8-21 February 2006

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The day after Christmas 2004, we led our first-ever hummingbird expedition from Hilton Pond Center to Costa Rica. Although we had done our homework on Ruby-throated Hummingbirds and knew some of them spend non-breeding months in Guanacaste Province on Costa Rica's Pacific Coast, we weren't exactly sure what we would find when we arrived. Thus, it was appropriate we nicknamed our first traveling troupe of teachers and citizen scientists the "Pioneers," for we truly were the first to systematically study and band ruby-throats on Costa Rican wintering grounds. Although there are plenty of anecdotal records of Ruby-throated Hummingbirds from Guanacaste, we could find no published reports of how many we might expect, where they might be concentrated, or exactly what their tropical food sources might be.

All text & photos © Hilton Pond Center

Fortunately, through Holbrook Travel we connected with Ernesto Carman, a crackerjack young field ornithologist who had spent some time observing ruby-throats around Liberia, Guanacaste's capital. The good news was that Ernesto had seen concentrations of ruby-throats feeding in cultivated fields of Aloe Vera. The bad news was that when we got to Guanacaste in December 2004 with Ernesto as our guide, we discovered we were too early and the aloe was not yet in bloom. Fortunately, we managed to locate a Jocote tree upon which a couple dozen Ruby-throated Hummingbirds were feeding--including an adult male (above)--and after running a pull-string trap up the tree the Pioneers and a follow-up group dubbed the "Second Wave" were able to capture, band, color-mark, and observe behavior of 15 hummers over a two-week span. Although 15 ruby-throats might not seem like much, it more than equaled the all-time total of 14 banded by various folks in Costa Rica who caught them incidentally from 1978 through 1988.

Aware of the difficulty we had finding and banding big numbers of of ruby-throats in Costa Rica in December 2004 and January 2005, for the 2006 trip we decided to travel to Guanacaste a bit later in the season, suspecting Aloe Vera would be in bloom by the second week in February. We were also hoping the ruby-throats would NOT have left Guanacaste by then on their way back north. We recruited a new group of hummingbird enthusiasts from Michigan, Missouri, Ohio, Pennsylvania, South Carolina, and West Virginia and--along with two Costa Rican teachers who participated via full scholarships provided by Hilton Pond Center and Holbrook Travel--met up again with Ernesto Carman in Liberia this past 11 February. This new group--called the "Oh-Sixers"--was just as enthusiastic and optimistic as their predecessors as they rendezvoused at the airport and traveled by bus halfway up a volcano to Buena Vista Lodge. That evening we talked extensively about our plan to scout aloe fields the next morning.

After a pleasant first night at Buena Vista, we arose early on Sunday (12 February) for our drive back down to the Canas Dulces community where several aloe plantations and last year's study site were located. Not long after leaving the lodge we noticed an overgrown pasture being grazed by horses and Zebu (above right), hump-backed cattle originally from India that are nearly omnipresent on Guanacaste's many ranches. However, what really caught the attention of Alice Slisher--an old friend from our days at Pennsylvania's Hawk Mountain Sanctuary--was an extensive stand of Purple Vervain within the pasture. Eagle-eyed Alice became the first Oh-Sixer to spy a ruby-throat, observable through the bus window as it flitted from one Vervain stalk to the next, feeding all the while on tiny quarter-inch flowers (left). Exuberant, the crew grabbed binoculars and poured out of the bus to observe more closely the object of our quest. In the next 15 minutes we spotted at least six ruby-throats--including one adult male with full red gorget--so we knew we could always try this pasture as a place to unfurl mist nets or deploy our hummingbird trap.

