Baby boids!

recently fledged Plumbeous Vireo

Down here in Honduras, 'tis the season when young birds are everywhere. This is a recently fledged Plumbeous Vireo, one of the members of the Solitary Vireo complex that is resident here. Its parents look more like Cassin's Vireos than northern Plumbeous, but that is how they remain classified for now. With some genetics work, this Central American population may one day be elevated to species level.

On a short walk I encountered a couple of Plumbeous Vireo families, now more easily detected because of the constant begging calls that the fledglings produce. 

these feathers were all grown at once, and thus – although new – are of poor quality

I photographed this bird a couple of days ago in the pine-oak forest of San Buenaventura, a small village 30 minutes south of Tegucigalpa, close to where we live. Also present there were recently fledged Eastern Bluebirds.

recently fledged Eastern Bluebird

This bird's dad was singing from the top of a tall, nearly dead pine tree. I recorded his song and posted it on Xeno-Canto:

Lesser Nighthawk breeding in Honduras

Incubating female Lesser Nighthawk

The Lesser Nighthawk is a common migrant and winter visitant in Honduras, occurring in the lowlands of both coasts and in the interior highlands to 1,200 meters. It prefers arid situations and is most abundant along the Pacific coast and in the arid interior valleys. It is also a regular migrant in the Bay Islands and the Cayos Cochinos. There is no direct evidence that the species breeds in Honduras, although several specimens have been secured in June (Eisenmann, 1963: 165).

Burt Monroe, 1968, A Distributional Survey of the Birds of Honduras

Twenty-seven years later, Howell & Webb (1995) did not know much more ("exact distribution poorly known"), and their map shows it (incorrectly) as a breeding resident in the interior of northern Central America, from Mexico through Guatemala to western Honduras. Juárez & Komar (2012) however described breeding of this species on the beaches of El Salvador and Guatemala, away from the interior. They noted that breeding of Lesser Nighthawk is still not reported for Honduras.

Yesterday, while in the company of one of these authors, I almost stepped on an incubating Lesser Nighthawk down at one of the salt ponds in the Honduran part of the Gulf of Fonseca. Although a brown bird against a green background should have been obvious, we just weren't prepared I guess. 

Nest of Lesser Nighthawk

As the female flew off, a little scrape on the ground revealed two eggs. We decided to quickly take photos and then leave, to let the female go back to her nest.

Can you find the nest?

When we passed again an hour later, we found her back on her nest brooding her eggs. This time I took some photos of the bird on the nest, but was careful not to flush her again.

Although near the coast, the habitat here is notably different from breeding habitat on the beaches of El Salvador and Guatemala, where the birds were found breeding on white sand close to the high water line (Juárez & Komar 2012). This Honduran nest was approximately 20 m from a shack used by the supervisor of the salt pond complex, and on short grass, about 7 km away from open water.

At times we have seen large numbers of Lesser Nighthawks at dusk in the lowlands of the Gulf of Fonseca. Are these birds perhaps breeding in the salt ponds here and there, and on the beaches of Choluteca, between Punta Ratón and Punta Condega?

Cited literature:

Howell, S. N. G. & S. Webb. 1995. A Field Guide to Birds of Mexico and Northern Central America. Oxford University Press.

Juárez-Jovel, R. C. & O. Komar. 2012. Nuevo sitios de anidación para el Chorlito Piquigrueso (Charadrius wilsonia) y el Chotacabras Menor (Chordeiles acutipennis) en El Salvador y Guatemala. Bóletin SAO, Vol. 21, 6 pp.

Monroe, B. L. 1968. A Distributional Survey of the Birds of Honduras. Ornithological Monographs No. 7, American Ornithologists' Union.

Spring shorebirding in Honduras

Buff-breasted Sandpiper

This second week of May, the shorebirding has been rewarding down here in Honduras. We were alerted to this by our friend Oliver, who found Baird's Sandpiper, Pectoral Sandpiper and Wilson's Phalarope on the Zamorano University campus last weekend. On Monday, we swung by and observed those birds with him.

