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Unusually high deer birth rate spurs debate on lethal culling

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  • Pat Scala
    By: David Campbell , Staff Writer 07/09/2004 Many explanations for large number of fawns among deer receiving birth-control vaccinations. Opponents of lethal
    Message 1 of 1 , Jul 9, 2004
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      By: David Campbell , Staff Writer

      Many explanations for large number of fawns among deer receiving
      birth-control vaccinations.

      Opponents of lethal deer management have been saying for years that
      killing deer is futile because it only spurs reproduction.
      And a recent disclosure of an unexpectedly high fertility rate among
      immunized deer by the Yale-educated wildlife biologist overseeing
      Princeton Township's experimental deer birth-control program only
      confirms that claim, they say.
      Last week, White Buffalo President Anthony DeNicola met with the
      Township Committee seeking about $27,000 to conduct the majority of
      third-round deer immunizations in August. The money would have been
      requested anyway to do the vaccinations this coming winter, when they
      were originally planned, he said.
      Seventy-eight does have been treated with experimental one-shot
      vaccine SpayVac in the study area in the southeastern corner of the
      township. Seven of those deer have died for reasons unrelated to the
      vaccinations. The experimental program began in the winter of 2003.
      Mr. DeNicola has said an unexpectedly high number of fawns became
      pregnant prior to last winter's round of treatments in the study area -
      the birth rate is about twice that of deer in areas where population has
      been managed through lethal sharpshooting and captive bolting. If the
      trend continues, the wildlife biologist said, births will outweigh
      natural deaths in the study area, and the township will not see the
      desired population reduction.
      The cause of the apparent reproductive anomaly is unclear, Mr.
      DeNicola said. It may be that the study area is in a heavily landscaped
      area with an abundance of foraging opportunities not available in parts
      of the township where culling has occurred, which he described as
      naturally wooded and already heavily browsed by deer.
      Another possibility may be that the founding population of does that
      first settled in the study area - a densely housed corner of the
      township that is not especially attractive to deer, he said - were
      genetically predisposed to high rates of fertility.
      "Why the research area has this unusual level of reproduction at this
      point I cannot explain," Mr. DeNicola said. But he said this
      reproductive "fluke" can hardly be held up as proof that culling in the
      other parts of the township has spurred a wave of reproduction and
      thereby has backfired.
      If that were the case, he said, the township would be seeing a
      comparable jump in the birth rate among deer in other parts of the
      township where culling has occurred, which he said it hasn't.
      But Nancy Bowman of the Mercer County Deer Alliance, a longtime
      opponent of the township's deer cull, says otherwise. She said the
      reproductive spike in the study area proves what she and fellow
      animal-protection activists have been saying for years.
      "When a significant number of deer are killed and the food supply and
      other factors remain about the same, it doesn't take a Yale-trained
      anything to figure out there should be more fawn survival, more does
      pregnant, and does mating younger than before," she said.
      Since the higher fertility rate is in the township's birth-control
      area where culling hasn't occurred, Ms. Bowman reasoned, the township is
      most likely witnessing "refuge seeking" by deer fleeing the cull areas.
      She said: "Deer have moved from where DeNicola is killing to where he
      is not killing - a predictable result."
      Mr. DeNicola conceded that the birth rate in culling areas has
      increased - maybe 10 percent, he said - but he described the rise as
      "minimal." He said deer were already reproducing at a high rate of about
      80 percent of their "maximal reproductive potential" in cull areas when
      the program began in 2001.
      "You couldn't get them to go much higher," he said. The wildlife
      specialist said deer in cull areas are now reproducing even closer to
      the maximum than when culling began, but added that, taking into account
      the fact that the population has been reduced by about 70 percent, a
      10-percent rise in fertility to date is relatively minimal.
      As for "refuge seeking," Mr. DeNicola said his study team has not
      witnessed any influx of deer into the study area.
      But Sue Russell, policy director with Rumson-based Center for Animal
      Protection, said the claim by Mr. DeNicola about reproduction rates
      already being high is one she's heard before, and she said it misses the
      "We say an increase will happen, they always come back and say it's
      incremental," Ms. Russell said. "If their rate is already high and you
      do something extra to kill them, it'll go a little higher, but not much
      "But people miss the point," she continued. "You're keeping the rate
      high, and that seems always to get lost. You're keeping them in the
      rapid-growth phase of their cycle."
      Ms. Russell said she wasn't sure if the high fertility rate in the
      study area is a "fluke" as Mr. DeNicola said. "If they were already
      pregnant with high numbers, it's a symptom of how wrongly they have been
      managing deer," she said. "If you are removing hundreds of deer, the
      survivors are going to breed like crazy. Those that have less stress are
      going to breed earlier."
      Ms. Russell said she believes the current township administration
      will not change its policies and will have to keep killing deer, adding:
      "Give that five years, and you will have a total deer farm in Princeton.
      It's going to be like rabbits."
      Jay Kirkpatrick of ZooMontana, one of the two suppliers worldwide of
      the contraceptive ingredient in SpayVac, said an outside objective and
      systematic population study would be needed to isolate the cause of the
      spike in fertility in the study area.
      Mr. Kirkpatrick said he's no deer biologist, but that when increases
      like that are witnessed in wild animal populations, "You can generally
      start looking at weather, grass, food, habitat, things of that nature."
      But he concurred that population reduction speeds reproduction rates
      - "that's zoology 101 in your freshman year in college. We refer to it
      as density-dependent reproduction. In virtually every species from rats
      to you name it, if you reduce populations, they simply speed up their
      reproduction rates."
      Mr. Kirkpatrick added that when it comes to deer population control,
      he steers well clear. He said he wants nothing to do with it, and that's
      because of the political turmoil that comes with it.
      "We don't touch deer contraception because of the irrational
      arguments that swirl about it," he said. "Objectivity vanished long ago.
      We just backed away."

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