From Gistaín Aínsa - Puerto de Sahún Itinerary

Starting point: The village of Plan.
Time: About half a day.

On reaching the village of Plan turn right to cross the bridge over the river, following the sign to Puerto de Sahún. Dippers are readily observed along this stretch of river. Follow the main track at all times until reaching the Puerto de Sahún, at some 11 kms distance from the bridge. The track is in relatively good condition but may be blocked by snow in the spring, although this is usually indicated at the start of the track.

In the lower reaches with enclosed fields, scrub and mixed woodland the most regularly observed species include Firecrest, Bullfinch, Jay, Great Spotted Woodpecker, Crested Tit, Coal Tit, Nuthatch and Short-toed Treecreeper. Use vantage points to look for Lammergeier, Golden Eagle, Griffon Vulture and both Red-billed and Alpine Chough.

The track ascends, here and there passing limited open areas with bare rock where the Rock Bunting can be seen. However, the most interesting part of the ascent is along the upper reaches, in the forest of pine and fir. Species such as Woodcock, Black Woodpecker and Tengmalm's Owl occur here, although there are times when none of them are easy to see.

Park near the hut just short of the pass and take a stroll around the area. This is the place for some of the most prized mountain species such as Alpine Accentor, Citril Finch, Rock Thrush, Ring Ouzel and Crossbill. Other species in the general area include Water Pipit, Northern Wheatear, Tree Pipit, Ortolan Bunting and perhaps Alpine Swift or Golden Eagle.

From here it is possible to continue to the Benasque valley, or to retrace your steps for a visit to Viadós, Revilla, Pineta, Añisclo, etc.