Wildlife biologists yesterday surveyed populations of four endangered Hawai'i waterbirds this week to gather information about their population trends and use of habitats.

Dozens of state Department of Land and Natural Resource biologists and volunteers looked for the Hawaiian stilt, Hawaiian moorhen, Hawaiian coot and Hawaiian duck.

The department says the survey provides insight into the status of various species and helps the state manage endangered waterbird populations.

Some of the sites to be surveyed include Hamakua Marsh, Ke'ehi Lagoon and the taro lo'i and lotus fields on O'ahu's North Shore.

Past surveys show the Hawaiian stilt population has grown from 553 in 1997 to 860 in 2007.