Field Notes: CWD Test Results, Fawn Collaring, Buck Behavior and Some Bobcat Kittens
Issue 6: August, 2018
In this issue of field notes, we bring you an update on our CWD test results and dig into how we radio collar fawns. Then we look at yearling buck dispersal and how it might affect the number and ages of bucks you see in your area. We take a moment to thank all of the partners who make this study possible, and we wrap things up with a few feisty bobcat kittens!
Click the titles below to read this issue’s full articles and view our videos.
Numbers Update: 2018 Deer Capture & CWD Results
We’re sharing the raw numbers from our winter adult deer capture season.
We Found a Fawn! Now What? [VIDEO]
Fawn collaring wrapped up in mid-June. Find out how we handle them and whether we made it to our goal of 100 fawns.
Is Buck Dispersal Influencing the Deer You See in Your Area?
Many yearlings leave their mother’s range to find new homes. GPS data is giving us a better look at this behavior and how bucks interact with other deer and the landscape.
CWD Study Gets a Little Help from Our Friends
The CWD study is a massive undertaking, and it wouldn’t be possible without the help of our many internal DNR partners.
My, What Big Claws You Have, Bobcat Kitten! [VIDEO]
With GPS data and a little scientific ingenuity, we found four kittens in the den of one of our collared female bobcats.
Numbers Update: 2018 Deer Capture & CWD Results
Assistant Crew Leader Dana Jarosinski restrains a captured doe in a clover trap. Photo Credit: Alison Cartwright.
In February 2018, the DNR’s Office of Applied Science released its preliminary findings on adult deer survival for the Southwest Wisconsin CWD, Deer and Predator Study. We went through the numbers and talked about what they might mean for deer in southern Wisconsin. (If you missed that article or want to reread it, you can find it in our archives.)
We started our second adult deer capture season in January 2018 with the goal of collaring 200 adult deer across our two study areas in southwest Wisconsin. We refer to these two areas as the East Study Area and the West Study Area. When we wrapped up in March, we had trapped 208 deer. We placed GPS collars on 194 of them. The other 14 were repeat captures already sporting collars. After two years, this brings us to 332 adult deer collared. The CWD numbers and survival analysis for last year’s adult deer can be found in our newsletter archive.
We received CWD test results from 185 deer that we caught during the 2018 winter capture season. Why isn’t this number exactly the same as the number of deer collared? There are a few reasons. First, 13 of the biopsy samples were not able to be successfully tested by the laboratory. Second, there are always a few deer each year who seem to react poorly to capture (e.g. the drug doesn’t fully take effect). In these rare cases, we opt not to perform the biopsy. Third, we caught and re-tested a few deer that we collared during the 2017 winter capture season.
Below are the number of deer that tested positive and negative for each sex, age class and study area. These are the raw CWD numbers from our 2018 adult deer capture season. In a future issue, we’ll report back on what these numbers might mean and how we test for chronic wasting disease in live deer.
We’re now at the half-way point in our deer capture for this study. It seems like we just started! There has been lots of hard workgetting here, but we feel like we’ve got a good system, and we’re ready to build on our success in the final half of our field work. We might be the only folks in Wisconsin dreaming of frozen ground and snow pack in the middle of summer. We’re already prepping for the coming capture season and dreaming of snowflakes and deer under the net!
We Found a Fawn! Now What?
Last fawning season, we talked about the process of finding fawns. It’s tough work! With their custom-made camouflage, fawns easily blend into grass, thickets, leaf litter and logs. We only have a few weeks to find and collar 100 fawns before they’re too big and fast to catch. To get the job done, we take out crews of DNR staff and public volunteers to help us find as many fawns as possible. This year we found our first fawn on May 7 and our last fawn on June 21.
Clockwise from top left: Deer and elk research scientist Dan Storm searchs woods for fawns;
research technician Samantha Bundick and assistant crew leader Hanna Manninen hold a
collared fawn; Field crew slip an expandable collar onto a captured fawn; A collared fawn
finds cover under
some mayapple.
More than 300 volunteers helped us find 104 fawns this spring! We’re so grateful for our volunteers, and we couldn’t have done this work without them. This collaring season was especially hot, with a heat wave over Memorial Day weekend. Even though we had to cancel several afternoon shifts due to high temperatures, our volunteers and crew managed to surpass our goal of 100 fawns collared. We placed collars on 52 buck fawns and 52 doe fawns.
Newborn fawns stay perfectly still or may walk a few paces, so they’re easy to catch. Fawns that are even four or five days old are much harder to get our hands on. If we find one napping, we have a shot at getting it collared, but they’re already quick on their feet. It’s humbling to be outrun by a baby! We’ll often give a very brief chase, but they get away most of the time.
