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Sifton Bog Wtd Ppt Dec16


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Presentation to the Animal Welfare Advisory Committee of London, Ontario on December 16, 2008. Summarizes the related paper that looks specifically into the non-lethal methods that have been proposed …

Presentation to the Animal Welfare Advisory Committee of London, Ontario on December 16, 2008. Summarizes the related paper that looks specifically into the non-lethal methods that have been proposed to deal with white-tailed deer.

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  • 1. White-tailed Deer ( Odocoileus virginianus ) in Sifton Bog: Reviewing non-lethal management options Presented by Elizabeth Gerrow on December 16, 2008 for the Animal Welfare Advisory Committee (AWAC), City of London, Ontario
  • 2. Outline
    • General list of methods (past, present)
        • Brief discussion of what has not worked
    • Options proven to work
        • Surgical sterilization , PZP , Anti-GnRH
    • Present status of non-lethal management options
  • 3. General list of methods
    • “ Do nothing”/”laissez-faire”
    • Supplemental feeding
    • Reduction of deer impacts
    • Live-capture and relocation
    • Surgical sterilization
    • Mechanical contraception
    • Hormonal contraception
    • Immunocontraception
  • 4. What has not worked
    • “ Do nothing”/”laissez-faire”
      • Populations continue to cycle: if density ↑ to “K”, deer may cause too much damage to ecosystem and/or die (starvation)
    • Supplemental feeding
      • ↑ grouping, tolerance, and populations that skew densities
      • Possible food poisoning
    • Mechanical contraception
      • Not proven to be effective , especially for the effort that would be required, making it impractical
  • 5. What has not worked (2)
    • Reduction of deer impacts
      • Efficacy is limited, short-lived, impractical (fencing issues, etc.)
      • ↑ grouping
    • Live-capture and release
      • Expensive, not effective, impractical
      • Difficult to capture a sufficient # of deer to ↓ populations
      • Stresses deer, with high pre- and post-release mortality rate
      • Difficult to find sites able and/or willing to accept relocated deer … especially as deer issue is so widespread.
  • 6. Still questionable
    • Hormonal contraception
      • ie. Norgestomet, Levonogestral, MGA, MPA, Altrenogest, GnRH agonists
      • Natural, active in deer and work over long time periods
      • EXCEPT…
      • Varied results, unreliable, many concerns (food chain)
      • Requires large/frequent doses (ie. MGA - daily)
      • Changes behaviours, produces health concerns (ie. Levonogestral- reduced food intake in spring)
  • 7. Options proven to work
    • Surgical sterilization
    • Immunocontraception
      • PZP (Porcine zona pellucida)
      • Anti-GnRH (gonadotrophin-releasing hormone)
  • 8. Surgical Sterilization
    • Males are captured, immobilized, and castrated or vasectomized.
    • Females are captured, and have:
        • Ovariectomy (removal of gonads), or,
        • Ovariohysterectomy (removal of entire genital tract), or,
        • Clamping (tubule ligation).
    • Benefits:
    • Highly effective, irreversible, long-term/permanent, 1 treatment
    • May reduce overabundant populations
  • 9. Surgical Sterilization (2)
    • Disadvantages:
    • Animals must be captured, immobilized, operated on, then released – extremely stressful, with possible anesthetic risks
    • Requires equipment, stationary location, expertise
    • Can impact behaviour
    • Difficult if sterilized individuals are continuously captured-released while attempting to capture non-sterilized individuals
    • Emigration (sterile) opens space for immigration (fertile)
  • 10. Immunocontraception I - PZP
    • PZP vaccine induces strong immune response: produces antibodies to attack invading antigen and reproductive system
    • Antibodies attach to sperm receptors of ova, blocking fertilization (or, alters egg and/or embryo development by preventing implantation/development of fertilized egg)
    • Interferes with processes of proteins, hormones = infertility.
    Adapted from Muller et al. (1997)
  • 11. Immunocontraception I – PZP (2)
    • Benefits:
    • Highly effective (80-100% in WTD), lasts 1-3 years, reversible
    • Negative side effects rare/minor,
    • Cannot pass through food chain (biodegradable)
    • Species-specific, specific to ovary
    • Requires smaller volumes than steroid treatments
    • Can be remotely delivered, without capturing
    • If pregnant: does not interfere with pregnancy/offspring health; treated females produce fewer fawns
    • Pregnancy in Yr 1 does not affect effectiveness in following year
  • 12. Immunocontraception I – PZP (3)
    • Disadvantages:
    • Estrus not inhibited: ↑ # of cycles + extended mating season
    • Question of long-term treatment effects - more studies needed
    • Forms using multiple inoculation system are difficult/impractical
    • Substantial ↓ in population may need high (50-90%) proportion of sterilized females
    • Concern for fawns born later due to the extended breeding season: survival rate compromised by winter season?
  • 13. Immunocontraception II – GnRH
    • GnRH is produced by the hypothalamus and controls release of hormones that control ovary function (females) and testes (male).
    • Critical to normal function of fertility systems
    • Anti-GnRH vaccine induces antibodies that prevent GnRH from binding with its receptors on the pituitary
    • Reduces active GnRH levels circulating in blood = ↓ released of reproductive hormones, FSH and LH = infertility.
    From lessons/images/200410-03/20041003f2.jpg
  • 14. Immunocontraception II – GnRH (2)
    • Benefits:
    • Highly effective ( 88% efficacy), reversible
    • Lack of adverse side-effects
    • Inhibits estrus cycles and testicular function
    • Treated females produce fewer fawns
    • Disadvantages:
    • May alter health and/or behaviour
    • Variability (efficacy < 100%) likely due to individual variation (immunocompetence)
    • If oral vaccine is developed, must be species-specific
  • 15. Conclusion: Present status of methods
    • There are many non-lethal methods that have had varied results when applied to wild WTD
    • PZP , GnRH vaccines have shown the most promise and are being actively developed and tested
    • Specific vaccines produced:
          • SpayVac® (PZP)
          • GonaCon™ (GnRH)
  • 16. Conclusion (2)
    • Fraker et al. (2002) and Locke et al. (2007):
      • SpayVac® administered once
      • 100% contraceptive efficiency
      • 2 to 3 year period
    • BUT SpayVac® is no longer available despite its success, leaving attention to other vaccines
  • 17. Conclusion (3)
    • Miller et al. (2008):
      • GonaCon™ administered once
      • >79% contraceptive efficiency over 5-year period
      • Note: it is a project of the U.S. Department of Agriculture’s Wildlife Services’ National Wildlife Research Center
      • For more information and the factsheet:
  • 18. References Specific articles mentioned: Fraker et al. 2002. Long-lasting single-dose immunocontraception of feral fallow deer in British Columbia. Journal of Wildlife Management 66(4) : 1141-1147. Locke et al. 2007. Effectiveness of Spayvac ® for reducing white-tailed deer fertility. Journal of Wildlife Diseases 43(4): 726-730. Miller et al. 2008. The single-shot GnRH immunocontraceptive vaccine (GonaCon™) in white-tailed deer: comparison of several GnRH preparations. American Journal of Reproductive Immunology 60(3) : 214-223. Muller, L.I., R.J. Warren, and D.L. Evans. 1997. Theory and practice of immunocontraception in wild mammals. Wildlife Society Bulletin 25(2) : 504-414. Information was extracted from the report, “White-tailed deer ( Odocoileus virginianus ) in the Sifton Bog of London, Ontario, Canada: A preliminary report reviewing non-lethal management methods and common (mis)perceptions”, written by E. Gerrow and submitted to AWAC on December 8, 2008.