The woodpecker project is now fully underway! I've been collecting data on vegetation, hydrology, roads etc as well as getting hold of a good DEM of the study area. The main factor determining habitat suitability is undoubtedly vegetation type. Woodpeckers are only found in native mature lenga (beech) forests. Which areas of these forests are more suitable is likely to be dependent on proximity to beaver colonies. The dams created by the beavers produce localised flooding which results in more rotten trees which suit woodpecker nesting.
The American Beaver (Castor canadensis) was introduced to Tierra del Fuego in 1946 and is thought to have reached its full abundance potential along the river systems. Although 8.5% of the Island’s Beech forest have been destroyed by beaver activity the swampland they create is favoured by the woodpeckers due to increased fungal action on trees facilitating nesting.
I should be getting some more data on beaver colonies from the Wildlife Conservation Society. The coverage is unlikely to be complete for my area of study so I will have to look at ways of identifying sections of river likely to contain beaver colonies.