Oregon biologists use technology to study what kills fawns
Oregon biologists use technology to study what kills fawns
By MARK FREEMAN
Apr. 13, 2018
APPLEGATE, Ore. (AP) — Tipped off by game camera images sent to their cellphones, biologists Tiffany Stoddart and Dan Ethridge know a 6-by-3-foot piece of land deep in the recesses of Boaz Gulch hold the furry quarry they seek.
The camera shows a nervous and almost assuredly pregnant black-tailed doe deer, soon to be known as doe No. 21-22, is standing inside a net trap erected on a bed of shooting star wildflowers and baited with salt, apples and alfalfa.
"We know she's in there," Stoddart says as they stand behind a curtain of ceanothus. "Let's keep her as calm as possible."
With that, they charge the trap in the first of several steps to have doe No. 21-22 join a passel of others that researchers hope will help decide the question decades of deer-camp denizens have posed for years: What kills Southern Oregon's blacktail fawns?
Using GPS technology attached to blacktail does in some usual and unusual body parts, biologists hope to monitor and track the fawns they will drop later this spring to see which ones live and, more importantly, the when, where and why the others die.
By investigating fawn deaths within hours of their mortality, researchers hope to tell whether they died at the teeth of predators such as cougars, coyotes and bears — as many hunters have theorized.
Or the data might point to other nuanced causes, such as the micro-habitat types does choose for their fawns, researchers say.
"For years we've been hearing the argument that bears and cougars are eating all the fawns," says Mark Vargas, the Oregon Department of Fish and Wildlife's Rogue Watershed manager. "But we don't have any good data to support it or refute it."
Doe No. 21-22 turns out to be a perfect subject for this study.
Stoddart and Ethridge collapse the cage on top of the waiting doe and wrestle her down so Stoddart can inject her with a quick dose of anesthesia. Then she pulls a cut-off piece of cut-off sweatpants over the deer's snout and over her eyes.
"It calms them down more when they can't see you," says Stoddart, an ODFW research technician.
Calm is one term not often used to describe sport hunters who blame predation for diminishing blacktail herds here and elsewhere.
"I suspect that's what they're going to find," says Duane Dungannon, spokesman for the Medford-based Oregon Hunters Association.
"Less than half the fawns survive, and predation is a natural part of that, for sure," Dungannon says. "But is it higher than normal? If so, what's the reason? Those are answers we want to know."
What biologists know is that spring herd composition counts show the Applegate has a ratio of anywhere from 70 to 90 fawns per 100 adult deer surviving any given winter. That's a high ratio, meaning the Applegate has very good recruitment, Vargas says.
But what that spring count doesn't account for are the phantom deer that don't make it to spring.
"We know we have a lot of deer in the Applegate, and we know we have a lot of predators," Vargas says. "This study is to see what rate of predation we have on fawns we didn't even know about, that don't make it to spring."
As doe 21-22 drifts into a narcotic snooze, Stoddart and Ethridge work quickly on their assigned tasks. Stoddart affixes blue ear tags 21 and 22 to her as Ethridge inspects her hide and teeth and draws blood.
Stoddart then screws on a GPS collar that will be used to track what habitat types she uses between now and when she gives birth in late May or early June. Researchers also will be able to determine if she chooses a different habitat for birthing.
Then the real work begins.
Stoddart loads a Vaginal Implant Transmitter, or VIT, into a plastic applicator. She slides it into the doe until it rests against her cervix.
When the doe gives birth, the transmitter will fall out and immediately trigger a signal to the phones and computers of Stoddart, as well as Chris Bottom and other technicians on the project.
Within hours, they'll find the newborn fawn and fit it with a small GPS collar of its own.
The collar allows biologists to track its whereabouts and analyze its habitat choices when alive. It will also send a distinct signal if the deer doesn't move for three consecutive hours, a general clue that it's dead, Bottom says.
When that mortality signal reaches their cellphones, technicians will track it down and investigate the scene to determine what killed the fawn, Bottom says.
"Those first few moments are very important," Bottom says.
Cougars, for instance, tend to attack their prey from behind, while coyotes make a complete mess of the carcass, Bottom says. Bears tend to gulp fawns down, he says.
Over time, the surviving fawns' activities and habitat choices will be tracked and perhaps reveal what if any habitat distinctions can be made between surviving and dead fawns, Bottom says.
When Stoddart finishes with doe No. 21-22, she injects a drug that will speed the recovery from the original sedative. Ethridge pulls the sleeve off the doe's eyes, bringing an end to this round of field work.
No. 21-22 is the fifth doe fitted with a GPS collar and VIT for this study, and they want to make sure she's doing well.
The plan is to collar 15 does a year for the next three years, just like a similar crew is doing in the Tokatee area of Douglas County.
Stoddard and Ethridge disappear from whence they came, using the cloak of ceanothus to watch how doe No. 21-22 revives.
"Some are vocal, some are not," Stoddart says. "It'll be interesting to see what she does."
After a few grunts, the doe stands amid the purple shooting stars and wanders back into the recesses of Boaz Gulch.
"Everything is good to go," Stoddart says.
Information from: Mail Tribune, http://www.mailtribune.com/