Herons, spring 2011

Purple Heron (Ardea purpurea)

First glimpsed at a distance on April 16, identification remained uncertain until better views a day later settled the doubt. This is my first sighting of Purple Heron ( Ardea purpurea) on La Palma, although the species is a "regular but scarce passage migrant, especially in spring, recorded from all main islands except El Hierro" (Birds of the Atlantic Islands, T. Clarke 2006).

There are presently at least two birds around the irrigation basins in Las Martelas and adjacent areas, while on the island of Tenerife, two groups of 7 and 4 individuals have been sighted this month - exceptional for a species which normally appears in ones and twos. See the SEO blog avescanarias.blogspot.com for more details.

The photo above was taken early in the morning, after waiting under a camouflage net for first light. At about 7:20, the bird glided in from out of nowhere and landed on the shady side of the pond, remaining almost motionless and partly hidden for about one hour, making no attempt to forage.

Getting the first images meant setting the ISO speed at 1600, shutter 1/6 second, f.5.6. After its initial inactivity, the heron finally flew over to the sunnier side of the basin, and, had it not been for the untimely appearance of a man who flushed the bird when he came to measure the water level, I might have got some more satisfactory, better-lit shots...

Purple Heron in early morning sun

The Squacco Heron (Ardeola ralloides) is a fairly regular visitor to the island, and is tolerant of stealthy approach. It seems to feed well while here, taking frogs, tadpoles, dragonfly larvae, and possibly the occasional small fish, hunting either by wading or from a perch. Two individuals are present at the time of writing, in various irrigation basins in Tazacorte.

Squacco Heron hunting in water

Squacco Heron: on the left, slightly out of focus, one of the 3 surviving Moorhen (Gallinula chloropus) chicks from an early February brood

Finally, the Night Heron (Nycticorax nycticorax) mentioned in my last post, has been seen on a number of occasions in Tazacorte and Las Martelas, both on the ground, and in flight.

Night Heron (Nycticorax nycticorax)

Spring Migrants 2011

Group of 3 Black-winged Stilt (Himantopus himantopus)

After a longish spell with little migratory activity, the above group of three Black-winged Stilt (Himantopus himantopus) photographed in Las Martelas on April 15 came as a pleasant surprise!

A small colony of this species established itself on Lanzarote in the 1990s, and the bird has also bred sporadically on Fuerteventura, Gran Canaria and, more recently, on Tenerife (Atlas de las Aves Nidificantes en el Archipiélago Canario, Ed. J.A.Lorenzo, 2007). On the remaining islands it is probably an uncommon but regular passage migrant (Birds of the Atlantic Islands, T. Clarke 2006).

The following record for La Palma was published in Ardeola 42/2 1995:

6 birds on April 11 1994 and 3 birds on April 15 1994 in irrigation basins in Las Martelas (Los Llanos de Aridane), and 1 female in the seawater pools near the airport on 13 and 15 April 1994 (D. Trujillo).

Black-winged Stilt (Himantopus himantopus)

The Night Heron (Nycticorax nycticorax) shown below was discovered in an irrigation basin in Tazacorte on the evening of April 16: the handheld shot was captured in poor light conditions, with ISO set at 1600, 1/250 second, with a 400mm lense without image stabilisation.

This species has bred recently on Tenerife, and possibly occasionally on Gran Canaria, and there are records of birds on passage from all the islands. In the case of La Palma, a sighting was published in Ardeola Vol. 55/2 2008 of an individual seen by I. Brito in Las Martelas on Sep 28-29 2000.

Night Heron (Nycticorax nycticorax)

The Squacco Heron (Ardeola ralloides) has been recorded regularly on La Palma in recent years, mainly around irrigation basins in Tazacorte, where the bird below was located on April 15.

Squacco Heron (Ardeola ralloides)

The following Wood Sandpiper (Tringa glareola) has been seen in various irrigation basins in Las Martelas since April 7. This individual appears to have exceptionally long tibia...

Wood Sandpiper (Tringa glareola)

Over the last few days, apart from the above species, there have been up to 6 Little Ringed Plover (Charadrius dubius) in Las Martelas, a Redshank (Tringa totanus) at the seawater pools near the airport, and a possible sighting of a Purple Heron (Ardea purpurea), also in Las Martelas but pending confirmation and photo.

Common Nesting Birds 2

Male Sardinian Warbler (Sylvia melanocephala)

Very common in forest or scrub, especially at low to medium altitude, the noisy rattle-like call of the Sardinian Warbler (Sylvia melanocephala) is unmistakable, and is emitted during foraging and when perched.

Interestingly, the natural habitat of Canary Island warblers in the past was probably the thermophilous forest, located between the coastal and montane zones, a kind of Mediterranean dry woodland in which wild olive trees, palms, dragon trees, juniper, buckthorn and various other trees and bushes once grew. As these areas were cleared to create farmland, or generally became degraded, warblers were able to expand their range both above and below their original habitat (Atlas de las Aves Nidificantes, Ed. J.A. Lorenzo, 2007).

The photos in this post were all taken in coastal scrubland, on a dull windy day with fairly poor light. Both the male and the female were foraging energetically, in order to deliver food to a nest hidden in a thicket of Rumex lunaria (Tree Sorrel).

Male emitting characteristic rattle-like call

Male Sardinian Warbler perched in a Rumex lunaria bush

Blackcap nest

The above image shows a patch of degraded scrub typical of uncultivated land in low-lying areas, consisting of a mixture of genuine Canary Island flora together with various invasive species.

