Animal populations are decimated by human greed—trophy hunting or participating in the illegal wildlife trade, for example. People worldwide collect species and animal parts not for preservation and not out of respect but for power and status. Traditional medicine in certain cultures also drives demand for animal components believed to have healing properties, like bones, fins, tusks, organs, horns, and meat.
Illicit wildlife trafficking is the fourth-largest global illegal trade, surpassed only by narcotics, human trafficking, and counterfeit products, according to Immigration and Customs Enforcement.
Humans also threaten species in less sinister ways, too—infrastructure and agricultural expansion being two prime culprits in this regard. As humans expand the footprint of their civilizations, they disrupt the delicate balance of the natural world. Nesting sites, habitats, food sources, and even behaviours are all changed or destroyed by the human-wildlife interface and inevitable conflict. For marine species, bycatch—or being caught in commercial fishing gear—is a primary threat to their existence.
Climate change, driven by humans and that which is part of the earth's natural cycle, is also a major contributor to the loss of species worldwide. A temperature increase of a couple of degrees can change the biology of an entire species. The temperature of the sand, for example, determines the sex of a sea turtle. Warmer sand will lead to more females and less genetic diversity among turtle populations. Beaches that are too warm will cook the eggs before they hatch. Warmer ocean currents change entire marine ecosystems that sustain species like penguins.
Citing the 2021 Annual Report on Conservation and Science from the Association of Zoos and Aquariums, Stacker looked at the 27 most targeted species focusing on the five main vertebrate groups. Additional data from the International Union for Conservation of Nature is included for each species.
Jan P. Zegarra // Wikimedia Commons
Puerto Rican crested toad
- Scientific name: Bufo lemur
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Forest, wetlands (inland), artificial/aquatic & marine
The only toad native to Puerto Rico, the crested toad has been threatened by habitat loss and nonnative species. The toad was believed to be extinct until it was rediscovered in 1967. With fewer than 3,000 adults estimated to live in the wild, conservation efforts are focused primarily on captive breeding programs.
USFWS Mountain-Prairie // Wikimedia Commons
Wyoming toad
- Scientific name: Anaxyrus baxteri
- Red List assessment: Extinct in the wild
- Population trend: Decreasing
- Habitat: Nearctic
The Wyoming toad, having once flourished in the wetlands of southeastern Wyoming, exists now only in captivity. Biologists attribute their near-extinction to the spread of harmful chytrid fungi, habitat loss, and predation. In 2020, there were 677 Wyoming toads in captivity.
USFWS Pacific Southwest Region // Wikimedia Commons
Mountain yellow-legged frog
- Scientific name: Rana muscosa
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Nearctic
The Mountain yellowed-legged frog lives in the southern Sierra Nevada and Transverse Mountain Ranges in high-elevation lakes, ponds, and streams. Once abundant, the yellow-legged frog has disappeared from 70-90% of its mountain habitats. Many factors have contributed to the species' decline, including the introduction of nonnative fishes, pesticides, pathogens, nitrate deposition from runoff, predation, recreational activities, and drought.
Doug Lemke // Shutterstock
Panamanian golden frog
- Scientific name: Atelopus zeteki
- Red List assessment: Critically endangered
- Population trend: Decreasing
- Habitat: Neotropical
The Panamanian golden frog is known for its bright yellow, highly toxic skin. It is a distant relative of the South American poison dart frog, and its skin is toxic enough to kill over 1,000 mice. The frog's distinct appearance made it a target for capture, being put on display in hotels, restaurants, and other popular tourist sites. In addition to human capture, chytrid fungus has also decimated wild populations. These small but mighty frogs may be close to extinction in their native natural habitat, but most of the remaining population is managed in captivity.
Jay Ondreicka // Shutterstock
Eastern hellbender
- Scientific name: Cryptobranchus alleganiensis
- Red List assessment: Near threatened
- Population trend: Decreasing
- Habitat: Wetlands (inland)
The Eastern hellbender is a giant aquatic salamander endemic to the eastern and central U.S. Though the species' current geographic range is mostly unchanged, abundance, or the number of individuals, has dropped more than 70% since the 1970s. Population declines can be attributed largely to water pollution and the damming of rivers and streams.
