Wednesday, June 29, 2022

Medium Ground Finch

Charles Darwin visited the Galapagos Islands in 1835. The Beagle first arrived at San Cristobal Island on September 16 and anchored in a bay near present-day Puerto Moreno on the south side. The Beagle spent eight days surveying the coast and Darwin landed on San Cristobal five times from September 17 to 22. The Beagle then visited Floreana Island from September 24 to 27. Isabela was the third island visited by the Beagle from September 29 to October 2. They traveled around Isabela, including the channel between Isabela and Fernandina and anchored in Tagus Cove (where we spent a night and did some hiking and snorkeling when we visited). Darwin spent time on the ground there and noted marine and land iguanas. From there the Beagle sailed around Pinta, Genovesa and Marchena Islands. Finally, Santiago was the last Galapagos island visited by Darwin, from October 8 to 17. Darwin walked the whole island with crew members and had them carry specimens for him back to the Beagle. There he noticed the difference in tortoise shells between the islands and tried tortoise meat in soup.

Darwin paid little attention to the finches (now classified as tanagers but still called finches). On the Beagles return he presented his finches to the Zoological Society of London on January 4, 1837 and the finch specimens were given to John Gould. Darwin thought he had collected blackbirds, gross-beaks and finches, but Gould determined that they were a series of 12 species of ground finches. The males were black and the females were brown and there were six species of graduated beaks. 

Now the various Darwin finches are known as (and vary greatly as to the islands they are found on): Genovesa ground finch; Espanola cactus finch; sharp-beaked ground finch; vampire finch; medium ground finch; Genovesa cactus finch; small ground finch; large ground finch; large tree finch; medium tree finch; small tree finch; woodpecker finch; mangrove finch; green warbler finch; gray warbler finch; Cocos finch and vegetarian finch. 
The Highlands of Santa Cruz Island.

The medium ground finch is found on Baltra, Floreana, Isabela, Fernandina, Seymour, Pinzon, San Cristobal, Santa Cruz, Santa Fe and Santiago Islands. 
Urbino Bay on Isabela Island.

The male is black with white tips on the undertail coverts. The female is a streaky brown. The size of the bill is quite variable, but the upper mandible is always greater than the depth of the bill at its base.
Tagus Cove on Isabela Island. 

1 comment:

  1. They appear to be fairly dull birds compared to some of the others you've written about in Ecuador, although there is a lot of variation among these photos. They all have very sturdy-looking beaks.