By Dominic Henry, Senior Conservation Scientist

We often see the phrase “endangered species” used to underscore the existential threat to a particular species. But what does that actually mean?

As humans, we love to classify things. Classification can help us create hierarchies, quantify importance, and generally try to make order out of chaos. Taxonomic classification has been happening for hundreds of years and has helped us make sense of the incredible diversity of life in the natural world.

Not all classification systems are positive. Unfortunately, the need to classify species based on their risk of extinction has arisen from the impacts humans have had on species and the habitats they depend on. However, without a clear understanding of the relative risk of extinction faced by each species, it is difficult to know where to start or which species need the most urgent attention.

There is a lot of terminology, and the Nature Trust uses several different ranking systems to support our decisions about which lands may be the most urgent to secure. It can become confusing! And in some cases, it is important to be precise about what we mean when we use terms such as “endangered,” “threatened,” and “at risk,” because these rankings can affect how we prioritize and track different metrics for effective conservation.

In this first installment on our series on conservation status ranking, we’ll start at the broadest level and explain how this is approached at the federal level.

One of the oldest and most widely used ranking systems is the International Union for Conservation of Nature’s Red List of Threatened Species, or IUCN Red List for short. Established in 1964, the Red List has grown to become the world’s most comprehensive source of information on the global conservation status of thousands of species of animals, plants, and fungi.

Assigning species to a specific category is a scientifically rigorous process that takes into account many factors, including population size, geographic range, and the severity of threats from human activities such as habitat alteration, poaching, and wildlife trade. Each species must meet the thresholds for one or more criteria before it can be assigned a conservation status.

The categories are based on the risk of extinction in the wild. From most to least severe, they include Critically Endangered (the highest category, indicating extremely high risk), Endangered (very high risk), and Vulnerable (high risk). Another important category is Near Threatened, which includes species that are close to qualifying as Threatened or are likely to qualify in the near future. The lowest category is Least Concern, which indicates that a species does not qualify for any of the aforementioned categories and therefore has a low extinction risk based on scientific assessments.

Sadly, more than 49,000 species worldwide are threatened with extinction under the IUCN Red List framework.

The good news is that once a species’ conservation status has been determined, it provides clear guidance on which species to focus on when actively managing populations and reducing threats. Governments will often incorporate IUCN Red List conservation statuses into official policies and legislation, providing a legal framework for protecting species and the habitats they depend on.

However, not all countries use the IUCN Red List framework directly. In Canada, at the federal level the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) is the official body that assesses the risk of extinction of wild species. The COSEWIC categories are slightly different from those used by the IUCN Red List and include: Endangered (species facing imminent extinction), Threatened (species likely to become Endangered if nothing is done to reverse the factors leading to extinction), and Special Concern (species that may become Threatened or Endangered because of a combination of biological characteristics and identified threats). Collectively, these are officially known as Species at Risk (SAR).

It is important to note that a COSEWIC assessment alone does not provide legal protection for a species. COSEWIC is an independent scientific body, not a policy-making or regulatory body; its assessments are not binding but rather are used to inform federal decisions about legal protection.

In 2002, the federal government enacted the Species at Risk Act (SARA), which is intended to prevent species from becoming extinct or extirpated (locally extinct from a specific geographic area), support the recovery of species at risk, and prevent species listed as Special Concern from becoming Threatened or Endangered. Once a species has been assessed by COSEWIC and assigned a conservation status, it can be considered for listing under SARA. Once listed, SARA provides a legal framework for protecting species at risk and their habitats, including prohibitions against harming or killing protected species and, in some cases, destroying their critical habitat. The SARA public registry holds a huge amount of information related to the administration of the act, lists of species in each category, recovery strategies, and more.

SARA also creates a mechanism to actively address species declines by requiring the federal government to develop recovery strategies and management plans for listed species. However, federal legal protections only apply once a species is formally listed under SARA. As a result, some species may be identified by scientists as being at risk but may not yet receive federal legal protection against harming individuals or destroying critical habitat.

In Nova Scotia, we have 53 SARA-listed species: 18 are Endangered, 15 are Threatened, and 20 are Special Concern. Birds make up 16 of these and include some much-loved species such as Chimney Swift, Canada Warbler, Roseate Tern, and Bobolink. Vascular plants make up the next largest group, with 15 species, including the beautiful Ram’s-Head Lady’s-Slipper, Plymouth Gentian, and Pink Coreopsis. The charts below provide a more comprehensive breakdown of these 53 species.

Hover over the elements of the chart to see detailed numbers. Click the image to move to the next chart (there are three in total). You can also view these charts in a new tab or view the source data in a table.

In the next installment of this series, we’ll dive deeper into how conservation status ranks are applied in Nova Scotia at the provincial level and how the Nature Trust reports on the protection of species at risk of extinction on our conservation lands.