After this initial encouragement we wanted to get down to the flatlands at Canas Dulces to see what the aloe fields had to offer. Arriving at the first plantation, we again took binoculars, exited the vehicle, and made our way through a hardwood thicket to get to the aloe. As we traversed a small stream serenaded by songs of Rufous-naped Wrens, our anticipation grew until we crested a small hill that looked over perhaps 40 acres of Aloe Vera--only to find that almost none of the plants were in bloom! For more than a year we had anticipated--even dreamed about--dozens of Ruby-throated Hummingbirds so intent on drinking aloe nectar we could capture them easily in our nets, but the near-absence of blossoms in this field quickly burst that bubble. We did see a female ruby-throat perched in a small tree from which she made frequent forays to a few aloe stalks with yellow blooms, but this one "trappable" bird would not comprise a successful field season in Guanacaste. We also noted several ruby-throats foraging on tree-top flowers on 50-foot-tall Pochote trees near the edge of the field; there was no way we could get to them, however, especially since Pochotes have trunks studded with rather nasty thorns (above right).

Needless to say, the near-absence of Aloe Vera flowers was NOT what we were expected nor what we wanted, but having traveled from the U.S. to Costa Rica we weren't about to give up easily on finding a concentration of Ruby-throated Hummingbirds. From the first almost-barren aloe plantation we traveled to the west side of Canas Dulces to check out the Jocote tree that last year had yielded most of our 15 banded hummers. Optimistically, we walked down the dusty road toward an old bridge that adjoined the tree and looked upward into the branches of the Jocote. It was covered by thousands upon thousands of tiny red flowers (above left), but not a single hummingbird was in sight! Again we were disappointed not to find ANY ruby-throats, but we weren't completely surprised. After all, even though there were dozens of Jocotes in full bloom along the road last year, only the tree at the bridge had supported any hummer activity. Maybe this year the birds had just moved on to another Jocote we needed to locate.

After waiting a few minutes for ruby-throats to appear at the bridge, we forged onward along a dirt road that led to the next Aloe Vera plantation. This was a dusty walk made pleasant by tropical birds songs and the occasional outburst of a Mantled Howler Monkey--to say nothing of interesting conversations among the Oh-Sixers. The road meandered through pastures and past a variety of flowering trees and shrubs, including the brilliant red Turk's Cap (above right) and orange and yellow Lantana; in 2005 we had observed ruby-throats foraging on both these flowers, but no birds were seen feeding this year, and we began wondering if there really were any hummers at this lower elevation. Finally, about a half-mile from the bridge, the road took a sharp turn to the left--just before a gate that led to the next Aloe Vera plantation. We had barely turned this corner when Ernesto shouted out excitedly: "They're blooming!"

Indeed, even from the road we could see that many Aloe Vera plants were producing single or branched four-foot stalks festooned with dozens of tubular yellow flowers. And--better yet--there were hummingbirds foraging on the blooms! Ernesto, who had promised us 'way back in 2004 that aloe plantations were THE place to find Ruby-throated Hummingbirds in Costa Rica, was finally vindicated.

All text & photos © Hilton Pond Center

The Oh-Sixers were spellbound by the scene: Acres and acres of spiny succulents--many blooming--with at least a dozen ruby-throats probing the blossoms for nectar. It looked as if we finally might have found the "mother lode" for hummingbirds in this part of Guanacaste. We watched for a long time, straining our eyes through binoculars and eventually came to a surprising conclusion: The local population of Ruby-throated Hummingbirds seemed to include females with white throats and streak-throated young males from 2005 that were finally getting some red gorget feathers. Try as we might, we couldn't spot any fully gorgeted males in adult plumage.

The initial question was why this aloe field was in flower when the first one we checked was almost barren. The answer likely lay at the ends of long rubber hoses, which ran from a holding tank to water sprinklers on tall stands. It seems this field was under irrigation and--judging from the chemical odor emanating from a small shed--may have been receiving pesticide and/or fertilizer treatments to boot. In other words, water plus chemicals yields flowers. Henceforth, to maximize our opportunities to see Costa Rican ruby-throats we'll always try to find a well-tended aloe plantation, and we'll visit just after the first of February.

