David Grubbs Billings Gazette - Jay
Kirkpatrick of ZooMontana holds a dart that is used to administer
contraceptives to deer.
While no one has invented a birth-control pill for does,
and fitting a buck with a condom would be a hazardous activity, some say
contraception is a viable means for controlling a population of urban
Critics of the method believe birth-control vaccines — delivered with a
dart gun — are costly, inefficient and perhaps dangerous to human
health, but in a recent interview a wildlife contraception expert said
those arguments don’t stand up to hard evidence.
“It matters not to me whether people use this or not ... the only thing
that gets my back up is when somebody says this doesn’t work,” said
Science and Conservation Center Director Jay Kirkpatrick, a life-long
hunter. “It does work, and it works well.”
The center, a nonprofit organization located at Zoo Montana in Billings,
makes the porcine zona pellucida vaccine, or PZP, used worldwide to
control populations of deer, horses, elephants and other mammals.
The vaccine, derived from pig eggs, distorts the membrane surrounding
mammalian eggs, closing the gate on fertilizing sperm.
The method has been used to control deer herds at the Fire Island
National Seashore, a 32-mile barrier isle off the coast of Long Island,
N.Y., and at the National Institute of Standards and Technology in
Kirkpatrick’s staff helped set up a lab in South Africa,
now making enough PZP to dart 1,000 elephants a year. The situation
there is similar to the urban deer management discussions taking place
in this country, he said.
“Half the public says, ‘Hell, shoot them,’ ... and the other half says
‘No, they’re a national treasure,’” he said. “It’s pretty much the
Darted animals need to be inoculated every year to prevent pregnancy.
Populations are reduced through natural mortality, once reproduction has
The method isn’t intended for large geographic areas and works best in
“small, discreet urban populations,” Kirkpatrick said.
The National Institute of Standards and Technology is located on a
sprawling 578-acre campus in Maryland, surrounded by a 10-foot fence.
In the mid-1990s, the agency’s land was home to more than 300 whitetail
deer, spokesman Michael Newman said, resulting in deer-vehicle
collisions — and the occasional rutting buck crashing through a window
after seeing his reflection.
“We looked at a lot of different (management) options,” Newman said.
Safety concerns at the 24-hour facility, along with public opinion in
surrounding neighborhoods, prompted officials to rule out hunting.
The Humane Society of the United States, which coordinates projects
using the PZP vaccine, offered to work with the facility and officials
jumped at the chance, Newman said.
The herd now numbers about 175 deer, he said.
“For us, it works particularly well,” he said. “It does allow us to
successfully manage the deer population. It doesn’t affect the behavior
of the deer.”
Newman said he’s unsure whether the vaccine would be as successful
Security concerns limit the campus to one controlled-access gate, and
areas where hills enable the deer to jump the fence are scarce.
Most of the deer inside the fence stay in, and it’s likely few make it
in from the outside.
A migratory barrier — in this case, water — also limits the coming and
going of deer on Fire Island, said Michael Bilecki, resources management
chief at the national park.
“The fact that it’s an island ... is significant for us,” he said. “I
can’t speak to how something like this would work on the mainland.”
But Kirkpatrick said the surrounding waters are a moot point.
Whitetail deer remain in the same half-square-mile range their entire
lives, he said, ruling out migration as a factor.
He said mule deer venture farther, but all of his projects have involved
On the 32-mile-long island, located east of New York City, the vaccine
has been a success over the past decade, Bilecki said.
PZP has been used to manage deer populations in the 15 or so communities
that dot the island’s west end.
“We’ve seen populations decrease and then, in some areas, populations
have leveled out,” he said.
“In some areas — and we can’t figure out why — we’ve seen little bumps
in the population going up,” he added.
On the Web:
Larry Kline can be reached at 447-4075 or
From pigs to deer
In all mammals, a membrane known as the zona pellucida surrounds each of
the female’s eggs.
The barrier includes molecular keyholes, which allow sperm from the same
species in to fertilize the egg.
The porcine zona pellucida vaccine, or PZP, is derived from pig eggs.
When it’s injected, it stimulates the female’s body to produce
antibodies, which distort her eggs’ openings.
“Now a sperm comes along, and its little molecular keys won’t fit the
little molecular keyholes,” researcher Jay Kirkpatrick said. “It’s kind
of like changing the tumblers in a lock.”