Reserch tehnicians take a genetic sample from a fawn’s ear; a captured fawn receives ear tags;
assistant project coordinator Katie Luukkonen and crew leader Logan Hahn weigh a fawn.
Regardless of age, finding fawns is the hardest part. We search for fawns with our gloves already on, so we’re ready to handle the next fawn as soon as we find it. When someone spots a fawn, they call out to the rest of the search party, and DNR staff come running with a collaring kit.
We place a blindfold over the fawn’s eyes right away to reduce stress on the animal during the handling process. Next, we weigh the fawn using a mesh sack and a hanging scale. This year, the smallest fawn weighed 4.4 pounds, and the largest weighed 19.9 pounds, with an average weight of 10.2 pounds.
Next comes the collar itself. GPS collars are still too big for fawns, so we use traditional VHF radio collars. The collars are made of elastic and have pleats sewn in. As the pleat stitching is exposed to the elements, the thread degrades, allowing the collar to pop open and expand as the fawn grows. When the last pleat pops, the collar falls away, usually between 12 and 18 months.
Clockwise from top: Measuring a fawn’s hind leg; a collared fawn with ear tags; crew find a fawn
under mayapple.
After the collar is on, we take a small genetic sample from the skin of one ear. Then we use a regular livestock ear tagger to place a tag in each ear. Once the collar falls off, these ear tags will allow us to identify the fawn and incorporate data from the animal into our study for the rest of its life.
We take a few final measurements before letting the fawn go. The condition of the umbilical site gives us a good indication of how old the fawn is during the first few days of life. Hind leg length is another way to assess the fawn’s age.
Once we’ve completed collaring and filled out the whole datasheet, we release the fawn where we found it. The process takes an average of four minutes. Often, fawns will bed down where we lay them. Slightly older fawns may run a small distance before bedding down again.
Clockwise from top: Field crew members Nick Forman, Erin Morrison, Samantha Bundick,
Dan Storm, Hannah Manninen and Joe Dittrich with a collared fawn; Logan Hahn
and volunteers search for fawns; Assistant crew leader Dana Jarosinski and Trevor
Johannes searching for fawns.
What's next?
Ok, so we have 104 tiny radio collars on the landscape. Now what?
Over the summer and into early fall, our study crew will cruise the back roads of our study area, scanning for each collar’s unique frequency. If the fawn has moved in the past eight hours, the collar will send out a pulse every second. If the fawn hasn’t moved for that amount of time, indicating it may have died, the collar will broadcast the pulse in double time. Using radio telemetry, we triangulate the collar’s location and perform a mortality investigation to determine cause of death. We incorporate these into our models to improve our understanding of deer population dynamics.
Stay tuned! We’ll be back with results of this field work in the fall.
Is Buck Dispersal Influencing the Deer You See in Your Area?
A whitetail buck in autumn
Spring brings a multitude of changes to Wisconsin: flowers bloom, sandhill cranes return north, the countryside turns a brilliant green. Deer are moving and changing as well. Ragged gray winter coats give way to sleek rusty-red. Winter’s lean times fill in with the flush of green growth and fresh browse, and those cute little spotted fawns take their first steps. Another big and perhaps unappreciated change also takes place among deer, one that’s akin to a giant game of musical chairs. Each spring, a whole bunch of yearling deer pull up stakes in search of a new home. This phenomenon is called dispersal. It is an important part of the life history of nearly all critters, and in the case of white-tailed deer in Wisconsin, it’s a process that might play a role in the spread of chronic wasting disease. This article describes the dispersal process, what we’ve learned so far about dispersal in southwest Wisconsin and what we hope to learn as the study progresses.
In the spring, last year’s fawns turn one year of age (hence the name ‘yearling’). By the time spring comes, they’ve spent nearly a year following mom, doing what she does and going where she goes. But once their mothers are ready to give birth to this year’s young, the yearlings find themselves unwelcome. Does drive their yearlings away so they can concentrate on their new fawns. Later in the summer, some yearlings will rejoin their mothers. Others will strike out on their own. Bucks are typically much more likely to disperse than does, who tend to rejoin their mother and new siblings.
Yearling bucks may also disperse in the fall, either for the first or second time, believed to be in response to buck aggression during the rut. Yearling bucks, being the small guys on the block, bear the brunt of this aggression and may decide to move on. Ideally, they find an area where there is less competition for does.
Why disperse?
A doe and a collared fawn browse a field in summer. Photo: Jerry Davis.