It was a no-brainer that this particular aloe field would be our primary research site for 2006, but we urged the Oh-Sixers to wander a little further, mostly because we knew from last year that additional patches of aloe lay ahead. We scoped out several of these smaller fields--some of which had limited blooms and a few ruby-throats--but since none looked as promising as the field we had just left we returned to it and estimated the number of hummers in view at any given moment at 18 or so. Then, since noon was approaching, we happily strolled back to the bus for the ride to the lodge and lunch--bubbling with anticipation over the next day's potential for netting and banding hummingbirds.

We were up bright and early at Buena Vista Lodge on the morning of 13 February. After our usual breakfast of fresh juice, locally grown fruit, scrambled eggs, and the ever-present black beans and rice, we loaded our net poles and other banding gear in the bus for the 40-minute ride back to Canas Dulces, arriving at the "Jocote tree bridge" by about 6:30 a.m. Our bus driver Fausto didn't trust the rickety wooden bridge, so we had to pack in all our gear from there; we finally got to the promising aloe field shortly before 7 a.m.--a little later than we might have liked. At that point some more experienced members in the group demonstrated how to hang a 42-foot-long and seven-foot-tall mist net down a row of Aloe Vera. This is no easy feat when you remember these succulents have leaves edged with tiny prickles just waiting to catch of the mesh of the net--especially when the wind is blowing (above left). We professionals had the first net up in short order, however, and were about to give the Oh-Sixers a chance to unfurl another when at exactly 7:12 a.m.--Poof! A Ruby-throated Hummingbird zipped right past us and into the net. Less than 15 seconds later--Poof! Another hummer, in the net only a few feet away from the first. Surely after working so hard last year for 15 hummingbirds it couldn't possibly be THIS easy in 2006?

We quickly extricated our first two hummingbirds from the net and carefully placed them in soft mesh lingerie bags--a safe way to store them temporarily as we set up a makeshift table and got out our banding tools. Meanwhile, Ernesto split up the rest of the group and helped them erect two more nets (above), one at the end of the first and the other at a lower area of the aloe field where there were lots of flowers. (The standard joke was: "How many Oh-Sixers does it take to set up a mist net in an aloe field." The answer: "All of them. Two to hold the poles, four to unroll the net, two to tie off the support stakes, and two more to untangle everybody else when they catch themselves and the aloe flowers in the net." Just kidding, of course. The Oh-Sixers did a terrific job all week long.)

Not to brag or anything, but that first day of running mist nets was exhilarating and exhausting--and very, very busy. Believe it or not, removing back to back to back to back hummingbirds from the nets, banding them, making measurements, and recording data can tire out everyone, especially the bander. To make our long story a bit shorter, between 7:12 and 10:37 a.m. on Monday, 13 February, we ended up catching 18 Ruby-throated Hummingbirds--three more than we caught in our entire two weeks last year. And after an all-day visit on Tuesday to Santa Rosa National Park (above right) to learn about tropical DRY forest ecosystems, we were back at the aloe plantation again on Wednesday (15 February), when we put up the same nets and a fourth one, this time capturing and banding 19 more ruby-throats. And on Thursday, our last day in the field, we caught 14 more--a total of 51 Ruby-throated Hummingbirds for 2006! Never in our wildest dreams . . . .

So what did we learn from all this early morning hummingbird work in Guanacaste Province, Costa Rica in February 2006? A lot, we think:

