A second outbreak of avian flu has been confirmed on the Vineyard after four backyard chickens were found dead last month. 

The U.S. Department of Agriculture reported positive results for a homeowner’s flock on Feb. 26, Island health officials said Thursday. The flock had 50 chickens total, but only four were reported dead to the state. 

The USDA euthanized the remaining chickens, and disposed of the chicken feed and eggs. The chickens were not part of a commercial farm. 

The Vineyard health departments said they are not releasing the location of confirmed cases, following a precedent set by the USDA, which only reports the name of the county. 

The previous outbreak, which is still awaiting further testing at a federal lab, was found in a flock of turkeys in Edgartown. 

“Our Island is small and our towns are small,” said Brice Boutot, the board of health agent for Edgartown. “It doesn’t serve a purpose to identify the specific location because an infectious wild bird going from backyard to backyard doesn’t care about town lines.”

He added that reporting the location of birds could dissuade homeowners from reporting deaths, which is essential to stopping the spread.

“Reporting works and we want to encourage flock owners to do so,” Mr. Boutot said.

In the event avian flu spreads to commercial poultry, the departments would release the location information, according to Mr. Boutot. As of Thursday, no Island farms have reported dead birds or abnormal behavior within their flocks, he said.

The Dukes County Emergency Management Association said the preliminary positive results indicate the virus is actively spreading among wild bird populations. 

The Island boards of health are urging the community to stay vigilant and follow precautionary guidelines, including removing bird feeders to deter wild birds from gathering.

Keeping pets away from birds and feces is also essential, Mr. Boutot said. Cats are highly susceptible to the disease and may die if exposed.

While humans can get avian flu, the county maintains that there is minimal risk to the general public. Human infections are rare and only occur when there’s direct contact with infected animals.