Laurel Pigeon

Laurel Pigeon
Conservation status
Endangered (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Columbiformes
Family:	Columbidae
Genus:	Columba
Species:	C. junoniae
Binomial name
Columba junoniae Hartert, 1916

The Laurel Pigeon, White-tailed Laurel Pigeon, Paloma rabiche, (Columba junoniae) is a species of bird in the Columba genus in the Columbidae family. It is a member of the family Columbidae of doves and pigeons, which is endemic to the Canary Islands, Spain. This Wood Pigeon is endemic to the Laurel forest habitat.

Generallity

It is a pigeon which is endemic to some Canary islands. Iits close relative and probable ancestor is the Common Wood Pigeon. Despite its bulky, long-tailed appearance, this pigeon has a fast, direct flight.

The major cause of its population decline is habitat loss from forest clearance, but hunting and nest predation by Introduced species and rats were also contributory factors. Protection of the laurel forests and an effective ban on hunting could enabled numbers to increase, although this species is still declining and endangered.

Description

The Laurel Pigeon is a rather plain, dark grey bird of 38 cm. Large, dark brown and grey pigeon. Mainly dark sepia-brown, redder on underparts. Pale grey tail with broad, whitish terminal band. Extensive green gloss to rear crown and hindneck becoming pink on upper mantle. Whitish bill and pale eye.

A rare resident breeder in the mountain laurisilva and Canary pine forests, the Laurel Pigeon builds a stick nest in a tree. There it lays one white egg.

At 40–43 cm, a Laurel Pigeon looks like a very dark Wood Pigeon. It is a basically dark brown bird, with a dark pink breast. The lack of any white markings, together with its darker markings, distinguish it from the other species.

Brown, rather than dark grey plumage, and the lack of dark bands on the grey tail distinguish it from the other pigeon endemic to the Canary Islands, Bolle's Pigeon.

A Laurel Pigeon's flight is quick and performed by regular beats. An occasional sharp flick of the wings is characteristic of pigeons in general. Often, the bird takes off with a loud clattering.

The call is a hoarse hiccuped cooing.

Dark tail base and rump and overall slate-grey colouration. Voice Crooning pu-pu-pooo.

The similar canarian species, the Dark-tailed Laurel Pigeon Columba bollii has pale grey subterminal band and blackish terminal band to tail.

Ecology

It prefers areas with steep slopes, escarpments and gullies, where it occurs in dry forest, laurel forest and Canary pine forest, as well as cultivated areas4. Nests are on the ground - in fissures, holes or small ledges, at the bases of trees, and under rocks or fallen tree trunks - in steep, rocky, shady areas with abundant shrubby vegetation4. The breeding season varies between islands, but extends from January to September, with a peak between April-June. At least on Tenerife, breeding success appears to be low, as a consequence of intense nest predation1,4.

Pigeons can breed from their first year, and nesting occurs throughout the year, although mainly from February to June. The displays are similar to those of the Common Wood Pigeon; the male climbs quickly in flight, gives a loud wing-clap, and then glides down with his wings and tail spread. The display may be repeated two or three times before the bird returns to a perch. On the ground the male performs a bowing display with his neck inflated to show off the iridescent neck patches; meanwhile, the tail is raised, fanned, then closed again. This display is usually accompanied by calling. The nest is a typical pigeon construction, a flimsy structure of twigs and grasses usually placed high in the floor of canyon walls with lots of vegetation. Nestled among the crevices in rocks, in gullies of the hills. The usual clutch has a white egg one smooth white egg. Breeding success and nest predation have effects on the two Canarian endemic pigeons, Bolle's Laurel Pigeon Columba bollii and White-tailed Laurel Pigeon Columba junoniae. Nest predation was the more important cause of nesting failure of both species (88%), but principally affecting the White-tailed Laurel Pigeon. It showed a greater predation on the ground than in trees and a lower predation in the Frebuary-March period than in June-July and September October. The abundance of predators, estimated by bait consumption, showed a similar seasonal pattern, while fruit availability decreased over time from the first to third period. Predators identified by automatic cameras showed that Black Rat Rattus rattus was the major nest predator of both pigeons. These general patterns of nest predation alfect the White-tailed Laurel Pigeon which breeds on the ground mainly during April-July, much more than Bolle's laurel Pigeon, which breeds in trees especially in February-June. All seems to indicate that rats are the key factor causing the scarcity of the White-tailed Laurel Pigeon on Tenerife.

The Laurel Pigeon is exclusively herbivorous. Nearly 60% of its diet is fruit, with most of the rest being leaves, and just 1% is flowers. The fruits of Til, Azores Laurel and Persea indica, and the fruits and leaves of Small-leaved Holly are the most frequently detected food items. Most seeds pass through the digestive system intact, apart from those of Azores Laurel, which are usually damaged. Fruit is the main component of the diet when it is readily available in autumn and winter, and leaves are consumed in spring and summer when fruits are scarce. In one study, 27% of the leaves consumed came from native trees, especially Small-leaved Holly, 61% from herbs and shrubs, and nearly 10% from introduced trees, mainly apples and peaches.^[2] This pigeon will feed in agricultural areas, where cabbage is the most commonly taken crop plant.

However, when the fruit crop of Til and Azores Laurel is poor, large numbers of pigeons may leave the forest to feed on cabbage, flowering cherries and vine shoots.^[3] Competition for food with rats can be significant in parts of the island.

