Socorro Dove

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Common Name: Socorro Dove
Scientific Name: Zenaida graysoni

Size: 10.4-12 inches (26.5-30.5cm)

Habitat: North America; Socorro in the Revillagigedo Islands, Mexico. It was apparently commonest in forested areas above 500 m, dominated by Bumelia, Prunus serotina, Guettarda, Ilex, Psidium and Ficus.

Status: Extinct in the wild. Global Population: 100+/- Mature individuals. The decline and extinction in the wild of the Socorro Dove has been attributed chiefly to predation by cats. Other factors, such as human predation and high levels of understory grazing by sheep, may have also been significant in its decline. Outbreaks of an introduced locust (Schistocerca piceifrons) swarm have occurred twice a year since 1994, resulting in damage to the leaves, flowers and fruit of indigenous forests, thus reducing the extent of prime habitat for the species. The last record of an individual of this species in its natural habitat was in 1972.

The Revillagigedo Islands were declared a biosphere reserve in 1994. In 1995, the European Association of Zoos and Aquaria recognized a breeding program for the species, as initiated by Cologne and Frankfurt Zoos (Germany) and the private interest group Wild Pigeons and Doves, as an official European Endangered Species Program. Individuals have been distributed to zoos and bird parks in Belgium, The Netherlands, UK, Poland, Austria, Luxembourg, France, Spain and Germany. Of 563 individuals listed in December 2006, 104 were known to be alive. In 2006, following an extensive survey of the origin of the founding individuals of the EEP population, a major software based population genetic analysis was conducted and recommendations for new pairs were given by the EEP coordinator. A special breeding unit for the species has been opened at Marlow Bird Park, Germany. A proposal is currently being developed to reintroduce the species, along with a restoration program for Socorro. DNA fingerprinting has revealed extensive hybridization with the Mourning Dove (Zenaida macroura) in the USA, however it also showed a high degree of relatedness between the European population and pure individuals kept in California. As a result, the European population will be used for reintroduction efforts. The construction of breeding aviaries on Socorro began in August 2003 and was completed by 2005. The island's populations of Mourning Dove and Socorro Gound-dove were screened in December 2003 and January 2004 to assess the presence of pathogens that might affect the reintroduction program. Avian malaria and Trichomoniasis were detected in both species, and as a result recommendations were put forward. In 2005, plans were outlined to control the locust outbreaks, restore native vegetation and assess the problem of erosion. The arrival on Socorro of the first captive birds from Germany was planned for June 2005, with the establishment of a captive flock by June 2006. However, there have been problems with import restrictions and permits. In the face of these restrictions a small insurance population will be established in the USA in 2008.

Some control of feral cats has been undertaken on Socorro, and there are plans to eradicate cats in 2009, at the earliest. Reports that rats have recently colonized Socorro have proved to be unfounded. The sheep population has been reduced to c.300 by the Mexican Navy. Sheep eradication is planned for 2008-2009

Diet: Preferred fruits; also depended on an intact understory of ferns and euphorbias.

Breeding: Male has deep cinnamon head and underparts, with black streak on lower ear-coverts, blue-grey nape and iridescent pink neck patch. Dark brownish upperparts, boldly spotted with black on scapulars, tertials and inner wing-coverts. Dark grey flight feathers. Dark brown central tail, outer feathers grey with black subterminal band and grey tips. Female duller, with smaller blue-grey nape and pink neck-side patches. Juvenile similar to female, except coarse breast streaking and cinnamon-buff tips to upperparts feathering. In all plumages has pale blue orbital ring, pinkish legs and dark grey bill with reddish-pink base.

Virtually nothing is known about breeding in the wild. In captivity the female generally lays two white eggs in a nestbox 1-2.5 m above ground. The incubation lasts 14–17 days. The young fledge after 14–20 days.

Cool Facts: On October 30, 2006, the Socorro Dove was successfully bred at London Zoo. The bird was named "Arnie", after Arnold Schwarzenegger, with reference to his famous line "I'll be back" (on Socorro Island). However when Arnie was sexed he turned out to be a she. It is hoped that the descendants of Arnie and her relatives can someday soon be reintroduced into the wild.

There is marked behavioral difference to the Mourning Dove. When Andrew Jackson Grayson discussed the species, he called it the "Solitary Dove" because he never saw more than one male and one female together. The doves, particularly the adult males, chase away their young as soon as these can fend for their own and the partners split for the time being. This too, is believed to be an adaptation to the former dominance of aerial predators, lest local concentrations of birds, let alone young, unexperienced ones, would present easy targets for the hawks. Typical of many birds on mammal-less islands, Socorro Doves show little fear of humans or, fatally, cats.

Found in Songbird ReMix Threatened, Endangered, Extinct 3

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