Leaves

Today a series of images that will speak for themselves. I photographed these leaves in national park Montecristo, El Salvador, on Friday 24 September 2010.

These images are copyrighted © John van Dort. If you like the photos, you are welcome to grab them for personal use, but you need my permission for redistribution in whichever form.

Green-breasted Mountain-gem

Green-breasted Mountain-gem - Lampornis sybillae adult male

In today's post we're taking a closer look at the Green-breasted Mountain-gem, a hummingbird species that is found in central Honduras (east of the Sula Valley) and northwestern Nicaragua. Closely related to the parapatric Green-throated Mountain-gem, which occurs in Honduras west of the Sula Valley and in northern El Salvador, Guatemala and southeastern Mexico, it is separated from that species by more extensive green mottling on the breast in males, a buffy wash on the throat and more green mottling on the sides of the breast in females, and more contrasting white on the outer tail feathers in both sexes.

Green-breasted Mountain-gem - Lampornis sybillae adult male

Adult male Green-breasted Mountain-gems are stunningly beautiful creatures, whose iridescent throat and breast feathers channel a dull green, or a bright aquamarine or light blue, depending on the angle of the sunlight and the position of the viewer.

Green-breasted Mountain-gem - Lampornis sybillae adult male

Mountain-gems, in the genus Lampornis, are fairly large hummingbirds, one species of which just barely reaches into the United States: the Blue-throated Hummingbird. They are generally associated with highlands, especially cloud forest, and are found throughout Central America. Currently, seven species are recognized, although some work, using mitochondrial and nuclear DNA sequencing, remains to be done on the taxonomy of this genus.

Green-breasted Mountain-gem - Lampornis sybillae young male

Here's a young male, with more or less complete greenish mottling on the throat and breast, like an adult. Both males and females soon after fledging acquire an adult-like plumage, but can still be aged by the presence of buffy edges to the dark green upper head and back feathers, and by the amount of bill striations, or bill corrugations.

Click on this photo for an enlarged view, and you'll notice this bird shows some buffy edges on the head feathers.

Along the side of the bill, little corrugations can be seen that are typical of young hummingbirds. They lose these striations as they get older, and the bill gets harder and smoother. Some adults retain up to 10% of bill striations. The bird in the photo above has a bill striations score of about 60%, and so is very likely a hatch year bird. For some northern species, for example Anna's Hummingbird and Rufous Hummingbird, the timing or rate of this process of bill smoothing is known, and the percentage of bill striations can thus be used to reliably age individuals of those species (see for example Yanega et al. 1997).

In tropical species, however, much remains to be learned about the rate of this process. I'm currently working on a paper about the Green-breasted Mountain-gem's sister species, the aforementioned Green-throated Mountain-gem. In this species, it appears that bill smoothing takes more than one year to complete. Bird banders working in the tropics are thus advised to exercise caution when using rate of bill striations for ageing hummingbirds.

Green-breasted Mountain-gem - Lampornis sybillae adult female

This is an adult female, with a buffy wash on the throat. Females of the more northerly/westerly sister species Green-throated Mountain-gem have white throats, while females of the more southerly/easterly White-throated Mountain-gem have orange throats. Geographically located between these two extremes, the female Green-breasted Mountain-gem appears to be intermediate in that particular aspect also.

Note that this bird has a modest amount (<10%) of bill striations near the base of the bill.

Green-breasted Mountain-gem - Lampornis sybillae adult female

Here an unusually pale-throated female Green-breasted Mountain-gem. A small percentage of females will look like this, approaching Green-throated Mountain-gem in this feature. Note however the green mottling on the sides of the breast and belly; in female Green-throated Mountain-gems, the green mottling generally does not extend beyond the sides of the upper breast.

Note that this bird has no bill striations, but a small abrasion on the distal part of the bill, a mark that's probably the result of some external impact.

Green-breasted Mountain-gem - Lampornis sybillae adult female

And here a top view of the same bird, showing the whitish outer tail feathers, a field mark good for Green-breasted, not Green-throated Mountain-gem. Note that the right outer tail feather is cut. We do this to mark individuals. Special permits are required for hummingbird banding.

All these photos were taken this past week in Reserva Biológica Monte Uyuca, Honduras. I was there to band birds with the banding crew of SalvaNATURA, a conservation NGO for whom I'm currently volunteering. If you want to learn more about the valuable work we do in SalvaNATURA's bird monitoring program, then please visit Maratón de Aves El Salvador / Birdathon 2010 and consider sponsoring the birdathon, which I have the honor of organizing this year. All funds collected in this 8th edition of the birdathon will go toward SalvaNATURA's bird monitoring project. Your contribution will be greatly appreciated.

Cited literature
Yanega, Gregor M., Peter Pyle & Geoffrey R. Geupel 1997. The timing and reliability of bill corrugations for ageing hummingbirds. Western Birds 28: 13-18.

