Does do some crazy things during the rut, too.
Deer research has come a long way in recent years. Thanks in part to the advent of GPS-fitted tracking collars, biologists can track a deer almost as if they were actually following the animal through the woods. Most of the tracking research has looked at buck activity with a heavy emphasis on the rut, but a handful of recent projects have also examined doe behavior. It turns out, they do some crazy things, too.
THE BREEDING SEASON IN DEPTH
To understand doe behavior, it’s critical to understand the rut. Biologists know the peak breeding season is based on the length of daylight (photoperiod), and it happens virtually the same time every year. In most parts of whitetail country, the rut takes place in early or mid-November.
“A small percentage of does can come into estrus as early as September, and bucks are capable and willing to breed that early, too,” said Minnesota Department of Natural Resources deer biologist Gino D’Angelo. “The vast majority don’t come into estrus for the first time until November, though, which is what most of us call the peak of the rut.”
Does that aren’t bred during their first cycle will come into estrus again 28 to 30 days later. Known as the second rut, it tends to be much less noticeable because the majority of does have already been bred. However, it can be a bit stronger in regions with low deer densities or with an overabundance of does. When there aren’t enough bucks to breed them all the first time, unbred does come into estrus again.
As researchers are learning, though, the rut isn’t all about bucks. Contrary to popular belief, females go through some significant behavioral changes, too.
Any deer hunter who has spent time in the woods during the rut has undoubtedly seen a chase. A doe sprints through the woods, stops to look back and then takes off again. Something about her behavior makes one thing clear: She isn’t running because she’s spooked.
She might be running with her tail down, and her gait might be more of a trot or a casual bounding instead of a flat-out sprint. Seasoned hunters get their guns ready because they know a buck won’t be far behind.
Many hunters believe chase behavior is nothing more than an evasion tactic, a way to shake off a buck that won’t leave her alone. D’Angelo said chasing behavior is simply part of the courtship process, not unlike human interaction.
“She’s not in standing estrus (the brief period when she is receptive) during the chase period, but it’s possible she is indicating that she is interested, but not quite ready yet,” he said.
Whatever the reason, does become nearly as active as bucks during the pre-rut period, according to a study that took place on Louisiana’s Barksdale Air Force Base during 2009 through 2011. Stephen F. Austin State University graduate student Kate Hasapes examined movements of bucks and does. She placed GPS collars on 15 bucks and 15 does and tracked their activity.
Surprisingly, doe activity increased as the rut grew closer. They exhibited a near equal amount of activity during parts of the pre-rut and rut periods. Hasapes can’t say if it had anything to do with chasing, or if does were simply becoming restless as the breeding season approached. Whatever the reason, it’s contrary to the belief that does simply wait for bucks to come to them.
“You would think does would be less active during the breeding season so they don’t use up valuable resources like fat reserves,” said Hasapes, who now works as a private lands biologist for the Louisiana Department of Fish and Wildlife. “This tells us does don’t just hang around and wait for a buck to find them. They seem to be actively searching for a partner.”
What surprised Hasapes and other researchers was that does actually go on long excursions during the breeding season, a habit once thought to be exclusive to amorous bucks. Hasapes learned that does actually take off on brief excursions more frequently than bucks.
Just two of the 15 bucks she tracked made excursions outside their home ranges. Ten of 14 does made long treks during the breeding season. Overall, does exhibited far more extreme daily distance movement than bucks in the winter, especially after the first rut.
Southern Illinois University Carbondale graduate researcher Matt Springer also observed does taking numerous long-distance excursions during a study in Illinois farm country. Although his research did not focus on doe behavior during the rut, he found that does took as many excursions outside their home ranges as bucks.
“There was no difference in movements by sex or differences by seasons,” Springer said. “Does made some excursions up to 2½ miles, but they were all for less than a day.”
One doe in Springer’s study not only left her home range, she swam across a lake at least 500 yards wide on two separate occasions. Then she swam back across the lake to return to her established home range. Both excursions were within a two-day period during the pre-rut of early November.
Springer can’t say for sure why she crossed a lake in late fall, but he wonders if she was being chased by a buck or was simply searching for a potential mate.
“She could have been trying to lose a buck, but that’s just speculation,” he said. “There’s no telling why she did that on two occasions.”
Other does in Springer’s study weren’t quite as daring, but several did leave their home ranges at least once during the first two weeks of November. All of the excursions were at night. (Hasapes’ study did not differentiate between daylight and nighttime activity.) Most stopped in forested habitat before returning to their home territories.
Again, Springer can’t say why the deer he studied did what they did, but he figures they either stopped in forested habitat for food or to find a suitable mate.
D’Angelo is likewise unsure why the does in his study went on excursions. However, he agrees the most likely reason was to find a mate. As they travel, they leave a scent trail bucks can easily detect and follow.
“Several does made second excursions 28 to 30 days after their initial excursions, which would indicate they did not get bred during their first estrus cycle and were actively searching for a partner during their second,” he said.
A number of does in Hasapes’ study also made excursions during the second rut. In fact, long-distance activity spiked in late December and January, with a number of excursions taking place mid- to late January.
To learn even more, she fitted does with vaginal implant transmitters which fall out when they gave birth. With that data, she was able to count backward and correlate the birth date to dates of excursions.
She was able to determine those excursions did indeed take place the same time those females were bred. Some of them took trips that covered more than 3 miles. Excursions averaged nearly 2 miles.
WHAT DOES IT MEAN?
“The first thing a lot of hunters who want to manage their deer herd say is, ‘We need to shoot more does,’” Hasapes said. “That might or might not be true, but hunters need to be careful about making blanket management decisions like that until they know what they have.”
Biologists know an unbalanced sex ratio skewed in favor of does will change breeding behavior by altering the length of the rut.
A prolonged breeding season also has a negative impact on the herd overall. Fawns born later in the year tend to be less healthy and grow smaller antlers. Also, the more a doe wanders in search of a mate, the less time she spends eating and resting.
There was a good buck-to-doe ratio and a good overall deer density on Hasapes’ study area, so the mere act of shooting more does for the sake of shooting more does likely wouldn’t change the activity she observed.
Other studies have shown high excursion rates by does in areas with high deer densities, so it might be impossible to prevent does from leaving, no matter how well you manage your herd.
To complicate things, Hasapes wonders if the excursions associated with the breeding season were simply a natural part of their breeding behavior. There is some agreement within the science community that bucks roam outside their home range to promote genetic diversity. Why wouldn’t does do the same thing?
Of course, that only further undermines any argument that hunters can manipulate genetics in their deer herd, a notion already disputed by deer biologists. If both bucks and does travel long distances to breed, it’s impossible to control genetics on a local level.
Despite the uncertainty, D’Angelo recommends managing for an even sex ratio and a herd that can be supported by the available habitat. That ensures a high percentage of does get bred during the peak breeding season.
“If they get bred the first rut, they may be less likely to wander off your land during the second or third breeding period,” he said. “That can help you better manage your herd by preventing mortality beyond your control.”
Read Recent Articles:
• Hook: Just because a buck changes zip codes doesn’t mean it’s gone for good.
• Too Hot for TV: An uncensored look inside whitetail bedding areas. This article was published in the November 2015 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.