(Story corrects fifth paragraph to say “caught” instead of “saw”, in August 31st instance)

NEW YORK (Reuters) - A former New York landfill transforming into a park is stirring scientists and environmental researchers to birdsong as wildlife flock to a haven once known as the world’s biggest garbage dump.

Scavenger seagulls, which once feasted on the daily dumps of up to 29,000 tons of solid waste in Staten Island’s Freshkills Park, are being replaced by ospreys and nesting pairs of grasshopper sparrows, an endangered species in New York State, as well as kestrels, snowy owls, foxes, groundhogs and deer.

Almost a decade into the redevelopment project, the landfill mounds have morphed into lush grassland growing on top of piles of trash, separated by layers of geo-membrane liner and dirt.

“If our species can survive in this environment and persist and thrive, that is a real amazing thing for conservation,” said Lisa Manne, a biology professor at College of Staten Island.

Manne and a group of researchers who sample bird populations in the 2,200-acre site caught a mockingbird there for the first time this year.

Once completed in 2036, Freshkills Park is expected to be almost three times the size of Manhattan’s Central Park, with recreational activities from mountain biking to catch-and-release fishing to kayaking.

Freshkills Park closed in 2001 after almost six decades as the city’s dumping ground and years of lawsuits by citizens complaining of health hazards and the stench of rotting garbage.