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White-tailed Deer
Fawns Wintered Well

March 30, 2000
Seeley Swan Pathfinder
Seeley Lake, Montana

by Mike Thompson,
Wildlife Biologist
Montana Fish, Wildlife & Parks
"Game Range Ramblings" column Seeley Swan Pathfinder
by Mike Thompson


A typical Sunday evening at the Rose and Thompson household sometimes makes us want to leave it. So, for the past two Sundays we've taken the proverbial busman's holiday up the Blackfoot to check on late-winter recruitment rates in your white-tailed deer population.

Actually, I don't start calling them "recruitment rates" until I arrive at the office on Monday morning, wearing my official uniform shirt, sitting in front of my computer. On Sunday evening, Sharon and I call them "adults" or "fawns," depending on what we see out the truck window in between sips of Coke and bites of candy bars.

Make no mistake about it. This is serious business.

Of course, I am a trained wildlife biologist. So, working with a layperson, even if that layperson is your wife (maybe especially if that layperson is your wife), requires patience and understanding.

"There's a mommy and baby," Sharon exclaimed as we began our survey up Lost Prairie Creek Road.

Biologists don't call them mommies and babies. We just don't. But, there was a more important point of instruction to be made.

"Why, honey, what a fine observation you've made!" (That's how I might have begun if I'd spent a little more time mulling over my reply.) "But, please let me caution you that we can't always be absolutely certain of gender after the bucks have shed their antlers. So, if it's not too much trouble, I wonder if you might record our observations as adults and fawns, just to make me feel better. It's a silly thing, I know."

The point of doing this survey in March, instead of December or earlier when the bucks still have their antlers, is to document fawn survival through winter. A fawn's life expectancy increases dramatically after it survives its first winter, so the percentage of fawns among the deer we count in March will be a reasonable indicator of the actual rate of increase for the deer population this year.

The other reason for doing these surveys in March is that deer really concentrate on the first morsels of green grass that first emerge at the lowest elevations along roadsides. By April, the whitetails will be a bit more dispersed and the fawns will be a little larger, making it more difficult to accurately classify lots of deer in a short period of time.

Sharon and I counted and classified 138 white-tailed deer along the Lost Prairie Road before our survey was interrupted by darkness. Deer were picking lichens from freshly fallen tree tops in logging units and nibbling at whatever was growing in spots where the snow had melted.

The work proceeded smoothly and professionally, save for a few uncomfortable minutes while Sharon detained us to marvel at a "flop-eared fawn." I had to agree it was cute before we could continue.

Things went so well that we agreed to conduct another survey the following Sunday. This time we worked Highway 83, from Clearwater Junction to Seeley Lake. We got off to a slow start after encountering a couple of Pathfinder readers who were flying their kites on the portion of the Game Range that remains closed until May 15th. Having effected their departure, we proceeded to classify 170 whitetails.

We found it a bit more challenging to classify deer along busy Highway 83. To the handful of you who came up behind our slow-moving vehicle before we could get to the next turnout, please accept our apologies.

The survey analysis was very encouraging. We counted 105 fawns and 203 adults, for a ratio of 52 fawns per 100 adults. This is higher than last year's average fawn:adult ratio of 45 in the Blackfoot and lower Clark Fork drainages, and much higher than the ratios of 28 and 29 we obtained in 1997 and 1998 after the hard winter of 1996-97. With another mild winter under our belts, we can expect still another good fawn crop in June. It's going to seem like there are a lot of white-tailed deer in the woods by the time they start showing up in second-growth alfalfa fields this September.

This healthy fawn:adult ratio in white-tailed deer also adds information to our analysis of declining calf:cow ratios in elk. Superficially, it appears that the forces causing low calf:cow ratios in elk are not having the same effect on white-tailed deer fawn:adult ratios. Fawn:adult ratios are on the upswing over the past two years, while calf:cow ratios have remained suppressed.

Based on these clues, we're looking for a problem in our elk population that affects calves at a higher rate than cow elk, but doesn't seem to be directed at deer fawns. This doesn't necessarily mean that deer are not affected at all, but apparently they are not affected in a way that lowers the fawn:adult ratio.

At the conclusion of our Sunday surveys, I had to envy Sharon. Her responsibility was over, but this "trained wildlife biologist" was left with an important problem to solve. Luckily, wildlife biologists benefit from each other's knowledge and efforts, as well as the assistance of others. Like Jack Rich. Jack called today to say he would be obtaining calf:cow ratios this summer in Youngs Creek to help us sort out the timing of our calf mortality. We hope to supplement his work on the ground with a summer survey from aircraft.

With help like this, who can complain?

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