San Cristobal Mockingbird Mimus melanotis Scientific name definitions

Up until recently the mockingbirds of the Galapagos were considered to form a separate genus, Nesomimus. Now molecular data confirms that they are imbedded within typical Mimus, so they have been shifted to this typical mockingbird genus. The San Cristobal Mockingbird forms a clade (related group) with the Española Mockingbird as well as the bauri subspecies of the Galapagos Mockingbird. San Cristobal Mockingbirds are uncommon but widespread on San Cristobal, their densities do not appear to be as high as that of Galapagos Mockingbirds on Santa Cruz Island for example. Visually the San Cristobal Mockingbird is somewhat intermediate between a Galapagos Mockingbird and a Española Mockingbird; showing a less prominent white neck collar than the Galapagos, but a darker plumage and more solid flank streaking than the Española Mockingbird. This mockingbird is found in the arid lowlands, but also ventures higher into moist areas and can be quite arboreal. They are seen in pairs, and after breeding in family groups.

25–26 cm; male average 53·2 g, female average 48 g. A smaller Nesomimus, intermediate in appearance between M. macdonaldi and M. parvulus, with decurved bill comparatively short. Has obscure narrow whitish supercilium, prominent black lores and blackish ear patch, narrow black malar stripe; crown and upperparts greyish-brown, somewhat streaked, upperwing-coverts tipped whitish (two wingbars); flight-feathers and tail dark brown, outer three rectrices with off-white tips; whitish below, sometimes slightly buff-tinged on throat, breast side with tiny dark spots, flanks with blackish-brown streaking; iris amber to dark reddish-brown; bill and legs blackish. Sexes similar, female c. 10% smaller than male in linear dimensions. Juvenile is more streaked below than adult.

San Cristóbal I, in E Galapagos Is.

Occupies a wide range of habitats, from lowlands up to island summit at 715 m: found in low and open arid scrub in lowlands, also mangroves, to low scrubby woodland with scattered trees (Bursera) and arborescent cacti (Opuntia), and taller Bursera and Piscidia woodland patches; also low woodland of introduced guava (Psidium guajava). Not all available habitat on island occupied; avoids dense lowland forest, taller, wetter woodland, Bursera-dominated scrub, and grassland.

Sedentary.

Feeds on terrestrial arthropods, including crickets and grasshoppers (Orthoptera); also takes fruits and berries. Occasionally picks ticks (Acarina) off marine iguanas (Amblyrhynchus), but not known to drink blood. No evidence of feeding on seabird eggs (perhaps owing to low availability). Forages mostly on ground , searches litter for arthropods; also low in vegetation for fruits.

Loud, melodious and disjointed territorial song typical of genus.

Jan–Apr, later at higher elevations. Territorial, often with additional adult; 25–50% of pairs had extra, subordinate male, but no evidence that latter assists in nest-building, nest defence, or feeding of young; territory 3–5 ha or more, considerably larger than in congeners, territory size increases with group size. Nest, built by both sexes, a bulky structure of twigs, lined with grasses, placed 4–5 m up in crotch of tree. Clutch 2–5 eggs, usually 4, greenish with reddish-brown spots and blotches; incubation by female alone, nestlings fed by both parents; no information on incubation and nestling periods.

ENDANGERED. Previously considered not globally threatened. Restricted-range species: present in Galapagos Islands EBA. Considered to be common on the single, large island of San Cristóbal (552 km²). Overall density is rather low, at 0·5–0·7 individuals/ha. Assuming that this species occupies c. 25% of the island, the total population has been estimated at 8280 birds, or 5300 mature individuals, although there are fears that it may be significantly smaller BirdLife International (2016) Species factsheet: Mimus melanotis. Downloaded from http://www.birdlife.org on 02/09/2016. . A combination of threats is suspected to be causing population decline. These include introduced species (predators, parasites and diseases), habitat degradation, and human disturbance (1 Wiedenfeld, D. A., and G. A. Jiménez-Uzcátegui (2008). Critical problems for bird conservation in the Galápagos Islands. Cotinga. 29:22–27. Close ). Introduced black rats (Rattus rattus) and feral cats may be causing increased nest predation rates. The bot-fly parasite Philornis downsi is likely to increase nestling mortality (2 Wiedenfeld, D.A., Fessl, B., Kleindorfer, S. and Valarezo, J.C. (2007). Distribution of the introduced parasitic fly Philornis downsi (Diptera, Muscidae) in the Galápagos Islands. Pacific Conservation Biology 13(1): 14-19. Close ). A number of disease vectors have been introduced, including the mosquito Culex quinquefasciatus, which transmits avian malaria (3 Whiteman, N.K., Goodman, S.J., Sinclair, B.J., Walsh, T I.M., Cunningham, A.A., Kramer, L.D. and Parker, P.G. (2005). Establishment of the avian disease vector Culex quinquefasciatus Say, 1823 (Diptera: Culicidae) on the Galápagos Islands, Ecuador. Ibis. 147(4): 844-847. Close ), and the growing number of small- and large-scale chicken farms have brought in new diseases and may increase the risk of disease spilling over into natural communities (4 Gottdenker, N.L., Walsh, T., Vargas, H., Merkel, J., Jiménez, G.U., Miller, R.E., Dailey, M. and Parker, P.G. (2005). Assessing the risks of introduced chickens and their pathogens to native birds in the Galápagos Archipelago. Biological Conservation. 126(3): 429-439. Close ). The incidence of parasitism and disease may grow in future with the greater frequency and intensity of El Niño events and increasingly humid conditions in the islands (2 Wiedenfeld, D.A., Fessl, B., Kleindorfer, S. and Valarezo, J.C. (2007). Distribution of the introduced parasitic fly Philornis downsi (Diptera, Muscidae) in the Galápagos Islands. Pacific Conservation Biology 13(1): 14-19. Close ). Habitat loss and degradation is caused by invasive exotic plants BirdLife International (2016) Species factsheet: Mimus melanotis. Downloaded from http://www.birdlife.org on 02/09/2016. . The relative effect of different threats on the species' population is not yet known BirdLife International (2016) Species factsheet: Mimus melanotis. Downloaded from http://www.birdlife.org on 02/09/2016. .