The Gone Birding Newsletter
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Vol. 6, No. 2 |
April 2005 |
White-crowned Pigeon Shows at Tortuguero
Within days of the publication of the previous newsletter, Paco Madrigal was already busy producing material for this issue. On 02 February, while birding with a group lead by Ken Wilson, they arrived at Tortuguero for the gran finale of their two-week tour. After having suffered poor weather elsewhere on the Caribbean side of the country, they were welcomed by clear skies as they set off on their first boat ride into the canals at 15:30. They had only gone 300 meters from the Laguna Lodge when a bird was spotted on a high branch of a Cecropia tree growing along the west bank of the river. Paco reports that “Ken thought it was a hawk and Jaison (the boatman) took it for a pigeon and didn’t even slow down. I hadn’t located the bird yet and asked Jaison to stop in order to verify the sighting. When I found the bird in my binoculars, I couldn’t believe that what I was seeing was a White-crowned Pigeon (Columba leucocephala)—a new bird for me! We came to within about 20 meters of the bird and watched it for 15 minutes.”
Given the timely diffusion of the news of this sighting, Julio Sánchez was able to visit Tortuguero a week later and still find the bird in the same general area. Both Ken Wilson and Julio got photos of the bird, and Julio reported that it was feeding on fruits of Conostegia xalapensis, a melastome commonly known as lengua de vaca.
Interestingly, during that visit to Tortuguero, Paco also saw a Band-tailed Pigeon (Columba fasciata). Odd that this highland species would be out along the Caribbean coast, but maybe the aforementioned bad weather might have had something to do with its occurrence.
Lark Sparrow Found at Las Cenizas de P.Z.
The phone rang as I was fixing breakfast on Saturday morning, 05 March. When I heard Jim Zook’s voice on the other end, I immediately thought, “This ought to be something good!” In fact, as we spoke, Jim was looking at a Lark Sparrow (Chondestes grammacus), a species which has only been reported on three previous occasions in Costa Rica.
Jim was birding along the road about 50 meters west of the church in the village of Las Cenizas de Pérez Zeledón, which is about six kilometers south of San Isidro de El General, when he spotted the bird in a brushy pasture. It was the next best thing to being there to hear Jim exclaim as he spoke on his cell phone, “There it goes, it’s flying to a tree!”
See Da Waxwings?
Well, no I didn’t, but lots of other lucky birders did.
Apparently, the two reports of Cedar Waxwing (Bombycilla cedrorum) mentioned in the last edition of the GBN were just the tip of the iceberg. This “sporadic winter visitor”, as the field guide terms it, definitely has had an irruptive year here in CR. The reports I received, in chronological order, are as follows:
05 Feb: Liz Jones of Bosque del Río Tigre wrote saying that “there have been several reports of the Cedar Waxwing on the Osa, including one today by Ulisis Quintero while birding behind our lodge.”
12 Feb: Jhimmy Castiblanco of Jacó discovered a group of about 60 waxwings feeding in some fruiting trees across the street from the Herradura gas station. Jhimmy stated that the birds were seen “sliding along the branches, eating small fruits and staying still for about one minute before jumping again to another branch to pick up another fruit. They kept coming to the same group of trees for about 14 days and as the food supply was running short, the number of individuals was also decreasing. They were very punctual and came every day at aprox. 6:00 and stayed for about one hour before they moved away.”
13 Feb: Jesse Ellis reported six individuals flying over Santa Rosa NP.
21 Feb: Luis Sandoval observed a group of waxwings feeding in a fig tree in Getsemani de San Rafael de Heredia, and was told that they had been there for about two weeks.
This same day, Daryl Loth reported seeing waxwings in Tortuguero.
26 Feb: Jim Zook had a flock of 11 birds near his home in Naranjo.
01 Mar: Rafa Campos and his Audubon group logged two sightings of Cedar Waxwing at the Wilson Botanical Garden. The first group consisted of four birds and the second had nine.
02 Mar: Daniel Martínez and Keith Larson spotted 15 individuals “in migration” at Tamarindo.
03 Mar: Jim Zook sighted seven waxwings near Volcán de Buenos Aires.
05 Mar: Liz Jones mentioned that “Cedar Waxwings are all over the place.”
Nor was the Osa Peninsula the only place they were that day, as the second annual La Amistad NP bird count produced 76 individuals near the community of Tres Colinas.
With all those sightings there must also have been others, news of which never reached me. However, it would seem that most of the waxwings departed in early March, since during my touring from 10 March to 22 April I neither saw any waxwings nor heard any further reports from other birders.
Migrant Round Up
Other North American migrants of note seen during the past three months were:
Northern Harrier (Circus cyaneus): On 11 February, Jesse Ellis saw one individual “being harrassed by magpie-jays out on one of the firebreaks at Santa Rosa NP.”
