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Heavy Snow & Cold Impacts Wildlife Populations

Fish & Wildlife - Region 7

Thu Mar 31 08:32:00 MDT 2011

It’s been a tough winter for area wildlife and the calendar shows spring months lay ahead of us before summer arrives. Spring and early summer can still bring weather that can have adverse impacts on already stressed wildlife. Typically early spring months can produce occasional heavy snow fall with intermittent cold and windy conditions. May and June can produce rainy conditions resulting in wet and cool days with limited sunshine.
            Especially hard hit this winter are resident wildlife populations of antelope, mule deer, pheasants, turkey, sage grouse, sharptailed grouse and Hungarian partridge. 
            The National Weather Service in Glasgow, MT. has reported snow accumulation in southeastern Montana was normal or above normal in many locations. Snow coupled with colder than normal temperatures are predicted to continue in the region through the spring months. Snow cover and cold temperatures began in November and continued into March. Stress on wildlife populations was extensive and continuous which has resulted in above normal mortality and for those animals that remain a decline of overall vigor, health and resistance to harsh conditions is evident.
            Prior to 2009 southeastern Montana experienced several mild winters resulting in good overwinter survival among resident wildlife populations. Wildlife populations responded with an increase in numbers that were consistently above the long term average. This provided Fish, Wildlife and Parks (FWP) an opportunity to increase and liberalize hunting permit and license opportunities. Annual post winter, spring and summer trend surveys showed population levels to still be at or above the long term averages. FWP biologists used this scientific data to support continued liberal permit and license opportunities.
            Beginning in 2009 wildlife populations in southeast Montana have experienced a combination of harsh cold and snow covered winters followed by wet cool springs. Late winter snow storms and spring rain events accompanied by cooler daytime temperatures have been common place. For upland game birds late winter snow storms made natural sources of food they were depending on immediately unavailable. Food sources remained unavailable until snow melt, dramatically increasing wildlife stress and spring mortality. Mule deer had to use precious energy reserves to feed resulting in lower vigor and resistance to environmental conditions. Aerial and ground trend surveys completed by regional biologists found a reduction in some wildlife populations across southeastern Montana.
            In response to lower population levels FWP limits hunter harvest through a reduction, or possible elimination of some permit and license opportunities. In making these determinations biologists consider current and anticipated conditions, winter mortality, herd health, trend survey results and population dynamics.
            Impacts to upland game bird populations may be severe in some locations. Snow conditions restrict the bird’s ability to forage and prolonged cold begins to wear the bird’s resistance down. Cold increases the daily nutritional requirements and over time uses up the fat reserves the birds need to weather such harsh conditions. Harsh winter conditions and prolonged exposure to cold and snow will result in increased winter mortality.
            Wildlife populations experienced a tough winter last year (2009-20010) and so far this year (2010-2011) snow and cold temperatures have been worse. According to FWP wildlife biologist, Bernie Hildebrand and game warden, Steve Marx young deer are dying in hay yards and pheasant populations have suffered higher than normal winter mortality. Surveys by wildlife biologists found antelope numbers to be 30 – 40% below the long term average in the fall of 2010. Mule deer surveys found the population to be 12% below the long term average. In response to the severe winter conditions and subsequent mortality on antelope populations, doe fawn licenses were reduced from 10,000 in 2009 to 2,000 in 2010 and either sex licenses were reduced from 13,000 in 2009 to 11,000 in 2010. For mule deer non-resident mule deer doe “B” Licenses were reduced from 3,000 (2009) to 1,000 (2010) and resident 2nd mule deer doe license reduced from 2,000 (2009) to 100 (2010). Further reductions are anticipated for this coming, 2011, hunting season. But specific reductions will not be set until population surveys are complete.
            Transition between late winter and early spring is a critical period for wildlife populations. Animals and birds are at a low threshold of fat reserves, vigor and health. Cold temperatures; a late snow storm or a prolonged storm can push the animals over the survival threshold. Mule deer in poor condition coming out of the winter cannot make the transition from winter food to new green vegetation and consequently expire. That’s why people may start to see more winter kill in early spring than they saw throughout the winter. In addition with snow melt the results of winter kill become more obvious.
            So far white-tail deer and elk populations seem to be weathering the harsh winter conditions. The public needs to know that our sustained winter conditions are having impacts on our local wildlife which results in reduced hunter opportunity in the immediate future.