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Michael Potter11 // Shutterstock
Grey-crowned crane
- Scientific name: Balearica regulorum
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Afrotropical
Grey-crowned cranes are the oldest crane species in the world, predating their relatives by millions of years. Their ancient status and unique plumage, notably a crown of golden feathers atop their heads, have made them a symbol of wealth, status, and thus a target. For years, grey-crowned cranes have been captured and illegally sold in large numbers. Some believe the cranes' eggs and feathers have medicinal properties. Aside from human threats, grey-crowned cranes also face threats to their breeding grounds, such as pollution and agricultural use.
Henk Bogaard // Shutterstock
African white-backed vulture
- Scientific name: Gyps africanus
- Red List assessment: Critically endangered
- Population trend: Decreasing
- Habitat: Afrotropical
The African white-backed vulture is integral to the sub-Saharan ecosystem, feeding on carrion and preventing the spread of harmful bacteria and viruses in carcasses. This species is threatened largely by poison ingested through the carcasses on which they feed. Anti-inflammatory drugs given to cattle by farmers are fatal to vultures. Additionally, some farmers lace livestock carcasses with poison as retaliation against the predators, such as lions, that killed them. As a result, however, vultures are also poisoned when they feed. Poachers and habitat loss have also contributed to diminishing populations.
Jearu // Shutterstock
Humboldt penguin
- Scientific name: Spheniscus humboldti
- Red List assessment: Vulnerable
- Population trend: Decreasing
- Habitat: Forest, desert, marine neritic, marine oceanic, marine intertidal, marine coastal/supratidal, artificial/aquatic & marine
Humboldt penguins are primarily threatened by natural and human-driven climate change, specifically El Niño, which can reduce their food source that thrives typically in the Humboldt current. Additionally, mining for guano, primarily used in fertilizers, destroys penguins' burrows and shifts breeding sites.
Connie Barr // Shutterstock
Whooping crane
- Scientific name: Grus americana
- Red List assessment: Endangered
- Population trend: Increasing
- Habitat: Nearctic
The whooping crane was brought to the brink of extinction in 1940 when roughly 20 birds remained in the wild. Their populations were decimated by habitat loss and hunting. Since then, conservation efforts have included a nonmigratory flock in Florida comprised of birds raised in captivity. A recent conservation project established a new flock of whooping cranes that spend summers in Wisconsin. After their parents raise the young, they're trained to follow an ultralight aircraft to Florida for their first migration.
Georgi Baird // Shutterstock
California condor
- Scientific name: Gymnogyps californianus
- Red List assessment: Critically endangered
- Population trend: Increasing
- Habitat: Nearctic
Lead poisoning from hunting bullets is the biggest threat facing the California condor. Scavengers, like condors, who feed on the remains of animals shot with lead ammunition inadvertently ingest the lead as it leaches into the carcass. If scavengers eat enough lead, it can fatally poison them. Microtrash such as bottle caps, plastic, glass, and pull tabs is also a leading cause of death among condors who feed them to their chicks, mistaking them for food. Captive breeding programs have helped save these birds from extinction.
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Sergey Uryadnikov // Shutterstock
African penguin
- Scientific name: Spheniscus demersus
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Shrubland, marine neritic, marine oceanic, marine intertidal, marine coastal/supratidal
Populations of the African penguin, endemic to South Africa, are declining due to overfishing and warming waters, both of which reduce the penguin's preferred food source. More frequent extreme weather events also destroy their natural habitats. Oil spills also threatened wild populations. Conservation efforts largely focus on close monitoring and rehabilitation of their natural habitat.
Valeri Potapova // Shutterstock
Sand tiger shark
- Scientific name: Carcharias taurus
- Red List assessment: Critically endangered
- Population trend: Decreasing
- Habitat: Not available
Sand tiger sharks face threats from commercial fisheries that hunt them for their fins, meat, and liver oil. They are often caught unintentionally as bycatch in trawls and gillnets. Their relatively accessible coastal habitat has led to overfishing, and due to their low reproductive rates, wild populations have not been able to rebound. Data transmitted through tags are helping to educate scientists on the little-known lives of these animals, which will aid in conservation efforts.