Long-billed Curlew (Numenius americanus): On 26 February, Daniel Martínez and Keith Larson found one bird amongst numerous Royal Terns (Sterna maxima), Elegant Terns (Sterna elegans) and Laughing Gulls (Larus atricilla) at Playa Azul.
Dunlin (Calidris alpina): In addition to the pair that was repeatedly seen at the mouth of the Tarcoles River, Rafa Campos reported finding two more at La Ensenada on 15 February.
Pomarine Jaeger(Stercorarius pomarinus): On 26 February, César Sánchez, along with Soo Whiting and her group, had excellent views of a bird flying slowly along the Tortuguero coastline at an altitude of a mere 15 to 20 meters.
Black-billed Cuckoo (Coccyzus erythropthalmus): On 18 April, Leonardo Garrigues had a bird at Rancho Naturalista. Then, on 21 April, he saw another one near Carara NP, along the road to Villa Lapas.
Warbling Vireo (Vireo gilvus): On 09 February, Jesse Ellis observed this rare migrant in the evergreen forest along the entrance road to Santa Rosa NP and wrote, “While I know it's supposed to be really rare here, I'm very familiar with this species (and Philadelphia Vireo) from birding in Minnesota and New York. I didn't get photos, but the vireo lacked any yellow or green on the belly. It had a dark eye, ruling out red-eyed, and the shape was wrong for that species as well. White supercilium, black behind the eye a bit, greyish-olive upperparts, grey head, and a fairly heavy but short bill (relative to red-eyed).”
Blue-winged Warbler (Vermivora pinus): On 18 February, Rafa Campos and his group watched a handsome male along the El Camino trail at Monteverde. Leonardo Garrigues also had a couple of sightings of this species at Rancho Naturalista in mid-March.
Magnolia Warbler (Dendroica magnolia): On 27 February, César Sánchez, Soo Whiting, and their group of birders had several individuals on the grounds of the Turtle Beach Lodge, north of Tortuguero. Additionally, I continued to see a bird on the grounds of Talari Mountain Lodge (near Rivas de Pérez Zeledón)—first with my family on 25 March, then again with Tim and Simon Jones on 20 April.
Black-throated Blue Warbler (Dendroica caerulescens): Nicole Street, of the Tortuguero banding program, reported that on 24 March, “while banding at the rancho de Juan Jose (approx. 1.5 km north of the COTERC station on Caño Palma, near the beach) we sighted two adult male Black-throated Blue Warblers in full breeding plumage. On 25 March, we set up a net near where they had been spotted the day before and captured a second-year male black-throated blue. We did not band the bird, but I did take several digital pictures.”
Yellow-rumped Warbler (Dendroica coronata): In mid-March, Leonardo Garrigues came across one individual on the hike to Cerro Silencio, near Rancho Naturalista.
Pine Warbler (Dendroica pinus): On 26 February, Julian Hough reported observing an individual at La Virgen del Socorro. And on 28 February, Alfredo Scott found a near fully adult-plumaged male along the Río Java trail at the Wilson Botanical Garden.
Palm Warbler (Dendroica palmarum): On 27 February, César Sánchez, Soo Whiting, et. al., spotted one individual on the grounds of the Turtle Beach Lodge.
Cerulean Warbler (Dendroica cerulea): In late March, Steven Easley saw one individual while doing the Cerro Silencio hike.
Mystery Raptor Photo Causes Puzzlement
In early March, Rudy Badia contacted me with news of someone who had posted to a local list-serve asking for help identifying a raptor in a photo taken while visiting Costa Rica. It turned out that the person posting was Elaina McCartney, who graciously responded to my questions with this information:
“My daughter and I were on a trail in the SkyWalk area of Monteverde/Santa Elena. The pictures were taken February 8 or 9 of this year. We were walking along the trail and it was one of the moments where you just stop in your tracks and look up. The bird was sitting on the same limb as in the picture, I'd say about 30-40 feet away. We had a digital camera and 8x25 binculars in our packs so we stood very still and fished them out. My daughter snapped a picture, and I looked through bincoculars, seeing the barring on the breast that doesn't show in the image. We switched (I took the camera, she took the binoculars), and she whispered to me wanting to know what the chicken was that we used to have that had that kind of striping--Plymouth Barred Rock!). When I took the camera I realized I couldn't see the bird so well. Sometime during another switch of camera and binoculars, the bird flew off to our left. I remember a long single-note sound as it flew, but I couldn't say in those surroundings if it was that bird, or something startled by its flight. With the naked eye, there was a sense of red in the eye area as it moved its head. The legs were strikingly orange, and the sense was of a large short-necked bird. We're not expert birders. We had planned to get a Costa Rican field guide after the trip (we were travelling with packs and it was kind of heavy!), thinking we'd look it up when we got back. I've e-mailed my daughter to ask her what she remembers about the encounter, and I'll let you know if she has any additions (or subtractions!)”
