Alderney conservationists say tougher laws are needed to protect the island's 340 puffins.
The colourful seabirds are returning to breed following a winter which killed about 16,500 of the northwest European population.
The Alderney Wildlife Trust said dog walkers who repeatedly allowed dogs to disturb nests should be prosecuted.
Dozens of storms killed an estimated 32,000 seabirds in northwest Europe, about half of them puffins.
Trust manager Roland Gauvain said: "Anywhere breeding birds are trying to establish, especially where you have dog access near to them, disturbance can put them off their nests or destroy the nests, not intentionally, just the activity itself can cause the damage.
"This year, because they've been so stressed during the winter period, the chance of that happening, we would argue, are massively increased."
Mr Gauvain would like to see more beaches closed to dogs during breeding season and a 1954 wildlife law toughened.
"People are not in any way inclined to hurt wildlife," he said, "but it's about not understanding that walking your dog when you're 30 metres away from a nesting site is causing it problems.