Loss and fragmentation of Siberian jay (Perisoreus infaustus) habitats

Abstract

We analyzed forest landscape changes in a western Finnish breeding area of Siberian jays utilizing Landsat MSS and TM satellite images taken during a 29-year period (1976- 2005). We found that Siberian jays appeared to favour closed spruce-dominated forest patches, possibly because they provide better visual protection against predators. Such spruce-dominated forest patches became smaller and increasingly fragmented during the study period. According to a 25-m pixel analysis, the total area of spruce-dominated habitats decreased from 14.7% to 11.0% and the mean patch size from 2.0 ha to 1.4 ha during 1987-2005. This was mainly due to intense loggings of spruce forests and a special form of land ownership, which has induced narrow forest estates measuring few dozens of metres in width. The parallel decline in potential breeding habitats as well as Siberian jay population size suggests that loss and fragmentation of key habitats, and possibly related changes in predator community, are the most probable causes for the decline of Siberian jay population in the study area. © 2012.