Free-roaming horses on the Eastern Slopes of the Rocky Mountains in Alberta are known locally as the Alberta Mountain Horse or "Wildie". On November 1, 2014, the non-profit advocacy group Wild Horses of Alberta Society (WHOAS) entered into a five-year agreement with the Alberta provincial government's Alberta Environment and Sustainable Resource Development (ESRD). This agreement authorized WHOAS to effectively and humanely manage the feral horse population in a 490 km2 portion of the Sundre Equine Zone on the Eastern Slopes. In May 2016 WHOAS completed the first year of a selective contraception program using Zona Stat-H, a form of Porcine Zona Pellucida vaccine, or PZP. WHOAS has vaccinated 73 mares to date, 16 of which have received booster shots. With one shot a mare is 70-80% less likely to conceive for the 1st year, depending on the time of year in which she is vaccinated. This increases to 90% with the administration of a booster shot. The contraceptive effects wear off with the chance of conception increasing every year post-vaccination. The WHOAS contraception pilot program aims to maintain the population at manageable levels and replace Government captures and culls. WHOAS also runs a 20 acre horse rescue facility west of the Town of Sundre for those horses that run into trouble and have to be removed from the wild. The rescue facility will also take in orphaned foals to be raised, gentled and adopted out.