Ranking Alaska Moose Nutrition: Signals to Begin Liberal Antlerless Harvests

• Published in: The Journal of Wildlife Management
• Main Authors: BOERTJE, RODNEY D., KELLIE, KALIN A., SEATON, C. TOM, KEECH, MARK A., YOUNG, DONALD D., DALE, BRUCE W., ADAMS, LAYNE G., ADERMAN, ANDREW R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2007
• Subjects: Alces alces; Tundra; Alaska
• Online Access: http://dx.doi.org/10.2193/2006-159; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2193%2F2006-159

Abstract: We focused on describing low nutritional status in an increasing moose ( Alces alces gigas ) population with reduced predation in Game Management Unit (GMU) 20A near Fairbanks, Alaska, USA. A skeptical public disallowed liberal antlerless harvests of this moose population until we provided convincing data on low nutritional status. We ranked nutritional status in 15 Alaska moose populations (in boreal forests and coastal tundra) based on multiyear twinning rates. Data on age‐of‐first‐reproduction and parturition rates provided a ranking consistent with twinning rates in the 6 areas where comparative data were available. Also, short‐yearling mass provided a ranking consistent with twinning rates in 5 of the 6 areas where data were available. Data from 5 areas implied an inverse relationship between twinning rate and browse removal rate. Only in GMU 20A did nutritional indices reach low levels where justification for halting population growth was apparent, which supports prior findings that nutrition is a minor factor limiting most Alaska moose populations compared to predation. With predator reductions, the GMU 20A moose population increased from 1976 until liberal antlerless harvests in 2004. During 1997‐2005, GMU 20A moose exhibited the lowest nutritional status reported to date for wild, noninsular, North American populations, including 1) delayed reproduction until moose reached 36 months of age and the lowest parturition rate among 36‐month‐old moose (29%, n = 147); 2) the lowest average multiyear twinning rates from late‐May aerial surveys (x = 7%, SE = 0.9%, n = 9 yr, range = 3‐10%) and delayed twinning until moose reached 60 months of age; 3) the lowest average mass of female short‐yearlings in Alaska (x̄ = 155 ± 1.6 [SE] kg in the Tanana Flats subpopulation, up to 58 kg below average masses found elsewhere); and 4) high removal (42%) of current annual browse biomass compared to 9‐26% elsewhere in boreal forests. When average multiyear twinning rates in GMU 20A (sampled during 1960‐2005) ...