From striking craggy pinnacles to cavernous underground lairs, the national parks are renowned for their grand wildernesses. However, the inhabitants of these landscapes – the wilds’ wildlife – are perhaps the most beloved of the parks’ draws. Animals of the national parks, including many threatened or endangered species, also provide a significant scientific service: They are indicators of the overall health of their environments.

Barrier islands play incredible roles for migrating shorebirds, offering them a place to stop, rest, and refuel. At Cape Cod National Seashore in Massachusetts, the beaches and marshes are important to common, least, and roseate terns and a number of other shorebird species during their migrations.

It sounds like a page from the script of Jaws, a blockbuster 40 years old this summer in which a massive great white shark terrorizes a fictional New England beach town during the Fourth of July weekend. No great white sharks are thought to be involved in the attacks at Cape Hatteras National Seashore, and there have been no deaths, but three separate incidents there in the past week have officials warning beach goers to stay out of the water if they fear sharks.

A bear attack at Great Smoky Mountains National Park, the mystery of a missing guide in Grand Canyon National Park, and word of two areas of Cape Cod National Seashore now open to leashed pets are among the news in the National Park System this week.