Official Site of the Aransas National Wildlife Refuge Complex

Mammals of Aransas NWR Complex

A mammal is a warm-blooded animal (it can regulate its own body temperature) which gives birth to live young (as opposed to laying eggs). Many mammals are nocturnal and/or live in burrows and are thus rarely seen. At Aransas, mammals range in size from the tiny least shrew, no more than ¼ of an ounce, to whales species over 1,500 pounds.

Marsupials
	Virginia Opossum (Didelphis virginiana). The Indians called him “opassom,” the French explorers “rat de bois”—rat of the woods. This animal with a ghost-like face has a long nose, a rat-like tail, and is grayish-white in color. It is mostly nocturnal, feeding on insects, frogs, nuts and berries. Opossum can sometimes be seen in the daytime around the picnic areas.
Armadillos
	Nine-banded Armadillo (Dasypus novemcinctus). A "little fellow in armor" to the Spanish, this animal may not look like a mammal, but it is. Armadillos are expanding their range from the tropics. They are most commonly seen nosing for insects along the tour road and trails in the late afternoon and evening.
Shrews & Moles
	Elliot's Short-tailed Shrew (Blarina hylophaga). A seldom-seen forager of live oak mottes, known to eat its weight in insects in one day. The Refuge's subspecies of Elliot's short-tailed shrew has been found only at Aransas.
	Least Shrew (Cryptotis parva). The smallest mammal at Aransas, this tiny shrew inhabits the brushlands and meadows. First reported in 1972, but is actually quite common.
	Eastern Mole (Scalopus aquaticus). A winding ridge of earth along the ground surface marks the passage of this burrower of the higher sandier soils.
Bats
	Eastern Red Bat (Lasiurus borealis). A seldom-seen brick-red bat that migrates through the Refuge. It flies quite low and may gather part of its food (insects) from the ground.
	Silver-haired Bat (Lasionycteris noctivagans). Found near the headquarters in September, 1978, this bat occurs in the area during migration.
	Eastern Pipistrelle (Pipistrellus subflavus). Although not recorded specifically for the Refuge, this small bat is probably a resident. It may inhabit wooded areas near water and is common in this part of the state. Look for a bat with a slow, erratic flight.
	Brazilian Free-tailed Bat (Tadarida brasiliensis mexicana). This chocolate-brown bat is a common migrant in spring and fall. The free-tails are high-flying bats with long, angular wings and rapid wingbeats. A dead bat was discovered in the Refuge Manager's quarters in 2005.
	Big Free-tailed Bat (Nyctinomops macrotis). Although uncommon to this area, this bat was sighted at the Refuge in 1974.
Canines
	Coyote (Canis latrans). A species found throughout the Refuge, but seen infrequently because of its nocturnal habits. Listen for the yipping chorus in the evening.
	Gray Fox (Urocyon cinereoargenteus). This species, first sighted on the Refuge in 1956, remains a seldom-seen bushy-tailed phantom of the night.
Raccoons & Relatives
	Ringtail (Bassariscus astutus). This nocturnal cat-sized carnivore has the face of a fox and the tail of a raccoon. In 2003, this species was first documented on the Refuge. This documentation also represents the only record of this species for Aransas County.
	Northern Raccoon (Procyon lotor). The common, masked prowler of the Refuge, whose tracks are often found in muddy or wet, sandy areas. Can often be observed around the main picnic area. Remember, feeding these or any other wildlife at Aransas is prohibited.
Weasels and Skunks
	Long-tailed Weasel (Mustela frenata). A small, brown and white weasel that has only been reported in 1972, 1985, and 2004.
	American Mink (Mustela vison). A brown, cat-sized weasel that was seen in 1968 and 1971 on Thomas Slough. Otherwise, very rare at Aransas.
	American Badger (Taxidea taxus). A two-foot long, short-legged, stocky, gray mammal with a black and white face. Formerly common on the Refuge, it is doubtful that any more badgers occur at Aransas. They do, however, occur fairly commonly on Matagorda Island. Badgers are more suited to upland, drier habitats.
	Eastern Spotted Skunk (Spilogale putorius). A small skunk with white spots on its neck, back, and sides. It is rarely seen on the Refuge, but occasionally occurs around area farms and ranches. It feeds on rats, mice, insects, eggs, and berries.
	Striped Skunk (Mephitis mephitis). The “enfant du diable”—child of the devil—to the French and anyone who’s ever been sprayed by one, this common night prowler has two large white stripes running from head to tail. Its food habits are similar to those of the spotted skunk.
