White-tailed Hawk

The White-tailed Hawk, a neotropical buteo of dry, open areas, is one of the most widespread yet least studied raptors of the Americas. It occurs from south Texas down to Argentina. I saw a couple of adults this morning on the campus of Zamorano University in Honduras, while walking Old Jack, the dog that's currently in my care. The hawks were low in a kettle of vultures that also had an immature Zone-tailed Hawk.

While entering today's observations into eBird, I was curious to see how many White-tailed Hawk records eBird has for the region. Well, surprisingly few! For Honduras, only 5 sightings, spanning the period May 29 - July 28, 2011 - all from Zamorano University campus! (Confession: I have seen this bird elsewhere in Honduras, for example just north of San Marcos de Colón, in the department of Choluteca, but this was before I started using eBird.) For El Salvador: nada! Nicaragua? Nada! Belize - which gets more tourist birders - has records scattered throughout the year, but most in the period Feb-Apr. Guatemala? Nada!

In Central America, only the birding eco-tourism countries - Belize, Costa Rica, Panama - have records in eBird for this species. Of course it occurs in the other countries, but with far fewer observers entering data, those countries remain at present 'white areas' on the eBird map for this (and many other) species.

For the time being, the eBird map for White-tailed Hawk does a better job mapping birding tourism than it does the distribution of this species. Hopefully this will change over time.

Pinnated Bittern

Yesterday I 'bagged' what I can't really call a nemesis bird, for I don't often have the opportunity to bird in its natural habitat. But it certainly was the one I was hoping for, as Milagro, Roselvy and I set out on a wobbly wooden boat on Laguna El Jocotal in El Salvador, to take part in an International Waterbird Count. We were accompanied by two park rangers, who impressed me with their knowledge of local birds.

Pinnated Bittern ranges widely from Mexico to South America and is probably not rare, but rarely observed, as it is a mostly nocturnal species occurring in habitat that's difficult to access without a boat.

We also got a fleeting glimpse of a Least Bittern we flushed from the same reed bed, as well as better looks at Snail Kite, Limpkin, White-tailed Kite, Black-bellied Whistling-duck, Ruddy-breasted Seedeater, Ringed Kingfisher, Red-winged Blackbird and other common species found in this type of habitat.

Here a shot of a Limpkin.

Collared Trogon

Today a photo and video of a Collared Trogon from Montecristo National Park, El Salvador. I just returned from bird monitoring (banding) there, and will be out in the field and away from internet for another week, starting tomorrow morning. This post will be brief.

Collared Trogon is one of the four red-bellied trogons in the region. The male, shown here, is distinguished from males of the other species by its finely barred undertail, and by voice. (From Mountain Trogon also by its leading white edges on the primaries.)

Even the best field guides contain small mistakes or omissions. Take for example Howell & Webb's excellent Guide to Birds of Mexico and Northern Central America. In the Collared Trogon species account, it describes the orbital ring of the male as "orange-red", and notes that the female "lacks bright orbital ring". Many trogon species do have bright orbital rings, and their color is often one of the field marks. In the Collared Trogon, however, there is considerable variation in this feature, and the individual shown above - with a dark orbital ring - is by no means unusual.

Literature cited:
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford Univ. Press, Oxford, UK.

A hummingbird surprise in La Laguna

Cinnamon Hummingbird, 3 July 2011, Jardin Botánico La Laguna

Today, Roselvy and I went to the botanical garden La Laguna in Antiguo Cuscatlán, a suburb of San Salvador. The birding there is rarely spectacular, but it's a neat little spot that's easy to get to. I've written about previous visits here and here and also here.

Plain-capped Starthroat, 3 July 2011, Jardin Botánico La Laguna

At least two hummingbird species are resident in the garden, and are always observed when we go there: Cinnamon Hummingbird and Plain-capped Starthroat. The former is really the default hummingbird anywhere in the city; no matter how small a garden, if it has flowers, chances are those flowers are visited by this species. The latter is more localized in the area, but often one of the first birds heard when entering the botanical garden.

