Most countries have a list of endangered species and international organisations too issue such lists of vulnerable and endangered species.
What mathematical or statistical models are those estimates based on?
Regardless of which techniques the lists use, what are some of the most popular mathematical models to find out whether a certain species is endangered or vulnerable given the population and/or other environmental data in the academic literature? What is the state of the art currently?
Especially, if I want to learn the models at an intermediate and then advanced level (I already have training as an Economics student on mathematical and econometric modelling), what are some books/ other sources you would recommend?