Researchers believe that one of the primary reasons for dispersal is to minimize inbreeding. Remember that all animals are trying to maximize the number of offspring they produce, so avoiding inbreeding and competition for mates makes sense. But why don’t they all disperse? Dispersal can be risky as the deer are venturing into unfamiliar territory. It can be energetically taxing (lots of walking!). It’s also not necessary for all animals to disperse in order to avoide inbreeding and mate competition. One of the many interesting avenues of dispersal research is in understanding (and predicting) which individuals will disperse and which will stay put. We’re also interested in dispersal distance and how the landscape facilitates or hinders dispersal.
Lessons from previous research
Deer research we conducted from 2011-2014 gave us some insight into dispersal. We had dispersal information for 319 yearling bucks in two study areas: northern forest and eastern farmland. Yearling bucks had a 41% dispersal rate in the Northern forest and a 55% dispersal rate in the eastern farmland. Average dispersal distances were about 3-4.5 miles. Bucks that were heavier at capture were more likely to disperse. We also found that bucks with forked antlers the subsequent fall were more likely to have dispersed than spike bucks, which indicates that there may be some threshold of physical vigor before a yearling buck will disperse. We found that rivers and roads had some effect on reducing dispersal distance, in that there was a tendency to end the dispersal on the near side of larger rivers and roads.
One limitation of our previous studies is that we didn’t have GPS collars. We had to find deer the old-fashioned way, using standard radio-telemetry to triangulate each deer’s position, usually once a week. We could tell when a deer left his natal range (a technical term for the place where the deer was born) and when and where he ended up, but we had no idea what path the buck took to get there. Now we’re using GPS collars, which give us many, highly-accurate locations for each deer.
What we're seeing so far in this study
Beginning in January 2017, we set out to place GPS collars on 200 adult deer, including yearling bucks, every winter for four years. We receive geolocations on each deer multiple times a day (up to once each hour). As these data accumulate, patterns will emerge. It will take some formal statistical analyses to really make sense of everything we’re seeing, but in the meantime, we’ve got some preliminary findings, some cool stories, and some even cooler animations of collared deer moving across the landscape!
In this article, we are looking at 46 GPS-collared bucks that received collars in 2017 and would have their first birthday during Spring of 2017. We found that 60% (28/46) displayed dispersal. Breaking it down further, 30% (14/46) dispersed in the spring and 41% (19/46) in the fall. This dispersal rate is certainly higher than observed in the northern forest deer and pretty similar to what we saw with the eastern farmland bucks.
GPS collars have enabled us to observe an interesting behavior that is linked to dispersal. Before their final move, many bucks go on what researchers call “excursions,” which might be scouting trips to look for a new home or possibly failed dispersal attempts. Yearling bucks will wander out and return to their natal range once or a few times before setting out for good. A great visual example of an excursion is from buck 5854. From the videos below, you can see two different excursions in June. Buck 5854 then returns to his natal range and stays there for the rest of the summer. In the second video you can see he disperses in the fall and, interestingly, lands in the area of his first excursion. The first excursion path is highlighted in red in the video. Obviously, there was something the buck found on that excursion that led to the selection of his new home range. This is a very neat example of GPS collars giving us a fuller picture and catching things we used to miss with older technology. We’re excited to dig into these data to see what they tell us about what bucks are looking for when they search for a new home.
Buck 5854 showed us what a relatively short dispersal movement can look like. From the natal area to his final landing spot, Buck 5854 moved about two miles, under our average of 4.3 miles. We had some extreme movers as well. They’re outliers, but they give us an idea of what is possible. Buck 5092 moved a whopping 28 miles in a little under a month! But he didn’t stop there. After that journey, he followed almost the exact same path backwards and finally settled on a new home range just under eight miles away from the natal range. A very cool thing to watch!
The story of buck 5092 then took another interesting turn. This buck died January 2018. Post-mortem testing revealed that he was infected with CWD. (He did not test positive at initial capture.) We can’t be certain whether he was infected prior to dispersing or if he became infected later. Did he contract CWD within his natal range? How many deer did he interact with on his journey? How many mineral licks did he visit? Do deer like this have an outsized role in the spread of CWD across the landscape? These are tough questions to answer, but they highlight the importance of understanding the dispersal process.
It will be fascinating to continue to follow the yearling bucks throughout this study. We will continue to study the why, how and impacts of these dispersals. The GPS collars will continue to help us look behind the curtain and give us data that will help inform future management decisions. Stay tuned for more updates on dispersal and other topics.
CWD Study Gets a Little Help from Our Friends
Wildlife biologist Matt Esser reads the weight of a captured fawn.
