Islas Ildefonso are a group of islands in Chile. The islands belong to the Commune of Cabo de Hornos in Antártica Chilena Province of Magallanes and Antártica Chilena Region. They lie 96 km west of Isla Hermite, part of Tierra del Fuego, and 93 km NNW of Diego Ramirez Islands, but only 27 km south of Isla Hoste or 23 km to rocks near Isla Hoste.

Description

The islands were named by the Spanish navigator Diego Ramírez de Arellano, who piloted the Garcia de Nodal expedition through the region in 1619. The islands consist of nine stacks, within two groups. They extend 6 km on a northwest–southeast axis. The land area measures about 200,000 sqm. More than 50% of this comprises the large single southern stack, which is 970 m long and between 80 and 200 m wide. The islands are steep and rocky, and covered in tussac grass.

Important Bird Area

The islands have been identified by BirdLife International as an Important Bird Area because they hold large breeding populations of both southern rockhopper penguins (86,000 breeding pairs) and black-browed albatrosses (47,000 breeding pairs). There are also smaller numbers of grey-headed albatrosses. Magellanic penguins, imperial shags and sooty shearwaters present.

Islands

Area data are from the USGS unless otherwise specified.