida) for in-kind support; and the National Fish and Wildlife Foundation (Peter Stangel), ConocoPhillips, and National Science Foundation (Paul Filmer) for general financial support of Operation RubyThroat.

We also thank residents of Canas Dulces for graciously allowing us to conduct research in their community and for providing a true cross-cultural experience (see photo below). Lastly, and most importantly, we acknowledge the 16 Pioneers and 13 Second Wave participants, without whose hard work, energy, positive attitudes, and financial commitment we could not have spent two weeks studying Ruby-throated Hummingbirds in Costa Rica.


Because of the great potential for learning more about behavior of Ruby-throated Hummingbirds (RTHU) in the tropics, we are planning additional trips in Guanacaste Province, Costa Rica in 2005/2006. Trips will be a mix of research, educational, and cultural activities and will be open to any adults--especially K-16 teachers. The December 2004 trip coincided with Christmas vacation in U.S. schools, but this may not be the optimal time to capture and band RTHUs; it's also an expensive time to fly into Costa Rica.

We have opened enrollment for an new eight-day expedition on 11-18 February 2006. Land costs (food, lodging, land travel, instructional activities, etc.) are $1,199, plus airfare (usually less than $700, depending on your distance from staging areas in Atlanta or Miami. Please note that because of difficulties with international connections, it may be necessary for you to spend an extra night traveling to and/or from Costa Rica).We are also offering a special late-winter trip for 11 thru 18 Feb 2006 d The expedition will focus on trying to capture and band Ruby-throated hummingbirds just prior to their departure for the migration north.

If you are interested in participating in our important hummingbird investigations, please contact Debbie Sturdivant at Holbrook Travel (1-888-890-0632). For details about the upcoming trip, please see Costa Rica Trip Announcement 2005.

Banded and color-marked female Ruby-throated Hummingbird feeding on nectar from Jocote tree flowers, Guanacaste Province, Costa Rica, December 2004

All text & photos © Hilton Pond Center

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NOTE: Be sure to scroll down for an account of all birds banded or recaptured during the week, as well as some other interesting nature notes.

"This Week at Hilton Pond" is written & photographed
by Bill Hilton Jr., executive director of
Hilton Pond Center for Piedmont Natural History.

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Oct 15 to Mar 15
Please report
your sightings of
Vagrant & Winter


1-14 January 2005

American Goldfinch--13
House Finch--8 *
Purple Finch--3
Northern Cardinal--3
Northern Mockingbird--1

* = New species for 2005

5 species
28 individuals

5 species
28 individuals

(since 28 June 1982)
124 species
45,335 individuals

All text & photos © Hilton Pond Center

This Week at Hilton Pond
is part of the

(with original banding date, sex, and current age)


--As noted above, we were in Costa Rica 26 Dec 2004 thru 9 Jan 2005. The first banded bird of the new year at Hilton Pond Center was a Northern Mockingbird caught 11 Jan in a pull-string trap baited with black sunflower seeds. We assume the bird was after insects but also may have been nibbling on scraps left behind by finches and other birds that typicaly eat seeds.


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Hilton Pond Center for Piedmont Natural History is a non-profit research & education organization in York, South Carolina USA; phone (803) 684-5852. Directed by Bill Hilton Jr., aka The Piedmont Naturalist, it is the parent organization for Operation RubyThroat. Contents of this Web site--including articles and photos--may NOT be duplicated, modified, or used in any way except with the express written permission of Hilton Pond Center. All rights reserved worldwide. To obtain permission for use or for further assistance on accessing this Web site, contact the Webmaster.

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