The following day, Elaina added, “My daughter's response was that the bird looked “hawkish” and the color was somewhere between “crow and mouse”. She said that she saw the bird leave the branch, and it soared (as opposed to flapped).”
I forwarded the images and info on to other local birders to see what people thought. A few responded with the suggestion that the bird was perhaps a Plumbeous Kite (Ictinia plumbea), though they found it odd that an individual of this species would be perched inside the cloud forest. Not only that, but I feel that the shape and color is wrong for Plumbeous Kite. Here is a composite of the two images that Elaina took and, below them for comparison, a Plumbeous Kite that I recently photographed near Caño Negro. Unfortunately, the images are not very clear and I don’t think we will ever be able to say with complete certainty just what species of raptor was at the SkyWalk that day in February.
It’s interesting that Elaina and her daughter noted “barring on the breast that doesn’t show in the image.” That detail would suggest a male Hook-billed Kite (Chondrohierax uncinatus). However, that species has a pale iris and the bird in the images seems to have a dark red iris. Of course, Barred Forest-Falcon (Micrastur ruficollis) would also show barring and is probably the most commonly seen raptor in the habitat where the photos were taken. For this species, though, the leg color is wrong as it shows distinctly orange (“strikingly orange” per Elaina’s description), not yellow.
Looking at the images with an open mind to any possibility, I have to say that what this bird most resembles is a Plumbeous Hawk (Leucopternis plumbea), although this rare raptor has never been reported in Costa Rica. Its known range extends from W Panama south to NW Peru. It also is only known to occur up to 800m in elevation, so to show up at 1500m in the Santa Elena area is quite a stretch in both distance and altitude. Nonetheless, a young bird might wander and Ridgely’s description in “Birds of Panama” states, “Immature has . . . thighs somewhat barred, belly somewhat flecked with white,” which could explain the barring that Elaina noticed. Furthermore, the habits fit well, as it is “an unsuspicious bird of the forest interior, usually seen at low and middle levels.”
For what it’s worth, Daniel Martínez also thought it might be a Plumbeous Hawk (which he and Ernesto Carman think they may have seen at MonteSky—a similar elevation forest near Tapantí—several years ago, but didn’t get a good enough look to be sure), and Alejandro Solano, who has seen this species in Ecuador, likewise concurred. So, maybe one day we’ll be able to confirm this species for Costa Rica; meanwhile we’ll just have to keep scratching our heads.
Other Raptor Sightings
Here are some unequivocal reports of recent raptor sightings.
On 01 February, while near the airport in Golfito, Luis Sandoval had the fortune of watching a Crested Eagle (Morphnus guanensis) do a fly-over.
Luis Sánchez, administrator of the Altamira sector of La Amistad International Park, reported that an Ornate Hawk-Eagle (Spizaetus ornatus) is nesting in the same tree for the second consecutive year. And while birding at La Selva on 12 April with Tim and Simon Jones, young Simon looked up and spotted an immature Ornate Hawk-Eagle high in a bare tree near the start of the CCC trail.
Pearl Kites (Gampsonyx swainsonii) continue to show up at new places. There have been numerous sightings at Playa Azul, near Tarcoles. Jhimmy Castiblanco informed me of one on the Marriott Los Sueños golf course at Playa Herradura. And John Landers wrote to tell me of one he saw at Playa Avellana.
Rusty-margined Flycatcher Update
On 29 March, while birding the entrance road to Esquinas Rain Forest Lodge during the recent Birdquest tour, Matt Denton tried playing some taped vocalizations of Rusty-margined Flycatcher at the spot where he had a bird last year. Sure enough, within moments a bird answered and came into view.
Additionally, on 02 March, at the Tiskita Lodge airstrip, near Pavones, César Sánchez and the Soo Whiting group observed what would be the second record for this species in Costa Rica.
Southern Lapwing Nest Found
The presence of Southern Lapwings (Vanellus chilensis) in CR is no longer a newsworthy item in itself, but finally, eight years after their first appearance, nesting has been confirmed. Leonardo Chaves reported that, on 01 March, Harry Castro filmed and photographed a lapwing nest in the horse pasture across the road from the Montaña de Fuego hotel at the base of Arenal Volcano. At least a pair of lapwings has been repeatedly observed in this pasture for more than a year now—and it seems there may now be more. According to Leo, another guide, Jesus Toledo, had seen the nest with two eggs on approximately 21 February.