Wilson's Phalarope Monday at Zamorano University campus

We figured, however, that the southern salt ponds in the Gulf of Fonseca should be productive as well, so Wednesday morning we set out to bird that area. In our haste to be in the field as early as possible, before the infernal heat of midday, I forgot my camera. I'm sure any photographer will back me up when I say that it is precisely at such times that great photo opportunities abundantly present themselves.

Pectoral Sandpipers with a Buff-breasted Sandpiper

A cattle pasture next to extensive salt pans had a large flock (150+) of Pectoral Sandpipers, with four Buff-breasted Sandpipers and four Baird's Sandpipers mixed in. In the salt pans themselves, we found scattered little flocks of Wilson's Phalaropes, one large peep flock that consisted of 93 Semipalmated Sandpipers and 8 Westerns, some scattered Leasts, as well as another Buff-breasted, some Pectorals, scattered Stilt Sandpipers, Semipalmated Plovers and various other shorebirds. The best bird there was a White-rumped Sandpiper, a first for me in Honduras. We had great looks at all these birds, but no way to document them other than with field notes.

The next morning, we went back there, this time armed with a camera. Upon arrival, shorebird numbers seemed to be a little lower than the day before, but in the end we managed to see – and photograph – every species we reported the day before, with the exception of Greater Yellowlegs. 

Baird's Sandpiper

Only one Baird's Sandpiper remained in the field where the day before we had observed four. This individual had a small bill deformity, and the bill color was a little off too, but otherwise structure and plumage were good for this species.

Wilson's Phalaropes

In the adjacent salinera, scattered groups of Wilson's Phalaropes were still present, and easy to find.

This White-rumped Sandpiper (right) is too tired to stand on its legs

We also found a White-rumped Sandpiper, but this individual was clearly much more rufous than the one from the day before. It was in the company of Western Sandpipers, but unlike them it just sat there looking utterly exhausted, probably having just arrived after a non-stop flight from Tierra del Fuego!

Buff-breasted Flycatcher

Buff-breasted Flycatcher is a fairly common resident of pine-oak forests from the southwestern US through Mexico to Guatemala and Honduras; apparently rare in El Salvador. eBird does not have records for Nicaragua, although I observed this species in Honduras not far from the Nicaraguan border in 2007 and 2008 (as eBird reminds me), so it may occur there also. There's a historical record for El Salvador of four specimens collected in Chalatenango in 1927 (Dickey & Van Rossem 1938), and a slightly more recent record - 1976 - from Thurber et al. (1987). Evidently, the SalvaNATURA database (unpublished) has a few more recent records from northern El Salvador.

Yesterday we found a pair in Reserva Biológica Misoco (Honduras), on the border between the departments of Francisco Morazán and Olancho. This observation put a new dot on the eBird map for this species and a new bar (for the first week of May) in the Honduras eBird bar chart. 

Since the birds were vocalizing, I grabbed some audio and uploaded that to Xeno Canto. Although in the middle of the day there was no singing, they did vocalize briefly every time they changed position.

Literature:
Dickey, D. R. & A. J. Van Rossem. 1938. The Birds of El Salvador. Field Mus. Nat. Hist. Zool. Ser. No. 23, 609 pp.
Thurber, W. A., J. F. Serrano, A. Sermeño & M. Benitez. 1987. Status of uncommon and previously unreported birds of El Salvador. Proceedings of the Western Foundation of Vertebrate Zoology, Vol. 3, No. 3, 294 pp.

Raptor migration at Derby Hill

Broad-winged Hawk

Last week I visited New York, and part of my trip was an excursion to the Derby Hill hawk watch, where I was a raptor counter in 2006 and 2007. I consider those spring seasons at Derby Hill formative in some ways, for these were my first seasonal field gigs in North America, and the first of several hawk watch engagements I've been on. I've counted hawk migration in Michigan, Texas, Florida, New Jersey, Veracruz Mexico, and even in Honduras, where I now live, but it all began at Derby.

Golden Eagle

It was good to see familiar faces, meet new people also, and of course the birding wasn't bad either. Birding in Central America means that I don't get to see Golden Eagle, Rough-legged Hawk or Northern Goshawk on a regular basis anymore, so those were my target species for the trip to Derby. I was not disappointed. I was also lucky to catch a spectacular (500+ both days) Black-capped Chickadee flight along the bluff.

