Weed & Pest
Ravens prove problematic in Wyoming, some control mechanisms availableWritten by Saige Albert
A 2011 study initiated by the Meeteetse Conservation District and USDA Wildlife Services aimed to examine the effect of predators on sage grouse populations within the Bighorn Basin.
“Everyone points the finger at grazing or oil and gas when we look at sage grouse impacts,” says Meeteetse Conservation District Resource Specialist Steffen Cornell. “We know that predation also has an impact.”
By partnering with a variety of groups, including conservation districts, industry people, county predator boards and others, Cornell noted they received ample financial and moral support from the region.
“We contracted with one researcher from the National Wildlife Research Center for the first two years and another for the remaining three years,” Cornell adds. “We’ve just ended the first five years of the study.”
Before concluding the study, the National Wildlife Research Center produced a preliminary report to the Wyoming Natural Resource Trust.
“The preliminary report indicated if we don’t do something about ravens on one of our study sites, the local sage grouse population faces possible eradication in spite of the fact that it has some of the best sage grouse habitat in the Bighorn Basin,” Cornell says.
The National Wildlife Research Center is now finalizing their study results for publishing in a peer-reviewed scientific journal.
Now that their contract with the National Wildlife Research Center has concluded, Cornell explains that they have decided to move forward with additional research.
“We decided we wanted to move on and focus more on ravens,” he continues.
Cornell explains that Meeteetse Conservation District, with continued field assistance from Wildlife Services, is moving forward with new research to determine if the impact of ravens can be alleviated.
“Ravens are tremendously successful at whatever they do, and one of those things is seeking sage grouse and depredating nests,” he says. “Since the inception of this project, we’ve secured funding through the Animal Damage Management Board and the Sage Grouse Local Working Group, and we are going to continue to approach those groups as well as others.”
As they continue to seek funding to continue the project, Cornell adds that they are approaching their first field season to look at reducing raven predation.
“We just got a scientific collecting permit on March 9 from Fish and Wildlife Service,” he says. “We will be capturing and radio marking 12 ravens in two locations in Park County.”
Six ravens will be trapped at each study side, along with 10 sage grouse.
“We will split each site into a treatment and control area,” Cornell continues. “On the treatment site, we will be actively locating and removing raven nests. Our permit allows us a quota on the number of eggs and chicks that we can remove.”
While their scientific collecting permit allows the removal of eggs and chicks, Cornell adds that their goal is to remove the nests prior to egg laying to avoid killing chicks, if possible.
Nest removal will occur primarily during the nesting season for sage grouse.
“Nesting pairs of ravens are very territorial,” Cornell explains. “Some research suggests that those nesting pairs are also the specialists when it comes to depredating sage grouse nests.”
“The logic behind our study is that if we can preoccupy the ravens enough that they are constantly trying to rebuild their nests, it would prevent them from having the time to go out and forage for sage grouse eggs,” he says. “We think they will be more worried about producing their own clutches than seeking sage grouse eggs.”
“We are hoping this study sheds some light on other management approaches that are non-lethal and maybe more socially acceptable,” Cornell adds, mentioning that they hope to continue to gather data into 2017.
Hayden Wing and Associates of Laramie, one of the foremost raven and sage grouse experts in the state, has been contracted to assist in the project.
“During our study, coyotes were the number one predators on sage grouse nests,” Cornell says, adding that coyotes more easily managed because of the lack of protection for the species. “We can manage coyotes, and that is being done today. Ravens are protected under the Migratory Bird Treaty Act. It’s much harder to knock their numbers down for the purpose of benefitting sage grouse, but we’re hoping that we see a rise in sage grouse nest success from raven nest removal.”
Throughout the state of Wyoming, USDA Wildlife Services State Director Mike Foster says that raven control work is being conducted for health and human safety reasons and to protect livestock.
“We do raven work to protect calves and lambs when they are born,” he says. “This happens all throughout the state when it's necessary.”
Raven control is conducted through the use of an avicide called DRC 1339. The avicide is only available to Wildlife Services.
“This avicide is a very effective product,” Foster says. “We use it on various baits including dog or cat food, which is allowed under a special use permit from the Environmental Protection Agency (EPA).”
When initiating a control activity, Foster explains that Wildlife Services begins by pre-baiting the area of concern. Once the ravens are taking the bait well, the avicide is introduced.
“The avicide affects the kidneys and heart, and the birds experience a quiet and apparently painless death one to three days following ingestion,” he says. “They usually die on their roosts, and there is no risk of secondary toxicity.”
DRC 1339 is generally unstable in the environment and is rapidly metabolized in the target species. Scavengers consuming the dead individuals are not affected.
“There has never been a known case of secondary poisoning,” says Foster.
“Ravens are protected under the Migratory Bird Treaty Act,” Foster mentions. “Wildlife Services has the permits to allow us to do this work. Private individuals can also get the permits, but DRC 1339 is only available to Wildlife Services.”