The role of forest maturation in causing the decline of Black Grouse Tetrao tetrix

摘要: Black Grouse Tetrao tetrix in Britain have declined through the 20th century, and most birds are now Scotland. Many causes for this decline been suggested, notably agricultural intensification, increased grazing levels moorland afforestation. We examine habitat correlates of distribution population change from a 700-km2 area core Scottish range, where numbers lekking male by an estimated 70% to 270 between 1990 2002. Habitat data were derived satellite imagery, combination with map field-collected data. Lek occurrence, lek size changes all correlated forest structure, either positively amount pre-thicket cover, or negatively closed canopy cover. Additional effects cover grass moor dry heath suggest that likely occur comprises Heather Calluna vulgaris mosaics. Analysis abundance within 1.5 km discrete blocks suggests maturation, which has dominant during course study, alone accounts 58–78% decline. Given close association occurrence woodland (and particularly conifer plantation) throughout much their British these findings can be used inform design management schemes recovery Grouse.