PATCH OCCUPANCY AND DISPERSAL OF SPRUCE GROUSE ON THE EDGE OF ITS RANGE IN MAINE

We surveyed 18 habitat patches (black spruce (Picea marinana)-tamarack (Larix larcina) wetlands) for spruce grouse (Dendragapus canadensis c anadensis) on Mount Desert Island, Maine, during April-May in 1992 and 1993 to determine patch occupancy relative to patch area. We also equ ipped nine juvenile grouse with radio transmitters to determine moveme nt and habitat use outside of patches during autumn dispersal. The 2 l arge patches (77 and 269 ha), 5 of 6 medium-sized (11-26 ha) patches, and 1 of 10 small (4-8 ha) patches were occupied. Spruce grouse occupi ed smaller habitat patches than previously reported, and occupied patc hes were closer (P <0.05) to the nearest occupied patch ((x) over bar= 1.2 km) than were unoccupied patches ((x) over bar=2.5 km). Eight of n ine juvenile grouse left their natal habitat patch during autumn dispe rsal, and net dispersal distance ((x) over bar=2.3 km) was greater tha n that reported for grouse in areas with more contiguous habitat. Disp ersing juveniles used all major forest types and 33% of relocations we re in deciduous forest. Thus, deciduous forest was not an absolute dis persal barrier.