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

Oops... I did it again!

I saw another Black-throated Blue Warbler today! About a week ago I saw an adult male (pictured above) in Moxviquil, today another adult male in Huitepec, which is maybe 10 km from Moxviquil.

These birds are not supposed to be here!

Again I quote from Cornell University’s Birds of North America:

In winter, mostly in the Greater Antilles, from Puerto Rico, Hispaniola, Cuba to Jamaica; also in the Bahamas. Occasional in the Lesser Antilles, as far south as Trinidad (ffrench 1991) and along the Caribbean coast of the Yucatan, Belize, Honduras. Recorded as rare or casual winter visitor along the Caribbean coasts of Costa Rica, Panama, Colombia, and Venezuela (Ridgely and Gwynne 1989). One record from Ecuador of a male present from February through early June along east slope of Andes near Cosanga, Napo province (Martin et al. 2004). Small numbers winter in s. Florida and a few occasionally farther north (Root 1988). (1)

I think we can add to that: occasional winter visitor in Chiapas, Mexico.

This second bird I didn’t get photos of, but like last week’s bird it was an adult male, not a terribly difficult ID.

Also a couple of Black-throated Green Warblers in today’s flock, but – you’ve guessed it – no Golden-cheeked Warblers.


(1):
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/087doi:10.2173/bna.87

A Black-throated Blue Warbler

Our GCWA field season in Chiapas officially kicked off today with the first flock of the season, here in the Moxviquil (“mosh-veekeel”) reserve in the hills surrounding San Cristóbal de las Casas. After having seen exactly zero goldencheeks in Costa Rica, I was eager to see one today.

When we left the field station at daybreak, we heard Wilson’s Warblers chipping left and right, and a little further away several Brown-backed Solitaires were singing their wistful dawn song. Other birds we encountered included a Yellow-faced Grassquit, a Yellow-bellied Sapsucker and some Rufous-collared Thrushes. And more Wilson’s Warblers: that bird is found here clearly in high densities.

However, a real warbler flock was somehow hard to find this morning. When we finally encountered one, it seemed more a loose association of insectivorous birds than a real flock to me. It had a Greater Pewee in it, a bird that calls frequently and is sometimes considered a ‘leader’ of such insectivorous flocks. The other birds were remarkably quiet for most of the time, and only the two Townsend’s Warblers and the two Hutton’s Vireos (and of course the six Wilson’s Warblers) called every now and then. Calling softly was a male Black-throated Blue Warbler, a bird whose main wintering area is in the West Indies and northern South America. I had certainly never seen one as a member of a warbler flock in the mesoamerican pine-oak forest, although I remember seeing one fly over the Cardel, Veracruz hawk watch site last September. That bird was headed this way.

We had lunch (antojitos) in the market hall in downtown San Cristóbal, and then we took a colectivo bus back to the field station. These colectivos are really revamped mini-vans that were originally designed to hold maybe eight people, but now fit 20 Mayans and a tall Dutch guy. Just barely, though.

Late afternoon, when the sun was out and the wind had died down a little, the birding was excellent right outside the field station. The courtyard that yesterday had White-eared Hummingbird now also had Green Violet-ear (another hummer) and Cinnamon-bellied Flowerpiercer.

In trees and shrubs surrounding the field station we found several Townsend’s Warblers, a troupe of Bushtits, a Brown-backed Solitaire, a Gray Catbird, a couple of Rose-breasted Grosbeaks, a Rufous-collared Sparrow, and a Rufous-collared Thrush. On one of the trails we saw a beautiful Red-faced Warbler (an oak specialist) and what appeared to be another warbler flock. We decided to revisit that location tomorrow morning.