Why is a Species Threatened, Part 1

Most people have heard the terms ‘critically endangered’ and ‘vulnerable’, but it seems to me few people know how those terms are generated and assigned.

There is indeed a scientific process that occurs behind these assignments, and it is generated by an expert, yet largely volunteer, group who are part of the IUCN, the International Union for Conservation of Nature. IUCN is the largest global environmental organization and professional conservation network. IUCN developed the Red List of Threatened Species, which is the most comprehensive database on the conservation status of plant, animal, and fungi species worldwide.

This database documents a species’ biology, research, threats, human use, and conservation needs and actions, all of which are evaluated against a defined set of criteria to determine risk of extinction. The information in the Red List is often used to enhance research, create national and international laws, and draw attention to global conservation needs and set priorities.

As Red List Authority for the IUCN’s Iguana Specialist Group, I have been working to review, edit, or create assessments for all 45 living species of iguanas.

Each assessment requires details about the species’ natural history, habitat characteristics, and threats. Details such as how often does it reproduce, are they affected by climate change, or are they suffering from introduced predators.

Once all this data is gathered, we analyze the information relative to the established thresholds within four IUCN criteria to determine its status. An important attribute of having quantitative thresholds in the criteria is that it allows comparability across all different types of species, from iguanas to whales to caterpillars.

The Red List is updated online two to three times a year and I am proud that the iguana group has 10 new assessments in this published version. Most of my iguana conservation work for San Diego Zoo Global has been focused in the Caribbean, namely Jamaica and Grand Cayman.

But in my role as Red List Authority, I have enjoyed the opportunity to learn about all the other iguana species in depth, and help forge connections for their conservation needs.

For example, one of the new assessments is for Roatán Spiny-tailed Iguanas, Ctenosaura oedirhina. The Iguana Specialist Group is holding their annual meeting on the island of Roatán in November and this updated assessment will help inform delegates attending the Species Recovery Planning Workshop we are hosting in conjunction.

We determined that Roatán Spiny-tailed Iguanas are Endangered, under Criteria B, which describes their restricted range and continued decline. They are only found on the island of Roatán and the small cay of Barbareta, encompassing an area less than 300 square kilometers. Iguanas used to be found all over the island, but they are now restricted to seven isolated subpopulations.

They are threatened by free-roaming domestic cats and dogs, as well as being hunted by local people for food and for sale to tourist restaurants. Their habitat continues to disappear with more tourist and residential development.

However, we are encouraged that our outreach programs have developed grass-roots collaborations among some local landowners to protect these beautiful iguanas. More of this is needed!

Stay tuned for more details about the other iguanas that were recently assessed on the Red List of Threatened Species.

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