252.

Northern Hoary Bat

Lasiurus cinereus

French: Lasiure cendré / German: Eisgraue Haarschwanzfledermaus / Spanish: Lasiuro cenizo

Taxonomy. Vespertilio linereus [sic] Palisot de Beauvois, 1796,

Philadelphia, Pennsylvania, USA.

See L. egregius . Lasiurus cinereus is in the Hoary Bat group. Monotypic.

Distribution. From Canada (S British Columbia, SE Northwest Territories, Hudson Bay, Quebec, and Newfoundland) S throughout the USA and Mexico to W Guatemala; also on Hawaii.

Descriptive notes. Head-body ¢.80-5— 83- 6 mm, tail 47-61 mm, ear 13-19 mm, hindfoot 8-13 mm, forearm 50-57 mm; weight 20-35 g. Dorsum is generally mixed brown-gray, with heavy white tinge, and strongly frosted; wrist and shoulder patches are whitish; and throat is yellowish. Dorsal hairs are frosted and tricolored, with dark bases, yellowish middles, and blackish distal bands. Ventral fur is not heavily frosted. Hair on elbows, thumbs, and upper arm is yellowish; wing membrane has brownish ventral hair from body to nearly the wrist. Ears are short, thick, rounded, and yellowish, with blackish edges. Tragus is short and broad. Uropatagium is densely furred; calcar is twice as long as hindfoot, with lobes on tip. Skull is large and broad; rostrum is broad, with wide nasal openings; and auditory bullae are large. Teeth are large, and P?is present and reduced, sometimes absent. Dental formula is I 1/3, C1/1,P2/2,M 3/3 (x2) = 32. Chromosomal complement has 2n = 28 and FN = 48, with medium-sized submetacentric X-chromosome and small acrocentric Y-chromosome.

Habitat. Temperate forests of pine-oak and lowlands of deciduous forests in dry and wet areas at elevations of 500-1900 m (Mexico). The Northern Hoary Bat has been caught in dense forests, open wooded clearings, and city parks.

Food and Feeding. Northern Hoary Bats have fast and straight flight that can reach 21- 3 km /h;itis considered one of the fastest North American bats. During flight, they can soar and glide. They might form groups when hunting and forage above treetops, along streams and lakeshores, and in wooded urban areas. Diet mainly contains moths but also flies, beetles, small wasps, grasshoppers, termites, and dragonflies. Northern Hoary Bats bite off the abdomen and thorax of insect prey, dropping the head and wings. Uncommon dietary items include leaves, grass, snakeskin, and Tricolored Bats ( Perimyotis subflavus).

Breeding. Breeding range of the Northern Hoary Bat in North America extends across Canada and north-central and north-eastern USA, south to Kansas, Kentucky, and possibly Arkansas, Louisiana, and Georgia. Copulations seem to occur mostly during autumn migration and parturitions from mid-May to early July; copulations might also occur on wintering grounds. Litters typical have two young (range 1-4). Lactating females were captured from late June to late July, and volant young started to be captured in late July. Neonates are brown, with much paler throat and head and nearly black feet. Silver-gray hairs cover dorsum, and eyes and ears are closed at birth. Young start to fly by three days old.

Activity patterns. Northern Hoary Bats emerge to forage as late as one hour and 15 minutes after sunset or later. Their activity peak is c.5 hours after sunset, but greatest success for captures in mist nets occurred 3—4 hours after sunset, and in south-western USA, they seemed more active after midnight. They also fly on warm winter afternoons. They were captured foraging at a wide range of temperatures (0-22°C). The Northern Hoary Bat is mainly found roosting in trees but occasional a woodpecker hole, a squirrel nest, buildings, and caves. When roosting in trees, it seems to prefer trees that border clearings, usually on foliage 3-5 m aboveground. Search-approach echolocation calls are CF, with c.10 milliseconds duration; frequency is low, sweeping from 20 to 17 kHz and produced every 3-3 milliseconds. Tracking calls sweep from 41 kHz to 21 kHz, and they are shorter and have higher rates than search-approach calls. Terminal-stage calls are steep FM signals, short, and at a rate that can reach 190 calls/second. Occasional predators include American kestrels (Falco sparverius), sharpshinned hawks (Accipiter striatus), and corn snakes (Pantherophis guttatus).

Movements, Home range and Social organization. The Northern Hoary Bat can wrap its uropatagium around its body for insulation and become torpid when inactive during the day or between foraging pauses at night. Migration seems to take place through northern Florida, with large groups flying in waves. Autumn migration occurs from late October to late November and spring migration from February to early May; spring migration seems to be less organized than autumn migration. Wintering grounds are in southern California, Mexico, and Guatemala. Some individuals probably remain in northern areas and hibernate. This species is solitary, roosting separately during the day. Sexes are generally separated during warm months, except during mating. Females seem to be more concentrated in western North America. In California, elevational separation of sexes is apparent, with females in lowlands and coastal valleys and males in foothills and mountains.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Northern Hoary Bat has a wide distribution that includes several protected areas. Main threats in Mexico are deforestation and human disturbance.

Bibliography. Alvarez-Castafieda & Gonzalez-Ruiz (2018), Anderson (2002), Baird et al. (2015), Baker & Patton (1967), Barbour & Davis (1969), Bickham (1979a), Bonaccorso & McGuire (2013), Gardner & Handley (2008), Gonzélez, Barquez & Arroyo-Cabrales (2016), Hall & Jones (1961), Jones (1965), Mikula et al. (2016), Miller (1897), Morales et al. (2014c), Novaes, Garbino et al. (2018), Shump & Shump (1982b), Simmons (2005), Williams & Findley (1979), Wilson & Ruff (1999).