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 west of Isla Hermite, part of Tierra del Fuego, and NNW of Diego Ramirez Islands, but only south of Isla Hoste or to rocks near Isla Hoste.
The islands were named by the Spanish navigator Diego RamÃÂrez 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 on a northwestâÂÂsoutheast axis. The land area measures about . More than 50% of this comprises the large single southern stack, which is long and between wide. The islands are steep and rocky, and covered in tussac grass.
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.
Area data are from the USGS unless otherwise specified.