The author suggests that management philosophies look towards attaining wildlife populations that are ecologically functional rather than managing populations in a way that only prevents them from becoming threatened or endangered (minimum viable populations). He states that "if species are only maintained at or near minimally viable population levels, indicator species or assemblages of species (guilds) represented by indicator species might be ineffective in performing their ecological function." He sites examples such as birds as seed dispersers, mammals as disseminators of mycorrhizal spores and the influence of insectivorous birds on populations of insects. Having only minimally viable populations of these species could have dramatic effects on their ability to carry out their ecological role.