NOAA Photo Library // Wikimedia Commons
Smalltooth sawfish
- Scientific name: Pristis pectinata
- Red List assessment: Critically endangered
- Population trend: Decreasing
- Habitat: Not available
Sawfish are large rays with a long serrated rostrum, or nose, resembling a double-sided saw. Their unique anatomy makes them vulnerable to getting caught as bycatch in fishing nets. In addition to commercial fishing, habitat loss to the construction of seawalls and human development is another major threat to the sawfish. Sawfish have lived on earth for more than 50 million years.
Tomas Kotouc // Shutterstock
Hammerhead shark
- Scientific name: Sphyrnidae
- Red List assessment: Critically endangered
- Population trend: Decreasing
- Habitat: Marine neritic, marine oceanic
Hammerhead sharks are threatened by commercial fishing for the shark fin trade. Their size and body shape also make them vulnerable to getting caught accidentally in gillnets.
Aaronejbull87 // Shutterstock
Manta ray
- Scientific name: Manta
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Marine neritic, marine oceanic
Commercial fishing is the largest threat facing manta rays. They are both intentionally fished for and caught as bycatch. Manta rays also have low reproduction rates, making it challenging for populations to grow and thrive. As recently as 2012, demand for manta ray gills, used in traditional Chinese medicine, spiked, driving the commercial fishing and trade of manta rays.
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Krzysztof Winnik // Shutterstock
Lake sturgeon
- Scientific name: Acipenser fulvescens
- Red List assessment: Endangered
- Population trend: Unknown
- Habitat: Nearctic
The lake sturgeon is the largest and oldest freshwater fish and native species in the Great Lakes. Before the introduction of commercial fisheries in the late 1800s, more than 15 million sturgeon were estimated to live in the Great Lakes region. Today, their population is just 1% of what it was back then. Modern threats faced by lake sturgeon include habitat loss or alteration from river dredging, channelization, and the construction of dams and hydroelectric facilities, as well as climate change and invasive species.
Jim Agronick // Shutterstock
White shark
- Scientific name: Carcharodon carcharias
- Red List assessment: Vulnerable
- Population trend: Decreasing
- Habitat: Not available
Bycatch, water contamination and pollution, coastal development, ocean acidification, and climate change are all major threats to white sharks. White shark populations off the U.S. coasts have been trending upward since the 1990s when federal and state regulations were enacted to protect them. Overfishing still threatens the species in other parts of the world where populations are declining.
vannoyphotography // Shutterstock
African elephant
- Scientific name: Loxodonta africana
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Afrotropical
Poaching fueled by the illegal ivory trade—and habitat loss—has decimated the African elephant population over the years. To more accurately and effectively focus conservation efforts, the International Union for Conservation of Nature announced in 2021 that it would separate and identify African elephants as two distinct species: savanna elephants and forest elephants. Both species face grave but unique threats.
Volodymyr Burdiak // Shutterstock
Giraffe
- Scientific name: Giraffa camelopardalis
- Red List assessment: Vulnerable
- Population trend: Decreasing
- Habitat: Forest, savanna, shrubland
Fewer than 69,000 adult giraffes remain in the wild. Poaching and habitat loss have threatened this species over the years. The U.S. is a top importer of giraffe products. Between 2006 and 2015, more than 40,000 products containing giraffe parts—from boots to bibles to pillows—were imported to the U.S. The Fish and Wildlife Service has until November 2024 to decide if giraffes warrant protection under the Endangered Species Act. If so, products of this kind would face greater scrutiny.
PHOTOCREO Michal Bednarek // Shutterstock
Lion
- Scientific name: Panthera leo
- Red List assessment: Vulnerable
- Population trend: Decreasing
- Habitat: Forest, savanna, shrubland, grassland, desert
Over the last century, lion populations have fallen by roughly 90% due to poaching fueled by the illegal wildlife trade, trophy hunting, loss of habitat, and climate change. An estimated 23,000 lions remain in the wild. While their population, on the whole, is decreasing, conservation efforts in some regions of Africa have allowed lions to rebound and thrive.
