Galapagos Species Database

Taxon category: Accepted

Taxon origin: Introduced - established

Preference for an altitude zone in Galapagos: Coastal zonera - humid zone

Habitat preferences: The species prefers open habitats, disturbed and human-altered agricultural zones, suburban areas including parks and second-growth forest. In Andean valleys it can be found up to 2800 masl. In Galapagos they can be found in all vegetation zones with highest numbers in the agricultural zone; during the cold periods of the year they group in the lower agricultural zone.

Feeding preferences: Feeds on insects in short to medium-length grass and forages opportunistically in trees and shrubs; picks berries from bushes. Often sentinel behavior while feeding. Smooth-billed ani is primarily insectivorous, in dry conditions the proportion of seeds increase. Their food preferences depend on the availability of food types in the areas where they live.

Trophic role: Omnivorous

Persistence mechanisms: The main characteristic that makes C. ani a persistent species is its ability to live in groups, where it shares feeding, roosting and nesting sites, including incubation and caring of the young. The communal breeding system is something uncommon among birds and might raise nesting success through input from various adult birds. Second broods are possible and depend on the food available. Young birds disperse in groups at age 8 to 12 month. They are food generalists showing a large array of insects, other invertebrates, small vertebrates, seeds and fruits. Outside the breeding season flocks of several groups can be found (up to 60 individuals observed in Galapagos). They are potential good fliers and some long-distance movement are known from the Americas.

Reproduction mode: Exclusively sexual

Reproductive biology: Smooth-billed ani constructs communal nests by all members of a group. The nest is large and deep cup-shaped. Every female can lay three to seven eggs; up to 7 females can lay in the same nest, sometimes burying the former eggs thus resulting in clutch sizes of 3 to 36 eggs. Only the top layer is incubated, resulting in up to 15 hatchlings. The eggs are green-blue. Incubation lasts 13-15 days. Incubation and chick rearing are shared tasks between the different pairs and other group members. A study conducted on Isabela Island in 1995 determined that anis begun reproduction in December and extended to July/August the following year. In the Galapagos Islands, smooth-billed anis nest in tree-canopies of thorny plants such as algarrobos, which often prevents direct observation. Breeding groups can produce three to four nests per year, depending on environmental conditions.

Distribution origin: Native bird to the Americas. It is distributed from Florida, Antilles including Trinidad y Tobago. From Costa Rica to the North of Argentina, Brazil, Ecuador and Peru. It is found from sea level to 2700 masl.

Distribution classification: Eutropical

Disease vector: Host of the lice (Vernoniella guimaraesi)

Mode of introduction: Intentional

Introduction Pathway: Intentional

Subpathway: Release in nature for use

Introduced status: Naturalized

Invasive status: Invasive

Invasion risk score: High risk

Impact in Galapagos: It is considered the most damaging introduced bird for the ecosystems of the Galapagos Islands. C. ani represents a threat to native plants and birds. The population size of Smooth-billed anis is increasing at an alarming rate. In 2010, 80, 000 individuals were estimated to live on Santa Cruz with over 250, 000 Smooth-billed anis in Galapagos as a whole. In 2009 a study on the stomach contents of Anis in Santa Cruz showed that 98% of samples individuals had ingested invertebrates. A high percentage of the seeds ingested corresponded to Rubus niveus, a highly invasive plant. Also, remains of finch chicks were identified, a finding that shows that there is direct consumption of native birds. These findings confirm a high degree of threat of C. ani for the Galapagos Islands. The propagation of seeds of invasive plants by C. ani can affect the landscape of the islands. Their high preference for consumption of invertebrates adds pressure to native birds and invertebrates in the form of completion and depredation respectively.

Impact elsewhere: Not to be reported as a problem species elsewhere.

Control History in Galapagos: Since 1980 the Charles Darwin Foundation (CDF) has conducted studies to understand the species and identify eradication methods. Capture using live lures has been tried, traps, nets and culling using rifles. So far the most efficient method for hunting is using rifles. The Galapagos National Park Directorate is the only institution that currently carries out control of the species. The CDF in mid 2014 started a Land Bird project, a component of which is to identify an efficient strategy to control this species.

Control methods elsewhere: Culling using rifles, is so far the most efficient method to hunt Smooth-billed anis.

Known Pest elsewhere: Widespread on the tropics and sub-tropics.

Prevention options: Report immediately if new colonies are found in previously unreported sites. The competent authorities can thus cull and thus prevent further expansion of this species.

Year of first record: 1962

Year of introduction: 1962

Map of specimen collection localities or observation records for this species in our collections database.

Distribution: Champion, Daphne, Fernandina, Floreana, Gardner, Genovesa, Isabela, Pinta, Pinzon, Plaza Sur, San Cristobal, Santa Cruz, Santiago.

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