Sunday, February 27, 2011

Birding Zamorano campus

male Barred Antshrike
It all started rather innocently, with just a walk around campus for a little birding. We did not bring any water, because we didn't think we would go very far. Five hours later, we were up to almost a hundred species, and were so fired up, that we went out a second time around dusk in search of a few more to get to 100, just for kicks.

Oliver, Roselvy and I went birding today on Zamorano University's campus in central Honduras, where Oliver recently started as a professor.

Zamorano is an agricultural school, not really a birding place per se. Nevertheless, it's got a lot of open space, some orchards and some ponds here and there. A decent number of birds can be found, including residents like Ruddy Crake, Crested Caracara, Nutting's Flycatcher, Yellow-billed Cacique, Grey-crowned Yellowthroat, Blue-tailed Hummingbird, Striped Cuckoo, Anhinga, Least Grebe, Common Tody-Flycatcher, Rufous-browed Peppershrike, Spot-breasted and Streak-backed Orioles, and Ferruginous Pygmy-Owl. Also here are winter visitors like Ruby-throated Hummingbird, Solitary Sandpiper, Baltimore and Orchard Orioles, Magnolia and Yellow Warblers, Common Yellowthroat, Rose-breasted Grosbeak, Least Flycatcher, Painted Bunting, Indigo Bunting, Dickcissel and Merlin.

We got a pair of Barred Antshrikes coming in on a Ferruginous Pygmy-Owl imitation. Going out around dusk we added Tropical Mockingbird and Common Pauraque, but left us still two species shy of that magic number, one hundred.

Tuesday, February 22, 2011

Black-throated Blue Warbler on the wintering grounds

Last week I assisted Roselvy and Lya with bird banding in Montecristo national park, in El Salvador, where we caught this female Black-throated Blue Warbler, a bird that normally winters in the Greater Antilles - Puerto Rico, Cuba and Jamaica primarily. Black-throated Blue Warblers don't leave the wintering grounds until late March to April (Holmes et al. 2005), so this bird likely spent the winter in Montecristo. This is one of the few warbler species that appears to be increasing, as fields and pastures in the heart of its breeding range (northeastern US) have been returned to forest (Holmes et al. 2005). In striking contrast, this species is likely encountering severe habitat degradation on its wintering grounds.

Regular readers may remember that I encountered this species also in Chiapas, Mexico: I saw two individuals in December 2008. And last week's capture was not the first time for this species to be recorded in Montecristo either, for there are single records from 2004 and 2006. It has also been caught twice in the last seven years at another SalvaNATURA banding station in El Salvador, at Los Andes (in Los Volcanes national park). Holmes et al. do not mention records from Pacific Slope Central America, they only mention that the bird is "occasional along the Caribbean coast of the Yucatan, Belize, Honduras (...) and a rare or casual winter visitor along the Caribbean coasts of Costa Rica, Panama, Colombia and Venezuela" (Holmes et al. 2005).

I realize at this point it is pure speculation on the basis of a few incidental sightings, yet I can't help but wonder if healthy breeding populations of Black-throated Blue Warbler faced with habitat destruction on the wintering grounds are looking outside their 'normal' winter range for alternatives?


Cited literature
Holmes, Richard T., N. L. Rodenhouse and T. S. Sillett. 2005. Black-throated Blue Warbler (Dendroica caerulescens ), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/087

Sunday, February 13, 2011

Coincidence or mimicry?

male Green-breasted Mountain-gem, Honduras, February 2011
The Green-breasted Mountain-gem, a hummingbird from central Honduras and western Nicaragua, sings a soft song that usually starts with a scratchy warble, or sometimes with variations of its buzzy call, and occasionally is embellished with a fast, lower trill at the end. Its sister species, the Green-throated Mountain-gem, sings a similar song.

That last part, the trill, is not always sung. I've recorded individuals that sang a few introductory phrases, and then broke off. Male mountain-gems usually sing this song from a perch, although I have heard (and recorded) the whole song, including the trill, being sung in flight, while the singer was pursuing another individual (male or female, who knows).

Ericsson 1950s bakelite telephone*
To my ears, the trill sounds a little bit like an old telephone: not the sound the telephone makes with an incoming call ("old telephone ring tone"), but rather the sound you'd hear from the receiver telling you the phone is ringing at the other end.

Last week, I was very surprised to hear a Slate-colored Solitaire finish its beautiful song with a similar phrase! This was in Monte Uyuca, Honduras, where Roselvy and I carried out SalvaNATURA's monthly bird monitoring pulse.

Slate-colored Solitaire, Honduras, January 2011
I researched this a little, and found that none of the eight Slate-colored Solitaires available through xeno-canto sing this phrase. Cornell's Macaulay Library has many more Slate-colored Solitaire songs, including extensive recordings from El Salvador made by Walter Thurber in the 1970's, but I didn't hear it there either. I did hear a wonderful variety in phrasing of this haunting, ethereal song, so characteristic of Central American cloud forests.

First listen to two Slate-colored Solitaire songs, both from the same individual:




Now listen to a recording of two songs of a Green-breasted Mountain-gem, made within 15 minutes and 20 meters of where that solitaire was singing:


To my ears, the last phrase in the Slate-colored Solitaire's song from Uyuca sounds a lot like the last phrase in each of the two songs of the Green-breasted Mountain-gem. Is this mere coincidence, or is the solitaire, a wonderfully accomplished singer, actually paying tribute in song to the more modest vocal skills of its neighbor, the mountain-gem?


*image licensed under Creative Commons Attribution Share-Alike 3.0 Unported

Fledgling White-eared Hummingbird

Yesterday I photographed this fledgling White-eared Hummingbird in Reserva Biol├│gica Monte Uyuca, Honduras. For many hummingbird species in northern Central America, the breeding season is nearly over. Note the extensive rufous edging on the head and back, indicating a young bird.

Tuesday, February 1, 2011

About Aratinga taxonomy

Two Red-throated Parakeets - Aratinga holochlora rubritorquis (left) and one Pacific Parakeet - Aratinga strenua
In the previous post, I mentioned some taxonomic confusion regarding the Aratinga parakeets in Central America. Having researched this a little further, I've found that there are two schools of thought regarding Aratinga taxonomy.

In the end, however, the American Ornithologists' Union (AOU) taxonomy is authoritative, and will be explained here. To avoid confusion, I'll leave the alternative taxonomy, used by BirdLife International for example, undescribed.

According to the AOU, the 'green' parakeet found on the Pacific Slope of Central America from southeastern Oaxaca and Chiapas south to southwestern Nicaragua is Aratinga strenua, the Pacific Parakeet. Last Saturday, we counted a large roost of this species in San Salvador.

The 'red-throated' parakeet we counted in much lower numbers Saturday is Aratinga holochlora rubritorquis, or 'Red-throated' Green Parakeet. Note that according to the AOU, red-throated birds are a form or subspecies - rubritorquis - of the Green Parakeet, Aratinga holochlora. This subspecies is found in central and eastern Guatemala, El Salvador, Honduras and northern Nicaragua.

The field of taxonomy is in a state of flux, and at any given time will reflect then current insights into relationships between populations. The current AOU check-list can be found here.