In September and October, a third species - Green-breasted Mango - can be very common in the botanical garden, with sometimes up to 10 individuals present. Today, we were rather surprised to find an immature male of this species!

immature male Green-breasted Mango, 3 July 2011, Jardin Botánico La Laguna

Immatures look similar to females, with white median underparts and a dark central stripe, but are distinguished from adult females by the presence of cinnamon borders surrounding the white on the underparts. This particular individual shows dark green feathers coming in on the belly and breast, and thus is molting from immature to adult male plumage. The outer tail feathers look rather abraded, and haven't been molted yet. (The cinnamon color in the proximal part of the rectrices in the photo is odd: possibly an artifact of backlighting.)

Green-breasted Mangos are found from Mexico to Costa Rica, with additional disjunct populations in northern South America. The species is migratory in the northern part of its range (northeastern Mexico). Last year, when I noted an influx of individuals into the botanical garden in September, I assumed these were Mexican migrants. According to Howell & Webb (1995), Green-breasted Mango breeds in eastern El Salvador and is a winter visitor in central and western El Salvador (and thus in the greater San Salvador area).

Curious then to find this individual here in early July!

Reference:
Howell, S. N. G. and S. Webb. 1995. A guide to the birds of Mexico and northern Central America. Oxford Univ. Press, Oxford, UK.

A new hybrid hummingbird from Honduras

Our monthly bird monitoring pulse in Monte Uyuca, Honduras, yielded a surprise this week in the form of this hummingbird, an apparent hybrid of Azure-crowned Hummingbird x Berylline Hummingbird. Although hybridization is relatively common in hummingbirds, we believe this to be the first report of this particular combination. We're preparing a short paper documenting this remarkable find.

Roselvy, Lya and I had just started our bird banding Thursday morning and this was the very first bird I pulled out of the nets. Not recognizing the species, I was excited that we captured yet another new hummingbird for the station, after three new hummingbird species last month! A review of the Howell & Webb guide, however, quickly made us realize that none of the species found in the region fit this bird, and that we were holding in our hands either a vagrant or a hybrid.

The second possibility seemed the more obvious, and once we figured that out, it didn't take us long to arrive at the most likely parental candidates.

In this partial side view, the bird looks much like a regular Azure-crowned Hummingbird, a locally abundant species.

Turning the bird a little, however, reveals a heavily spotted throat and breast, where Azure-crowned has more white. The crown is not blue ("azure"), but green. (Go back a few blog posts for shots of a regular Azure-crowned Hummingbird.) Berylline Hummingbird has a green throat and crown.

The tail of this individual is not at all like an Azure-crowned tail, but a lot like a fresh Berylline tail. The purple gloss in the tail of Berylline hummingbird tends to fade to rufous on more worn individuals, usually notable on the outer rectrices especially.

Beautiful tail!

Here's a view of the underside of the bird, showing a mix of characters of Azure-crowned and Berylline Hummingbirds.

Berylline Hummingbird has a large rufous flash in the wings, absent in Azure-crowned. This individual has a weak rufous flash.

This weak rufous flash is also visible on the upperside of the wing.

What a lovely bird!

There's an extensive body of literature on hybridization of hummingbirds, handily summarized here. Intra- and intergeneric hybrids have been described for various Amazilia species, including Berylline, but apparently not Azure-crowned. The latter is common at the study site, Reserva Biológica Monte Uyuca near Tegucigalpa, Honduras, while the former has never been recorded there - at least not by us, during monthly banding pulses that started in January of 2010. Berylline does occur in Honduras, reaching the eastern edge of its range in the area of the study site.

We took photographs and measurements, before we released it back into the wild.

Postscript 2 July 2011:
It seems this hybrid has been reported once before, by a French ornithologist who sorted through the specimen collection of the British Museum, encountered what he thought was this combination, and published his notes. See Jacques Berlioz, 1932, Notes critiques sur quelques Trochilidés du British Museum, Oiseau 2: 530-534. Berlioz describes his find as the probable result of a cross between Azure-crowned and Berylline Hummingbirds, showing a perfect mix between the two parent species. He notes that this individual was collected near Jalapa, the capital of the Mexican state of Veracruz, where both species occur.