On 05 March, Leo, along with Ernesto Carman, was able to personally see the nest, which actually was no more than a scrape on top of some dried horse droppings. By this time, the nest had four eggs, which Leo described as “light brown with dark spots.” I haven’t heard any further news, but would assume that by now—barring predation—there must be young lapwings out in that field.
As mentioned above, this is the first confirmed and documented nesting of Southern Lapwing in CR, however, readers may remember the apparently successful nesting at the Coopeagri-Cenizas waste treatment facility, reported last year by Jim Zook.
Incidentally, Leo also mentioned that Jesus had seen a “mockingbird” near the same horse pasture. So, if you’re in the Arenal area and looking for the lapwings, you might also keep an eye out for the mockingbird—presumably Tropical Mockingbird (Mimus gilvus), which has not previously been reported for that region of CR.
Second Report of Prevost’s Ground-Sparrow near Monteverde
On the morning of 22 March, while birding with Richard Clifford, Robert Dean discovered a Prevost’s Ground-Sparrow (Melozone biarcuatum) a little below the town of Santa Elena. The bird was actually in the garden of the house where Robert lives, though there is also a coffee plantation nearby.
This location is several kilometers (in a straight line) from where Eduardo Amengual and Robert found this species in November 2002.
Birds of Pacific Mangroves Subjects of Two Studies
The intertidal zone upstream from the mouths of rivers and streams along the Pacific coast is a fascinating ecosystem and of special interest to birders as the place where one is most likely to find the following species: Mangrove Black-Hawk (Buteogallus subtilis), Rufous-necked Wood-Rail (Aramides axillaris), the endemic Mangrove Hummingbird (Amazilia boucardi), Northern Scrub Flycatcher (Sublegatus arenarum), Panama Flycatcher (Myiarchus panamensis), Mangrove Vireo (Vireo pallens), and the “mangrove” race of the Yellow Warbler (Dendroica petechia erithachorides), as well as being good for numerous species of shorebirds and waders. [The migrant Mangrove Cuckoo (Coccyzus minor) is, in fact, rarely found in this habitat when visiting CR.]
The use of mangrove habitats by NA migrant species has brought John Woodcock of the Thunder Cape Bird Observatory to the Guanacaste coast for the past two winter seasons. Here is summary of what the work entails for John and his wife, Maureen:
“Maureen and I work in four different locations in the province of Guanacaste in northwest Costa Rica. We purchased a small car last year, a Hyundi Excell, to get around in and essentially live out of. We spend about a week at each of our four bird banding locations mid-November to mid-March and usually return to Liberia, the provincial capital, at the end of each week. We usually stay at Hotel Liberia, in the center of town where we are close to grocery stores (Supermercado), Internet cafes, and where we can get some laundry done. We are camping most of the time so it is always a treat to sleep in a bed once in a while and have a nice shower. To get to our banding locations we either drive to Playa Grande and Estero Tamarindo, about an hour and a half away, or drive to Playa Panama then take a boat ride with our friend El Gato to Estero Iguanita, or hire Eladio to take us to Estero Naranjo in his 4 wheel drive Toyota Landcruiser. Either way it’s a full day to get into one of the sites and set up, followed by 3 days of bird banding then another day to get back to Liberia.
“We’ll take you through a trip to Estero Naranjo, a mangrove swamp adjacent to Playa Naranjo in what was formerly known as Santa Rosa National Park but is now part of the Area de Conservacion Guanacaste, Sector Naranjo. After driving to Eladios, about half an hour north of Liberia, we load up his Landcruiser with enough food and water for a week, along with all our camping and bird banding equipment then head north to Santa Rosa. The trip across Santa Rosa to the Pacific Ocean is on a very rough road and takes about and hour and a half. About half the ride is through regenerating tropical dry forest that was once pasture. On the slope down to the ocean the forest is more mature and we see a rich diversity of trees. When we arrive in November, at the end of the rainy season, everything is very green but over the course of the winter we see a great change as the trees gradually lose their leaves. Many of these trees are covered with gorgeous blossoms by the middle of the dry season. Arriving at Playa Naranjo we set up camp near the ocean then go for a swim as it is generally mid-day by this time and the temperature has climbed to at least 30C. Around 3 in the afternoon we take our mist-nets into the mangroves, about a ten-minute walk from the campgrounds, and set up for the next day. We have wooden net poles in place so it is just a matter of attaching and adjusting the nets. This usually takes a couple of hours, leaving just enough daylight left to return to camp and prepare dinner on our little one burner propane stove. By 6pm it is dark, Pacific Screech Owls and Common Pauraques serenade us as we do a little reading and prepare for the next day.
