lunes, 11 de febrero de 2013

Ring-necked or Tufted Duck?

 Partial view of the Laguna de Barlovento

First of all, my apologies for the exceptionally poor quality of the photos in the present post. To give an idea of the observing conditions, above is an uncropped, partial view of the Laguna de Barlovento reservoir. There are at least 5 birds in the photograph: fairly conspicuous in the lower centre is a Coot (Fulica atra); to the right of it are 3 very indistinct Common Teal (Anas crecca); and in the centre of the image, up against a clump of vegetation, is a solitary black and white duck. It is the latter bird which enticed me up to the far northeast corner of the island on what turned out to be a miserable, windy day...

As mentioned in the previous post, in January this year a male Ring-necked Duck (Aythya collaris) was reported by a visiting birder at the Laguna de Barlovento. This is a difficult location without a telescope, as the entire reservoir is fenced off, and it is impossible to get close enough to its banks for good views of the water with binoculars. An added incovenience is that weather conditions are often less than ideal, with poor light and blustery winds being frequent.

The reservoir is presently full to about 30% of its capacity, according to an estimate in the local press. This implies height differences of at least 20-30 metres between all accessible vantage points and the water surface. The resulting downward angles of vision may account for the fact that, in these photos, the drake's head does not look as characteristically large and pointed as might be expected for Aythya collaris. Perhaps the following view from the rear gives a better idea of its true shape...

Moreover, several other identifiction features visible in these photos indicate the Ring-necked (A. collaris) rather than the Tufted (A. fuligula) Duck: absence of tuft, white subterminal band on bill and white band at its base, flanks grey in colour with white vertical  "spur" at front, upper edge of flank panel more markedly S-shaped than on Tufted, longer tail...

After close examination of all the photos I managed to obtain yesterday, my opinion is that this is the male Ring-necked Duck, correctly identified and reported to the Spanish Rarities Committee by another observer in January this year. Opinions and comments would be greatly appreciated.

viernes, 8 de febrero de 2013

Black-tailed Godwit

 Black-tailed Godwit (Limosa limosa)

At the end of January, I observed the plainer of these two birds in an irrigation pond in Las Martelas (Los Llanos de Aridane). Presumably, this is a non-breeding adult, probably a female due to its larger size and longer bill. I was unable to get decent photos on that occasion, so didn't bother to post the sighting, and, as there are very few ponds available for waders at present (water levels are generally too high), I assumed the bird would fly on rapidly.

 Black-tailed Godwit (Limosa limosa) - male acquiring breeding plumage

However, on returning to the area on Feb 7, I was surprised to find not only the first bird still there, but also a second individual, presumably a male moulting into breeding plumage. The following images allow size comparison, differences in bill colour and length, and other plumage details to be appreciated.

Although both birds have relatively steep foreheads as in islandica, on the basis of distribution, the most likely race would appear to be the nominate limosa.  According to "Shorebirds of the Northern Hemisphere" (Richard Chandler), islandica only winters as far south as Morocco (where it overlaps with the nominate race), while limosa reaches sub-Saharan Africa. Comments would be appreciated.

Just to discount the remote possibility of haemastica (Hudsonian Godwit), the image below shows the white - not black! - underwing coverts.

Black-tailed Godwits have been recorded previously on La Palma, and are classed as regular winter visitors and passage migrants to the Canaries (all islands), but this was my first sighting of the species on the island.

Incidentally, the female Ring-necked Duck (Aythya collaris) featured in a previous post, was still in Las Martelas on Feb 7, together with 13  Tufted Ducks (Aythya fuligula). A male Ring-necked Duck was also reported by a visiting birder in January, at the Laguna de Barlovento.

martes, 5 de febrero de 2013

(White-tailed) Laurel Pigeon

 (White-tailed) Laurel Pigeon (Columba junoniae)

The present species, now simply known as the Laurel Pigeon (Columba junoniae) is endemic to the Canaries, but restricted to the western islands. It inhabits steep terrain covered with heath and patches of thermophilous woodland (probably its original habitat), and also certain pine forested areas, and has a marked tendency to move towards cultivated land at lower elevation.

It lays a single egg in nests constructed on ledges or cracks in rock faces usually hidden by vegetation, and breeds between March and September, often laying several times. The bird's diet consists mainly of fruits and shoots of trees growing in the laurel forests or thermophilous woods, together with a variety of cultivated fruits, plus the occasional addition of certain invertebrates and assorted vegetables.

La Palma has the largest population of Laurel Pigeons of all the Canary Islands, the species being particularly abundant in the Barranco del Agua (San Andrés y Sauces) and other ravines in the northeast and north of the island. [Info adapted from Atlas de las Aves Nidificantes  en el Archipiélago Canario (1997-2003), Lorenzo, J. A. (Ed.) 2007].

The present images were all taken in the Barranco del Agua this morning. The Laurel Pigeon is not an easy species to photograph with a 400mm lens. The sides of the barrancos are so steep that getting close to where the birds perch is virtually impossible. Light is also a problem, as the remaining patches of thermophilous woodland grow on the north facing slopes, which are in shade throughout the day at this time of year.

Both the Laurel Pigeon, and the more abundant Bolle's Pigeon (Columba bollii), are much easier to photograph outside their natural habitat, for example, when found feeding on cultivated fruit trees in sunnier locations.

It is interesting to note that while Bolle's Pigeon is closely related to the Common Wood Pigeon (Columba palumbus), and is a recent colonizer to the Canaries (5My),  the Laurel Pigeon is not closely related to either and is probably an old lineage that might have colonised the Canaries a long time ago (20My). [Field Guide to the Birds of Macaronesia, García-del-Rey, E. Lynx Edicions 2011].

Two more birds above

The present species, with its shorter wings, has a much slower and flappier flight action than Bolle's. All the birds observed today only made occasional, short sallies out from the sides of the gorge, and spent relatively long periods of time perched close to the cliffs or hidden from view on ledges. None flew for any distance along the length of the valley or crossed to the other side: their discreet behaviour may well indicate that some are already incubating eggs.