U.S. National Park Service

cougar_kittens_die_83331.jpg

In this undated photo provided by the National Park Service shows mountain lion kittens known as P-57 and P-58, who were abandoned by their three-year-old mother. The two mountain lion kittens have died in the Southern California wilderness after being abandoned by their mother. The male and female were part of a study of cougars by researchers with the Santa Monica Mountains National Recreation Area near Los Angeles. (National Park Service via AP)

zion_highway-rock_slide_16494.jpg

This Friday, May 19, 2017 photo released by the National Park Service shows motorists stopped on the Zion-Mount Carmel Highway in Zion National Park, Utah, after heavy sand and rocks fell on the main road through the park. (John Marciano/National Park Service via AP)

zion_highway-rock_slide_84049.jpg

This Friday, May 19, 2017 photo released by the National Park Service shows heavy sand and rocks falling down along the main road through Zion National Park in Utah. The National Park Service said the hazard has forced the closure of the Zion-Mount Carmel Highway until further notice. (John Marciano/National Park Service via AP)

wilderness_noise_71272.jpg

In this photo provided by the National Park Service, a National Park Service staffer sets up an acoustic recording station in the temperate old-growth Hoh rainforest of Olympic National Park, Wash. The call of the wild is getting harder to hear. Peaceful natural sounds, bird songs, rushing rivers and rustling grass, are being drowned out by human-made noise in nearly two-thirds of America’s protected parks, forests and wilderness areas, a new study finds. (National Park Service via AP)

noise_pollution_81275.jpg

In this photo provided by the National Park Service a National Park Service staffer sets up an acoustic recording station on Going-to-the-Sun Road to capture the impact of traffic on acoustic conditions in Glacier National Park, Mont. The call of the wild is getting harder to hear. Peaceful natural sounds, bird songs, rushing rivers and rustling grass, are being drowned out by human-made noise in nearly two-thirds of America’s protected parks, forests and wilderness areas, a new study finds. (National Park Service via AP)

missing_hikers_grand_canyon_55896.jpg

This Sunday, April 16, 2017, photo provided by the National Park Service shows Tapeats Creek in Grand Canyon National Park in Arizona. Authorities are searching for Jackson Standefer, 14, and Lou-Ann Merrell, 62, after the pair lost their footing Saturday and fell into the water during a family trip in a remote area of the Arizona park. (National Park Service via AP)

missing_hikers_grand_canyon_52679.jpg

This Sunday, April 16, 2017, photo provided by the National Park Service shows Tapeats Creek in Grand Canyon National Park in Arizona. Authorities are searching for Jackson Standefer, 14, and Lou-Ann Merrell, 62, after the pair lost their footing Saturday and fell into the water during a family trip in a remote area of the Arizona park. (National Park Service via AP)

mountain_lion_kitten_76056.jpg

This Feb. 27, 2017 photo provided by the National Park Service shows a four-week-old mountain lion kitten. Researchers with the National Park Service and the California Department of Fish and Wildlife said the female kitten, dubbed P-54, was born sometime in January. The kitten's mother is a GPS-tagged mountain lion called P-23. (National Park Service via AP)

rare_frogs_57147.jpg

This March 17, 2017 photo provided by the National Park Service shows an egg mass from the California red-legged frog (Rana draytonii), found in a stream in the Santa Monica Mountains near Los Angeles. The discovery involving the rare frog has researchers hopping for joy. The NPS says the egg masses from the frog are evidence that the endangered species is reproducing. (National Park Service via AP)

rare_frogs_54017.jpg

This March 14, 2017 photo provided by the National Park Service shows a pair of California red-legged frogs (Rana draytonii), found in the Santa Monica Mountains near Los Angeles. The discovery involving the rare frog has researchers hopping for joy. The NPS says egg masses from the frog were found last week in a stream in the mountains adjacent to the Los Angeles metropolitan area. It's evidence that the endangered species is reproducing. (National Park Service via AP)

rare_frogs_13238.jpg

This March 20, 2017 photo from the National Park Service shows a California red-legged frog (Rana draytonii), found in the Santa Monica Mountains near Los Angeles. The discovery involving the rare frog has researchers hopping for joy. The NPS says egg masses from the frog were found last week in a stream in the mountains adjacent to the Los Angeles metropolitan area. It's evidence that the endangered species is reproducing. (National Park Service via AP)

