Baby bighorn sheep are some of the many new arrivals in Yellowstone this spring. Image: NPS   Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. By signing up, you confirm you are 16+, will receive newsletters and promotional content and agree to our Terms of Use and acknowledge the data practices in our Privacy Policy . You may unsubscribe at any time. Even though many parts of the northeastern United States have seen surges of summer temperatures, it’s technically still spring in the Northern Hemisphere, which means many animals are having babies.  That’s true also at Yellowstone National Park , which is home to everything from moose and black bears to river otters and gophers. In a recent social media post , the popular park highlighted some particularly adorable young’uns, including a young bison , black bear, yellow-bellied marmot, three bighorn sheep, an elk, and two pronghorns. All of Yellowstone National park is considered bear country.…