01-09-2006, 06:41 PM
Bighorn die-off forces cancellation of hunting season By Wayne Ortman, Associated Press Writer
CUSTER — A die-off of bighorn sheep in Custer State Park in southwest South Dakota is as extensive as first believed and likely will mean restocking and canceling another hunting season, a park official said.
The herd had grown to a target range of about 200 animals when a form of pneumonia — likely contracted from a domestic sheep herd — spread through the park herd last year.
“The numbers we counted in the fall rut supported a 75 percent mortality rate,” Gary Brundige, a Game, Fish & Parks Department wildlife biologist in the park, said. “We still have around 50 head in the park.”
Park staff concluded that the disease affected all age classes and both rams and ewes, he said, and it is believed to have reduced the survival rate of lambs born last summer.
“That’s something you tend to see after a die-off,” Brundige said.
“We’re not sure why. There’s some speculation
the mother or the herd still has some carriers, if you will, of the pathogenic bacteria, and lambs are then exposed sometime after birth.”
Building a herd through natural reproduction is a slow process under the best of circumstances because of predators, disease and other factors affecting lambs.
“When we were doing research in the late ’80s and in the late ’90s, we were seeing — generally speaking — mortality rates approaching 75 percent in the first year for those lambs. Eighty-plus percent of the ewes of breeding age were dropping a lamb, but the yearling-to-ewe ratio was down to 20 percent.”
The survival rate for lambs improved — likely because new genetics were introduced — after the park transplanted 16 ewes and four rams from a herd in Canada, increasing the herd size from 150 in 1999 to the 200 mark, he said.
Restocking with sheep from another state is a likely next step, though it wouldn’t be for another year or so.
“One of the things we wanted to do is wait and see what our residual herd looks like and let this episode go through a whole cycle and see what’s going on with our lambs and lamb survival,” Brundige said.
The Game, Fish & Parks Commission canceled the park’s bighorn hunting season, scheduled for this month. Three licenses were available for rams. Typically, hunters target the oldest rams because they have the largest horns.
“We’re probably not looking at having a season next year. There may be a ram or two that would be in that category, but it’s unlikely we would open the season with such a limited number of rams,” Brundige said.
The pneumonia did not spread to a handful of bighorn herds elsewhere in the Black Hills, and the fall hunting season for three bighorn sheep outside Custer State Park went on as scheduled.
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CUSTER — A die-off of bighorn sheep in Custer State Park in southwest South Dakota is as extensive as first believed and likely will mean restocking and canceling another hunting season, a park official said.
The herd had grown to a target range of about 200 animals when a form of pneumonia — likely contracted from a domestic sheep herd — spread through the park herd last year.
“The numbers we counted in the fall rut supported a 75 percent mortality rate,” Gary Brundige, a Game, Fish & Parks Department wildlife biologist in the park, said. “We still have around 50 head in the park.”
Park staff concluded that the disease affected all age classes and both rams and ewes, he said, and it is believed to have reduced the survival rate of lambs born last summer.
“That’s something you tend to see after a die-off,” Brundige said.
“We’re not sure why. There’s some speculation
the mother or the herd still has some carriers, if you will, of the pathogenic bacteria, and lambs are then exposed sometime after birth.”
Building a herd through natural reproduction is a slow process under the best of circumstances because of predators, disease and other factors affecting lambs.
“When we were doing research in the late ’80s and in the late ’90s, we were seeing — generally speaking — mortality rates approaching 75 percent in the first year for those lambs. Eighty-plus percent of the ewes of breeding age were dropping a lamb, but the yearling-to-ewe ratio was down to 20 percent.”
The survival rate for lambs improved — likely because new genetics were introduced — after the park transplanted 16 ewes and four rams from a herd in Canada, increasing the herd size from 150 in 1999 to the 200 mark, he said.
Restocking with sheep from another state is a likely next step, though it wouldn’t be for another year or so.
“One of the things we wanted to do is wait and see what our residual herd looks like and let this episode go through a whole cycle and see what’s going on with our lambs and lamb survival,” Brundige said.
The Game, Fish & Parks Commission canceled the park’s bighorn hunting season, scheduled for this month. Three licenses were available for rams. Typically, hunters target the oldest rams because they have the largest horns.
“We’re probably not looking at having a season next year. There may be a ram or two that would be in that category, but it’s unlikely we would open the season with such a limited number of rams,” Brundige said.
The pneumonia did not spread to a handful of bighorn herds elsewhere in the Black Hills, and the fall hunting season for three bighorn sheep outside Custer State Park went on as scheduled.
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