telli us w many are left. some of the numbers appear to be large. e carner blue butterfly has 40,000 left. but that's relate. >> sometimes if it's less than 50,000, it's in trouble. because it shows us that thgs are happening to our environment, to our climate, to our ecosystem that's seriously impacts the world. >> reporter: some numbers so low that they're on the verge of extinction. the living dea as some conservationists call them. and too often there is a zero or a question mark. losing one species can have a detrental effect on other species because they're all connected. >> that flower population goes away, that butterfly's going to go away, and we need to be concerned about all of those nnections. >> reporter: the signs explain, human development, habittal degregation, hunng, oil pipelines all contribute to the loss of this plant, this animal, this insect. the photographs look out from the national geographic so that you can see them as u pass by. lit at night, they become especially beautiful and wanting. species can become extinct over time