	Hog-nosed Skunk (Conepatus leuconotus). A rare skunk on the Refuge with an all-white cap, back, and tail. The last two sightings at Aransas were in 1972 and 1973.
Felines
	Mountain Lion (Puma concolor). A species with infrequent sight records at Aransas but with no recent documentation by specimen or photo. Its status is considered a casual vagrant. See description under Bobcat.
	Jaguarundi (Herpailurus yagouaroudi). Several sight records at Aransas exist for this unusual and endangered species. However, since no specimen or photo documentation exists for the Refuge, and because its range is mostly tropical, its status is hypothetical. See description under Bobcat below.
	Bobcat (Lynx rufus). At Aransas, visitors see cats on less than 5 percent of their visits, and the vast majority of these sightings are of bobcats. Bobcats show quite a bit of variation in both size and coloration. Some may show very prominent spots, while others may appear almost solid brown. And the tail, which some observers may expect to be a short stub, can actually reach a length of 7 inches. The bobcat differs from the above two cat species by the tail and body proportion, and by overall size. The bobcat’s tail is quite short and does not even come close to touching the ground when the animal stands (it does, however, “swish” like a regular tail). The other two cats have tails that easily reach the ground. In size, the jaguarundi is about ½ size larger than a regular house cat, the bobcat similar to a medium-sized dog, and the mountain lion the size of a large dog. The bobcat is the only one of the three with pointed, tufted ears. All of these identification tips should be used together to help determine which cat you are observing. Many observations, however, are of very short duration. Make your cat identification with care, and keep in mind that feral house cats also occur occasionally at Aransas. Report any sightings of cats, especially of mountain lion and jaguarundi, to the Refuge staff.
Whales, Porpoises, and Dolphins The following species of Whales, Porpoises, and Dolphins have been found stranded alive and dead on Matagorda Island:
	Pygmy Sperm Whale (Kogia breviceps). These whales are found in waters world-wide. This species of whale has been found stranded on Matagorda Island.
	Dwarf Sperm Whale (Kogia sima). Similar in appearance to the pygmy sperm whale, this species has also been found stranded on Matagorda.
	Cuveier's Beaked Whale (Ziphius cavirostris). This whale at first glance looks like a large dolphin with its beak protruding in front of the eye. This species was found stranded on Matagorda Island in 2004.
	Pygmy Killer Whale (Feresa attenuate). Found in deep tropical, subtropical, and warm temperatures of the world.
	Melon-headed Whale (Peponocephala electra). Found world-wide in tropical and subropical waters, this species travels in groups of 100 -1,000.
	Risso's Dolphin (Grampus griseus). Found world-wide in warm temperature and tropical waters, they are uncommon in the Gulf of Mexico. This medium-sized dolphin averages 3 meters in length.
	Bottle-nosed Dolphin (Tursiops truncatus). A common gulf dolphin often seen swimming in the bays and waterways. Often follows boat wakes. Most common species found stranded on Matagorda Island.
	Clymene Dolphin (Stenella clymene). Also known as the short-snouted spinner dolphin, this species is found only in the tropical and subtropical waters of the Atlantic Ocean.
Hoofed Mammals
	Wild Boar or Feral Pig* (Sus scrofa). These common Refuge mammals are a cross between domestic hogs and imported wild boar. Already a wild population when Aransas was established in 1937, the hogs have become common throughout the Refuge, despite large-scale efforts to remove them in the past. Feral hogs can be identified by large black or black and white bodies, big ears, and straight tails.
	Javelina or Collared Peccary (Pecari tajacu). This is a hog-like animal with a pepper-gray coat, a whitish-gray collar, small ears and no visible tail. The javelina can be seen, often in groups of 4 to 12, at various places along the tour road, and occasionally at the picnic area.
	White-tailed Deer (Odocoileus virginianus). An abundant species throughout the Refuge. Fawns appear in late April and most of May, often twins. Antlers lose velvet by late summer, and stay on the bucks well through the winter. In past years, thousands of deer were live-trapped here by the Texas Parks and Wildlife Department for restocking other parts of the state.