“We’re up at 4:30 am; if we don’t hear the alarm clock the Howler Monkeys will wake us up with their pre-dawn loud ‘woof-woof-woofing’. It’s still very much nighttime and the stars are still out. Every night they are visible as there a very few clouds in Guanacaste in the dry season (Nov. – March). We see the North Star, very low at about 10 degrees about the horizon, reminding us how far south we are. By 5:20 am we’ve had coffee and breakfast and are heading out with backpacks on loaded with bird banding equipment, water, and snacks for the day. The sky is showing enough gray in the east so we can see where we are going but we have headlamps handy to illuminate our way through grassy areas where Rattlesnakes or Vipers may still be out hunting. Depending on the tides, the mangroves may be dry enough for tennis shoes or wet up to our knees, usually somewhere in between. When there’s lots of water we are always on the lookout for crocodiles, though we see few and those we do encounter are generally shy and retiring. While opening nets we make our first observations of birds for the day, we always keep a daily list. Herons, Ibises, and Egrets squawk their displeasure at our intrusion into their domain. We split up to open nets and rendezvous after half an hour at our banding site not far from net 8: we open 16 nets each day. It is fully light by 6 am and at this time the many parrots that roost in the mangroves are dispersing to feed in the nearby dry forest. There are many Yellow-naped Parrots, often traveling in pairs, greeting us with their cheerful ‘move it, move it’ calls. The White-fronted Parrots have more raucous voices and there are also small flocks of Orange-fronted Parakeets. The doves start calling at this time too. We hear the low hoot of the White-tipped Doves and the more elaborate calls of White-winged Doves that seem to be saying ‘take off your shoes’, which is good advice if the tide is high. Great Kiskadees and Brown-crested Flycatchers are the first songbirds we hear, as well as the cheeky White-throated Magpie Jays that often follow us around squawking alarms at our presence.
“At 6:30 am we check our nets for the first time. We split up for this job too, each of us taking care of 8 nets. This is always the busiest time of day with more birds captured than at any other time. This first net run usually yields 5 or more Prothonotary Warblers, the most abundant songbirds in the mangroves at this time of year, as well as lesser numbers of Northern Waterthrush, Tennessee Warblers and Yellow Warblers. We often catch bats at this time too, the largest of which has a 30 cm wingspan and a set of teeth to match and thus needs to be handled with care. All the birds we capture are placed in cloth bags and returned to our ‘banding station’, a plank in the shade beneath a large mangrove tree at the edge of the swamp. Here we identify, band, measure, age, sex, and weigh all birds before they are released. By the time all birds have been processed and released it is time to check nets again. Checking the nets is physically demanding, they are spread out over a 1 km trail through the mangroves and we are either wading through water or trudging through mud. We estimate that we walk 10 km through the mangroves each day. It is exciting though, with the expectation of surprise captures at each net. We capture a lot of birds that we do not band because they are not migratory. These are resident ‘Costa Rican’ birds that we document the same as the birds we band. We capture quite a lot of hummingbirds, Cinnamon Hummingbird and Steely-vented Hummingbird being the most abundant. It’s always a treat to find such colorful birds as Black-headed Trogons in our nets.
“And so goes our day, check nets, process birds, then do it again until the day is over. Our day’s work is often terminated by noon when the wind begins to blow making mist-netting impossible. These winds are typical of the Guanacaste dry season and often continue to blow until well into the night. They often come in strong gusts that sound like freight trains as they come roaring through the dry forest. Our last task of the day is to furl up our nets so that birds will net get caught again until we re-open them the next day. On average we process 30 to 40 birds each day (as few as 5 and as many as 98) of 5 to 10 species. Our list of observations for each day typically includes 30 to 50 species. We do three days of mist-netting and then take down our nets for use at our next stop. The following day Eladio picks us up and takes us back to his place where we store our car. Then we’re off to Liberia to overnight and re-supply in preparation for a visit to one of our other study sites.
“We do love our work despite the feeling of being homeless for the four months we are in Costa Rica, moving once a week, setting up and taking down camp and nets, and packing everything into our little car. We meet tourists from all over the world who show great interest in our work and we have made many friends among the people of Costa Rica. It is a great treat to have our friends from Canada come down to visit us. There are many exciting encounters with wildlife, other than birds, such as the 3.5 m Boa Constrictor that ate a 1 m long Iguana at the campsite at Playa Naranjo last week. Capuchin Monkeys, Raccoons, Agoutis, and Coatis are animals we frequently encounter while camping.”
Another interesting post included the following:
“Fri. Jan. 14 – was our busiest day ever mist-netting and banding in Costa Rica with 98 birds captured (40 banded, 46 recaptures, and 12 un-banded) at Estero Tamarindo. We are starting to think that maybe the tides do influence the number of captures, particularly with respect to Northern Waterthrush, of which we banded 11 and recaptured 20 today. Northern Waterthrush frequent water edges and today the high tide pushed through the mangroves about the same time as sunrise, which has always been the time of the greatest number of captures of all birds, and for the following couple of hours the tide slowly receded. We caught most of our waterthush during this time today. We also banded 11 new Prothonotary Warblers today and recaptured 11 more.”
