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Grant Project Launched to Help Wild Burros

The Humane Society of the United States receives five-year grant aimed at improving herd management and adoptions

As the recipient of a five-year $760,000 grant from an anonymous donor, The Humane Society of the United States has launched “The Platero Project” to promote the protection of wild burros managed by the Bureau of Land Management. The aim of the project is to develop partnerships and programs to research the effectiveness of contraceptive vaccine on wild burro herds and to reduce the number of wild burros currently living in BLM holding areas, by increasing adoptions and relocating difficult to place burros to sanctuaries. The project was financed by a donor who cares deeply about the humane treatment of burros, and it is named for the Spanish Nobel Laureate Juan Ramon Jimenez’s book about a faithful and friendly donkey named Platero.

Heidi Hopkins, The Platero Project manager for The HSUS, said: “There are many challenges to the management of wild burro herds, and through innovation we can find a way forward that saves burros from suffering and saves tax dollars and agency resources. We are grateful for this generous donation that allows us to step up our work to protect and celebrate these animals.”

Over the past five years, the rate of wild burro adoptions through BLM has drastically decreased, and more than 1,300 burros remain in federal holding facilities in the western U.S. The HSUS plans to develop a training program for wild burros that aims to increase the number of burros adopted annually.

The immunocontraception vaccine commonly known as porcine zona pellucida (PZP) was registered by the Environmental Protection Agency (EPA) to manage wild horse populations on the range last year, but it has not yet been used by the BLM on burros. The Platero Project will assist in a long-term research project to determine the efficacy and cost-benefits of using PZP to manage wild burros on the range. Increased use of PZP by the BLM could save taxpayers millions of dollars over the next decade while helping to maintain healthy wild horse and burro populations.  


  • There are more than 20 Herd Management Areas in five western states that are home to over 5,000 wild burros.
  • Wild burros are decedents of the burros used by early settlers and miners in the 1800s.
  • The Wild and Free Roaming Horse and Burros Act of 1971 is a federal law that was enacted to protect these animals and their habitat.
  • In many species, including wild horses, PZP, registered under the brand name ZonaStat-H, causes the production of antibodies that bind to sperm receptor sites on eggs and block fertilization. The Science and Conservation Center (SCC) based in Billings, Montana, produces the vaccine, which has been used to treat more than 1,600 wild, sanctuary and tribal horses annually at dozens of trial sites across the U.S., including east coast barrier islands, western wild horse ranges, Navajo and Pima/Maricopa tribal horses.
  • PZP was first used on wild horses in 1988 when a team led by Jay F. Kirkpatrick, Ph.D., the director of the Science and Conservation Center, began a pilot project on the famous wild ponies on Assateague Island National Seashore off the coast of Maryland. This project, which has been supported by The HSUS for more than 20 years, was so successful that the National Park Service began to utilize PZP as a population management tool in 1994.
  • About 300 burros live at Cleveland Amory Black Beauty Ranch, an animal sanctuary operated by The Fund for Animals, an affiliate of The HSUS.
  • Earlier this month, the National Academy of Sciences (NAS) released an extensive report that called for an increased use of on the range management tools, including PZP. See the report here 

Media Contact: Stephanie Twining, 301-258-1491, stwining@humanesociety.org

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