Discussion
Last Update/Review: August 12, 2002
The Northern Moose Management Program has greatly increased our understanding of moose and moose management in Alberta. This information will permit a more precise modelling of the population and development of harvest goals. The hunting regime for moose will have to be changed to ensure there is a system in place which allows for a reasonably reliable prediction of hunter harvest.
At the outset of the program moose management parameters including population density, bull cohort structure, calf recruitment and cow moose mortality were established to provide a framework for future moose management discussions. The information from the Northern Moose Management Program has provided valuable insight into these parameters that are now under consideration for the preparation of a Moose Management Strategy for Alberta — to be released in 1999.
Information
Population Density
In WMUs with productive habitat (most of MMAs 5 and 6, see Figure 1) an overall density of at least 2.0 moose per square mile was believed to be achievable. Density information gathered from all of the surveys in MMA 5 and 6 indicated a population density range of 0.39 to 2.52 and an average of 1.34 moose per square mile, which is considerably below expectations. In MMA 7 an overall density of somewhat below 2.0 moose per square mile was considered more reasonable given the varying degrees of habitat alteration. Population surveys in MMA 7 indicated a range of 0.88 to 2.55 and an average of 1.67 moose per square mile. In the more productive habitat of MMA 8, 1.0 moose per square mile was viewed as a target, while the poor quality habitats of MMA 8 and 9 were not expected to produce more than 0.5 moose per square mile.
Density information from all of the surveys in MMA 8 and 9 indicated a range of 0.26 to 1.60, with an average of 0.58 moose per square mile.
The more productive moose ranges were providing densities that are believed to be less than habitat capability. Densities of moose in MMAs 8 and 9 are consistent with poorer quality habitat in those areas.
Bull Structure
In the most productive ranges of moose habitat, MMAs 5, 6 and 7, a pre-season bull:cow ratio of 40:100 is desirable, this equates to a post-season ratio of 32 bulls per 100 cows. The survey information gathered from the program (post-hunting season surveys) indicated that bull:cow ratios remained in the 15 to 28 bulls:100 cow range. Notes from the surveys indicated that access is a major factor. In areas where access is limited, a greater number of bulls were found. In areas with greater access the number of bulls declined.
In MMAs 8 and 9, a preseason bull:cow ratio of 50 to 60 is believed to be desirable. The surveys found that in these MMAs post-season bull:cow ratios ranged from 27 to 87 bulls:100 cows, and these numbers were also influenced greatly by access. Unfortunately, the current survey technique does not isolate bull:cow ratios for the accessible versus inaccessible areas of the WMUs.
From a moose population perspective it is believed that at least one-third of the bulls in a population should be experienced breeders and be greater than 2.5 years of age. Analysis of incisor bars from harvested moose showed encouraging trends in MMAs 5 and 6 where less than 30% of the bulls were found to be greater than 2.5 years of age in 1993. Over the past four hunting seasons the numbers of bulls greater than 2.5 years of age has grown from 18 to 24% in MMA 5 and from 29 to 40% in MMA 6. In MMA 7, the number of bulls greater than 2.5 years of age remained stable at only 27%, likely a result of heavy hunting pressure in these predominately agriculture WMUs. In MMAs 8 and 9, the number of bulls greater than 2.5 years of age remains well above 50%.
Calf Recruitment
Initially, it was believed that a minimum of 50 calves per 100 cows entering the yearling cohort would be desirable. Information from the program indicated that calf:cow ratios entering the early winter period were less than desired. Calf:cow ratios in all WMUs rarely exceed 50:100 during the post-hunting season surveys. Given that the surveys are generally flown in early winter, it is expected that winter related mortality would reduce the number of calves entering the yearling cohort. Having 50 calves per 100 cows entering the yearling cohort would then be viewed as very optimistic. We believe post-winter calf:cow ratios of 35:100 are more realistic.
Cow Mortality
Moose populations are very sensitive to the level of mortality on cows. It is believed that an annual loss of greater than 20% of adult cows will result in a population decline. Cow and calf survival information provided by the radio telemetry project indicated that natural related causes of death (predation, winter losses etc.) can amount to 5 to 8% of the causes of cow mortality.
Human related causes were significantly higher and resulted in greatly reduced cow survival rates. Of the three study areas, WMU 346, 350 and 358, the greatest cow moose mortality was experienced in WMU 358 at 23.6% per year. Natural related causes of death attributed to only 5% of the moralities in this WMU. Despite the high annual mortality in WMU 358, the cow cohort of the population remains stable. In WMUs 346 and 350 where the cow mortality rates are 7.7 and 13.4% respectively, the cow cohort of the populations remains stable as well.