Rodents
	Mexican Ground Squirrel (Spermophilus mexicanus). This brown ground squirrel, with nine lines of light, buffy spots on its back, has not been seen on the Refuge since 1968.
	Eastern Fox Squirrel (Sciurus niger). The only tree-climbing squirrel at Aransas, the fox squirrel is often seen searching the large live oak stands looking for its favorite food: acorns. The color of this squirrel is grayish-orange above and an attractive yellowish-orange below.
	Attwater's Pocket Gopher (Geomys attwateri). Gophers tunnel under-ground after roots and tubers, but come to the surface to deposit their diggings and to collect acorns and berries. The result of this surfacing by the gophers are numerous mounds of brown dirt that visitors see along the tour route.
	Hispid Pocket Mouse (Chaetodiphus hispidus). A seldom-seen mouse of disturbed areas, this pocket mouse comes out at night to fill its fur-lined cheek pouches with seeds and insects.
	Marsh Rice Rat (Oryzomys palustris). This is a brown, nocturnal, semi-aquatic rodent of the wet lowlands. Common, but seldom seen.
	Fulvous Harvest Mouse (Reithrodontomys fulvescens). A rusty-sided, grassland mouse which nests in burrows and old bird nests as well as in brush and grass.
	White-footed Mouse (Peromyscus leucopus). A common, big-eared, long-tailed, brown and white mouse of fields and brushlands. Common food preferences are seeds and acorns.
	Deer Mouse (Peromyscus maniculatus). Hypothetically, this mouse should occur on the Refuge, although it has not been recorded. Closely resembling the white-footed mouse in general appearance, the deer mouse can be told by its sharply bicolored tail, white beneath and dark above.
	Northern Pygmy Mouse (Baiomys taylori). This tiny mouse looks like a young house mouse but has a pale lower side to its tail. Common, but fond of dense cover and seldom seen.
	Hispid Cotton Rat (Sigmodon hispidus). A common, brown rat whose maze of runways can be found in areas of lodged bluestem, cordgrass, and sedges.
	Southern Plains Woodrat (Neotoma micropus). An uncommon, steel-gray rat of the brush, whose favorite foods include acorns, mesquite beans, and cactus pads and fruits. Often constructs large nests which are easily visible by the amount of sticks and other debris collected to construct them. This practice, along with their affinity for bright man-made objects (such as coins, jewelry, foil, and pieces of trash), have earned them the oft-used name “packrats.”
	Norway Rat* (Rattus norvegicus). Like the black rat, this species is also found in close association with man.
	Roof Rat* (Rattus rattus). Sometimes called the “roof rat,” this large black or brown rat with an extremely long tail is found in close association with man, usually in buildings.
	House Mouse* (Mus musculus). A small, gray mouse found in and around human habitation. The hairless tail is a good way to identify this species.
	Nutria* (Myocaster coypus). A large, brown rodent that looks like an oversized, large-headed muskrat. Mostly aquatic, it has become a pest along the gulf coast since its introduction from South America. Infrequently occurs on Matagorda Island and rare on mainland.
Rabbits and Hares
	Swamp Rabbit (Sylvilagus aquaticus). This rabbit prefers wet, lowland areas, including in and around bays. Distinguishing this rabbit from the cottontail is not always easy, but swamp rabbits are larger and darker, with less contrast between the brown back and the reddish-brown on the back of the neck (a contrast which is quite pronounced in the cottontail). One good field mark is the top of the hind feet (if you can see them): on the cottontail the tops of the feet are light tan, whereas on the swamp rabbit they are reddish-brown.
	Eastern Cottontail (Sylvilagus floridanus). A brown coat and a cottonball tail characterize this rabbit of the higher brushlands. Common at time, its numbers are regulated by cycles and weather.
	Black-tailed Jackrabbit (Lepus californicus). Once common at Aransas, most, if not all, of the population of this large hare has disappeared from the Refuge. Aside from strays which may reach the Refuge on occasion, the jackrabbit can sometimes be seen around area ranches and farms. Common on Matagorda Island at the headquarters area, more rare in dunes.
Although a positive sighting or identification has not happened, the following list of species could possibly occur on refuge land due to recent land acquisitons.

