Vulnerability

Vulnerability

Vulnerability normally refers to the susceptibility of the species to intrinsic or external effects which increase the risk of extinction (even when mitigating factors are taken into account).

There are a number of taxon- or case specific biological and other factors that may affect the extinction risk associated with a given percentage decline, small population size or restricted area of distribution. These can be, but are not limited to, aspects of any of the following:

• Intrinsic factors: distribution, dispersal, population size / density, genetic diversity, reproductive capacity, niche width, and role in the ecosystem
• Extrinsic factors: domestic use, legal and illegal trade, human induced impacts (such as habitat loss, pollution, human-animal conflict), invasives, diseases, and any other relevant threats.

The vulnerability of a species to threats of extinction depends on its population demographics, biological characteristics, (such as body size, trophic level, life cycle, breeding structure or social structure requirements for successful reproduction), and vulnerability due to aggregating habits, natural fluctuations in population size, and/or residency/migratory patterns.

Remember: This makes it impossible to give numerical threshold values for population size or area of distribution that are applicable to all taxa.

Rollover each box to see a brief explanation on the relationship between the volume in trade and the vulnerability of the species.