  • NONE of the 51 RTHUs we banded was an "adult" male with a complete red gorget. (Our guess is that most older males had already left Guanacaste on their northward migration. This makes sense, since at typical U.S. locales the first adult males RTHUs arrive a week or so ahead of adult females. However, it could be that many adult male RTHUs overwinter further north, perhaps in Mexico or Guatemala or Nicaragua. Or they may use different food sources and habitats than females and younger males on the wintering grounds--although two of the 15 RTHUs we banded last year in January WERE fully gorgetted adult males. All this requires further investigation; field studies of RTHUs are needed in EVERY country where they overwinter.)
  • Of our 51 banded Ruby-throated Hummingbirds (RTHUs), 22 were second-year males that hatched out in 2005 somewhere in the U.S. or Canada and had varying numbers of red feathers in their gorgets (right). (If these guys intend to migrate north to breed in 2006, they'd better hurry up with completing their throat molt.)
  • The remaining 29 RTHUs were all females. Their ages could not be determined precisely because by this time of year all female age classes look pretty much alike. (There may be intricacies of molt sequence that could allow age determination on the wintering grounds, but this will require further study and analysis. We did find that, by February, corrugations--those tiny etchings found along the upper bill of younger birds--have disappeared and are useless as a clue to age.)
  • Nearly all RTHUs captured in 2006 had almost completed molting their primaries--the ten long outer wing feathers. Typical birds had replaced their inner seven or eight primaries with new feathers but, interestingly, most were bringing in a new outermost primary #10 while still holding the old #9 primary next to it. (This actually makes sense, since primary #9, which is a bit heavier and wider, may be more important for long-distance flight and needs to be as fresh as possible as northward migration begins. Last year, when we were in Costa Rica about six weeks earlier, most RTHUs still carried four outermost primary feathers that were old and worn, as shown above right.)

  • Recently fledged RTHU males resemble females; i.e., they have white or lightly streaked throats but no red gorget feathers; young males and females also have white rounded tips on their outer three tail feathers. By comparison, adult males have black-tipped tail feathers that are pointed. One young male we banded in the aloe field in 2006 demonstrated asynchronous tail molt, retaining juvenile white-tipped feathers on one side of his tail while bringing in adult feathers on the other. (See photo above, in which a worn and brown-faded #9 primary also appears at left foreground.)
  • Many male RTHUs we caught had yellow pollen caked on their toes--something not observed in females we captured. Although we didn't observe it directly, we suspect this means the males--which are 25% smaller--may grab onto aloe flowers as they feed, while the somewhat larger females may tend to hover more. (This could mean males and females are making slightly different use of the aloe resource. We did photograph one female perching on an aloe flower stalk--but not the blossom itself--as she stretched her bill into the lowermost open aloe flower; see photo at bottom of this page. CAVEAT: It may be that sticky yellow pollen on males' toes didn't actually come from aloe flowers but from some other blossom males--not females--were visiting; next year we'll take pollen samples from aloe flowers and hummer toes and compare the pollen microscopically.)
  • With one same-day exception NONE of our banded RTHUs in 2006 were recaptured locally. We doubt they all got net-wary so we hope this means we caught these birds as they were already in migration and moving north--which could enhance the possibility they'll be encountered in a month or two or three as they arrive to breed in the U.S. or Canada. (Please be alert this spring for our banded Costa Rica RTHUs with BLUE dye on their throats, and don't forget we're still using GREEN color marks on RTHUs we band at Hilton Pond Center.)
  • We learned bunches of other stuff while banding Ruby-throated Hummingbirds this year, but choose to stop the list here so we can talk about a small sampling (below) of other things experienced by the Oh-Sixers while in Costa Rica.


GREEN-BREASTED MANGO, Anthracothorax prevostii (male)

In the Aloe Vera field we saw numerous birds besides ruby-throats, and actually netted but did not band three other resident hummingbird species, all males: Green-breasted Mango, Cinnamon Hummingbird, and a very-long-billed Plain-capped Starthroat. Also foraging for aloe nectar were a Steely-vented Hummingbird and a Garden Emerald.