However, what really caught my attention was a note towards the end of that message mentioning that on 16 January they had captured “a Mangrove Hummingbird, we have only seen one other.”
The field guide gives the range of Mangrove Hummingbird as extending from the Gulf of Nicoya S to the Golfo Dulce. Therefore, its presence in mangroves on the N Pacific coast is quite noteworthy. John actually attached this image of the hummer in his post. But looking at the image, I thought the bill better fit the field guide’s description of a White-bellied Emerald (Amazilia candida) than a Mangrove Hummingbird. There also seem to be bits of purple flecking on the crown.
Intrigued, I inquired of John if he had any other photos or could give me more details about the bird’s plumage, especially the tail pattern. John kindly responded writing, “Unfortunately I have only the one picture, the bird escaped before I could get another! I can only hope to capture it again next week when I re-visit Estero Tamarindo. I have no experience with either the Mangrove or the White-bellied Hummingbird but came to the conclusion that it was a Mangrove Hummingbird by: a) its size, closer to that of a Cinnamon Hummingbird than a Ruby-throated, both of which I handle regularly b) it’s weight was 4.4 g, Stiles & Skutch give 4 g for the Emerald and 4.5 g for the Mangrove and c) the green on the breast more closely approximated the illustration of the Mangrove in Stiles & Skutch. I don’t know if it helps but the wing cord was 52mm, unfortunately wing cords are not listed in S & S. Upon re-reading the descriptions in S & S, with respect to the bill coloration, it appears the bird had more than pinkish base to the lower mandible as in Mangrove but rather a pink with a black tipped lower mandible. Should I correct my i.d. on this bird to White-bellied Emerald?”
I wish I could say!
John also included this photo of a bird captured last year at Estero Tamarindo. Again, the bill seems more like that of a White-bellied Emerald, but since the tail is not visible, it’s hard to say with certainty which of the two species it might be. Although the scattered records listed for the emerald in the field guide do not suggest the Guanacaste coast, Rudy Zamora reported seeing this hummer at Playa Coyote (well south of Tamarindo) in December of two successive years at about the turn of the millenium.
The second bird study referred to above deals specifically with Mangrove Hummingbirds and is being realized by The Herman Institute of Biological Studies. Director Drew Wheelan sent out this information:
“Our main focus this year as most of you may have read in our last update was/is the Mangrove Hummingbird, and habitat factors that may or may not influence this endangered hummingbird's distribution throughout the Pacific coast of Costa Rica.
In January we met with some scientists from the Mangrove Lab at the Smithsonian Tropical Research Institute in Panama and trained in some of their methodology. From there we began our own studies which encompassed performing point counts and taking vegetation data. By we I mean myself, and mostly two very committed interns from the Evergreen State College: Jacob Patchen and Charles Hammel. Both of these guys put in a huge effort and worked their butts off. I was amazed at their dedication and attention to their studies of the language, general tropical biology, as well as the mangroves and, of course the birds. We were also blessed with several volunteers: Michelle Calischibeta, Melanie Pishalko and James Melton. They all helped out immensely and were fun to have around. So we all slithered, slid and slurped through the mud of the mangroves to collect data on this wonderful bird and this truly intriguing ecosystem.
“The vegetation data takes a huge amount of time to collect, and we did not get as much done as hoped. That's what pilot years are for. The scope of what we aim to do is huge, and if we learned anything this year it is that we have bitten off a lot. However, the questions grow more colorful and the relationships between these organisms are beginning to come alive, and it's exciting. So much so that Jacob Patchen is hoping to return next year, possibly as a grad. student to work on this stuff.
“With the bird data that we did collect we are beginning to see some trends. It certainly looks as though forests devoid, or very low in density of Pelliciera rhizophorae have very few, if any, Mangrove Hummingbirds, and in fact they were not recorded on any point counts. In forests where this species was more common, the bird was sometimes everywhere. One thing that we learned was the species composition of trees in these mangrove forests varies hugely, even in seemingly similar ecological situations. It will be very interesting as patterns begin to emerge as to why.
“Some of our work was travelling to sites on the edge of the bird's distribution. Outside of Golfito toward the southern extent of the range we found an island that was nearly 50% P. rhizophorae and Mangrove Hummingbirds were everywhere, and so were other hummingbird species. We recorded at least six total species of hummingbird, where elsewhere in our point counts we recorded just two, the Mangrove and Scaly-breasted Hummingbirds. Interesting stuff.”
