Why were immigration and emigration not a factor in the golden toad population growth?

By immigration, we mean going to a different country for a permanent residence. By emigration, we mean the act of leaving one country to live or settle in another. By such definitions, we can say that immigration and emigration were not a factor in the population growth of golden toad because they never immigrate nor emigrate. Since the time (1964) they were discovered until they became extinct from 1989 due to climate change, the golden toads had lived in the forest of Costa Rica.