Costa Rica is home to four species of Cecropia, a tall tree whose 18"-diameter leaves (above and below left) cast considerable shade. Most individual Cecropia trees are "myrmecophytic"; i.e., host plants for ant colonies of ants (Azteca spp.) that--while finding shelter in the hollow tree--drive away potential herbivores and even snip vines that start to grow on the Cecropia. Surprisingly, at Santa Rosa National Park we found horizontal rows of holes in a Cecropia trunk (below right)--sure signs that a Yellow-bellied Sapsucker from the far north had flown at least this far south to spend the winter.

. .

GROOVE-BILLED ANI, Crotophaga sulcirostris

Almost everywhere you look in Guanacaste Province there are pairs, trios, or small flocks of Groove-billed Anis, birds that superficially resemble blackbirds but are actually in the Cuculidae--the same family as New World cuckoos and the Greater Roadrunner. The huge, black, sculpted bill of this species is an indisputable field mark.

. .


Despite our field guides and the considerable natural history knowledge of expert guide Ernesto, there were plants and animals we couldn't confidently identify to species as we explored Santa Rosa National Park. These included a colony of bats hanging in the wooden rafters of an interpretive center (above left), a foot-long terrestrial lizard (above right), and a shrub with diminutive red-orange flowers (below). Please let us know if you recognize any of them.

. .


One social highlight of our Costa Rica trips always comes on the last full day at Buena Vista when we saddle up and ride horseback to a volcanic spa on the lodge's vast property. After bouncing along the trail through savannahs and upland forest, it's great fun to spend a few minutes getting sweaty in the steam room and then plastering hot and gritty volcanic mud onto each other--including the ever-smiling locally born Sandra Perez Brenes (above right). Everyone's final reward for this muddy mess is a quick cold shower followed by a restful hour in whichever of several warming pools is set at a temperature that feels most pleasant.


In addition to assisting with our Ruby-throated Hummingbird field work in Guanacaste Province, all Oh-Sixers also got certified in hummingbird observation protocols we designed for Operation RubyThroat: The Hummingbird Project and The GLOBE Program. Through GLOBE, certified participants--students, teachers, and citizen scientists--from Canada, the U.S, Mexico, and all seven Central American countries observe Ruby-throated Hummingbirds and submit their data electronically via GLOBE's Web site. These data can then be correlated on-line with observations about atmosphere, climate, soils, hydrology, land cover, phenology, and other factors that may influence hummingbird behavior. Maria Auxiliadora Portugez--our Oh-Sixer computer science teacher from near San Jose--was already certified in many of these other protocols, and thus became the FIRST Costa Rican GLOBE teacher to be certified in hummingbird observation techniques!

PAINTED BUNTING, Passerina ciris

Other birds that hit our mist nets in the aloe field included three Neotropical migrants that breed in the U.S. or Canada: Tennessee Warbler, Indigo Bunting, and--our favorite since we'd never handled one before even though the species nests in coastal South Carolina--a brilliant, breathtaking male Painted Bunting, whose multi-hued plumage rivaled even the brightest of resident tropical species. Whew! What a bird!


Following our long morning of catching and observing hummingbirds and a typical afternoon of nature-photography, birding, exploring, water-sliding, canopy-walking, or just plain chilling out, the Oh-Sixers gathered at Sunset Lookout each evening to gaze at Sugarloaf Mountain and watch the golden orb sinking into the Pacific Ocean nearly 20 miles away. It was a great show of which folks never grew tired, even though they always seemed to know how the drama would finally come out.


And for folks with real staying power, if you waited long enough after a sunset in the west, at least once a month you'd be rewarded by a full moon rising in the east. In this photo the gravid Moon breaks through clouds that typically hung just above the active Rincon de la Vieja volcano that towers over Buena Vista Lodge.


Left to right: Bill Hilton Jr. (York SC, trip leader), Fausto (San Jose, Costa Rica bus driver), Maria Auxiliadora Portuguez (San Jose, Costa Rica GLOBE teacher), Bruce Moorman (Ypsilanti MI, and a veteran Second Wave participant from last year), Chris Moorman (Ypsilanti MI), Sandra Perez Brenes (Liberia, Costa Rica educator-naturalist), Jim & Ramona Edman (Circleville OH), Alice Slisher (Reading PA), Chuck Wirtz (Charleston WV), Pat & Joan Esserman (St. Louis MO), and Ernesto Carman (Paraiso, Costa Rica, expert guide and interpreter).

