What Makes a Species Endangered?

We’ve all heard it before--whether it’s about giant pandas in China, or polar bears in the Arctic, there are endangered wildlife populations all around the world. But how do we know which species are endangered and who gets to decide?

Endangered species are animal populations who have seen a sudden and steep decline, or a gradual lowering from historical population numbers. Recovery is the ultimate goal for an endangered species; and depending on specific population needs, there are two key opportunities of focus. Recovery initiatives may focus on habitat protection and/or restoration, and in some cases, captive breeding programs may be developed to reintroduce extremely vulnerable or rare species. Government entities such as the U.S. Fish and Wildlife Service make the call on what species are put on watchlists. Here in Oregon, the Oregon Department of Fish and Wildlife includes both endangered species and species of concern (also known as threatened species) in their conservation strategy plans.

May 21st is Endangered Species Day, so I thought I’d take a moment to highlight some of Oregon’s vulnerable critters, and what’s causing them to decline.


A large seabird with a yellow-tinged head and mottled white and brown back and a pink beak with a blue tip, lays in the grass.

The first endangered species profiles we’re looking at is the short-tailed albatross, also known as Steller’s albatross. I might be a bit biased here, dear reader, as albatross are one of my favorite bird species. Albatross are large sea-faring birds who only land in order to nest. This is possible due to the high altitudes at which they fly--through the use of a technique called dynamic soaring, albatross harness the power of wind currents to do the majority of the work for them. Additionally, they have unique locking joints in their wings that allow a fully articulated wingspan to be activated without any energy expenditure. In nesting season only one egg is incubated by both father and mother, who take shifts to hunt for food and lay on the nest.

These beautiful birds have been listed as endangered throughout their entire habitat range since 2000, though their steep decline began in the early 20th century after being over-hunted for their down and attractive feathers. Before commercial hunting, the population was estimated to be in the millions. Now, there are only about 1,200 birds left. Their comeback is slow and tumultuous due to the limited number of breeding colonies, small population, and environmental threats such as severe and lengthening storm seasons caused by climate change.


A black and gray leatherback sea turtle nests in the sand in what appears to be night time.

If you’re lucky enough to see a sea turtle on your trip to the Oregon coast, you can safely assume you’re seeing an endangered species. All six species of sea turtles found in the United States (four of which can be found in Oregon) are endangered. For this article, I’ll be focusing on the leatherback turtle. Leatherback turtles are the largest sea turtle species in the world. Unlike most turtles, they don’t possess a hard outer shell, but instead have tough rubbery skin as their name suggests. This species has remained unchanged since the age of dinosaurs, making them living fossils. They are migratory, and have been known to travel 10,000 miles per year. They’re also adept divers, reaching depths up to 4,000 feet.

In the past three generations, an estimated 40% of the global population has disappeared. In some regional nesting areas, this decline is markedly worse. In Malaysia for example, there were about 10,000 nests per year in 1953. Since 2003, there have only been one to two nests per year. Those are drastic and disturbing numbers to be seeing. For the Pacific leatherback populations, there has been a 90% decline in nesting populations in the past three generations. The biggest threats to the leatherback turtles and their speeding decline is a combination of declining access to nesting habitat, ocean pollution, vessel strikes, and the ever looming effects of climate change. Warming climate causes a multitude of issues for food and habitat access to many marine creatures, but it has one unique effect on sea turtle nests. Higher sand temperatures can actually alter the development of turtle eggs, causing an uneven ratio of male to female turtle hatchlings.


A small silver and white fish lays on a piece of mesh for observation
Image courtesy of the Oregon Department of Fish and Wildlife

You may or may not have heard of a shortnose sucker. Once abundant in the Klamath Basin, the population has decreased by over 85% since 2001. These fish have an impressive lifespan, averaging 12 years, but can be found living up to 33 years. These fish feed on detritus (decomposing organic material), algae, zooplankton, and small aquatic insects. Shortnose suckers prefer to reside in deep waters of lakes and reservoirs, and spawn along tributary rivers.

The primary cause of decline for these fish is habitat loss. Historically, the Klamath Basin had over 350,000 acres of wetlands. Today, the wetland area has drastically decreased due to changing land and water use for agricultural purposes. Additionally, poor water quality due to overgrazing of riparian zones (plant-filled areas bordering waterways) has led to less efficient filtering and an overabundance of blue-green algae growth.


An orange, brown, and white checkered butterfly sits atop a cluster of white flowers with its wings spread.

Our last endangered species feature is one you can look for in your own garden this summer if you live within the Willamette Valley. Taylor’s checkerspot butterfly is a prairie species which was historically found in abundance throughout the grassland areas of the Pacific Northwest and Canada. Adults emerge in spring, and lay clusters of eggs that will become larvae in the late spring and early summer, and hibernate throughout the winter before reemerging.

The primary cause of decline is the significant loss of suitable habitat. This is caused by urban development, spread of invasive plants, and the encroachment of trees. This has led to a few small population sites that are isolated from each other. While a few colonies still exist, it is unlikely they can intersperse due to physical obstacles, and these extant colonies must face the instability that small populations bring in order to fight the odds of survival.


It’s always sad when yet another species gets added to the endangered species list. However, with help from local governments, third-party groups, nonprofit organizations, and conservation-focused individuals, there are lots of people fighting to protect species at risk.


If you’d like to learn more about Oregon’s endangered and threatened species, you can see the full list of animals here. To learn more about Endangered Species Day, click here. And if you’d like to support the habitat and wildlife protection work that OWF does, donate today to ensure that these vulnerable species get to see tomorrow.





Jess Bynum is OWF’s Digital Communications Coordinator. She has a background in Geography and Environmental Science, and enjoys writing about conservation topics for general audiences.

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