Angel Island Mouse
Encyclopedia
The Angel Island mouse or La Guarda deermouse (Peromyscus guardia) is a species of rodent
in the family Cricetidae
. It is endemic to Mexico
, where it is historically known only from the island of Ángel de la Guarda
, and nearby islets. The species is believed to be extirpated
from the three smaller islands, and may be extinct
on Ángel de la Guarda as well. The species is threatened by predation by feral cat
s, and by competition from introduced rodents.
, and to three much smaller islands in the same group. Within the islands, the species appears to be confined to sandy beaches, and perhaps to rockier areas nearby, and has not been found in the high mountainous terrain that forms most of their land area.
Three subspecies are formally recognised, although two of these are now extinct:
, possibly belonging to the P. e. fraterculus species or subspecies The critically endangered San Lorenzo mouse
, which inhabits a smaller group of islands to the south, may be descended from the same stock, isolated when the islands separated from the mainland as sea levels rose at the end of the last Ice Age
. The two species remain able to interbreed, although it is not known whether the resulting hybrids are fertile. Little is known of the behaviour or detailed biology of the species, although it is believed to breed in the spring.
and black rat
s, which compete with the endemic species for resources. The subspecies resident on the two northern islets are now listed as extinct
, while the entire population on the southern islet of Estanque was probably driven to extinction by a single cat
, present on the island only between 1998 and 1999.
The species is currently listed as critically endangered
by the IUCN, but since no living specimens have been seen for twenty years, as of 2011, it may well be entirely extinct. It has been estimated that, if the species still survives, it is likely restricted to an area of no more than 10 square kilometres (3.9 sq mi).
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the family Cricetidae
Cricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
. It is endemic to Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, where it is historically known only from the island of Ángel de la Guarda
Isla Ángel de la Guarda
Isla Ángel de la Guarda, also called Archangel Island, and called Xazl Iimt east of Bahía de los Ángeles, and separated from the Baja California Peninsula by the Canal de Ballenas . It is the second largest of the eleven Midriff Islands or Islas Grandes. It is part of the state of Baja California,...
, and nearby islets. The species is believed to be extirpated
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
from the three smaller islands, and may be extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
on Ángel de la Guarda as well. The species is threatened by predation by feral cat
Feral cat
A feral cat is a descendant of a domesticated cat that has returned to the wild. It is distinguished from a stray cat, which is a pet cat that has been lost or abandoned, while feral cats are born in the wild; the offspring of a stray cat can be considered feral if born in the wild.In many parts of...
s, and by competition from introduced rodents.
Description
The Angel Island mouse has pale grey-brown fur with white underparts and feet, and large, hairless, ears. It is most readily distinguished from closely related species on the mainland by subtle characteristics of the skull, or through genetic or biochemical analysis. Adults range from 19 to 22 cm (7.5 to 8.7 ) in total length, including a 9 to 12 cm (3.5 to 4.7 ) tail. Females have four abdominal teats.Distribution and habitat
The Angel Island mouse is endemic to Ángel de la Guarda Island, a mountainous 359 mi2 island off the east coast of Baja California SurBaja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
, and to three much smaller islands in the same group. Within the islands, the species appears to be confined to sandy beaches, and perhaps to rockier areas nearby, and has not been found in the high mountainous terrain that forms most of their land area.
Three subspecies are formally recognised, although two of these are now extinct:
- Peromyscus guardia guardia - Ángel de la Guarda, Estanque
- †ExtinctionIn biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
Peromyscus guardia harbisoni - Isla Granito - † Peromyscus guardia mejiae - Mejia
Biology
The Angel Island mouse is believed to be descended from an isolated population of cactus miceCactus Mouse
The Cactus Mouse is a species of rodent in the family Cricetidae.It is found in Mexico and the United States....
, possibly belonging to the P. e. fraterculus species or subspecies The critically endangered San Lorenzo mouse
San Lorenzo Mouse
The San Lorenzo Mouse is a species of rodent in the family Cricetidae. It is endemic to Mexico, where it is known only from the islands of San Lorenzo Norte, San Lorenzo Sur, and Salsipuedes off the east coast of Baja California. The species is threatened by predation by feral and domestic cats,...
, which inhabits a smaller group of islands to the south, may be descended from the same stock, isolated when the islands separated from the mainland as sea levels rose at the end of the last Ice Age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
. The two species remain able to interbreed, although it is not known whether the resulting hybrids are fertile. Little is known of the behaviour or detailed biology of the species, although it is believed to breed in the spring.
Conservation status
As recently as the 1960s, the Angel Island mouse was reported to be abundant on at least three of the four islands it was known to inhabit. However, no specimens have been found on the islands since 1991, despite a number of surveys. The main risks to the species come from feral cats, and from introduced house miceHouse mouse
The house mouse is a small rodent, a mouse, one of the most numerous species of the genus Mus.As a wild animal the house mouse mainly lives associated with humans, causing damage to crops and stored food....
and black rat
Black Rat
The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...
s, which compete with the endemic species for resources. The subspecies resident on the two northern islets are now listed as extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
, while the entire population on the southern islet of Estanque was probably driven to extinction by a single cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
, present on the island only between 1998 and 1999.
The species is currently listed as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
by the IUCN, but since no living specimens have been seen for twenty years, as of 2011, it may well be entirely extinct. It has been estimated that, if the species still survives, it is likely restricted to an area of no more than 10 square kilometres (3.9 sq mi).