OUR "OH-SIXERS" TICAS (female Costa Ricans)

Sandra Perez Brenes (left) and Maria Auxiliadora Portuguez at a gateway to Buena Vista Lodge.

Female Ruby-throated Hummingbird, Archilochus colubris,
perch-feeding on a yellow, tubular Aloe Vera blossom

All text & photos © Hilton Pond Center

POSTSCRIPT #1: After our overwhelmingly successful 2006 Ruby-throated Hummingbird expedition to Costa Rica, you can bet Hilton Pond Center and Operation RubyThroat: The Hummingbird Project will be offering trips again in the winter of 2007. Next year we'll travel a little earlier to see if adult male ruby-throats are still on the non-breeding grounds the first week in February. For information about going on one (or both!) of our two eight-day trips planned for 3-10 and 10-17 February 2007, please visit Upcoming Costa Rica Hummingbird Expeditions and join us for a once-in-a-lifetime experience in the balmy tropics--when much of the U.S. is still locked in the cold of winter!

POSTSCRIPT #2: If you like coffee but feel guilty about drinking a product that leads to the decimation of tropical forests, consider switching to shade-grown coffees that thrive under a tree canopy that supports a great diversity of wildlife. Ernesto Carman (right), our intrepid Costa Rican guide, grew up on family-owned "Finca Cristina"--a fully organic, shade-grown coffee farm that is home to 272 species of birds and countless other tropical animals and plants. In his "spare time" when he's not working as an expert guide, Ernesto creates frog ponds, plants native trees, and further tries to return part of the property to its natural state. In support of the farm's sustainable industry and conservation efforts, Ernesto's mother Linda will be happy to take your order for Cafe Cristina via the farm's Web site or toll-free number.

All text & photos © Hilton Pond Center

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Be sure to scroll down for an account of all birds banded or recaptured during the week, plus other nature notes of interest.

"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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Vagrant & Winter


8-21 February 2006

American Goldfinch--78
Purple Finch--49
House Finch--3

* = New species for 2006

3 species
130 individuals

11 species
209 individuals

(since 28 June 1982)
124 species
46,790 individuals

(with original banding date, sex, and current age)
American Goldfinch (4)
02/15/02--6th year female
12/11/02--after 5th year male
02/01/05--3rd year male
04/20/05--3rd year male

Carolina Chickadee (1)
06/10/05--2nd year unknown

Purple Finch (1)
01/26/04--after 3rd year female

House Finch (1)
08/02/05--2nd year male

All text & photos © Hilton Pond Center

This Week at Hilton Pond
is part of the

--With our Costa Rica trip
(see photo essay above) and an out-of-town family funeral taking up most days between 8-21 Feb, we actually banded only on 10 & 19-21 Feb. Nonetheless, thanks to Purple Finches and House Finches, we had our most productive period of the winter at Hilton Pond Center; 130 captures more than doubled the 58 birds banded 1-7 Feb.

--Ticks continue to be more prevalent than usual this winter on birds handled at the Center. A still-brown Purple Finch banded 26 Jan 2004 as an after-hatch-year bird of unknown sex was found dead on the back deck of the Center's old farmhouse on 21 Feb. The bird, now classified as an after-third-year female, had three large ticks around its right eye and another over its left eye--possibly enough to impair its vision and lead it to fly into a glass patio door. A free-flying second-year male House Finch trapped the same day had one fully engorged 7mm tick over its right eye.

--A mini-raft of Ring-necked Ducks--one male and two females--has been cruising Hilton Pond for at least two weeks, leaving picturesque ripples in its wake.


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