266.

Northern Yellow Bat

Lasiurus intermedius

French: Lasiure du Mexique / German: Nordliche Haarschwanzfledermaus / Spanish: Lasiuro de México

Other common names: Big Yellow Bat, Eastern Yellow Bat, Florida Yellow Bat, Greater Yellow Bat

Taxonomy. Lasiurus intermedius H. Allen, 1862,

“Matamoros, Tamaulipas,” Mexico .

See L. egregius and L. insularis . Taxon floridanus was previously described as a full species and later included as a subspecies of L. intermedius based on morphology and restriction-enzyme analysis of mtDNA. Lasiurus intermedius 1s in the Yellow Bat group. Two subspecies recognized.

Subspecies and Distribution. L.i.intermediusH.Allen,1862—extreme SETexas,andfromSSinaloaandTamaulipas(NW&NEMexico)StoHonduras,withanisolatedrecordfromCostaRica.

L. i. floridanus G. S. Miller, 1902 — S & SE USA (SE Virginia to SE Texas), with an extralimital record from NewJersey.

Descriptive notes. Head-body ¢.76—- 80 mm, tail 51-70 mm, ear 15-19 mm, hindfoot 8-13 mm, forearm 46-7-54- 4 mm; weight 14-20- 2 g. Females are on average larger than males. Fur is buff yellowish to yellowish orange,lightly washed with black. Whitish patches on shoulders or wrists are absent. Hair is silky and long, reaching 12 mm in interscapular region. Ears are pointed and short and externally furred on medial onehalf; tragusis triangular. Face is blackish. Wing membranes are brown, with proximal one-half of uropatagium furred. Calcaris slightly keeled. Rostrum is long; coronoid process is high; and sagittal crest is pronounced. I? is in contact with C'; there is only one upper premolar. Dental formula is11/3,C1/1,P 1/2, M 3/3 (x2) = 30. Chromosomal complement has 2n = 26 and FN = 42, with seven pairs of large metacentric and submetacentric autosomes, one pair of medium metacentric autosomes, one pair of medium acrocentric autosomes, three pairs of small acrocentric autosomes, large submetacentric X-chromosome, and small acrocentric Y-chromosome.

Habitat. Coniferous forests, deciduous forests, pine-oak forests, and dry thorn scrub from sea level up to elevations of ¢. 3000 m. Northern Yellow Bats are usually found in forested regions near water and open areas.

Food and Feeding. The Northern Yellow Batflies fast, foraging on treetops, forest edges, and open areas, such as pastures, lake edges, marshes, savanna-like habitats, coastal beaches, and golf courses. It forages 3-4 m aboveground in open areas and 10-15 m aboveground on treetops in closed habitats. They will forage in groups; females and young can form large groups of more than 100 individuals; males form smaller groups. Stomach contents of one individual contained fragments of mosquitoes,flies, dragonflies, leathoppers, ants, beetles, and diving beetles.

Breeding. Spermatozoa are produced from September to mid-February. Mating takes place in autumn and winter. Pregnant Northern Yellow Bats were captured in May-June, and parturition occurs in May-June. Litters have 2—4 young (mean 3-4). Lactating females were captured in June-July. Flying young were observed in June-July.

Activity patterns. The Northern Yellow Bat is crepuscular/nocturnal. Individuals were captured at dusk. Roosts are mainly in dead palm fronds and clumps of Spanish moss ( Tillandsia usneoides, Bromeliaceae) but also in buildings. Nursery colonies have been found among hanging dried corn stalks. Echolocation calls are long (10 milliseconds). Calls sweep from c.47-5 kHz to narrowbandtails of ¢.28 kHz. Those calls vary in different habitats. In more open areas or at higheraltitudes, tail frequencies drop to below 25 kHz; pulses are longer with lower repetition rates.

Movements, Home range and Social organization. Migratory movements occur in northern parts of the distribution; individuals that remain in those areas become torpid at low temperatures. The Northern Yellow Bat is gregarious to some degree, forming unorganized groups. It has been found roosting with the Southern Yellow Bat ( L. ega). Nursery colonies of c.45 females and their young can form in spring and summer. Sexual segregation occurs year-round. Females do not carry non-volant young when foraging.

Status and Conservation. Classified as Least Concern on The IUCNRed List. The Northern Yellow Bat is widespread, presumably with large population, and occurs in protected areas. It is uncommon to locally common. No major threats are known.

Bibliography. Alvarez-Castafeda & Gonzalez-Ruiz (2018), Baird et al. (2015), Baker & Patton (1967), Briones-Salas et al. (2013), Hall & Jones (1961), Handley (1960), Miller & Rodriguez-Herrera (2016a), Morales & Bickham (1995), Morales et al. (2014e), Novaes, Garbino et al. (2018), Rodriguez-Herrera et al. (2003), Rydell et al. (2002), Simmons (2005), Webster et al. (1980), Wilson & Ruff (1999).