[As a botanical note, Pelliciera rhizophorae—referred to in the field guide as Pacific mangrove, and also known as tea mangrove, since it is a member of the Theaceae family—can be easily recognized when exploring Pacific coast mangroves as it is the only tree species in these swamps that has buttresses.]
How Active Are Hummingbirds?
Thanks to the little “content related” links that Google's Gmail service runs along the right column of the page, my attention was attracted by a link entitled, “Hummingbird Foraging Bouts.” Clicking on it took me to the Stanford Alumni website where I read this fascinating article:
“Like other small animals that are "warm-blooded" (that is, like us, maintain a high body temperature by generating metabolic heat), hummingbirds need a prodigious energy intake. In spite of this, Rufous Hummingbirds don't feed constantly. In fact, they make only 14-18 foraging bouts per hour, each taking less than a minute. For the remainder of the hour the bird perches quietly. Ecologists William Karasov, Duong Phan, Jared Diamond, and Lynn Carpenter discovered the reason for this inactivity.
“They found that the hummers pass nectar through their digestive tracts very rapidly -- average transit time through the gut is less than an hour. In this short time, they are able to extract about 97 percent of the sugars from the nectar. But why do they sit around so much "doing nothing" when they could be sipping more nectar? The answer was discovered with a clever experiment using radioactive isotopes as tracers to follow what happens to the nectar. In fact, the "resting" hummers aren't "doing nothing" -- they are emptying their crops (specially modified parts of the digestive system that store food immediately after it is taken in). They apparently wait until the crop is about half empty before foraging again, and it takes about four minutes for this to happen (which would account for the roughly 15 bouts of nectar gathering per hour). They forage only as often as required to keep up with the rate at which the crop can pass nectar into the rest of the digestive system; more frequent foraging would carry a high energy cost but provide no further benefit. While it is emptying its crop, therefore, the bird conserves energy by remaining immobile.
“The hummers don't have room to take in any more nectar until the crop is partly drained. What limits the rate of crop emptying is not yet clear, but it is probably how fast the intestine can absorb the sugar, or how fast the stomach can acidify the crop contents (an important step in digestion). As Diamond and his colleagues say, '. . . despite external appearances, hummingbirds may be energy maximizers, taking in energy as rapidly as their digestive processes permit.'”
Copyright ® 1988 by Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye.
Go to the Stanford Alumni website and click on “Essays/Alphabetical Order” for more than 100 informative pieces on everything from “Adaptations for Flight” to “Walking vs. Hopping” (sorry, there aren't any entries beginning with Z yet).
Mystery Bird Photo Quiz
Flycatchers can be difficult to identify correctly, and the image provided by Noel Ureña was no exception. The proposed identities of this bird included: Yellow-margined Flycatcher (Tolmomyias assimilis), Mountain Elaenia (Elaenia frantzii), Panama Flycatcher (Myiarchus panamensis), Northern Scrub Flycatcher (Sublegatus arenarum), Zeledon’s (Rough-legged) Tyrannulet (Phyllomyias burmeisteri), Gray-capped Flycatcher (Myiozetetes granadensis), and “some sort of vireo.” In fact, the image is of a Yellow-crowned Tyrannulet (Tyrannulus elatus).
Just to go through the guesses: Yellow-margined Flycatcher would not show distinct wing-bars; Mountain Elaenia has an olive, not gray, head; Panama Flycatcher would look more uniformly grayish-olive above, the wing-bars would be grayish and less distinct, and there would be now yellowish edging on the secondaries; Northern Scrub Flycatcher would be uniformly brownish-gray above with grayish wing-bars; Rough-legged Tyrannulet is actually very similar to Yellow-crowned Tyrannulet and perhaps best distinguished by the bicolored bill together with the white superciliary extending across the forehead, neither of which is visible in the original image, though their lack is apparent in the “answer” image—so I suppose congratulations to Carlos Jiménez are in order for having made a very good wrong guess; and finally, Gray-capped Flycatcher has neither wing-bars nor wing-edging. Noel was helpful in providing the little arrow pointing to the hint of yellow crown feathers in the insert in the above image.
Hopefully this image will be less challenging to accurately identify. The answer will be announced in the July 2005 newsletter. Good luck!
Thanks to everyone who contributed news of rare sightings and good finds. I hope that you've enjoyed this newsletter and welcome any comments at gonebirdingcr@gmail.com or if you're in Costa Rica, feel free to give me a ring at 293-2710.
