Justification of Red List Category
This species is classified as Endangered because it is likely to be declining within its very small range on a single island, as a result of habitat degradation and the impact of alien invasive species.
R. Curry (in litt. 2005) estimated that this species occupies c.25% of the 552 km2 area of San Cristobal, i.e. 138 km2. The density of birds in occupied habitat is 0.6 birds / ha, giving a total population size estimate of 8,280 birds, perhaps best rounded to c.8,000 individuals. This roughly equates to c.5,300 mature individuals. However, the population may be significantly smaller than this (D. Wiedenfeld in litt. 2012).
Despite a lack of new data on population size or trend, the threats facing the population remain unchanged, suggesting that slow to moderate declines may be continuing.
Mimus melanotis is endemic to the island of San Cristóbal in the central Galápagos islands, Ecuador (Sibley and Monroe 1990). Its population has recently been estimated at c.8,000 individuals, on the basis that it occupies c.25% of the 552 km2 area of the island, with occupied areas holding approximately 0.6 birds/ha (R. Curry in litt. 2005).
It occupies a wide range of habitats from lowlands up to the island summit at 715 m, including arid open lowland scrub, mangroves, scrubby woodland with scattered trees (Bursera spp.) and arborescent cacti (Opuntia spp.), low woodlands of introduced guava (Psidium guajava) and taller patches of forest. It tends to avoid dense lowland forest, taller, wetter woodland, grassland and urban areas (Cody 2005). The species forages on the ground for arthropods, also taking fruit and berries and occasionally picking ticks (Acarina) off marine iguanas (Amblyrhynchus spp.). It breeds in January to April, apparently not cooperatively, in contrast to other Nesomimus spp. (Cody 2005).
Several threats are suspected to be causing population decline, including introduced species (diseases, parasites and predators), habitat degradation, and human disturbance (Vargas 1996, Wiedenfeld and Jiménez 2008, R. Curry in litt. 2005, H. Vargas in litt. 2005, A. Tye in litt. 2005, D. Wiedenfeld in litt. 2005). The presence of the Dipterid nestling parasite Philornis downsi is likely a significant threat (Wiedenfeld et al. 2007). A number of disease vectors have been introduced, including Culex quinquefasciatus (vector of avian malaria) and Simulium bipunctatus (Peck et al. 1998, Vargas and Bensted-Smith 2000, Whiteman et al. 2005), and chickens in the growing number of chicken farms have brought in new diseases and may act as intermediary hosts (Gottdenker et al. 2005). The incidence of parasites and diseases could be more important in the future with the increase in frequency and intensity of El Niño events and the more humid conditions in the islands (H. Vargas in litt. 2005, Wiedenfeld et al. 2007). Habitat loss and degradation is caused by invasive introduced plants (Psidium guajava, Syzygium jambos, Rubus niveus) (Vargas 1996), overgrazing by goats, and increased human settlement. Black rats and feral cats have been introduced and are thought to be responsible for high nest predation rates (Curry 1989). The relative importance and impacts of these different threats are not yet known.
Conservation Actions Underway
The Galápagos National Park was gazetted in 1959, and includes almost all the land area of the islands. In 1979, the islands were declared a World Heritage Site (Jackson 1985).
25-26cm. Large mimid, greyish-brown above and pale below, with prominent black lores and blackish ear patch. Sexes similar, female c. 10% smaller than male in linear measurements. Juvenile is more streaked below than adult. Voice Loud, melodious and disjointed territorial song, typical of other members of its genus.
Text account compilers
Butchart, S., Ekstrom, J., Gilroy, J., Harding, M., Sharpe, C J, Temple, H.
Tye, A., Vargas, H., Wiedenfeld, D., Curry, R.
BirdLife International (2019) Species factsheet: Mimus melanotis. Downloaded from http://www.birdlife.org on 13/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 13/11/2019.