Middle-ground finch
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Middle-ground finch ( Geospiza fortis ) |
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| Geospiza fortis | ||||||||||||
| Gould , 1837 |
The middle-ground finch ( Geospiza fortis ) is one of the songbird species that Charles Darwin found in the Galápagos Islands . He is one of the Darwin's finches named after him . Middle-ground finches mainly colonize undergrowth and forest edges.
description
The beak is strong and slightly longer than it is wide. The shape of the beak varies depending on the island. The shape of its beak allows it to crack seeds . He prefers smaller seeds because he can only crack these with less effort. In dry years, when smaller seeds are scarce, the ground finches feed more on large seeds than usual. Berries and occasionally also insects serve as a source of food for the ground finches .
Middle-ground finches also often preen Galápagos giant tortoises or land iguanas by pecking parasites from their skin 1 .
According to a study published in 2007, Geospiza fortis can be seen as an example of an early stage of development in the process of sympatric speciation . Sarah Huber demonstrated two morphs of the middle-ground finch with beaks of different sizes, which live in the same area, but prefer to mate with individuals of the same morph. Genetic analyzes showed a decreased gene flow between the two morphs. Vocal differences due to the diverging beak sizes were given as the cause of the preferences in partner finding .
Male animals present themselves in front of a dome-shaped nest, which is often built from opuntia . The females incubate the three to five eggs alone, and both parents feed the chicks.
Hazard and protection
The main threats to the finch are rats and certain diseases. In addition, it is known that middle-ground finches are infested by the parasitic fly species Philornis downsi , which leads to increased chick mortality .
The species is not endangered.
literature
- Irenäus Eibl-Eibesfeldt : Galápagos. Noah's Ark in the Pacific . Piper, Munich 2001, ISBN 3-492-21232-8 (EA Piper, Munich 1960).
- Peter Raymond Grant : Ecology and Evolution of Darwin's Finches . Princeton University Press, Princeton 1986, ISBN 978-1-4008-8671-5 .
Web links
- Videos, photos and sound recordings of Geospiza fortis in the Internet Bird Collection
- Geospiza fortis inthe IUCN 2013 Red List of Endangered Species . Listed by: BirdLife International, 2012. Retrieved October 26, 2013.
Individual evidence
- ↑ Medium Ground-finch (Geospiza fortis). Retrieved April 16, 2020 .
- ^ Sarah K. Huber: Reproductive isolation of sympatric morphs in a population of Darwin's finches. Proceedings of the Royal Society B, published online on May 15, 2007, doi : 10.1098 / rspb.2007.0224
- ↑ a b Galapagos Species Checklist. Retrieved April 16, 2020 (UK English).