Densities of the Eurasian Threetoed Woodpecker Picoides tridactylus calculated from sap row surveys are on par with estimates from fixed route bird censusing
SPECIES-SPECIFIC TRACKS of animals can be an effective way of mapping species that are hard to find even if they are present. We used observations of sap rows on trees to calculate densities of Eurasian Three-toed Woodpeckers Picoides tridactylus. We surveyed 14 fixed routes in northern Sweden below the montane forest for sap rows during the autumn of 2020. We used our observations of fresh sap ro
