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Galapagos Hawk (Photo by Harriet Thorpe)
Galapagos Hawk (Photo by Harriet Thorpe)
Although mostly dull in color, many of the birds’ extreme tameness makes them especially attractive to visitors. American naturalist, William Beebe, was foiled in his attempt to photograph a flycatcher because the bird clung to his camera. Charles Darwin remarked on the extreme tameness of the Galapagos Doves, which alighted on his arms and head.
Thirteen of the 22 endemic species are known collectively as Darwin’s finches and 4 are mockingbird species (endemic at the level of genus). The remaining 5 endemics include the Galapagos Hawk (Buteo galapagoensis), the Galapagos Dove (Zenaida galapagoensis), the Galapagos Flycatcher (Myiarchus magnirostris), the Galapagos Rail (Laterallus spilonotus), and the Galapagos Martin (Progne modesta).
The 4 endemic taxa at the subspecies level include the Galapagos Short-eared Owl (Asio flammeus galapagoensis), the Galapagos Barn Owl (Tyto alba punctatissima), the Galapagos Mangrove Warbler (Dendroica petechia aureola), and the Vermilion Flycatcher (Pyrocephalus rubinus nanus). The final three indigenous species are the Dark-billed Cuckoo (Coccyzus melacoryphus), the Common Gallinule or Moorhen (Gallinula chloropus) and the Paint-billed Crake (Neocrex erythrops).
Of special interest are the four island-endemic species – the Hood or Española Mockingbird (Mimus macdonaldi), the Floreana Mockingbird (Mimus trifasciatus), the San Cristóbal Mockingbird (Mimus melanotis), and the Medium Tree Finch (Camarhynchus pauper), only found on Floreana.
The land birds as a group include two of the most impressive examples of evolutionary change in Galapagos – Darwin’s Finches and the Galapagos Mockingbirds. The group of 13 species of Darwin’s finches (with a 14th species found in the Cocos Islands some 650 km to the north), as a whole, are among the most abundant land birds. There are few textbooks of biology that fail to mention this amazing group. Each species has a distinctive beak size and shape, and their feeding behavior is specialized to their specific niche. Some eat seeds, some eat insects, some remove ticks from tortoises and land iguanas, some eat leaves, some eat flowers, some drink blood from seabirds, and two finch species use twigs or cactus spines to extract insect larvae from holes in dead tree branches. Together they fill the roles of seven different families of birds found on mainland South America. All of Darwin’s finches are sparrow-sized, ranging from the smallest Warbler Finch to the large Vegetarian Finch. Woodpecker (Cactospiza pallidus) and Mangrove (Camarhynchus heliobates) Finches use twigs and cactus spines to search for insect larvae. The Sharp-billed Ground Finch (Geospiza difficilis) parasitizes seabirds by hopping on the backs of Nazca and Red-footed Boobies where they peck at the skin until they are able to drink their blood. Drs. Peter and Rosemary Grant, along with their students and colleagues, have been studying the evolution of this incredible group of birds since the late 1970s.
Mockingbirds are often the first animals to greet visitors when they land on an island. The four mockingbirds, all in the endemic genus Mimus, constitute the second largest group of endemic species. While three of the species are island endemics (Floreana, San Cristóbal, and Hood/Española), the fourth species is found on three or more islands. Mockingbirds live primarily in the littoral, arid, and transition zones. Though omnivorous (feeding on a wide variety of food types), they tend to be more predatory than their mainland relatives. They will eat young finches, lava lizards, insects, centipedes, carrion, and seabird eggs, among other things. They often form cooperative breeding groups consisting of a breeding pair plus their offspring from previous broods. The younger birds assist their parents in territory maintenance and defense and in rearing the new brood. Some groups contain more than one nesting female. Confrontations among mockingbirds from different breeding groups often occur at the borders of their territories and are fascinating to watch.
The avian predators of the Galapagos Islands include the Galapagos Hawk, the Galapagos Short-eared Owl, and the Galapagos Barn Owl. The Galapagos Hawk feeds in the day while the Galapagos Barn Owl feeds at night. Short-eared Owls, on the other hand, feed at night on islands where Galapagos Hawks are present and in the day on islands that have no hawks. The female hawk has the unusual habit of mating with several males (polyandry), all of which help to incubate the eggs and rear the young. Hawks feed mainly on insects such as locusts and giant centipedes, as well as small lava lizards, snakes, and rodents. It is not uncommon for hawks to take young marine and land iguanas, and sea turtle and tortoise hatchlings. Barn Owls are generally found in drier and more sparsely vegetated areas than the Short-eared Owls. Barn Owls nest in cavities of rock outcrops, holes in trees and abandoned (and sometimes not abandoned) buildings, whereas Short-eared Owls tend to nest under trees and shrubs. The partly diurnal Short-eared Owl, widespread in the Galapagos Islands, tackles large seabird chicks by attacking the neck. The barn owl feeds mostly on rodents and insects.
Galapagos Doves are often seen near the coast and in the arid zones of many of the islands. Galapagos Doves feed primarily on seeds picked up from the ground. They will also take caterpillars when available. Cactus pulp also forms part of their diet and probably provides their main source of water. They nest on the ground and lay two white eggs. As ground-nesters, they are vulnerable to introduced rats. They have a beautiful blue eye ring and bright red legs and feet.
Two flycatchers are found in Galapagos – the endemic Galapagos flycatcher or Broad-billed Flycatcher and the Vermilion Flycatcher (endemic at the subspecies level). The Galapagos Flycatcher is the more widespread of the two species. The Vermilion Flycatcher population appears to be declining on the inhabited islands. The male Vermilion Flycatcher is bright red, while the female is a more orange-rust color. Both feed on insects caught in flight or from a perch or picked up from the ground.
Among the lesser known endemic land birds of Galapagos are the tiny, secretive Galapagos Rail, which inhabits higher ground above 1500 feet where it feeds on invertebrates and seeds and rarely flies, and the Galapagos Martin, which feeds on insects caught in the air.
Critically Endangered species include the Mangrove Finch and the Floreana Mockingbird – both of which have conservation programs aimed at their protection and recovery. The only currently Endangered land bird species is the San Cristóbal Mockingbird. Vulnerable species include Galapagos Hawks, the Medium Tree Finch, Galapagos Rails, the Española Mockingbird, and the Galapagos Martin.
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