and then

Continuing our Successful Research and Behavioral Management of Wild Horses


We have completed our 16 years of studies on our four wild horse herds.  What we have found is so crucial to the future of all wild horses on public lands and this is why we need your support! 

Our two herds, whose families have not been touched in 16 years, are growing at a rate of 7%-8% - while BLM herds are growing at 20%

They are given the best forage & the best opportunities to reproduce and they growth rates remain low and stable.

Our findings can create an entirely new management program for wild horses on public lands.

  • Allowing wild horses to live in their natural state without disruptions
  • No need for drastic measures of sterilizations proposed by the BLM (removing ovaries of pregnant mares, laser of ovaries through the vagina, and other gruesome procedures)
  • Abiding by the law using “minimal feasible management”
  • Stopping helicopter removals of wild horses
  • Saving taxpayers millions of dollars
  • And ending the mass warehousing of animals removed from public lands.
  • Allowing stable family bands allows for healthy stable populations.


Since the Act in 1971 protections of horses/burros are failing

  • There were 303 herd areas identified when Wild Horse Annie and ISPMB were instrument in getting the 1971 law passed.  Now we have LOST almost half of them.
  • According to Gus Cothran, leaded equine geneticist, a herd must have 150 effective breeders (those animals that are breeding which excludes bachelor bands, youngsters, and old mares who no longer carry to term or get pregnant) to maintain their genetic diversity.  Approximately 75% of BLM herds do not have 150 effective breeders.
  • Out of 123 herds studied by Dr. Cothran nearly 20% show CRITICAL or NEAR CRITICAL loss of genetic diversity.
  • ISPMB’s studies show that wild horses are infertile after 5 years of PZP and may drop as low as 4 consecutive years of administration of PZP while the literature states 7 years.
  • We must STOP the disruption of family bands regardless for what purpose they are disrupted.  This is the KEY to creating healthy herds and LOW population growth.


This is a PLEA to everyone today to support ISPMB and our efforts to save “truly” the LAST of America’s wild horses and burros.  ISPMB herds must survive.  They hold the key to so many more important studies.

International Society for the Protection of Mustangs and Burros joins forces with Princeton University to Study Equine Behaviors


Celebrating more than 50 years of wild horse and burro education and conservation, ISPMB continues its vision and mission as an international leader.  Joining with Princeton University's Dan Rubenstein, PhD, Department of Ecology and Evolutionary Biology, the research will begin this June to identify the "functional" social behaviors in wild horse society.


Gila Herd

ISPMB manages a conservation center in South Dakota where 4 distinct wild horse herds live undisturbed. "One of the main reasons we have kept the groups isolated is so we can study various herd cultures," says ISPMB President Karen Sussman. "Even though the herds have been living in the same habitat for 12 years, the groups have maintained their individual cultures, so we are eager to understand as much as possible about the social behavior of wild horses and how they may affect management."


Dr. Rubenstein is well known for his global work on behavior and decision making in wild equids, particularly with zebra sociality. Investigating how animals "network" and what determines "leaders" in animal society will translate well into the ISPMB studies.


Joined by Dr. Cassandra Nunez, PhD, currently a research scholar at Virginia Tech and past wild equid researcher at Princeton, Dr. Nunez has been involved in previous wild and feral horse studies in the US.


Miss Little EarsPrinceton student, Lydia Anderson will be in the field for about 10 weeks this summer working on her senior thesis and identifying critical factors in wild horse networks. "I am so incredibly excited to be able to live in the field and study wild horses", comment Lydia. " I grew up in a small town in Wisconsin, loving nature, so this will be a wonderful opportunity to experience both horses and nature."


Princess and Ellie

ISPMB Research Director, Mary Ann Simonds, MA Whole Horse and Equestrian Science Institute has been studying social behaviors, leadership and cognition in wild horses since her undergraduate work the early 1970s at the University of Wyoming. "I am thrilled to have such a great team of folks dedicated to assisting with this project. Being able to identify sustainable behaviors and how leadership takes place in functional herds will help us identify why the herds have maintained their various cultures and hopefully give insight into management strategies."

Sign up form
Enter your e-mail address below and click on go.


Copyright © 2017 ISPMB All Rights Reserved