Northern Goshawk

Derby Hill, located in the southeastern corner of Lake Ontario, does best on southeast winds, and as luck would have it, the two days I was there the winds were from that most favorable direction. Such winds push the stream of migrant raptors to the lakeshore, which they then follow, trying to stay close to land where thermals form. Especially the second day started out beautifully with a parade of low-flying Broad-winged Hawks and other raptors. However, with plentiful sunshine and relatively light winds, the inevitable happened: the hawk flight got higher and higher, and birds were seen further and further out over the lake. This is a classic scenario that Derby regulars have observed many times. Gradually, the flight becomes a 'scope flight', in which observers scan just over the tree line in the direction of the lake, occasionally picking up distant kettles that shimmy in and out of vision, and sometimes are barely visible even in the scope. 

Whenever this happens, the locals speak of birds 'cutting the corner of the lake' or 'jumping off at Nine Mile (Point)' – Nine Mile Point being the name of the nuclear power plant 13 km (8 miles) west of Derby Hill. If the thermals, which the SE wind gently blows out over the lake, take the hawks high enough, the distance to the east shore of lake Ontario doesn't seem so threatening anymore, and hawks can bypass Derby.

Back in 2006 and 2007, I remember looking at NEXRAD radar from weather sites and being fascinated to see a hawk flight out over the lake – on radar. We always wondered if this would be visible by an observer on the ground also.

To field test this, my travel companion and I went over to Selkirk Shores State Park on Tuesday afternoon. For about 35 minutes, we scanned the skies toward Nine Mile Point and observed small groups of raptors coming in off the lake. Between 3:00 and 3:35 PM, we observed 15 Turkey Vultures, 1 Osprey, 1 Golden Eagle, 9 Sharp-shinned Hawks, 2 Bald Eagles, 135 Broad-winged Hawks, and 14 Red-tailed Hawks making landfall at Selkirk Shores. Not bad for an afternoon half hour of hawk watching!

But if the observers at Derby Hill cannot see all the birds 'cutting the corner', we in turn probably didn't see the entire flight either.

Here are some radar images from today (28 April 2013), with a very similar weather situation (light SE winds):

The clusters of green dots are groups of raptors flying along the lake shore. We can see them fly over Oswego, but when they get to Nine Mile Point, where the lakeshore topography changes direction, they seem to simply continue in more or less the same direction, passing north of the corner where Derby Hill is located. The birds appear to make landfall between Selkirk Shores and Sandy Pond, after which the stream of green dots changes course and follows a more northerly route, parallel to Highway 81.

At Derby Hill, the official count got to 843 raptors today, and counter Steve Kolbe noted a high flight in blue skies. Here's some more radar imagery, from almost an hour later. From 1:22 EDT to 2:10 EDT, several flight lines are shown: one over the lake, one over Derby Hill, and even some flight south of Derby Hill. The change of direction west along Highway 81 remains visible.

Isn't it incredible that hawk flights can be seen on radar this way? And what about other hawk watches? The NEXRAD radar network covers the entire United States, so in theory it ought to be possible to see these flights for other major hawk migration sites. The thing is: it all depends on how far the hawk watch location is from the nearest radar station.

Think about it: the earth is round, while the beam of the radar is straight. Thus, the radar samples relatively close to the ground in its immediate vicinity, but at higher air strata further away.

Here's a look at a slice of today's radar for Braddock Bay, like Derby Hill a Great Lakes raptor count site with a good spring hawk flight. At the time of writing, they hadn't posted their day totals yet. Around midday, there was only a modest flight visible on radar:



Birds can be seen following the lakeshore east, but the gray and green blocks zip off the screen, presumably as the flocks gain altitude and fly above the radar.

What about Whitefish Point, Michigan? Sadly, that site is at the edge of the range of the nearest radar (in Marquette) and thus radar images for Whitefish show nothing. There may well have been a flight there today, but due to its location relative to the nearest NEXRAD radar, it will never be visible on that radar.