Distribution and habitat

Macaronesian Laurel forest

The Laurel Pigeon is endemic to the mountainous subtropical Atlantic west Canary islands, where it occurs on the islands of La Palma, La Gomera, Tenerife and El Hierro. In the 1980s, the population was estimated at 1,200-1,480 individuals, but more recent surveys have shown that it is more numerous, and more widely distributed. The largest subpopulation is found on La Palma, where it occurs across much of the northern half of the island. The species is common on La Gomera, where it is found primarily in the north, and also occurs patchily on the northern slopes of Tenerife. It has recently also been recorded on El Hierro; however, breeding there has not yet been confirmed3,4. Although the species was recently suspected to be declining on Tenerife. Formerly also bred on the neighbouring Gran Canaria. It mainly occurs on the northern slopes of the mountains, but smaller numbers are found in the south where suitable patches of laurel forest remain.

The natural habitat is tall laurisilva forest or dense tree heaths which are cloud-covered for much of the year.^[4] The forests consist mainly of Azores Laurel, Oreodaphne foetens,^[5] Til, Madeira Mahogany, Canary Laurel, Faya, Lily of the Valley Tree and the Picconia. The Trocaz Pigeon prefers primary forests, but secondary growth is used for feeding, and agricultural land is also visited, especially at times of fruit shortage.^[3] Most of the pigeons are found below 1000 m (3300 ft), and their prime environment appears to be steep ravine-indented slopes along artificial watercourses, with the occasional large dead laurel tree and much tree heath.^[4] This species is highly mobile between different areas at different times of year.

It was very abundant when the islands were first colonised by humans, but was extirpated. The losses on the islands were largely due to deforestation for wood and to create agricultural and grazing land.

The exclusion of livestock from the native forest allows it to regenerate and create more suitable habitat. Some illegal hunting and poisoning continues because of the damage this pigeon can do to crops. Perhaps the main limiting factor on the rate at which the pigeon increases its numbers is eggs and young being taken by introduced Black Rats. It is now classed as Near Threatened on the IUCN Red List, an improvement on its Threatened status in 1988. This species is protected under the European Union Birds Directive, and the laurel forests under the Habitats Directive.

Taxonomy

The genus Columba is the largest within the pigeon family, and has the widest distribution. Its members are typically pale grey or brown, often with white head or neck markings or iridescent green or purple patches on the neck and breast. The neck feathers may be stiffened and aligned to form grooves. One of several subgroups within Columba consists of the widespread Eurasian Common Wood Pigeon, Bolle's Pigeon, the Trocaz Pigeon, and the African Afep Pigeon. The two Macaronesian endemic pigeons, Bolle's and Trocaz, are thought to be derived from isolated island populations of C. palumbus.^[6]

The Atlantic archipelagos of the Canaries, Azores, and Madeira have a volcanic origin and they have never been part of a continent. The formation of Madeira started in the Miocene and the island was substantially complete by 700,000 years ago.^[7] At various times in the past, the major islands of these archipelagos were all colonised by ancestral wood pigeons, which evolved on their respective islands in isolation from the mainland populations. Mitochondrial and nuclear DNA sequences suggest that the ancestor of Bolle's Pigeon may have arrived in the Canaries about 5 mya, but an older lineage that gave rise to another Canarian endemic, the Laurel Pigeon, C. junoniae, may date from 20 mya.^[8] The most recent wood pigeon arrival on Macaronesia was that which gave rise to the subspecies C. palumbus maderensis.

The Trocaz Pigeon was formally described in 1829 by Karl Heineken. He recognised it as different from the now-extinct local form of the Madeiran Wood Pigeon a sub-species of the Common Wood Pigeon. This is a monotypic species, although in the past the canarian Bolle's Pigeon was sometimes regarded as a subspecies of the Trocaz Pigeon.^[9]

References

1. ^ BirdLife International (2004). Columba junoniae. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Database entry includes a brief justification of why this species is endangered and the criteria used
2. ^ Oliveira, Paulo; Marrero, Patricia; Nogales, Manuel (2002). "Diet of the endemic Madeira Laurel Pigeon and fruit resource availability: a study using microhistological analyses" (PDF). The Condor 104 (4): 811–822. doi:10.1650/0010-5422(2002)104[0811:DOTEML]2.0.CO;2. http://digital.csic.es/bitstream/10261/22475/1/CND-2002-104-811.pdf. 
3. ^ ^{a b} Gibbs (2000) pp. 188–189.
4. ^ ^{a b} Snow (1998) p. 848.
5. ^ Hartert, E (1912–21) (in German). Die Vögel der paläarktischen Fauna. Volume 2. Berlin: H. Friedlander & Sohn. p. 1480. http://www.archive.org/stream/dievgelderpal02hart#page/1480/mode/1up. 
6. ^ Gibbs (2000) p. 175.
7. ^ "Madeira". Global Volcanism Program. Smithsonian Institution. http://www.volcano.si.edu/world/volcano.cfm?vnum=1802-12-.  Retrieved 20 July 2010
8. ^ Gonzalez, Javier; Castro, Guillermo Delgado; Garcia-del-Rey, Eduardo; Berger, Carola; Wink, Michael (2009). "Use of mitochondrial and nuclear genes to infer the origin of two endemic pigeons from the Canary Islands". Journal of Ornithology 150 (2): 357–367. doi:10.1007/s10336-008-0360-4. 
9. ^ Martin, A (1985). "Première observation du pigeon Trocaz (Columba trocaz bollii) à l'Ile de Hierro (Iles Canaries)" (in French). Alauda 53 (2): 137–140. 

References

External links

• BirdLife Species Factsheet.