Study of whitetail deaths continues
Madison — The multi-year, $2 million project by the DNR and other wildlife researchers to follow and document the causes of death in bucks, does, and fawns passed the halfway mark this past winter.
“We were able to radio-collar a great number of adult and fawn bucks in each study area, which will greatly assist us in improving our estimates of buck harvest and mortality rates,” said Jared Duquette, who joined the DNR’s Bureau of Science Services in January as coordinator of the project.
Duquette describes himself as a “lifelong hunter and angler.” He fills the position formerly held by Christopher Jacques, who resigned last year.
“Our excellent and dedicated technicians, as well as favorable winter snow and temperatures, contributed greatly to capture success this year,” Duquette said.
Funded by the Federal Aid in Wildlife Restoration Act, an excise tax on firearms, ammunition, and hunting equipment commonly known as Pittman-Robertson, the project includes two study areas: Price, Rusk, and Sawyer counties in the northwest region of the state, and Outagamie and Shawano counties in east-central Wisconsin. The areas were chosen because they represent two different habitat types – northern forest and farmland – and because they both have relatively large numbers of deer.
New sites, capture tactics
Lead assistant Mike Watt, who’s responsible for training technicians, making sure crews have equipment and dealing with other day-to-day issues, has been involved with the project since its inception. He noted that some changes were made this year related to capture methods and in focusing on different sections of the study areas.
The project began in 2011 by attempting to capture deer by using a helicopter, but the chopper soon was permanently grounded by mechanical problems, adverse weather conditions, and higher-than-anticipated mortality. Researchers then turned to traps, looking for greater success.
“For this third season we took the information we learned over the past two winters and were able to improve our techniques,” Watt said. “We knew that drop-netting was extremely effective in the eastern study area, and this year because our focus was more on capturing bucks, the drop nets were very useful in helping us selectively capture bucks with very good success in that area.”
In the northwestern region, more net and cage traps were added, according to Watt. “But we also used box traps and drop nets up there,” he said. “We used the same techniques, but focused our energy more on the net and cage traps in that area.”
Watt noted that in previous years crews in the east-central area had captured and collared most of the deer west of the Wolf River.
“This year we focused more east of the river in the area between Seymour, Appleton, and Green Bay,” he said. “That has smaller woodlots, smaller blocks of woodland, and a lot more agricultural land. We definitely wanted to sample that area, and we had really good luck there.”
During the first two winters, researchers focused more attention in the Flambeau River State Forest area in the northwestern study area. “This year our capture efforts were more concentrated near Winter, and we also trapped in the Chequamegon,” Watt said.
Winter takes a toll
Because winter has persisted longer than normal this year, the impacts on deer were seen in both study areas. Watt said some deer may have succumbed to starvation.
He declined to offer any numbers until the final results are in, but one source said that at least five deer in the east-central area died of starvation, which is unusual in a farmland area. No numbers will be released until an official “cause of death” is determined by a veterinarian.
“If we have a case where we suspect starvation, we send those to our state veterinarian who will conduct an examination to determine if they died from starvation,” Watt said.
“We’re still waiting for results from tests of different organ tissues, because you can have very stressed animals with low levels of fat and they can still survive the winter, but there are certain indicators that can really tell if starvation occurred,” he said.
“But it looks like we may have had a few cases of starvation in both study areas.”
A part of Door County (outside the study area) with extremely high deer numbers where the natural winter browse has been depleted saw about two dozen deer die from starvation.
“The situation was very indicative of malnutrition,” said Jeff Pritzl, DNR Northeast District wildlife supervisor. “All but two of more than 20 carcasses were last year’s fawns. It’s symptomatic of a deer population out of balance with its habitat.”
2013 capture results
In the east-central study area, 144 new deer were captured: 32 adult bucks, 54 buck fawns, 29 adult does, and 29 doe fawns. There were 55 animals that were captured more than once.
Duquette said the DNR is now monitoring 137 animals in the eastern area.
“These include 45 adult bucks, 30 of which are from the 2013 capture season and 15 from 2011 and 2012,” he said. “We are also monitoring 58 buck fawns, including 46 from this winter and 12 from 2012, along with 26 adult does from 2011 and 2012, and eight doe fawns from 2012. No adult does were collared in 2013.”
In the northern study area, 217 new animals were captured in 2013. Included were 38 adult bucks, 58 buck fawns, 86 adult does, and 35 doe fawns. There were 130 recaptures.
According to Duquette, there are 143 animals currently being monitored, including 47 adult bucks – 35 collared in 2013 and 12 from 2011 and 2012. Fifty-one buck fawns are being monitored, including 45 from 2013 and six from 2012.
Also, 39 adult does collared in 2011 and 2012 are being monitored, along with six doe fawns from 2012. No adult does were collared in 2013.
Buck study results
In the northern study area, 41 males (at least 1.6 years old) and 70 male fawns (8 to 10 months old) were radio-collared and ear-tagged. In the east-central study area, 36 bucks (at least 1.6 years old) and 70 male fawns (8 to 10 months old) were radio-collared and ear-tagged.
Adult and yearling male survival in the northern study area increased from 38 percent in 2011 to 53 percent in 2012, with hunter harvest the greatest source of mortality for adults (65 percent) and yearlings (52 percent).
Adult and yearling male survival in the east-central study area decreased from 45 percent in 2011 to 38 percent in 2012; hunter harvest was the greatest source of mortality for adults (86 percent) and yearlings (82 percent).
Between 35 and 55 percent of male deer (10 to 18 months old) dispersed from one to 22 miles in the north and east-central (2 to 20 miles) study areas, respectively. Capture mortality was less than 3 percent.
Spring yearling male dispersal rates and distances were similar between study areas. However, fall dispersal in northern Wisconsin occurred at a 50-percent greater rate than fall dispersal in east-central Wisconsin. In the northern area, 11 to 15 percent of adult female deer migrated seasonally, but no seasonal migration was detected in the east-central study area.
Fawn study continues
Because it was considered a lower priority, the fawn recruitment study was scheduled to end with the 2012 spring capture and tagging. Watt said that additional funding has been made available, and fawn capture efforts will be begin around May 18 and continue until mid-June.
Anyone who wants to help the DNR find and capture fawns this spring may call the northern (Winter) crew at (608) 219-0771 or the eastern (Shiocton) crew at (920) 373-3565 to get scheduled.