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Critically Endangered Wolves Make Valuable Contributions to Genetic Health of Rare Species

The Wolf Conservation Center (WCC) participates in the Species Survival Plan (SSP) and Recovery Plan for two critically endangered wolf species, the Mexican gray wolf (Canis lupus baileyi) and the red wolf (Canis rufus). The Mexican gray wolf and the red wolf are among the rarest mammals in North America; both species at one time were completely extinct in the wild.  An SSP is a breeding and management program designed to ensure the long-term sustainability of captive-based animal populations. The primary goal for the Mexican gray wolf SSP and red wolf SSP is to breed wolves for maximum genetic integrity for reintroduction into the wild.  Organizations participating in the SSP are tasked with housing and caring for the wolves, collaborating in the captive breeding program, sharing observations and recommendations for release, and engaging in the sometimes unusual and often controversial measures to save the species.

Because the entire existing populations of Mexican wolves and red wolves are derived from such a limited founding populations (just 7 individuals for the Mexican wolf and 14 for the red wolf), genetic health is the primary consideration governing decisions re: reproductive pairings and captive-to-wild release events.  It’s also the reason that the SSP programs for both wolf species pursue an extraordinary conservation measure to save these species – gamete cryopreservation.

Photo: Chris Evers

So last weekend, at the height of breeding season, WCC staff and volunteers set out to collect semen from 3 Mexican wolves and 2 red wolves in hopes that the genetic material could be stored for potential future use.  This is an important option when trying to maintain diversity with a species that was once extinct in the wild.  The first task was to capture all 5 wolves, not an easy job in a few feet of snow…  Thankfully for the wolves, they won’t remember much beyond the capture. Semen collection from wolves requires anesthesia first,  and then electroejaculation. Dr. Cheryl Asa,  Saint Louis Zoo’s Director of Research and reproductive specialist, lead the procedure with the help of the WCC’s amazing volunteer veterinarians, Norwalk Veterinary Hospital‘s Charlie Duffy, DVM and North Westchester Veterinary Office‘s Paul Maus, DVM. The procedure was a two day event and proved to be a great success!  Dr Asa was able to determine how productive each wolf was by examining each deposit under the microscope to determine the number of sperm, the proportion of sperm moving and the quality of their movement, as well as the percentage of sperm with normal shape and an evaluation of the abnormal shapes present. Dr Asa then stored the samples in “straws” to prepare for cryogenic preservation at the St Louis Zoo.

Through the microscope (photo: Chris Evers)

So here’s a breakdown of what the wolves produced:

  • Mexican wolves M1139 & M1140: Both wolves extremely productive requiring a record number of “straws”
  • Mexican wolf M804: productive collection – no surprise for the proven breeder
  • Red Wolf M1565: no sperm at all. Possibly due to his transfer to the WCC in December when spermatogenesis occurs. Stress of travel might have interrupted the process.
  • Red Wolf M1394: productive collection.
  • Mexican wolf M904 (he underwent a reverse vasectomy in January): partially successful collection. Some sperm intact but most in pieces. His semen will need to be collected again in 2015 to determine if this reverse vasectomy was a 100% success.

Enormous thanks to Dr Cheri Asa, Charlie Duffy, DVM, Paul Maus, DVM, our family of awesome volunteers (especially Jim Horton who postponed his vacation to help out!) But most of all, we owe our thanks to M1139, M1140, M804, M1565, and M1394 for making a very personal and valuable contribution to the genetic health of their rare species!