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enky03 // Shutterstock
Tiger
- Scientific name: Panthera tigris
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Indomalayan|palearctic
It is estimated that fewer than 4,000 tigers remain in the wild. They have been hunted to meet the demand of the illegal wildlife trade. Tiger meat is used in traditional Asian medicine. Tigers are also threatened by habitat loss from agricultural expansion. In addition to the loss of territory, farmers have also been known to take retaliatory measures against tigers that kill their livestock. Since 1975, tigers have been protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora, banning international commercial trade.
Stu Porter // Shutterstock
Cheetah
- Scientific name: Acinonyx jubatus
- Red List assessment: Vulnerable
- Population trend: Decreasing
- Habitat: Savanna, shrubland, grassland, wetlands (inland), rocky areas (e.g., Inland cliffs, mountain peaks), desert, artificial/terrestrial
Habitat destruction, hunting, and climate change all threaten the cheetah, which has faced extinction in the past. Their low reproduction rates make the species less adaptable to immediate and long-term changes. Inbreeding due to low reproduction and dwindling population has degraded the genetic diversity of cheetah populations.
tropicdreams // Shutterstock
Green turtle
- Scientific name: Chelonia mydas
- Red List assessment: Endangered
- Population trend: Decreasing
- Habitat: Afrotropical|australasian|indomalayan|nearctic|neotropical|palearctic
Some of the biggest threats faced by green turtles include getting incidentally caught in commercial and recreational fishing lines, boat strikes, loss of nesting habitat, and climate change. In the past, green turtles were hunted for their fat, meat, and eggs. Today, green turtles are protected in many countries, including the U.S.
Sergey Uryadnikov // Shutterstock
Komodo dragon
- Scientific name: Varanus komodoensis
- Red List assessment: Endangered
- Population trend: Stable
- Habitat: Indomalayan
The Komodo dragon, endemic to Indonesia, is the largest lizard in the world. The most significant threat this species faces is habitat loss. The International Union for Conservation of Nature predicts that the suitable habitat for Komodo dragons will be reduced by at least 30% in the next 45 years due to rising sea levels and warming temperatures.
Evgeniapp // Shutterstock
Kemp's ridley turtle
- Scientific name: Lepidochelys kempii
- Red List assessment: Critically endangered
- Population trend: Unknown
- Habitat: Marine neritic, marine oceanic, marine coastal/supratidal
The Kemp's ridley turtle faces threats to its nesting habitat, bycatch in fishing gear, exposure to oil and gas products, and ocean dredging. The most endangered sea turtle species in the world is the Kemp's ridley turtle. Conservation efforts include protected nesting sites in Rancho Nuevo, Tamaulipas, Mexico, and along Padre Island National Seashore.
Natursports // Shutterstock
Loggerhead turtle
- Scientific name: Caretta caretta
- Red List assessment: Endangered
- Population trend: Unknown
- Habitat: Marine neritic, marine oceanic, marine intertidal
The Loggerhead turtle faces many threats, including bycatch in fishing gear, loss or degradation of nesting sites, vessel strikes in high-traffic boat areas, meat and egg harvesting, pollution, and climate change. Loggerheads are found worldwide.
William Farah // Shutterstock
Leatherback turtle
- Scientific name: Dermochelys coriacea
- Red List assessment: Vulnerable
- Population trend: Decreasing
- Habitat: Marine oceanic, marine intertidal, marine coastal/supratidal
The leatherback turtle was once abundant in every ocean except the Arctic and Antarctic. This prehistoric species—which coexisted with dinosaurs—has survived hundreds of millions of years. Today, its biggest threat is humans. It is estimated that over the last three generations, the global population of leatherbacks has declined by 40%. The population is declining due to bycatch, being hunted for its meat and eggs, encounters with vessels, pollution, and climate change.
