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.

Hummingbirds in Monte Uyuca

Azure-crowned Hummingbird

After two months of hawk counting on Sandy Hook, NJ, I'm back in Central America, really now my home away from home. I was very happy, obviously, to be reunited with my girlfriend Roselvy, and also to see my good friend Oliver again. They picked me up from the airport in Tegucigalpa Wednesday around noon, and a couple of hours later Roselvy and I were already putting up mist nets in Reserva Biológica Monte Uyuca, not far from Tegucigalpa. This is a biological reserve where we have banded together many times before since Roselvy set up the banding station here in January 2010. Since then, we've carried out monthly banding pulses consisting of 400 net hours each month, most of which I have worked on as a volunteer bird bander.

The station is located in pine-oak forest with a well-developed shrub layer, and is home to many hummingbirds. Five species are found here more or less year-round, although their numbers fluctuate seasonally, in some cases dramatically so.

In May of 2010, we caught more birds (the majority hummingbirds) than in any other month of that year, and we were of curious to see if this surge would repeat itself in 2011. The previous record number of captures during one banding pulse there stood at 202 birds, caught in May 2010.

This May, we caught 217 birds - no fewer than 156 of them hummingbirds!

Besides the expected species, we caught three new hummingbird species for the station!

Many Central American hummingbirds are considered non-migratory, resident species. However, a lot of these resident species opportunistically undertake small-scale movements in search of flowers, which may be locally available at different altitudes during the year. Local altitudinal migration may account for the seasonal patterns we've found for various hummingbirds at Uyuca (Juárez & Komar, 2011).

Azure-crowned Hummingbird

In Uyuca, no species exhibits this seasonal variation more than Azure-crowned Hummingbird. We typically catch a handful of this species throughout the year, but their numbers increase in April and then explode in May. This week, we had 93 captures of this species, with only a few recaptures. We suspect that during the rest of the year, these birds are found a few hundred meters downslope, when the shrubs there are in flower. An afternoon walk in that area, just outside the reserve, seemed to support our conjecture, for we found few hummingbirds and few flowers where both can be very common at other times of the year.

hummingbird's eye view of Palicourea padifolia

Right now, a shrub with yellow flowers (Palicourea padifolia) is blooming abundantly in the area where the net lanes are situated. This plant depends on hummingbirds for its pollination, and provides food for many hummingbirds. It is found in middle-elevation cloud forests from southern Mexico to Panama (Taylor 1989).

Azure-crowned Hummingbird probably breeds in modest numbers right where the banding station is located, but moves into that area - possibly from downslope - in larger numbers a few months after the breeding season. Many adults we caught were either molting or had just finished their prebasic molt. This molt usually takes place after breeding.

White-eared Hummingbird

Another species that shows the same pattern, albeit less pronounced, is White-eared Hummingbird, also a pine-oak specialist. This pulse we caught 37, against only a few during each month the rest of the year.

immature female Green-breasted Mountain-gem

The Green-breasted Mountain-gem shows a different pattern. This species is a common breeder at the bird monitoring station, and we typically catch most of them right after the breeding season, in January and February, when their numbers are augmented with recently fledged individuals. They are present in good numbers most of the year, with a dip in July and August (Juárez & Komar 2011). Possibly this species does something similar to what the Azure-crowned and White-eared Hummingbirds do: it may visit their principal breeding area further downslope in the middle of the rainy season, when flowers in that drier part of the mountain are abundant. Obviously, this is all still speculation at this point, and could be an excellent topic for further study.

The other two species that we catch most banding pulses but do not seem to show any distinct seasonal variation are Magnificent Hummingbird and Green Violetear. While we did catch a violetear, we didn't have the mag this time.

That said, no fewer than three new hummingbird species for the station were found this banding pulse! After more than 6,000 net hours since January 2010, I'd say that is quite remarkable.

adult male Slender Sheartail

One of them was this stunning Slender Sheartail, a species found in southeastern Mexico (Chiapas), Guatemala, El Salvador and Honduras. In Uyuca, we are at the southeastern edge of its range.

adult male Slender Sheartail

Holding this bird in the hand was a first for me.

adult male Blue-tailed Hummingbird

Another was this equally gorgeous Blue-tailed Hummingbird, found in southern Chiapas and in the three countries around the Gulf of Fonseca: eastern El Salvador, southern Honduras and western Nicaragua. This species is usually found at lower elevations, and was certainly a surprise at Monte Uyuca, located between 1600 and 1700 masl.

adult male Blue-tailed Hummingbird

This bird also was in fresh plumage.

Cinnamon Hummingbird

Also more a lowland species - very common even in disturbed habitats like major cities - is Cinnamon Hummingbird. We had never caught this species before in Uyuca, but this pulse caught no fewer than three individuals. The above individual is molting its primaries.

Thanks to José Linares for help with the identification of Palicourea padifolia.

Cited literature:
Juárez, R. & Komar, O. 2011. Monitoreo Permanente de Aves en Reserva Biológica Monte Uyuca, Honduras, durante 2010, primer informe anual. SalvaNATURA, Zamorano, ICF.
Taylor CM. 1989. Revision of Palicourea (Rubiaceae) in Mexico and Central America. Systematic Botanical Monographs 26: 1–102.

