[4] She next conducted graduate work in Manitoba at Cornell University's Delta Waterfowl field station, but both Cornell and Wellesley refused to credit her with a master's degree for her work, studying ruddy duck breeding biology; Wellesley said her study was "not relevant".

[4] Without an advanced degree, Hays began her career in 1956 in low-level positions cataloguing specimens and performing secretarial work.

[1][6] In 1969 Hays began spending six months of the year on the island working to restore the local population.

[2] Her tracking of the bird numbers and health also enabled her to raise an early warning about the harmful effects of PCBs.

[4] In 2021, a documentary film titled Full Circle was completed about Helen and the island, winning several awards.