Northern Yellow Bat (Lasiurus intermedius)
- Protection Status Notes
- This bat's population trends and status have not been investigated, but dramatic decline has been reported from areas of Florida where pesticide use is especially heavy. L. intermedius is not considered endangered or a species of special concern by the U.S. Fish and Wildlife Service.
- Lasiurus intermedius is one of the largest bats in the eastern United States. Its fur ranges in color from yellowish orange or brown to nearly gray, often with dark tips. All yellow bats have fully furred upper tail membranes and lack the distinctive white patches on the shoulders and wrists that characterize other bats of this genus. This bat's forearm is 51-63 mm long and it weighs 15-28 g. The southern yellow bat, found in southeastern Texas, is smaller in size, with a forearm of 49 mm or less.
- Life History
- Mating primarily occurs in fall, though males are reproductively active from September through mid-February. It is believed that northern yellow bats, like red bats, copulate in flight. Females store sperm in their reproductive tracts until they ovulate in early spring. They give birth from late May through June, bearing two to four pups, each weighing about 3 grams at birth. The average litter size in Florida is three, though it may be two in southeastern Texas. Like other bats of this genus, females have four breasts to accommodate a litter of four. Pups begin to fly by the middle of June, and all are weaned by late July. Most adult males appear to live apart from mothers and young throughout much of the year. There are no longevity records for this species, but the fact that they typically produce litters of three suggests relatively short life spans compared to most other bats. Owls and rat snakes are likely their primary predators.
Although groups of Northern Yellow Bats often roost in a single tree or group of trees, each mother and her young usually hang alone. Adult males have been found roosting in close proximity with other members of their feeding groups, but rarely with females and young. Their breeding season is in the fall, and females give birth from late May through June, bearing two to four pups. Pups begin to fly by the middle of June, and all are weaned by late July. Most adult males appear to live apart from mothers and young throughout much of the year. There are no longevity records for this species, but the fact that they typically produce litters of three suggests relatively short life spans compared to most other bats.
Northern Yellow Bats typically feed 16 to 20 feet above clearings, among scattered clumps of trees and palms, along forest edges, and above sand dunes and beaches. Grassy areas, from pastures and golf courses to lake edges, are preferred. Large feeding aggregations occur only where such habitats are located near roosts. Over 100 individuals may congregate in prime foraging habitat when young begin to fly. They eat leafhoppers, damselflies, small flies, predaceous diving beetles, other beetles, and flying ants.
During the winter, northern yellow bats may undergo torpor during periods of inclement weather, though they will emerge to feed on warm evenings. In Florida, these bats are most abundant in the drier uplands, where they live in stands of long-leaf pine, turkey oaks, or in live oak hammocks. In Texas, they are best known from coastal palm groves.
- The Northern Yellow Bat is a non-migratory species that lives along the southeastern Atlantic and Gulf Coasts, especially in areas where Spanish moss is prevalent. In Florida, these bats are most abundant in the drier uplands, where they live in stands of long-leaf pine, turkey oaks, or in live oak hammocks. In Texas, they are best known from coastal palm groves.
Northern Yellow Bats roost year-round in Spanish moss or beneath the dead, hanging fronds of fan palms.
- The northern yellow bat ranges from South Carolina south through all of Florida into Cuba and west along the Gulf Coast through Texas and coastal Mexico to Honduras. A few apparent wanderers have been found in coastal areas along the Atlantic Ocean, north to Virginia and New Jersey.
In the eastern and southern parts of Texas as far north as Shelby County and as far west as Bexar County.
- Threats and Reasons for Decline
- Pesticide poisoning and loss of Spanish moss, which reduces roosting opportunities, appear to pose the greatest threats. The practice of removing old palm fronds destroys additional roosting habitat.
- Ongoing Recovery
- Protection of specific roosting areas from moss and dead frond removal may prove beneficial, as would public education on the bat's value and needs.
- Little is known about yellow bat diets or their possible impact on forest and agricultural pests. Status and conservation needs remain unstudied.
Additional details can be found in the online version of The Mammals of Texas for the Northern Yellow Bat