| Ildefonso Islands | |
| Native Name: | Islas Ildefonso |
| Image Caption: | Arrow shows the position of Ildefonso Islands |
| Map: | Tierra del Fuego |
| Coordinates: | -55.75°N -69.43°W |
| Waterbody: | Pacific Ocean |
| Total Islands: | 9 islands and islets |
| Area Km2: | 0.2 |
| Country Admin Divisions Title: | Region |
| Country Admin Divisions: | Magallanes |
| Country Admin Divisions Title 1: | Province |
| Country Admin Divisions 1: | Antartica Chilena |
| Country Admin Divisions Title 2: | Commune |
| Country Admin Divisions 2: | Cabo de Hornos |
| Additional Info: | NGA UFI=-884851 |
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 96km (60miles) west of Isla Hermite, part of Tierra del Fuego, and 93km (58miles) NNW of Diego Ramirez Islands, but only 27km (17miles) south of Isla Hoste or 23km (14miles) to rocks near Isla Hoste.
The islands were named by the Spanish navigator Diego Ramírez de Arellano, who piloted the Garcia de Nodal expedition through the region in 1619.[1] The islands consist of nine stacks, within two groups. They extend 6km (04miles) on a northwest–southeast axis. The land area measures about 200000sqm. More than 50% of this comprises the large single southern stack, which is 970m (3,180feet) long and between 80and wide. The islands are steep and rocky, and covered in tussac grass.[2]
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.[3]