Pronghorn Fawns Battle in Utero!
Take a look at these three pronghorn fawns we recently observed in Yellowstone! They're likely triplets, which is unusual as pronghorn usually twin.
Pronghorn are unusual for a number of reasons, for one they're the only surviving member of the Antilocapridae family, other members went extinct during the Pleistocene iceage. (A pronghorns nearest relatives are giraffes!) These fawns reminded us of another crazy thing about pronghorn, they are the only species we know of who battle for survival as embryos!
During gestation, there may be more than 7 embryos fighting for space. Initially, the embryos are threadlike and can become entangled, pulling each other apart! The remaining embryos then develop an elongated structure known as a necrotic tip. Seven or more embryos may be developing inside the womb, and as space gets tight those closest to the middle pierce their neighboring siblings, eventually leaving just two (or in this instance 3!) embryos spread out on opposite ends of the uterus.
It's hard to imagine this cute trio battling it out in utero. Yet as a result, they are the strongest survivors and will have the best chance of thriving in the challenging Yellowstone landscape. We've always admired pronghorn for their strength and tenacity, and now we know where it all starts.
This week we're learning about Yellowstone wolves, newborn pronghorn fawns, subadult grizzlies, and more! Tune in on Facebook at 5:30 pm MST for our video digest of the past week's wildlife sightings with Naturalist Tenley Thompson. Photo by Naturalist @joshmettenphoto