According to the International Union for the Conservation of Nature (IUCN), more than 48,600 species — out of 172,600 assessed on the IUCN Red List — are threatened with extinction, representing 41% of amphibians, 38% of sharks and rays, 44% of reef-building corals, 34% of conifers, 27% of mammals, and 11.5% of birds. Land degradation and habitat loss, shifting climate conditions, extreme weather events, disease, infestations, and overexploitation are all contributing factors. Among the most direct and effective responses is restoring healthy forest habitat.
For many species, trees are quite literally the infrastructure of survival. Nuts, fruit, and leaves supply food for herbivores. Canopy and undergrowth provide hunting cover for predators. Nesting sites perched high in branches allow birds and bats to raise their young in relative safety. Even after a tree has sustained damage or died — what ecologists call a snag — it continues to serve wildlife as a nest, nursery, food cache, foraging site, and roost. Decaying logs on the forest floor retain moisture and nutrients that support earthworms, beetles, and the broader soil ecosystem, while acting as ground cover that reduces erosion and limits overgrazing by herbivores.
Some species make the stakes of forest loss immediately legible. The 'Ōpe'ape'a — the Hawaiian Hoary Bat, whose name translates to "half-leaf" for the taro-like shape of its open wings — traveled approximately 2,000 miles across the Pacific Ocean to reach Hawaiʻi roughly 10,000 years ago. It is now the last native land mammal on the islands, currently listed as endangered, and its entire existence is structured around trees: it roosts in them by day, leaves at sunset to hunt moths and other insects among the canopy, and is primarily threatened by habitat destruction and collisions with infrastructure including wind turbines and barbed wire fences. The State of Hawaii's Division of Forestry and Wildlife and the U.S. Fish and Wildlife Service currently advise restoring 40 acres of forest for each breeding pair of Hawaiian hoary bats — a figure that translates canopy coverage directly into population viability.
The Philippine Eagle makes a similar case from the other side of the Pacific. Among the largest forest raptors in the world, it now exists on just four Philippine islands — Luzon, Samar, Leyte, and Mindanao — with an estimated 392 pairs remaining in the wild, a number that has declined as the country loses an estimated 47,000 hectares of forest annually. Each pair requires between 4,000 and 11,000 hectares of continuous canopy to thrive, which means a single deforested hillside can collapse the viability of an entire breeding territory. "The commitment extends far beyond the eagle itself," Felicia Atienza, Chairperson of the Board of Trustees of the Philippine Eagle Foundation, told the Manila Bulletin, "encompassing extensive efforts in culture-based conservation, reforestation, habitat restoration, and forest protection to guarantee the survival of not only the Philippine eagle but also the diverse flora and fauna, and the community within its habitat."
The Eastern Migratory Monarch butterfly doesn't nest in trees the way a bat or eagle does — it overwinters in them, clustering in Oyamel pine forests high in Mexico's mountains by the millions. Or it did. The species has declined by more than 80% since the 1990s, and the 2023–2024 overwintering season in central Mexico recorded the second-smallest colony area since monitoring began — just 2.2 acres, down 59% from the prior year.
In December 2024, the U.S. Fish and Wildlife Service proposed listing the monarch as threatened under the Endangered Species Act. The loss compounds beyond the butterfly itself: monarchs are prolific pollinators whose nectar-based diet supports wildflowers across their range, and they provide a food source for birds, small animals, and other insects. Dwindling milkweed, widespread herbicide and pesticide use, and the degradation of their overwintering grounds in Mexico have created a set of pressures that no single intervention can reverse. Work in and around the Monarch Butterfly Biosphere Reserve plants Oyamel pine and other native species to convert deforested farmland back to native forest, restore areas clearcut for timber or lost to fire, and return the monarch's overwintering habitat to something it can actually use.
Recent censuses show about 74 Southern Resident killer whales remain in the stretch of Pacific Ocean between Northern California and British Columbia — barely more than the 71 counted when population surveys first began in 1976. K pod, now at just 14 individuals, is at its lowest count on record. "What we had was a bunch of calves being born and half of those calves dying, and you can't sustain a population if you can't get calves to be born and survive their first couple years of life," Michael Weiss, research director with the Center for Whale Research, told Save Our Wild Salmon. The orca's dependence on forest health is mediated entirely by water: they rely on West Coast Chinook salmon for nearly 80% of their diet, and salmon depend on healthy river systems — which depend on the trees along their banks. Riverside forest stabilizes banks, filters agricultural runoff, and keeps water temperatures cool enough for salmon to thrive. Strip those trees and the river warms, the salmon decline, and the orca follow. A multi-year project in the Pacific Northwest, plants trees along rivers and streams to restore water quality and improve the health and quantity of salmon the orca depend on — a chain of cause and effect that runs from a seedling in Oregon soil to a pod of killer whales hunting offshore.
The wood turtle once ranged widely across eastern North America along cobble-bottomed streams, living both on land and in water, vulnerable to the loss of either. It is now listed as endangered by the IUCN, threatened by agricultural machinery, invasive plants colonizing nesting habitat, road crossings, degraded water quality, disease, and illegal collection for the black market. One wood turtle behavior, the worm stomp — in which it stomps its feet and shell on the ground to mimic falling rain or burrowing moles, drawing worms to the surface to eat — is a small, strange proof of how intimately a species can adapt to its specific place in a landscape. Fields planted in Nova Scotia that had been farmed as a cornfield for nearly 90 years, edged on two sides by the St. Mary's River and a brook and bordered by mixed wood forest, sit directly within critical wood turtle habitat. Planted with Red Maple, Silver Maple, Red Oak, and other native species, it will slowly reclaim its original character, returning the riverbank corridors the wood turtle needs to move, nest, and forage.
