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THIS WEEK at HILTON POND
1-14 January 2005
Installment #253---Visitor #
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RUBY-THROATED HUMMINGBIRDS 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 INTRODUCTION 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 (www.rubythroat.org) 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.
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. 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. 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.
Our collective hearts pounded, but as we crested a hill overlooking vast acres of aloe, those quickening hearts nearly stopped beating entirely. 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. 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.
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. 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. 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. 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. 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; 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. 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. 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. 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. 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. 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. 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. 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. 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.
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). 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). SUMMARY & CONCLUSIONS 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. 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.
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. 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. ACKNOWLEDGEMENTS 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; 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. FUTURE PLANS 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
Comments or questions about this week's installment? 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 You may wish to consult our Index of all nature topics covered since February 2000. You can also use the on-line Search Engine at the bottom of this page. For a free, non-fattening, on-line subscription to "This Week at Hilton Pond," just send us an E-mail with SUBSCRIBE in the Subject line. Please be sure to configure your spam filter to accept E-mails from hiltonpond.org.
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SPECIES BANDED THIS WEEK: * = New species for 2005 WEEKLY BANDING TOTAL YEARLY BANDING TOTAL (2005) BANDING GRAND TOTAL
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NOTABLE RECAPTURES THIS WEEK
NONE THIS WEEK OTHER SIGHTINGS OF INTEREST VAGRANT HUMMINGBIRDS
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