This is a list of the mammal species recorded in Guam. There are 10 mammal species in Guam, of which 0 are critically endangered, 2 are endangered, 0 are vulnerable, and 0 are near-threatened. 1 of the species listed for Guam is considered to be extinct.
The following tags are used to highlight each species' conservation status as assessed by the IUCN:
Some species were assessed using an earlier set of criteria. Species assessed using this system have the following instead of Near Threatened and Least Concern categories:
Sirenia is an order of fully aquatic, herbivorous mammals that inhabit rivers, estuaries, coastal marine waters, swamps, and marine wetlands. All four species are endangered.
Family: Dugongidae
Genus: Dugong
Dugong Dugong dugon VU
The bats' most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals in the world naturally capable of flight. Bat species account for about 20% of all mammals.
Family: Pteropodidae (flying foxes, Old World fruit bats)
Subfamily: Pteropodinae
Genus: Pteropus
Mariana Fruit Bat Pteropus mariannus EN
Guam flying fox Pteropus tokudae EX
Family: Emballonuridae
Genus: Emballonura
Polynesian Sheath-tailed Bat Emballonura semicaudata EN
The order Cetacea includes whales, dolphins and porpoises. They are the mammals most fully adapted to aquatic life with a spindle-shaped nearly hairless body, protected by a thick layer of blubber, and forelimbs and tail modified to provide propulsion underwater.
Suborder: Mysticeti
Family: Balaenopteridae
Subfamily: Balaenopterinae
Genus: Balaenoptera
Sei Whale Balaenoptera borealis EN
Bryde's Whale Balaenoptera edeni DD
Subfamily: Megapterinae
Genus: Megaptera
Humpback Whale Megaptera novaeangliae VU
Suborder: Odontoceti
Family: Physeteridae
Genus: Physeter
Sperm Whale Physeter macrocephalus VU
Superfamily: Platanistoidea
Family: Kogiidae
Genus: Kogia
Dwarf Sperm Whale Kogia sima LR/lc
Family: Ziphidae
Subfamily: Hyperoodontinae
Genus: Mesoplodon
Blainville's Beaked Whale Mesoplodon densirostris DD
Family: Delphinidae (marine dolphins)
Genus: Lagenodelphis
Fraser's Dolphin Lagenodelphis hosei DD
Genus: Peponocephala
Melon-headed Whale Peponocephala electra LR/lc
Genus: Feresa
Pygmy Killer Whale Feresa attenuata DD
Genus: Pseudorca
False Killer Whale Pseudorca crassidens LR/lc
Genus: Globicephala
Pilot whale Globicephala macrorhynchus LR/cd
Genus: Orcinus
Orca Orcinus orca LR/cd
