AUGUSTA — Endangered piping plovers are making an early arrival on Maine beaches, and state officials are warning beachgoers and their pets to stay away from their nests.

Each summer, the birds nest on sand beaches where threats include the weather, beachgoers, pets and predators. They’ve been listed as federally threatened since 1986, and they’ve been on the state’s Endangered Species List since 1997.

Part of the bird’s problem is that its camouflage is too good. The birds and their sandy eggs are often overlooked by people and pets that inadvertently destroy nests.

Despite this, last year represented the most productive year in more than a decade for Piping Plovers, with 33 nesting pairs producing more than 70 young birds.