Sunday, July 28, 2013

Fonseca Rails

I've written here a couple of times before about the Clapper Rails of the Gulf of Fonseca. I've even written a short note documenting breeding in Honduras for El Esmeralda, the bulletin of the Asociación Hondureña de Ornitología (ASHO).

Clapper Rail was first found and documented in the Honduran part of the Gulf of Fonseca in 2010, by Robert Gallardo and Mayron Mejía. In 2012, the species was first reported from the Nicaraguan side of the Gulf by Jens Olek Byskov, Salvadora Morales, Orlando Jarquín and Juan Carlos Alaniz, and in 2013, Oliver Komar, Roselvy Juárez and I found it on the Salvadoran part of the Gulf.

I corresponded about these birds with James Maley, a rail researcher from the University of Wyoming, who expressed an interest in sampling specimens from this population. Together, we wrote a research proposal which we submitted to ICF, the Honduran governmental organization in charge of research permits. James is here right now and we have just finished a week of field work, in which we collected a total of 8 specimens. This series will be used for a taxonomic description of this population.

This week, with the help of playback, we got a sense of how common this species really is in the Gulf of Fonseca. For example, one transect that was about 450 m long had an estimated 15 pairs and 3 single individuals – that's 33 individuals, on a relatively small stretch of mangrove. In some parts, densities seemed so high that we wondered if Clapper Rail was perhaps the second most common species there, after (Mangrove) Yellow Warbler! While few birders or biologists have seen this species in Honduras, most locals that we talked to in the salt ponds and shrimp farms of the area knew the bird well. One of them assisted us with field work, and he told us those birds have been common there for as long as he could remember – at least 40 years!

Remarkable then that this population, apparently never rare, went undiscovered for so long. Given available habitat and abundant food resources, there are probably thousands if not tens of thousands of these rails in the Gulf of Fonseca.

Monday, July 15, 2013

Two tropical birds: one expected, one not

Last Saturday, Roselvy and I set out to find Long-tailed Manakin and Blue-tailed Hummingbird in Choluteca, two species that we hadn't observed yet this year in Honduras. While we easily found those species in a community called La Fortuna, situated in humid middle elevation forest among coffee and mango plantations more or less in the middle of the department of Choluteca, I did not get any (reasonable) photos.

I did get photos of Tropical Pewee (top) and Tropical Gnatcatcher. While the former was expected and indeed quite common there, the latter wasn't really on our radar screen for that part of the country. 

When we heard a descending trill, we didn't immediately recognize it. Locating the singer was not difficult, and upon seeing a gnatcatcher producing that song, I instantly realized it had to be Tropical Gnatcatcher. It occurs in eastern and northern Honduras, and is no doubt common in many areas, but these are exactly the areas far from where we live, where we haven't done that much birding yet.

For us, this was a cool and unexpected find, well outside its known range.

Monday, July 8, 2013

Great Swallow-tailed Swift calls

Yesterday I recorded Great Swallow-tailed Swifts vocalizing near El Obraje, in the Honduran department of El Paraiso. I just uploaded these calls to Xeno Canto, and as far as I've been able to ascertain, these are the first public recordings of this species.

I went to El Paraiso yesterday morning with Roselvy Juárez, Oliver Komar and Ruth Bennett to bird another data-deficient eBird quadrant. It was a pleasant and productive morning of birding, as we found 92 species for the quadrant, including Little Tinamou, White-tailed Hawk, Rufous-tailed Hummingbird, Fork-tailed Flycatcher, Lesser Greenlet, Rufous-and-white Wren, Tropical Parula, and Giant Cowbird. 

Chantler and Driessens, in their 1995 book "Swifts: a Guide to the Swifts and Treeswifts of the World" cite Edwards' 1989 book "A Field Guide to the Birds of Mexico and Adjacent Areas", which describes the call of the Great Swallow-tailed Swift as "a plaintive tyee-ew". Yesterday, one of the individuals in a flock of five gave that call, illustrated in the following recording:

Howell & Webb (1995) give another description of a Great Swallow-tailed Swift vocalization, noting a "reedy, screechy chipping, including a distinctive, accelerating series, ending emphatically, may recall Pileated Flycatcher song: kree kri-kri-kri-kri kree-kreeh!" One of the birds yesterday also gave that call, illustrated in the following recording:

I recorded these calls from a single-species flock of five individuals, at an elevation of 1000 m, as they flew over us. The habitat there was montane semi-humid forest, with some shade coffee plantations, and steep rocky canyons.

Until now, neither Xeno Canto nor the Macaulay Library had any recordings of this species, which appears to be fairly common in the highlands of Honduras.

Cited literature:
Chantler, P. & G. Driessens. 1995. Swifts: a Guide to the Swifts and Treeswifts of the World. Pica Press, Sussex.
Edwards, E. P. 1989. A Field Guide to the Birds of Mexico and Adjacent Areas: Belize, Guatemala, and El Salvador, Third Edition. Corrie Herring Hooks Series.
Howell, S. N. G. & S. Webb. 1995. A Guide to the Birds of Mexico and Northern Central America. Oxford University Press, Oxford.

Thursday, July 4, 2013

eBirding southern Honduras

female Rose-throated Becard
Roselvy and I targeted another data-deficient eBird quadrant yesterday morning, trying to fill gaps in our knowledge of bird distribution in southern Honduras. We did seven complete checklists of about twenty minutes each (plus one incidental list) in a quadrant just north of Nacaome, in the department of Valle, where most of the habitat is Pacific dry forest interspersed with corn and bean subsistence cultivations, small mango orchards here and there, and small-scale cattle farming. Some of the birds we found are uncommonly reported from Honduras (such as White-bellied Chachalaca, or Thicket Tinamou), while others we found in higher than usual densities (like Striped Cuckoo). In total, we dug up 68 species for this quadrant. Not bad, considering all winter visitors aren't there right now. We'll come back for them later.

the 'empty quadrant' we visited yesterday

We stopped at three different river crossings, and thus likely biased our counts toward waterbirds. This explains three kingfisher species on our list (Ringed, Amazon and Green), and the high frequency of riparian birds like Rose-throated Becard (present on 70% of our checklists yesterday). Cuckoos appear to be genuinely common in this area, with Groove-billed Ani on 85%, Striped Cuckoo on 70%, and Squirrel Cuckoo and Lesser Ground-cuckoo each on 40% of our checklists. The only species present on all of our seven checklists yesterday was White-tipped Dove. Curiously absent was Black Phoebe, diligently looked for but not found, while Social Flycatcher only appeared on one out of seven checklists – normally a more common species in disturbed areas.

Sulphur-bellied Flycatcher

Our best birds yesterday included Collared Forest-Falcon, White-bellied Chachalaca, Thicket Tinamou, and Green-breasted Mango. Soon we'll try to hit the quadrant above it, to continue eliminating as many holes on the map as we can. The area around Tegucigalpa is starting to look pretty good!