I've loved the concept behind the London Zoo's EDGE of Existence website since I discovered it back in 2011. I remember being frustrated at all the attention various subspecies of charismatic animals were getting, while monotypic genera and even families of less charismatic species got relatively little. So the idea of an objective measure of which species is worth saving is nice, however I have a number of issues. 1. My biggest issue is that they combine the ED (evolutionarily distinct) and GE (globally endangered) rankings for one score. I wish that it were possible to break out these rankings and even sort via multiple fields. So, for example the highest ED rankings of all critically endangered animals, then merely endangered, and so it. 2. There methodology is opaque. Does the fact that all three long-beaked echnidnas are critically endangered impact their EDGE score? 3. Their rankings of conservation attention seem to be less-than-useful. "Limited" includes that tooth-billed pigeon, where conservation effort seem to amount to conservationists wringing their hands over its endangerment, but it also includes the long-whiskered owlet, where the government of Peru has set up a protected area in its habitat and the local people are trying to preserve it. I feel like a numeric value here would be more useful than catch-all categories. 4. Captive populations don't seem to factor into calculations unless the species is extinct in the wild; though this is a pet peeve I have with a lot of conservation organizations. If you have a species that is critically endangered in the wild but has a large captive population with a diverse gene pool; I would argue that it is less of a priority than a vulnerable species with no captive population or a severely inbred one. 5. Evolutionary distinctiveness is based on the amount of time since an animal diverged from its last common ancestor, but I can't determine how they determined this, let alone the level of certainty that they have for various animals. 6. I feel like evolutionary distinctiveness shouldn't just be time since divergence. If a species developed new morphological features, that makes it more important to preserve; if it filled a new niche, that makes it more important to preserve; if it is a keystone species in its environment that makes it much more important to preserve. Mind you, these are somewhat subjective factors, which are harder to quantify. Despite these objections, I still find the EDGE website a useful guide, since it tends to highlight things like bats, rodents, seabirds, and small songbirds which currently get very little attention under models which focus on well-known charismatic megafauna.