Task: Question Answering
Input (English): Passage: Two groups of goldcrest taxa are found on the Atlantic islands of Macaronesia. Birds on the Canary Islands are ancient colonists, whereas those on The Azores are of more recent origin. There are no goldcrests on Madeira, where the Madeira firecrest is the only Regulus species.The Canary Islands were colonised in two waves. The first step was the occupation of Tenerife and La Gomera 1.9–2.3 million years ago, followed by a separate invasion of El Hierro and La Palma 1.3–1.8 mya.
Birds from the Canary Islands are particularly distinctive having a black forehead, pink-buff underparts and a darker closed wing, and have been sometimes treated either as a subspecies of the common firecrest or as a different Regulus species altogether. They were sometimes called the Tenerife goldcrest, no matter which of the islands they lived on; however, a 2006 study of the vocalisations of these birds indicate that they actually comprise two subspecies of the goldcrest that are separable on voice; R. r. teneriffae occurring on Tenerife and the newly described subspecies, R. r. ellenthalerae, the western Canary Islands goldcrest, occurring on the smaller islands of La Palma and El Hierro. 
Tenerife goldcrest R. r. teneriffae (Seebohm, 1883). Found only on Tenerife, Canary Islands; it is a distinctive, small subspecies with a black forehead and pink-buff underparts.
Western Canary Islands goldcrest R. r. ellenthalerae (Päckert et al., 2006). Resident on La Palma and El Hierro, Canary Islands.Differences in songs, genetics and morphology suggests that the Azores were colonised in a single invasion in the late Pleistocene, about 100,000 years ago. It is likely that the initial colonisation was of the easternmost islands, with a subsequent spread to the central and western island groups from the western caldera of São Miguel, where both eastern and western song types are found. 
Question: Which two islands does the subspecies  R. r. ellenthalerae occur?
Output (English): El Hierro.