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Idaho Fish and Game

Winter is the busiest time for big-game management

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By Roger Phillips, Idaho Fish and Game public information specialist With big-game seasons winding down, it might seem like a time for big-game managers to take a break, but the opposite occurs. They're taking inventory of the state's deer and elk herds, figuring out how they are faring and trending, and using a variety of methods to do it. Winter is a tricky time of year for managing wildlife because what happens now affects next fall's hunting seasons, and what happens is often difficult to predict without intensive monitoring. Fall hunting seasons removed tens of thousands of deer and elk from the herds. The animals are heading into their most vulnerable time of year when winter kill, predators and bad luck can take an additional toll. It's also the season when deer, elk and other big game are most visible, so it's a good time to figure out how many are out there. Fish and Game crews will spend December and January counting, trapping, monitoring and tabulating individual animals, local and regional herds and statewide populations and decide if any changes are needed to the current regulations. Although Fish and Game went to a two-year cycle for setting hunting seasons and regulations, the commission can change them in response to winter die-offs or other things that affect populations. "We're doing every bit as much, if not more, population monitoring than we used to do," state game manager Jon Rachael said. Population monitoring is done in many ways. Big-game hunters help by filling out hunting reports on the internet at http://fishandgame.idaho.gov. Fish and Game crews will be out in aircraft doing aerial surveys during winter. While these may seem self-explanatory, crews do two basic types of surveys: "sightability" surveys and "herd composition" surveys. A sightability survey is flying over a precise geographic area and counting how many animals are there. Doing that same route over multiple years gives biologists a comparison from year to year how many animals inhabit that piece of ground and whether herds are growing or shrinking. But it's not as simple as just counting animals. Biologists know they won't see them all on any given flight, and factors such as weather, snow cover and whether a herd is stationary, moving or bedded affect counts. Fish and Game has developed formulas to calculate how many animals are actually there based on how many they spotted and the various factors affecting the count. A "composition" survey is done similarly, but surveying to get an estimate of the total number of deer or elk in a game unit or zone, biologists select smaller areas to sample within the unit or zone with the goal of classifying enough bucks, does and fawns or bulls, cows, and calves, to reliably estimate the ratio of males, females and fawns or calves, as well as the general age of the bucks and bulls based on their antler size. A composition survey helps them understand the dynamics of the herd. For instance, if there are few fawns or calves, biologists know herd numbers will likely decline in the future because there aren't enough young animals to replace the older ones that have died during the year. Both types of survey provide important, but incomplete, information. Biologists also know some of the animals they counted won't make it to fall. Fish and Game needs to know how many deer and elk will survive through winter and spring. Because young animals are the most vulnerable, they are most closely watched. Every winter, crews trap calves and fawns to fit them with radio collars in numerous areas around the state. They are monitored well into spring because the term "winter kill" can be misleading. Warmer weather and newly sprouted vegetation in late winter/early spring is not the finish line for deer and elk, but the final hurdle. Bodies stressed by winter must adapt from low-nutrient forage to new vegetation with high nutrients. Animals in a weakened state can't always make that transition and will die in March and April even though the worst winter conditions are behind them. Fish and Game also has hundreds of adult doe mule deer and cow elk radio collared, and some of those die every year from various things, including predation, hunting season, traffic accidents and other hazards. During winter, at the same fawn and calves are trapped, Fish and Gamecaptures and fits radio collars to enough adults to offset the numbers lost in the previous year. All that big-game monitoring means Fish and Game is taking on Idaho's big, rugged backcountry during the toughest weather of the year. It's a labor-intensive challenge that's usually uncomfortable and often dangerous, but it's also critical to ensure the department gets a real-time look at how Idaho's prized big-game animals are faring during their most vulnerable time of year.