LAST EDITED ON Jun-19-06 AT 11:49AM (MST)[p]ansonlynn.
I was about to address an earlier message in this thread about the breeding of does requiring a high buck-to-doe ratio, but your recap covered it all very well. The main benefit a high buck-to-doe ratio provides is more targets.
My take:
For the most part, our problems with low mule deer populations in the West right now are pretty much habitat/predation related and not a result of the lack of sexcapades between bucks and does.
Also, if I recall a conversation with Brian Wakeling, the head of the Ariz. G&FD big-game branch, the fewer bucks that are breeding actually results in better physical condition to make it through the winter. Reason: the most energy they expend is warding off other bucks and not from the actual rigors of breeding does.
Below is a snippet from an article (Oh, How They Thirst) I did a couple years ago after that interview. -TONY
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The major concern of biologists when it comes to the relationship of rain and deer is timing. Rains that come at the wrong time of the year provide little benefit to big game. In the case of deer, the two key periods to benefit them are late winter and late summer.
Wakeling points to the 1998 deer population jump as a perfect example of what can happen.
"We had normal winter rains, good spring rains and adequate summer rains. Statewide, fawn recruitment went to nearly 40 fawns per 100 does in areas of the state where it had dropped to as low of 20 fawns per 100 does. On the Kaibab Plateau, somewhat different climatic conditions caused the corresponding recruitment to rise to nearly 90 fawns per 100 does. It was an exceptional year. Unfortunately, it was only one, and that won't do it.?
According to Wakeling, the lack of moisture to sustain ideal deer populations started in 1988 and pretty much reflects the trend that occurred about 40 years ago.
?Our deer numbers reached the highest ever in the 1960s, but the population dropped very rapidly from those numbers to all-time lows by the late 1970s. That's why we put deer on the permit system in 1972. And if we look back at the weather conditions from the late 1960s and early 1970s. we would quickly see they mirror the same patterns that are occurring right now. The deer population is also following the pattern.
?Then the deer numbers shot up again in the early and mid-1980s because we had an anomaly of sorts with rains that produced three 100-year floods over a five-year period. Even the normally dry Salt River was running at 200,000 feet per second and washing out bridges in downtown Phoenix.
?The result on our deer herds was quite predictable. For a few years running, all of the does had twins, their twins had twins, and those twins?and so on. So we wound up with more deer than we knew what to do with. Over the next several hunting seasons, we had more permits available than we had hunters to apply for them. In 1986, we set the all-time record with 95,821 permits. That is more than double the permit allocation for 2000.
?The one thing hunters shouldn't do, however, is think we'll ever get to that point again. The floods were very uncommon occurrences that created the best deer habitat we've ever had. So unless those conditions repeat themselves, which isn't too likely, our traditional optimum deer numbers will be considerably less than what we had in 1986.?
Fortunately, even though the permit numbers are at an all-time low right now, there are still more deer today in Arizona than there were in the 1970s when the population hit bottom. The reason is a different management concept put into place by the AGFD.
When the herds plummeted in the 70s, the hunter success did likewise, averaging 16 to 18 percent statewide -- a result of supply and demand with only so many deer to go around. This prompted many complaints from hunters. Rather than allow that trend to continue, the game department began adjusting the permit allocation whereby the hunter success remained fairly consistent at 21 to 24 percent in most units. So while fewer hunters go afield now, more of those that do get to a tag a buck.
The relationships between moisture and deer populations can be somewhat difficult to understand, but what it mostly comes down to is habitat.
The simple explanation: when plants gets rained on they grow and provide moisture, nutrition and cover for deer. And obviously, lots of rain also provides more standing water. The more complicated explanation involves all the interrelationships within the simple one, including what appears to be increased predation.
For the most part, the number of deer and predators are intertwined with each other, with the latter?s population increasing or declining in proportion to that of deer. But the adjustment takes time, according to Wakeling.
?When the deer herds are large and healthy, the predators are also healthy and numerous. When deer numbers begin dropping, though, the predator numbers stay high for considerably longer. They continue to kill the same number of deer as before. So over time, the percentage of a deer herd killed by predators in any particular area goes up, and that trend continues until the predator numbers drop in relationship to the deer decline," Wakeling said.
?To illustrate, consider a healthy deer population of 100,000 and a predator base of 1,000 that kills 10,000 deer annually. The resulting loss to predation is 10 percent of the deer population, thus cutting the deer herd size to 90,000. If that herd contains 60,000 does that kick out 40 to 50,000 fawns, the loss to predators is considered minimal. Now consider the same predation on the deer if their number falls to 20,000 animals; the loss of 10,000 animals now amounts to 50 percent of the herd and leaves maybe 6,000 does left to drop 3,000 or so fawns. All of a sudden the predation rate is three times the fawn production. This would rapidly cause the demise of that deer herd if the predator population didn't eventually adjust to the deer numbers. Fortunately, it always happens. It just takes time and consequently causes the deer population to recover more slowly.
?In years of good moisture, deer can normally get all the moisture they need by eating. As the rains decrease, they have to find other sources, which are mostly tanks or other standing water. That walking and use of standing water sources increases the chance for predation and burns up additional energy.
?Without water, a doe doesn't put on weight, and the chances for her to drop twins go down considerably. She also has a lower milk production when she does drop a fawn, and the lack of good cover makes the survival of that fawn more iffy because of predation. And we're not talking a lot of weight to make a difference. If a doe can increase her weight by 5 percent, it's likely her fawn will weigh a pound more when born. That is significant for the survival of a fawn that weighs five or six pounds at birth.?