exchange_national_parks_visitor_25025.jpg

ADVANCE FOR MONDAY, MARCH 20 AND THEREAFTER - In a Tuesday, March 7, 2017 photo, Park Ranger Kathy Sanders talks with Mikah Meyer, telling him what the he can do at Padre Island National Seashore on his trip to become the youngest person to visit all the National Park Service sites. At 30 years old, Meyer is traveling throughout the United States to become the youngest person to visit all 417 National Park Service sites. (Courtney Sacco/Corpus Christi Caller-Times via AP)

exchange_national_parks_visitor_23082.jpg

ADVANCE FOR MONDAY, MARCH 20 AND THEREAFTER - In a Tuesday, March 7, 2017 photo, Mikah Meyer stamps his National Park passport with the Padre Island National Seashore stamp on his trip to become the youngest person to visit all the National Park Service sites. He plans to donate the stamped book to the Smithsonian's National Museum of American History at the request of the curator in charge of LGBT artifacts. At 30 years old, Meyer is traveling throughout the United States to become the youngest person to visit all 417 National Park Service sites. (Courtney Sacco/Corpus Christi Caller-Times via AP)

mountain_lion_killed_93784.jpg

This June 22, 2016 photo taken by a National Park Service remote camera shows two of three mountain lion kittens, known as P-50, P-51, and P-52 in the eastern Santa Susana Mountains. P-51, one of the orphaned mountain lions has been struck and killed on the same stretch of Los Angeles-area freeway where her mother and one of her two siblings were killed separately in the past two months. It's not known if P-51 is seen in this photo. P-39 was fatally struck on the same freeway Dec. 3 and the sibling, P-52, was killed on Dec. 20. (National Park Service via AP)

mountain_lion_killed_95624.jpg

FILE - This May 30, 2015 file photo from a National Park Service remote camera shows an adult female mountain lion, known as P-39, right, and one of her kittens while feeding in the Santa Susana Mountains north of the Los Angeles metropolitan area. An orphaned mountain lion has been struck and killed on the same stretch of Los Angeles-area freeway where her mother and one of her two siblings were killed separately in the past two months. NPS researchers identified it as a kitten designated P-51. It's not known if P-51 is seen in this photo. P-39 was fatally struck on the same freeway Dec. 3, 2016, and the sibling, P-52, was killed on Dec. 20. (National Park Service via AP, File)

rogue_tweeters_22454.jpg

This photo shows a Twitter post from the National Park Service's Redwoods National Park account, noting that redwood groves are nature's No. 1 carbon sink, which capture greenhouse gas emissions that contribute to global warming Legal experts say the Justice Department could prosecute tweets from federal agency accounts by unauthorized users under federal hacking laws. Some say that even employees authorized to use official agency Twitter accounts could face legal jeopardy posting messages they weren’t supposed to write. (National Park Service via AP)

climate_tweets_deleted_37213.jpg

This image shows a Twitter post from the National Park Service's Death Valley National Park account. The National Park Service employees' Twitter campaign against President Donald Trump has spread to other parks. A day after three climate-related tweets sent out by Badlands National Park were deleted, other park accounts have sent out tweets. Death Valley National Park tweeted photos of Japanese Americans interned there during World War II, a message that some saw as objecting to Trump's pledge to ban Muslims from entering the country and a proposal to restrict the flow of refugees to the United States. A park service spokesman declined to comment on Jan. 25. (National Park Service via AP)

climate_tweets_deleted_22454.jpg

This photo shows a Twitter post from the National Park Service's Redwoods National Park account. The National Park Service employees' Twitter campaign against President Donald Trump has spread to other parks. A day after three climate-related tweets sent out by Badlands National Park were deleted, other park accounts have sent out tweets. This one, by Redwoods National Park in California, notes that redwood groves are nature's No. 1 carbon sink, which capture greenhouse gas emissions that contribute to global warming. A park service spokesman declined to comment on Jan. 25. (National Park Service via AP)

crater_lake_closure_36810.jpg

This Tuesday, Jan. 10, 2017 photo provided by the U.S. National Park Service a road blocked by snow in Crater Lake National Park as severe weather forced the southern Oregon park's closure. The park announced Tuesday that due to heavy snowfall combined with downed trees and an avalanche on Highway 62, the park would close until road crews could clear the area. (National Park Service via AP)

california_storms_14830.jpg

In this photo taken Thursday, Jan. 5, 2017, provided by the National Park Service, the Merced River flows through Yosemite National Park, Calif. Residents of California from the coastline to the Sierra Nevada are bracing for heavy rain and snow that's already shut down Yosemite National Park and is expected to swell rivers and topple trees. Rangers at Yosemite on Friday closed access to the valley floor, raising memories of flooding in 1997 that forced the park to shut down for two months. (Jamie Richards/National Park Service via AP)