A strong flier with yellowish fur, the southern yellow bat is a lowland species, adapted to both dry and wet habitats. It roosts in trees, particularly palms. These bats are often seen hunting over water, including over swimming pools. Very few species of bats have more than one or two young at a time, and most have just two nipples, but some bats in the genus Lasiurus have four nipples and can have triplets or quadruplets. Southern yellow bats most often have triplets. The young bats nurse for about two months before they are able to fly and forage for themselves.

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Southern Texas, Eastern and Southern Mexico south to Bolivia, Argentina, Paraguay, Uruguay, and Brazil; Trinidad (Simmons 2005). Also found in Colombia, Venezuela, Guianas and Suriname.

Lasiurus ega is widely distributed from Mexico south to Argentina, but the range seems to be extending northward into parts of California, Texas, Arizona and New Mexico.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) South America from Uruguay and Argentina north through Central America and eastern Mexico to extreme southern Texas; generally a lowland species but reaches elevations of up to 2300 m (Baker et al. 1988, Kurta and Lehr 1995).

A whitish buff, yellowish, or orange, usually with a blackish wash. Tail membrane is well furred.

Range mass: 10 to 18 g.

Average mass: 12 g.

Length: 13 cm

Weight: 23 grams

Sexual Dimorphism: Females are larger than males.

Length:
Average: 115.1 mm
Range: 102-118 mm

Weight:
Average: 11.9 g
Range: 10-14 g

See Kurta and Lehr (1995).

Habitat and Ecology

Systems

• Terrestrial

Bats of the genus Lasiurus generally occur in wooded areas and roost in foliage. Occasionally these bats roost in tree holes or buildings. In the U.S. L. ega is associated with introduced palms, which is thought to be a reason for its recent expansion northward.

Terrestrial Biomes: forest ; rainforest ; scrub forest

Comments: Preferentially roosts in trees, generally palms in the southern U.S.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

May be migratory, in at least part of range (Barbour and Davis 1969). Apparently present all year in southern Texas (Schmidly 1991).

L. ega eats primarily insects caught in flight but is also known to alight on vegetation to pick off insects. Feeding flights are 6-15 m. above ground.

Normal litter size is 2 or 3 young, although individuals have been known to have single young. Estimated gestation period is 80-90 days. Mating occurs in the late summer or fall with sperm being stored overwinter in the uterus. Ovulation and fertilization occur in the spring with births occurring from late May to early July.

Range number of offspring: 2 to 4.

Range gestation period: 90 to 105 days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; sperm-storing

In Texas, 7 pregnant females were taken in late April and early June, and 9 females were lactating in June (Hoffmeister 1986). Females carried 2-4 embryos (Schmidly 1991).

Temperate North American bats are now threatened by a fungal disease called “white-nose syndrome.” This disease has devastated eastern North American bat populations at hibernation sites since 2007. The fungus, Geomyces destructans, grows best in cold, humid conditions that are typical of many bat hibernacula. The fungus grows on, and in some cases invades, the bodies of hibernating bats and seems to result in disturbance from hibernation, causing a debilitating loss of important metabolic resources and mass deaths. Mortality rates at some hibernation sites have been as high as 90%. While there are currently no reports of Lasiurus ega mortalities as a result of white-nose syndrome, the disease continues to expand its range in North America.

CITES: no special status

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N1 - Critically Imperiled

Rounded Global Status Rank: G5 - Secure

Population

Population Trend

Major Threats

Conservation Actions

Several cases of rabies have been reported in Lasiurus ega in southen California. In one instance, an individual landed on a human's bare foot and punctured the toe. Before 1979, there were no known instances of this species carrying rabies.

May help to control harmful species of insects.

Comments: Lasiurus xanthinus formerly was included in L. ega. Koopman (in Wilson and Reeder 1993) and Kurta and Lehr (1995) retained xanthinus within L. ega, as did Kurta (in Wilson and Ruff 1999). L. xanthinus was recognized as distinct by Baker et al. (1988), Baker et al. (2003), and Simmons (in Wilson and Reeder 2005). Baker et al. (1971) established the range of L. ega panamensis as extending north of Chiapas through eastern Mexico to Brownsville, Texas, and restricted xanthinus to western Mexico and the southwestern U.S., east to southwestern New Mexico. MtDNA data indicate that L. xanthinus (within the range described above) and L. insularis are distinct species separated from L. ega and L. intermedius, respectively (Morales and Bickham 1995).

New World Lasiurus were placed in the genus Nycteris by Hall (1981), who based the change on nomenclatural (rather than biological) concerns; few if any other authors have followed this change.