ELLENSBURG, Wash. — The search for edible vegetation, more than the disturbance by people driving snowmobiles and trucks, is the primary force driving the late-winter movements of the Colockum elk herd.

So say the just-released findings of a 31/2-year study of the 4,500 Colockum elk, during which the herd’s state-managed wintering range was closed to motor vehicles from February through April.

However, state wildlife officials are expected to extend that closure on that 44,000-acre, heavily-roaded portion of the Whisky Dick and Quilomene wildlife areas through this spring as well. One reason is that the spring closure is consistent with the timing of other wildlife-area closures. There’s also the fact that the last three spring closures coincided with decreases in the Colockum animals’ often expensive forays onto neighboring agricultural land.

In many elk-populated areas in Yakima County, winter feeding programs and elk fences help minimize the issue of elk foraging on private farmlands. The Colockum — located northeast of the Kittitas Valley — with no winter-feeding effort and no elk fences, poses an entirely different set of management issues.

“The elk have unrestricted access to a wide-ranging landscape,” state Department of Fish and Wildlife elk expert Scott McCorquodale said. “They can go where the want to go.”

Fewer elk have ventured onto private lands neighboring the closure area over the past three winters, and not surprisingly, most of those landowners have supported the closure.

But many Kittitas County recreational users of the area have not and that divide was evident during a Monday presentation of the study results before a crowd of about 150 at Central Washington University in Ellensburg.

Most audience questions revolved around the closure. One spectator suggested the elk study was part of “some pre-determined mission to close roads in the Colockum.”

The Colockum herd study began in the winter of 2008-09 and involved putting radio collars on 109 elk, some for one winter and others for repeat winters.

Despite what McCorquodale called “some major movements” of elk westward from the closed winter range toward the Park Creek/Caribou Creek area, very few of the animals actually ended up in private crop fields.

But that wasn’t necessarily due to a lack of winter-range disturbances, McCorquodale said. Some elk moved out of the lower-elevation winter range as early as February, while others stayed another five months.

“There’s all this deviation that makes it difficult (to link elk movements to the closure),” McCorquodale said. “Are there some elk movements impacted by the closure? It’s entirely possible. But when you fold them into all the elk we have up there, there’s more noise than signal there.”

Why, then, continue the motorized winter-range closure?

“There are closures on winter ranges across the West, pretty much in every state, and there are a lot of reasons why people do that,” McCorquodale said. “Preventing elk from going where you don’t want them to go is probably one of the less common reasons.”

A bigger reason, he said, was to minimize disturbance to elk whose body-fat content is down to a surviveable minimum after a fall spent avoiding hunters and finding diminishing forage as the winter approaches.

The average body fat for Colockum elk females in the early fall is roughly 15 percent. By the end of the winter that can be below 4 percent.

“Most of the cows are in pretty modest condition in the winter,” McCorquodale said. “They’re not ready to fall over and die, but they’re pretty lean. I think one of the best reasons to contemplate some kind of closure or restriction on access during the winter is just that those elk, we’ve harassed them pretty much all fall.”

McCorquodale said there was “pretty broad support” for the closure. The Wenatchee Sportsmen’s Association and Rocky Mountain Elk Foundation, unlike many vocal members of the Kittitas Field and Stream Club, have supported the winter-range closure.

After this spring, any extension of the closure by temporary or permanent rule will be as part of the “Naneum Ridge to Columbia River Recreation Plan” being developed by the state Department of Natural Resources, the wildlife department and a 16-member citizen group made up of landowners and user-group representatives. That 15-year management plan, the crafting of which is expected to last beyond 2014, will encompass an area more than five times the current spring closure area.

And, of course, no public meeting involving wildlife management would be complete without a mention of the state’s newest predator.

One audience member on Monday night generated nods and chuckles when he asked, “What are your plans for keeping wolves out of this area?”

But that’s another story.