The Department of Conservation says "reckless behaviour" by some beachgoers is threatening nesting dotterels in the Bay of Plenty.
The agency says only about 1700 North Island dotterel are left, so it has fenced several nesting sites on Matakana Island and Maketu Spit to protect the birds.
But it says some people are ignoring the fences and warning signs and using the areas to relieve themselves. Cars are being driven over the sites.
DoC says the dotterels are very well-camouflaged, so people might not realise they are walking or driving over them.