Notes from the Field: Deer Winter Range
There is probably no species of wildlife more iconic of Central Oregon than mule deer (Odocoileus hemionus). Their elegant adaptations to the arid ecoregions east of the Cascades and their seeming ubiquity across both rural landscapes and urban areas give us the impression of an abundant population. But long-term studies show significant declines in regional mule deer herds. Protecting their winter range is one of the most effective measures we can take to slow and reverse this decline.
Now in the last weeks of fall, “muleys” are wrapping up their annual breeding season, known as the “rut.” Early on, bucks scar up larger trees and convert younger trees to standing toothpicks by maniacally stripping away branches and shredding bark while rubbing the itchy, vascular velvet off their antlers. Then, with newly sharpened racks and driven by a spike in reproductive hormones stimulated by changing daylight hours, they’ve got just one thing on their minds: the relentless pursuit of does looking to mate. While a doe in estrus nonchalantly browses here and there, she will be closely trailed by an intensely interested buck in a characteristic posture referred to as the flehmen response: thickened neck extended forward and mouth open, with the upper lip curled and frequently licked by a protruding tongue to waft female scent molecules up into contact with his vomeronasal organ, or the “second nose,” in the roof of the mouth. He uses this scent to assess her sexual readiness.
Mule deer buck exhibiting the flehmen response (Robert Franz, FranzFoto)
With the rut winding down and fawns not born until spring, mule deer are now focusing on surviving the winter. Having fattened up on the lush grass, forbs, and browse of the higher elevation summer range, they carry out their age-old migration downslope. With remarkable fidelity, they travel along the same braided network of trails to the same lower elevation winter range of juniper woodland, scrub steppe, and grassland, where the snow will not be as deep and forage, though sparse, is more available. Winter range is absolutely critical to the survival of deer and the health of the herd. Highways and fencing are barriers that interfere with getting there. Recreational impacts and other disturbances during this sensitive period cause additional stress and behavioral disruption which result in the expenditure of precious energy reserves, increased mortality, and decreased fecundity. What’s more, habitat fragmentation and sprawling development diminish and degrade the shrinking acreage of this crucial winter range.
Central Oregon LandWatch has been and remains dedicated to protecting critically important winter range. We led the initiative in 2009 that resulted in permanent protection of the Metolius Winter Range with the designation of the Metolius Area of Critical State Concern. Similarly, for decades we have helped protect the Skyline Forest just northwest of Bend, a 33,000 acre privately held parcel nearly surrounded by the Deschutes National Forest. This forest segment comprises much of the Tumalo Winter Range, and we will continue to fight efforts to develop it. LandWatch is also working on protecting wildlife corridors in Central Oregon that are essential for migration and dispersal. We know how valuable winter range is and will continue to defend this essential habitat so that it can support thriving herds of the region’s iconic mule deer in perpetuity.
What you can do
There are some actions we can all take to help mule deer during the winter. Decreasing speed and increasing vigilance while driving road segments known for deer crossings, especially at dawn and dusk, lower the incidence of vehicular collisions with wildlife. Observing winter range road closures lessens additional stress on mule deer. Feeding deer is not helpful; it taxes their digestive systems with rich feed they are not adapted to and unnaturally concentrates them, in turn amplifying their impacts on residential landscaping, attracting predators and parasites, and facilitating disease transmission.