San Cristobal Mockingbird

In comparison with the mockingbirds occupying the other islands, the San Cristobal mockingbird is somewhat shy (3). Much of its time is spent foraging through leaf litter for arthropods such as grasshoppers and crickets. Fruits and berries are also taken from low vegetation, and on occasion it can be seen darting amongst the marine iguanas, picking off their ticks (2) (5). Unlike the other mockingbird species, the San Cristobal mockingbird is not known to breed cooperatively (2) (3) (5). Instead the relatively large, three to five hectare territories are normally occupied by just a single pair, sometimes accompanied by another adult. Breeding takes place from January to April, with each breeding pair building a bulky twig nest, high up in the crotch of a tree, out of reach of introduced predators (3) (5). Incubation of the two to five eggs is left to the female, but both parents share feeding duties (5).

For their unique biological diversity and significance, the Galapagos Islands are designated both a National Park and a World Heritage Site (2). As a consequence, conservation of the islands' native fauna and flora is a high priority. Currently the San Cristobal mockingbird is monitored on an annual basis to assess the health and status of the population (6). This is to be supported in the future by further research to identify which factors are of greatest threat to the species so that appropriate conservation action can be taken (2).

One of the first animals Darwin encountered when he arrived in the Galapagos in 1835 was the San Cristobal mockingbird (3) (4). His subsequent discovery of two more species of mockingbird, each occupying a different island and differing subtly in appearance, provided tinder for the incendiary theory of Natural Selection (3). The San Cristobal mockingbird has a somewhat streaked, greyish-brown crown and upperparts, and an almost white throat, chest and belly. Prominent black lores mark the base of its relatively short downwards curving bill and black ear patches are conspicuous below its amber to reddish-brown eyes. The loud and melodious, territorial song of this species is typical of all the Galapagos mockingbirds (2) (5).

The San Cristobal mockingbird is found in a wide range of habitats all over the island, from mangroves and arid lowland scrub, to taller forest patches and stands of arborescent cacti. However, it does tend to avoid dense lowland forest, wet woodland, grassland and built up areas (2) (5).

Endemic to San Cristobal Island in the central Galapagos (2) (6).

Classified as Endangered (EN) on the IUCN Red List (1).

The global population of the San Cristobal mockingbird, restricted to a single island, is believed to be declining as a consequence of human activities (2) (6). The introduction of invasive plants and animals, and an increase in the size of the human population, has contributed to the loss and degradation of large areas of habitat on San Cristobal. Furthermore, feral rats and cats are thought likely to be responsible for high rates of predation on mockingbird nests, and there is a growing threat of avian parasites and diseases spreading to mockingbirds from local chicken farms (2).