Shorebirds in Los Cóbanos

Least Sandpipers - Calidris minutilla

Saturday, Roselvy and I went birding in Los Cóbanos, a spot in southwestern El Salvador where El Salvador's east/west coastline curves south a bit. Birds that migrate along the coast are going to come closest to land right there, I reasoned. While we did see some migration, notably of medium-sized groups of Whimbrels and Willets, I was surprised how few birds were actually visible over the ocean. With the exception of modest numbers of Brown Pelicans and Magnificent Frigatebirds, the horizon was largely devoid of birds. Not a single tern or gull, for example. Amazing!

As we walked along the beach - some parts rocky, some parts sandy - we found Spotted Sandpipers everywhere, but not much else. Eventually, we did stumble upon a mixed group of shorebirds which included several Wandering Tattlers, two Black-bellied Plovers, a Collared Plover, four or five Semipalmated Plovers, ten Wilson's Plovers, a Ruddy Turnstone, about twenty Least Sandpipers and four or five Western Sandpipers. The latter two species were industriously working the beach toward a point where a little stream flowed into the sea, and once there, would repeat their routine.

I immediately saw the photographic opportunity provided by this behavior, and laid down in the sand flat on my belly at the very end of their trajectory. Here is a series of Least Sandpiper shots from that spot.

Two Least Sandpipers in winter plumage

Most birds were adults in winter (basic) plumage, like these two. The bird in front appears to be molting its greater coverts, for it lacks the bigger, darker feathers clearly visible on the bird behind it.

juvenile Least Sandpiper

Here's a more colorful juvenile, with all feathers looking equally (lightly) worn.

Juvenile Least Sandpiper

The same bird head-on.

Juvenile Least Sandpiper

Juvenile Least Sandpipers are very pretty.

This adult bird in basic plumage appears to be molting at least one primary: note the pale area between the longest primary and the three shorter, fresher-looking white-tipped inner primaries.

Molting starthroats

Plain-capped Starthroat preening

I've been frequenting the San Salvador botanical garden lately, which is only a 15 minute bus ride from my apartment, and offers opportunity for study of hummingbirds. Sadly, it is not the oasis of tranquility it could be, and many botanical gardens across the world often are. The garden is located inside an old volcano crater, right next to a noisy factory, and practically every weekday and Saturday gets inundated with school kids. Despite all that, the garden boasts a number of flowering trees and shrubs, and these of course attract hummingbirds.

The Plain-capped Starthroats I reported on a couple of weeks ago, have become regulars for me. These birds very likely are residents of the garden, and possibly breed there.

I've noticed that at least one of these birds is in flight feather molt, i.e. undergoing a post-breeding prebasic molt.

The photo at the top of a bird preening is of poor quality, but shows a spread wing with all six secondaries. Clearly visible are new (darker) S1 and S2, an ingrowing S3, and old (paler) S4-6. Click on the photos for bigger views.

Plain-capped Starthroat

The bird in this photo, taken in the botanical garden also but on a different day, could be the same individual, or could be its mate. Note that this bird is molting its central rectrices. This photo too is heavily cropped, and of poor quality. Still, we can see molt centers in the wings also: both in the secondaries and primaries.

Last week I noted the arrival of Green-breasted Mangos in the garden. First there was one adult male. Last Saturday, that male was gone but a female was there. And Sunday, I found no less than five males and a female, all in the same tree! I wonder if these birds are passing through, or will spend the winter in the botanical garden.

Yard birds

Gray Hawk - Buteo nitidus (immature)

Like every self-respecting birder, I keep a yard list. I've had Clay-colored Thrush, Rufous-naped Wren, Roadside Hawk, Cinnamon Hummingbird, Ferruginous Pygmy-Owl, Mottled Owl, Inca Dove, Ruddy Ground-Dove, White-winged Dove, Golden-fronted Woodpecker, Grayish Saltator, Great Kiskadee, Social Flycatcher, Tropical Kingbird, Orange-chinned Parakeet, Bronzed Cowbird, Melodious Blackbird, Great-tailed Grackle, Yellow Warbler, Yellow-winged Tanager, Blue-gray Tanager, White-collared Seedeater and Scrub Euphonia all in the yard. I've had a bunch more as flyovers.

And then late this afternoon there was this young Gray Hawk, caught by the rays of the setting sun.

Erm... Wait a minute... yard list?

What yard? Which blog is this? Is this still "On the road"?

"Have binoculars, will travel"? And what's with the fluffy new design?

Well... all right. You got me. I started the blog when I was traveling, and I named it in admiration of the Kerouac novel, but lately I have been spending a lot of time in San Salvador. As a consultant, it's hard for me to look into the medium to long distance future, but I'll be here at least until November. It's fast becoming my home away from home.