Wishing you all great birding,
Richard Garrigues
https://www.angelfire.com/bc/gonebirding/index.html
Archives:
Red-billed Tropicbird,
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Gull, Parasitic Jaeger, Cory’s Shearwater, Yellow-breasted Chat, Golden-cheeked
Warbler, Dunlin, CBC results, Eurasian Collared-Dove, Blue-tailed Hummingbird,
Greater Ani, Red-throated Caracara
Black-vented Shearwater, Sabine's Gull, Brown
Noddy, Brown-chested Martin, Cerulean Warbler, Blackpoll Warbler, Connecticut
Warbler, Violaceous Quail-Dove, Rusty Sparrow
Dr. Skutch eulogy, Shiny
Cowbird, Crested Eagle, Cinnamon Woodpecker, Warbling Vireo, Keel-billed
Motmot, Rufous-necked Wood-rail, White-throated Magpie-Jay
Rusty-margined Flycatcher,
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Eagle, Uniform Crake, Paint-billed Crake, White-rumped Sandpiper,
Maroon-chested Ground-Dove, Rufous-vented Ground-Cuckoo, Tropical Mockingbird,
Blue Seedeater
Christmas Bird Count
results, American Bittern, Gray Kingbird, White-eyed Vireo, Brewster's Warbler,
Great Swallow-tailed Swift, Unspotted Saw-whet Owl, Maroon-chested Ground-Dove,
Worldwide Ornithological Literature website
Cory's Shearwater,
Swallow-tailed Gull, Black Tern, Gray-breasted Crake, Gray Kingbird,
Orange-crowned Warbler, Blue-headed Vireo, Bobolink, Lincoln's Sparrow,
Peg-billed Finch, Buffy-crowned Wood-Partridge, rare raptors
Greater Ani, Green Heron,
Bat Falcon, Orange-breasted Falcon, Swallow-tailed Kite, Keel-billed Motmot,
Spot-tailed Nightjar, Black-whiskered Vireo, Lincoln's Sparrow, Yellow-breasted
Chat, Mouse-colored Tyrannulet, Strong-billed Woodcreeper
Large-billed Tern, Green
Heron, Golden-cheeked Warbler, Yellow-rumped Warbler, Keel-billed Motmot,
Red-throated Caracara, Pheasant Cuckoo, Wattled Jacana, Tropical Mockingbird
Christmas Bird Count
results, Southern Lapwing , Short-tailed Nighthawk, Lanceolated Monklet ,
Sunbittern, Magnolia Warbler, Prevost's Ground-Sparrow, Tricolored Munia
Golden-cheeked Warbler,
Migrant monitoring, Southern Lapwing, Harpy Eagle, Violaceous
Quail-Dove,Wedge-tailed Grass-Finch, Rusty Sparrow
Dr. Skutch update, Veraguan
Mango, Pearl Kite, Red-breasted Blackbird, Tody Motmot, Mourning Dove, Red
Knot, Pinnated Bittern, Black-and-white Owl
Harpy Eagle, American
Avocet, Pacific Golden Plover, Ruff, Cave Swallow, Southern Lapwing, South
Polar Skua, Maroon-chested Ground-Dove
Southern Lapwing, White Tern,
Chipping Sparrow, Black-headed Grosbeak, Ash-throated Flycatcher, Migrant
warblers, hummers and more hummers
South Polar Skua, Pomarine
Jaeger, Sharpbill, Long-billed Curlew, Lovely Cotinga, Black-banded
Woodcreeper, Blue-and-yellow Macaw, White-tipped Sicklebill, Bicolored Hawk,
Lanceolated Monklet
South Polar Skua,
Silvery-fronted Tapaculo, Scaled Antpitta, Pearl Kite, Scarlet Macaw, Mystery
hummers, White-eyed Vireo, Nashville Warbler, Masked Duck
Crested Oropendola, Rosy
Thrush-Tanager, Wattled Jacana, Brown-throated Parakeet, Lanceolated Monklet,
Black-banded Woodcreeper, Lovely Cotinga, Cinnamon Teal, Silvery-throated Jay,
Migrant wood-warblers, Violaceous Quail-Dove
Crested Oropendola, Lark
Sparrow, Oilbird, Double-striped Thick-knee, Pheasant Cuckoo, Y2K CBCs,
Ochre-breasted Antpitta, Crested Eagle, Rufous-necked Wood-Rail
first migrants and rare
warblers, disappearing migrant shorebird habitat, Mallard (sic), Rufous-necked
Wood-Rail, Scaled Antpitta, Black-and-white Owl
Blue-tailed Hummingbird, Prairie
Warbler, Tiny Hawk, Red-throated Caracara, Western Slaty-Antshrike,
Red-breasted Blackbird, Clapper Rail, Swallow-tailed Gull
Green-winged Teal, Painted Bunting, Green Ibis, Western Slaty-Antshrike, Pearl Kite, Southern Lapwing, Lanceolated Monklet