PORTLAND — Maine environmental officials are proposing to add two bird species to the state’s list of endangered animals.

The species, the black-crowned night heron and great cormorant, could be upgraded from threatened to endangered, State Department of Inland Fisheries & Wildlife spokesman Mark Latti said. The change is subject to public hearings and approval by the state Legislature.

The cormorants’ population has declined to about 50 pairs in the state, down from about 250 pairs in the late 1990s, said Brad Allen, a state wildlife biologist. The herons have dwindled to about 250 pairs in the state, down from about 400 pairs in the state 1980s, he said.

The cormorants have declined in part because of the predation of their young by bald eagles, which have become more prevalent in Maine, Allen said. More research is needed to determine why the herons have declined, he said.

“Their numbers are getting to where we are concerned that if we don’t do work for them, we might lose them as a nesting species,” Allen said of both birds.

Presence on the state’s threatened and endangered lists entitles the birds to protection under the Maine Endangered Species Act, Allen said. Both birds live on coastal islands in Maine. The herons range from Saco Bay to Muscongus Bay and the cormorants from outer Penobscot Bay to Jericho Bay, he said.

The Maine Audubon Society supports listing the animals as endangered, said its director of conservation, Sally Stockwell.

“Once you lose a piece of the fabric of the habitat, that can cause unforeseen problems with other populations,” she said.

State officials are also considering listing the little brown bat and northern long-eared bat as endangered. Three invertebrates ”“ the cobblestone tiger beetle, frigga fritillary butterfly and six-whorl vertigo snail ”“ could also be listed endangered. The eastern small-footed bat faces threatened status. The bat species are in jeopardy because of die offs caused by white nose syndrome, state officials have said.

The state lists 22 species as endangered and 23 as threatened.

There will be two public hearings where public comments will be taken concerning the list. The first is at 6:30 p.m. on Monday, Aug. 4 at the Portland City Hall, 389 Congress St.; and the second is at 6:30 p.m. on Tuesday, Aug. 5 at the Roberts Learning Center at University of Maine in Farmington.

Those interested in submitting public comments in writing must do so by Aug. 15. Comments submitted by email should be sent to becky.orff@maine.gov; or send written comments by mail to: Becky Orff, Inland Fisheries & Wildlife, 284 State St., No. 41 State House Station, Augusta, ME 04333.