Baby Watch: Assateague Pony Pregnancy Tests Are In

The pony known as Ms. Macky is pregnant. Photo: Assateague Island Alliance

Pregnancy test results are in for three dozen Assateague Island ponies, and the island will be looking forward to at least one foal in the spring.

Back in early November, Assateague Island National Seashore collected “little bags of poop” from 35 mares of foaling age. The samples were sent to the Saint Lous Zoo endocrinology lab, which tests for fecal estrogen levels. The tests found one mare, Ms. Macky, was more than three months along in her pregnancy.

There could be even more pregnant mares among those whose estrogen levels did not test high, if they were less than three months along. The National Seashore says that for most mares, baseline estrogen values do not start to increase for the first 60 days post-conception. Gestation time for horses is about 11.5 months. The test can’t predict Ms. Macky’s due date, but most mares foal in April, May or June.