Socorrogrundammer
| Socorrogrundammer | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Pipilo maculatus socorroensis | ||||||||||||
| Grayson , 1867 |
The Socorrogrundammer ( Pipilo maculatus socorroensis , syn .: Pipilo socorroensis ) is a subspecies of the spotted basal bammer ( Pipilo maculatus ) from the genus of the basal bammer in the family of the New World chambers (Passerellidae). It has been considered an independent species by the Handbook of the Birds of the World , BirdLife International and the IUCN Red LIst since 2016. She is on the Revillagigedo Archipelago counting Island Socorro in the eastern Pacific endemic .
features
The body length is 15.0 to 17.5 cm, the weight of three examined males 29 to 30 g and the weight of four examined females 29.5 to 35.0 g. The upper elytra and the mantle have small white spots. The Socorro ground hammer resembles the nominate form of the speckled ground hammer, but it is smaller with an average wing length of around 70 mm. The head, the chest and the coat are dark gray-green to dark brown in the Socorrogrundammer, while these areas are black in the Fleckengrundammer. The stains on the coat and shoulders are reduced. The control springs have relatively inconspicuous white tips. The iris is red in adult birds, the beak blackish and the legs flesh-colored. The female is similar to the male, but the crown and top of the head are more blunt and more gray. In juvenile birds, the head and top are probably more blunt than in adult birds. The feathers of the young birds are lined with light brown and pointed. The elytra on them show clear yellow-brown tips. The underside of them is whitish with dark stripes and the iris is brownish.
Vocalizations
Most of the chants and calls of the Socorrogrundammer are similar to those of other subspecies of the Fleckengrundammer, but the Socorrogrundammer apparently has an additional song in the form of a descending vibrato , which is unknown in the continental subspecies.
habitat
The Socorrogrundammer inhabits bushy thickets, cactus undergrowth and wooded bushland from sea level to at least 650 m. They rarely venture into open living spaces. It is most commonly found in areas undisturbed by domestic sheep and dominated by shrubs and ferns with plenty of leaf litter and very little bare soil.
Way of life
The Socorrogrundammer feeds on insects and other invertebrates, probably also on seeds and fruits. Like other primaries, it mainly looks for food on the ground, where it scratches the leafy layer. The foliage of shrubs and small trees is also searched for insects. The breeding season apparently takes place at different times of the year. A nest was found in a shrub at sea level in August 1946 and contained indistinctly marked blue-gray eggs typical of the genus. The clutch size is not specified. Adult birds feeding the young birds were observed in November, February and March.
Hazard and protection
The IUCN classifies the Socorrogrundammer into the category of "high risk" ( endangered ). Their distribution is limited to the Endemic Bird Area Socorro. The total population is estimated at 2500 to 10,000 individuals. Expedition reports from the 19th century agree that the Socorrogrundammer was once frequent, widespread and trusting. In 1869 sheep were released on Socorro, which severely impaired the former habitat of the Socorrogrundammer. Surveys conducted in 1990 showed that the population density of the basal chambers ranged from zero to two birds per hectare in heavily damaged habitats by sheep and six to eight individuals per hectare in undisturbed areas. By 2014, the feral sheep on Socorro were eliminated, but the long-term negative impact of the sheep on the island's habitats is uncertain. In addition, the feral cats remaining on Socorro are very likely to pose a serious threat to the Socorro ground hammer and other native birds. Further research is necessary to assess the size and development of the population using systematic surveys and the influence of feral cats on the population to determine the Socorrogrundammer.
literature
- Bayard H. Brattstrom, Thomas R. Howell: The birds of the Revilla Gigedo Islands, Mexico. Condor 58 (2), 1956, pp. 107-120.
- Ricardo Rodriguez-Estrella, Jose Luis Leon de la Luz, Aurora Breceda, Aradit Castellanos, Jorge Cancino, Jorge Llinas: Status, density and habitat relationships of the endemic terrestrial birds of Socorro Island, Revillagigedo Islands, Mexico. Biol. Conserv. 76 (2), 1996, pp. 195-202.
- Antonio Ortiz-Alcaraz, Alfonso Aguirre-Muñoz, Federico Méndez-Sánchez, Alfredo Ortega-Rubio Feral sheep eradication at Socorro Island, Mexico: a mandatory step to ensure ecological restoration. Interciencia 41 (3), 2016, pp. 184-189.
- Josef del Hoyo, Nigel Collar, Jeff S. Marks: Socorro Towhee (Pipilo socorroensis) . In: J. del Hoyo, A. Elliott, J. Sargatal, DA Christie, E. de Juana (Eds.): Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona, 2018, accessed December 27, 2018.
Web links
- Pipilo socorroensis inthe IUCN Red List of Threatened Species 2018.2. Posted by: BirdLife International, 2016. Retrieved December 27, 2018.