The Trump administration announced a major overhaul Monday to the Endangered Species Act that it said would reduce regulations. Environmentalists said the changes would push more animals and plants to extinction because of threats from climate change and human activities.

The changes end blanket protections for animals newly deemed threatened and allow federal authorities for the first time to take into account the economic cost of protecting a particular species.

With the Endangered Species Act in the news, here are a few of the USA's most endangered or threatened species:

Florida panther

The panther is one of the most endangered mammals in the country, according to the Defenders of Wildlife. First listed as endangered in the 1970s, there are only about a couple of hundred left.

They are found in southern Florida in swamplands such as Everglades National Park and Big Cypress National Preserve. "The subspecies is so critically endangered that it is vulnerable to just about every major threat," the National Wildlife Federation said. Construction and development in Florida causes habitat loss, and roads and highways pose a danger to panthers attempting to cross.

Lesser prairie chicken

An icon of the Southern Plains, the lesser prairie chicken is being reviewed for listing under the Endangered Species Act, the Defenders of Wildlife said. "This bird once numbered in the millions but its population has declined by as much as 97%. It is imperiled because of habitat loss and fragmentation from oil and gas development, cropland conversion, livestock grazing and drought." There are an estimated 30,000 birds left.

Devil's Hole pupfish

The entire species of this bright blue fish lives only in a single pool in Nevada. First listed as endangered in 1967, this iridescent blue inch-long fish's only natural habitat is in the 93-degree waters of Devils Hole, located in Nye County, Nevada, which is a detached unit of Death Valley National Park. As one of the world's rarest fishes, the U.S. Fish and Wildlife Service said it could be "at significant risk of extinction. Species with limited distribution like the Devils Hole pupfish are at greatest risk of extinction since they do not have the flexibility to change locations to adapt to changing environments."

Bryde's whale

The Bryde's whale, of which there are only about 40 left in the Gulf of Mexico, is "in danger of extinction throughout all of its range due to its small population size and restricted range, and the threats of energy exploration, development and production, oil spills and oil spill response, vessel collision, fishing gear entanglement, and human-caused noise," according to the National Oceanic and Atmospheric Administration.

North Atlantic right whale

The North Atlantic right whale is one of the world’s most endangered large whale species, with only about 400 whales remaining, NOAA said. "Entanglement in fishing lines attached to gillnets and traps on the ocean floor is one of the greatest threats" to the animal, along with vessel strikes and ocean noise. Underwater noise pollution interrupts the normal behavior of right whales and interferes with their communication.

Monarch butterfly

With its count falling to the low tens of thousands in the western United States last year, the monarch is now under government consideration for listing under the Endangered Species Act. For monarchs, farming and other human development have eradicated state-size swaths of native milkweed habitat, cutting the butterfly’s numbers by 90% over the past two decades.

Delta Smelt

Some of the most endangered animals may not be cuddly or photogenic, but they are nevertheless worth saving. One example is the delta smelt, a small fish that swims in the San Francisco Bay and has almost been eliminated from the wild. "The tiny delta smelt is one of the best indicators of environmental conditions in the San Francisco Bay Delta, an ecologically important estuary that is a major hub for California's water system – and an ecosystem that is now rapidly unraveling," according to the Center for Biological Diversity.

The “smeltdown in the Delta,” as the extinction path of the delta smelt is known, has left the once-abundant species in critical condition due to water diversions, pollutants, and harmful non-native species that thrive in the degraded Delta habitat, the center said.

Contributing: The Associated Press