From the looks of it, a Boeing 747 sitting on the tarmac has as much business being in the sky as a rhinoceros. And yet, somehow, it flies. Through engineering and ingenuity and collaboration, the thing goes airborne.
We’ve said before that the Southwest Wisconsin CWD, Deer and Predator Study is the largest deer study ever undertaken in Wisconsin. We’re out to collar and monitor 200 adult deer, 100 fawns, 30 bobcats and 30 coyotes. Every year. For four years. Over two study areas. Coordinating with nearly 200 volunteer landowners and hundreds more fawn volunteers. It’s the wildlife research equivalent of a Boeing 747.
How do you launch something like that? Where do you start, and how do you sustain it?
This study operates out of the DNR’s Office of Applied Science. We house the research scientists who design and coordinate our studies as well as the field technicians who do much of the field work. We have collaborating partners from other institutions across Wisconsin who lend their expertise on data analysis and CWD pathology. But to get off the ground and sustain such a large operation, we rely on the help of our internal partners as well.
Training up
At the 2.5-year mark, our crew is a mix of old hands and fresh faces. Every November before adult deer trapping begins, our crew expands to meet the workload ahead. New recruits come from Wisconsin and all over the country to work on this study. They train up on ATV safety, deer handling, capture protocols and learn to work together as a team before heading out to the trap lines. Lindsey Long, DVM, of the DNR’s Wildlife Health section helps us train new crew to perform rectal biopsies in the field. As part of her job, she develops protocols for animal handling and sedation, and she makes sure staff are trained to go into the field. To get crew ready for adult deer capture season, Dr. Long teaches biopsy tissue collection. We use these tissue samples to test live deer for CWD, so this is a critical component of getting the new crew ready for field work.
County wildlife biologist Nancy Frost (left) and Travis Anderson (right) join field crew lead Wes Ellerson (center) to collar a coyote trapped on a volunteer landowner’s property in Iowa County.
Whose field is this?
This study requires a lot of field work, but whose field is it? We do some work in State parks and natural areas, but most of our collared animals come from private land. Our colleagues in DNR’s Wildlife Management, Forestry and Law Enforcement programs helped us identify landowners who might be interested in volunteering with the study.
“We have a pretty savvy group of landowners out here,” says forester Jason Sable. Together with the help of Sable, forester Tom Hill and wardens Joe Frost and Karl Brooks, we’ve recruited more than 200 volunteer landowners who allow us to collar animals on their land. (If you’re located within our study areas and would like information about becoming a volunteer landowner, email us at DNRDeerResearch@wisconsin.gov.)
Wildlife biologist Meg Ziegler holds a bobcat collared on her property.
One of our volunteer landowners is also a DNR employee. Meg Ziegler is a wildlife biologist in the Dodgeville area. In her day job, she restores habitat and manages public lands along the lower Wisconsin River. She’s also fascinated by bobcats and saw this study as an opportunity to learn more about them. From October to April, she checks traps for us every day on her property in Iowa County. After four months, she captured her first cat. “There’s really good habitat here for them,” she says, “Lots of rocky outcroppings.” She’s interested in learning about what the GPS collar data will tell us about their movements.
Helping hands
Many other DNR employees have joined us in the field. Wildlife biologists Travis Anderson and Nancy Frost have been trained to handle animals under sedation, and they sometimes accompany us to collar bobcats and coyotes. WDNR deer biologists Matt Esser and Curt Rolland have lent their time collaring fawns and netting adult deer.
Now halfway through year two, we’re humming. We’re hitting our goals, and we’re starting to see patterns emerge in the data that we’ve collected so far. So many of our DNR colleagues have pitched in to make this study possible. The list is too long to name everyone here. But you know who you are, and so do we. And we’re grateful!
My, What Big Claws You Have, Bobcat Kitten!
As part of this study, we’re also collaring and tracking bobcats and coyotes. Our researchers have developed methods to identify potential bobcat breeding events and dens using GPS data. We spotted a cluster of overlapping GPS collar points for a male and female bobcat back in March. Two months later, another cluster of GPS points led us to the female’s den, where we found a litter of kittens, three females and one male. We weighed and measured them before putting them back in the den.
Close-up on a bobcat kitten (left); bobcat kitten hiding in brush (right).
We don’t know much about kitten survival rates during the first few months of life, and GPS collars are helping our researchers fill in the gap. These bobcat kittens are young, but they’re feisty! Our staff has been trained and vaccinated, and we keep handling to a minimum. If you see a bobcat kitten in the wild, admire those paws and claws from afar!