In the shady area on the left is a species of Sorrel (Rumex lunaria) and, right of centre, the bright green, succulent foliage of a Verode (Kleinia nerifolia) can be seen. It is in this latter bush that a pair of Blackcaps (Sylvia atricapilla) have decided to nest...

Both parents assiduously feed the chicks, usually perching on the Sorrel bush before first swooping down, and then up, through the branches of the Verode, often in one single movement, as the following image attempts to illustrate.

Male Blackcap (Sylvia atricapilla) carrying food to nest

At ISO 400 and 1/3200 of a second, this photo leaves plenty of room for improvement! When either of the birds briefly perches before flying up to the nest rim, as was the case with the female below, it is obviously much easier to freeze the action.

Female Blackcap perching before flying up to nest

The remaining images show the two birds transporting food items to the breeding site, which is located in a ludicrously exposed position very close to a track, in an area which offers an almost unlimited supply of more secluded, virtually impenetrable vegetation of exactly the same type. So why there precisely?

Common Nesting Birds 1

Canary (Serinus canarius)

Ancestor of the numerous caged varieties bred over the centuries, the Canary (Serinus canariensis) is plentiful and widely distributed in both natural and man-made habitats, including pine forests, heathlands, coastal and summit scrub, and gardens and farmland. The three images shown here were taken in degraded scrub in Las Martelas, an area of irrigation basins outside Los Llanos.

Regarded as a subspecies of the Common Chiffchaff (Phylloscopus collybita), the endemic Canary Islands Chiffchaff (P. canariensis) is extremely common in a wide range of habitats, at all altitudes. It is one of the only four warblers found on the island, the other three species being the Blackcap (Sylvia atricapilla), the Sardinian (S. melanocephalus) and the Spectacled Warbler (S. conspicillata).

Canary Islands Chiffchaff (Phylloscopus canariensis)

Female Blackcap (Sylvia atricapilla)

Abundant in both forest and scrubland habitats, this species is largely absent from pure pine forests. The male's melodious warbling is frequently heard in urban surroundings, coming from the dense foliage of the Ficus microcarpa trees planted in squares and streets throughout the island.

Moorhen: first brood of 2011

Parent with five of the six chicks

The Moorhen (Gallinula chloropus) breeding season is already underway: the first brood of the year, consisting of 6 chicks, appeared in one of several regularly-monitored irrigation basins in Tazacorte on Feb 13.

Information on this species has appeared previously in this blog, but here is a brief summary of the figures:

In 2009, 5 irrigation basins were monitored and a total of 13 broods detected, with 49 chicks hatching altogether, of which 10 were observed to survive until they eventually left their respective ponds as fully-independent young birds.

In 2010, the same 5 basins were monitored plus 3 others. Altogether, 18 broods were detected with a total of 67 chicks, of which 14 survived until they finally abandoned their ponds as independent juveniles.

The percentage of surviving chicks from the total number hatched is remarkably similar in both years: in 2009, 20.4% and in 2010, 20.8%.

As a matter of curiosity, the first brood of 2010 was discovered slightly later in February, at a different location, and also consisted of 6 chicks, of which 2 survived.

Both parents feed the recently-hatched chicks, most of which fail to survive, due to factors outlined in previous posts.
(see 28 Jul 2010 and 16 Dec 2009)

Annual Ardeidae Census - RESULTS

Mouth of the Angustias Ravine on the west coast of the island

The results of the Annual Ardeidae Census were better than expected on the west side of the island: at least three communal roosts have been identified, and smaller numbers of Little Egret (Egretta garzetta) and Grey Heron (Ardea cinerea) were also counted at other sites.

As suspected, some birds of both species fly past the mouth of the Angustias Ravine from early evening onwards, and then head up the coast towards Tijarafe. The precise location of the roost remains unknown, but is probably somewhere on the cliffs opposite the offshore fish-farm (see previous post). One of our observers positioned on the old quay at Puerto de Tazacorte, on the evening of Jan 28, counted 51 Little Egret and 5 Grey Heron flying northwards over the sea at low altitude.

The old harbour wall at Puerto de Tazacorte, looking north

Another member of the our team visited the Dos Pinos reservoir, shown below. Although up to 35 Grey Heron have been recorded around the inner rim of this large irrigation basin in the past, on Jan 28 only 9 birds turned up. Prospections carried out a few days earlier revealed similarly reduced numbers. Perhaps higher counts have included contingents of birds on passage, and not only overwintering individuals.

Dos Pinos reservoir, south of Los Llanos

The recently-discovered roost in Tazacorte, featured in the previous post, yielded a total of 52 Little Egret and 1 Grey Heron, from 18:00h to about 19:25h, when light conditions made further counting impossible. The solitary Cattle Egret spotted on Jan 19 was not recorded on the evening of the census.

The Little Egret roost in Tazacorte. Birds spend the night in the tops of the banana plants located above and to the right of the irrigation basin. The photograph was taken on the evening of the census, from my chosen vantage point.

Other sites where significant figures were obtained:

Los Barros, a mainly avocado-growing and residential area above Los Llanos, yielded a total of 12 Little Egret and 3 Grey Heron in the vicinity of the numerous irrigation tanks.

The floating cages of the fish-farm in Tijarafe added a further 14 Little Egret and 12 Grey Heron.

TOTAL FIGURES FOR THE ISLAND:

134 Little Egret + 35 Grey Heron