Individual study: Effects of predator treatments, individual traits, and environment on moose survival in Alaska
Keech M.A., Lindberg M.S., Boertje R.D., Valkenburg P., Taras B.D., Boudreau T.A. & Beckmen K.B. (2011) Effects of predator treatments, individual traits, and environment on moose survival in Alaska. The Journal of Wildlife Management, 75, 1361-1380
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Remove or control predators
A before-and-after study in 2001–2007 in a mosaic of shrub, forest and taiga in Alaska, USA (Keech et al. 2011) found that control of American black bear Ursus americanus, brown bear Ursus arctus and wolf Canis lupus increased moose Alces alces abundance and calf survival. Moose abundance and calf survival were higher after predator control (abundance: 0.56 moose/km2; calf/adult ratio: 51–63 calves/100 adult females) than before control (abundance: 0.38 moose/km2; calf/adult ratio: 34 calves/100 adult females). In May 2003 and 2004, 109 black and nine brown bears were translocated at least 240 km from a 1,368-km2 area, reducing the populations by approximately 96% and 50% respectively. In 200–2008, wolf numbers were reduced by 11–33 animals/year across a wider 8,314-km2 area by aircraft-assisted shooting, conventional hunting and trapping (density in 2001: 5.1 wolves/1,000 km2; density in 2006: 1.3 wolves/1,000 km2). Aircraft surveys (3.1 min/km2) were used to monitor moose numbers and calf/adult ratios annually, in autumn, at 87 sites within the study area, each of 15.7 km2.
(Summarised by Ricardo Rocha)