Peru's health ministry is asking people to avoid beaches in Lima and north of the capital until officials can determine what caused the deaths of hundreds of dolphins and pelicans.
Last month, the country's production ministry said the authorities were investigating the deaths of more than 538 pelicans, and other birds, on the northern coast.
State-run TV Peru estimated that as many as to 1,200 birds have been found dead along the 100 miles (160km) of northern shoreline extending from Punta Negra, in Piura, to San José, in the state of Lambayeque.
That discovery came after close to 900 dolphins washed up dead on the northern coast of Peru this year.
The investigation into the deaths of both the dolphins and the birds is ongoing, and it is not clear whether they are connected.
The health ministry advised anyone who might handle any of the dead birds to wear protective clothing, such as gloves and masks.
Peruvian Deputy Environment Minister Gabriel Quijandria told CNN last month the dolphins may have died from an outbreak of Morbillivirus or Brucella bacteria.
Morbillivirus is a class of viruses that are part of the same family as human measles; Brucella bacteria are the cause of many serious diseases in animals.
Officials have said the dolphins' deaths were not due to lack of food, interaction with fisheries, poisoning with pesticides, biotoxin poisoning or contamination by heavy metals.
"When you have something this large, my gut would tell me that there's something traumatic that happened," Sue Rocca, a marine biologist with the Whale and Dolphin Conservation Society, told CNN last month. She raised a number of possibilities as to what could have killed the animals, including acoustic trauma.
Preliminary reports ruled out the possibility that seismic sound waves created by oil exploration in the area could have killed the birds, the environment ministry has said. Bird flu has also been ruled out.