Shrews and Moles
	Desert Shrew ( Notiosorex crawfordi)
Bats
	Hoary Bat (Lasiurus cinereus)
	Southern Yellow Bat (Lasiurus ega)
	Northern Yellow Bat (Lasiurus intermedius)
	Big Brown Bat (Eptesicus fuscus)
	Evening Bat (Nycticeius humeralis)
Canines
	Red Wolf (Canis rufus). Extirpated, the refuge exists in its historical range.
	Red Fox* (Vulpes vulpes)
Raccoons and Relatives
	White-nosed Coati (Nasua narica)
Weasels and Skunks
	Northern River Otter (Lontra canadensis)
Felines
	Ocelot (Leopardus pardalis). Extirpated, the refuge exists in its historical range.
Whales, Porpoises, and Dolphins The species of whales, porpoises, and dolphins that follow may be found off the Coast of Matagorda Island.
	Northern Right Whale (Eubalaena glacialis)
	Minke Whale (Balaenoptera acutorostrata)
	Sei Whale (Balaenoptera borealis)
	Bryde's Whale (Balaenoptera edeni)
	Blue Whale (Balaenoptera musculus)
	Fin Whale (Balaenoptera physalus)
	Humpback Whale (Megaptera novaeangliae)
	Sperm Whale (Physeter macrocephalus)
	Blainville's Beaked Whale (Mesoplodon densirostris)
	Gervais' Beaked Whale (Mesoplodon europaeus)
	Killer Whale (Orcinus orca)
	Short-finned Pilot Whale (Globicephala macrorhynchus)
	False Killer Whale (Pseudorca crassidens)
	Rough-toothed Dolphin (Steno bredanensis)
	Pantropical Spotted Dolphin (Stenella attenuata)
	Striped Dolphin (Stenella coeruleoalba)
	Atlantic Spotted Dolphin (Stenella frontalis)
	Spinner Dolphin (Stenella longirostris)
	Fraser's Dolphin (Lagenodelphis hosei)
Manatees
	West Indian Manatee (Trichechus manatus)
Hoofed Mammals
	Axix Deer* (Cervus axis). A possible sighting was made by refuge staff of a single individual in 2004. No other observations were made since.
Rodents
	Spotted Ground Squirrel (Spermophilus spilosoma)
	Thirteen-lined Ground Squirrel (Spermophilus tridecemlineatus)
	Eastern Gray Squirrel (Sciurus carolinesis)
	Merriam's Pocket Mouse (Perognathus merriami)
	Gulf Coast Kangaroo Rat (Dipodomys compactus)
	American Beaver (Castor canadensis)
	Northern Grasshopper Mouse (Onychomys leucogaster)
	Eastern Woodrat (Neotoma floridana)

* Introduced or non-native species.

References:
The above names are taken from The Mammals of Texas.

McAlister, W.H., and M.K. McAlister. 1993. Matagorda Island: A Naturalist's Guide. Austin: University of Texas Press.

Schmidly, D.J. 1994. The Mammals of Texas. Austin: University of Texas Press. 501 pp.

Revision 2006

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