Immature hummingbirds

Green Violetear

In Reserva Biológica Monte Uyuca (Honduras), where Roselvy, Vicky and I banded last week, five species of hummingbirds are common: Green-breasted Mountain-gem, Green Violetear, White-eared Hummingbird, Magnificent Hummingbird, and Azure-crowned Hummingbird. They've all recently bred or are still breeding, for we caught immatures of each species, as well as an adult female Green-breasted Mountain-gem with an egg in her oviduct.

Let's take a look at these immature plumages. Few field guides illustrate them, although the Howell & Webb guide to the region does routinely describe them, if not in very much detail. Generally, younger birds are characterized by buffy feather tips on the upper and sometimes under parts. In the hand, presence of bill striations (fine corrugations along the side of the maxilla) indicates a younger individual. (Double clicking on these photos will reveal them in some cases.)

The top bird is a young Green Violetear. It will lose those buffy tips on the head and back through a first prebasic molt during its first life year. Those dusky underparts will become metallic green.

Azure-crowned Hummingbird

 Here's a young Azure-crowned Hummingbird. This bird too has extensive buffy fringes on the head and upper parts. In this species, the buffy tips of younger birds even extend to the tertials.

Magnificent Hummingbird

Immature Magnificent Hummingbird, with buffy (upper side) or whitish (under side) feather tips all over, again including the tertials.

White-eared Hummingbird

A tiny White-eared Hummingbird, weighed only 3 grams (the adults are tiny also, of course). Here we see buffy tips to the head and lower back feathers.

White-eared Hummingbird

Here's another look at the same bird, showing those buffy tips to the lower back feathers. Adults have all-green backs.

Both sexes of Green-breasted Mountain-gem show dusky greenish throat feathers, which they quickly replace with (usually buff-tinged) whitish feathers in the case of the female, or bright green feathers with white borders in the case of the male.

Green-breasted Mountain-gem

Here's a female. Note the buffy tips on the head and back, and the dark throat feathers, both characters associated with immatures in this species.

Green-breasted Mountain-gem

And here's a male. This individual shows a distinct rufous spot over the eye, found in many but not all young individuals of both sexes in this species. A few basic (post-juvenal) throat feathers have already grown in.

Green-breasted Mountain-gem

Young Green-breasted Mountain-gems too show rufous tips to the feathers of the lower back. In this species, males of all ages show dark upper tail coverts, a character lacking in females.

Banding in Monte Uyuca

This little ball of feathers is one of many, many hummingbirds we caught this week in Monte Uyuca, Honduras. It's an Azure-crowned Hummingbird, a common pine-oak resident that here in Monte Uyuca, a forest with an exceptionally well-developed middle layer, reaches high densities. This may be one of the plainer species, but the azure crown for which it is named is spectacularly beautiful. Brilliant colors on hummingbirds, however, are a product of refracted light, and are only visible from certain angles. From this angle, it does look rather plain.

The bird has just been processed, and is ready for release. They sometimes wait a little before takeoff. One moment it sits quietly in your hand, the next moment it blasts off full throttle.

This is a female Magnificent Hummingbird, a larger species. In SalvaNATURA's bird monitoring program, we don't band hummingbirds; a special permit is required for that. Thus, processing a hummingbird means determining its age/sex class; measuring its weight and its wing cord; assessing its breeding condition, its molt condition, and fat score; and determining flight feather wear by looking at the four outermost primaries. The tip of the right outermost rectrix (tail feather) is cut, and the bird is released.

We left San Salvador Monday morning and met with Honduran forestry staff at the ICF in Tegucigalpa in the afternoon; Monday late afternoon we arrived at the site. Although not fully recovered from the flu that kept him at home last week, Carlos Zaldaña joined Roselvy and me on this trip. In Montecristo, we had occasional assistance from park rangers. Here in Uyuca, it was just the three of us. We caught so many birds - nearly 200 in 25 hours - that it would have been difficult to do this with a crew of just two (one of whom - me - being less experienced). Especially hummingbirds need to feed constantly and have to be processed quickly. The first day of banding, Tuesday, we caught 103 birds, 70 of which were hummingbirds. Azure-crowned and White-eared Hummingbirds were particularly numerous, as were Green-breasted Mountain-gems, a hummer as beautiful as the name suggests. I did not take many photos on this trip, partly because we were just too busy processing birds and partly because it was overcast and dark most of the time. The top two photos show a few rays of sunlight but we had mostly light rain.

This Anna's Eighty-eight (Diaethria anna), a typical cloud forest denizen, found the collar of my rain coat to be infused with delectable salts and minerals from sweat, and fed on it for quite some time.

It's interesting how this site shows a mix of pine-oak and cloud forest residents. Birds that are primarily associated with cloud forest, like Slate-colored Solitaire and Resplendent Quetzal, mix here with pine-oak birds like White-eared Hummingbird, Olive Warbler, and Crescent-chested Warbler. Birds like Yellowish Flycatcher and Mountain Trogon, typical of transitional zones between pine-oak and cloud forest, are found here also.