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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
1972). They ranked thirteenth in abundance out of 16-17 species (five bats among 855 individu¬ 
als) captured in mist nets over ponds during 1970 at Nogal Canyon in the San Mateo Mountains, 
Socorro County, New Mexico, in habitats described as pinon-juniper, pine-oak woodlands, and 
mixed-conifer forest (Black, 1974). Somewhat farther south, Jones (2016) documented bats 
captured during surveys of the Greater Gila region of Catron, Grant, and Sierra counties of New 
Mexico; they ranked second-to-least abundant, with two captures among 282 individuals of 16-17 
species (Jones, 2016). This species ranked fourteenth among 21 species (15 bats among 1,752 indi¬ 
viduals) captured over water during 2006 at sites with previous records throughout their range in 
New Mexico (Geluso, 2006, 2017). 
Central Rocky Mountains: Utah: Allen’s big-eared bat ranked twelfth in relative abundance 
of 15 species (nine individuals out of 572 bats) in the Henry Mountains of southeastern Utah, 
where they were netted over water at 1,439 to 2,396 meters elevation (Mollhagen and Bogan, 
1997). At Arch Canyon on the Colorado Plateau, also in southeastern Utah, these bats were among 
the least abundant species, with one bat captured out of 295 individuals of 15 species taken at ele¬ 
vations ranging from 1,474 to 1,707 meters (Mollhagen and Bogan, 2016). 
Foraging and Dietary Analysis.— The flight of Allen’s big-eared bat was described as 
slow and direct (Jones, 1961), although they can show agile flight in confined spaces (Commis- 
saris, 1961). They were observed foraging around pinon pine trees at White Rock Spring, Red Rock 
Canyon in the Spring Mountains, Clark County, Nevada. At this location they also were seen to for¬ 
age slowly, hover near vegetation, and occasionally attack small insects in or on the vegetation 
(Simmons and O’Farrell, 1977). They produce distinctive, loud audible calls in flight (Jones, 1961; 
Barbour and Davis, 1969; Simmons and O’Farrell, 1977) and were reported to fly at heights of 
about 10 meters above ground during general observations in New Mexico (Barbour and Davis, 
1969). These bats were categorized as moth strategists and between-, within-, and below-canopy 
foragers in dietary analysis of bats sampled in the San Mateo Mountains of New Mexico (Black, 
1974). Moths were the only dietary component noted in fecal analysis of a small sample of indi¬ 
viduals from ponderosa pine forests of northern Arizona (Warner, 1985). Ross (1964, 1967) exam¬ 
ined digestive-tract contents from 25 bats taken in New Mexico and Arizona. Microlepidopterans 
six to 12 millimeters in length were the predominant food group, but other groups also identified 
included beetles and flying ants, the latter suggesting opportunistic foraging on swarms (Ross, 
1964, 1967). Lepidopterans constituted 98% by volume and 100% in frequency of fecal pellets 
sampled from 13 individuals in southwestern New Mexico, with coleopterans only a very minor 
component (Geluso, 2006). 
Roosting Habits. — Winter Roosts: Little is published about the winter roosts of Allen’s 
big-eared bat. Three specimens were obtained from a mine in southwestern New Mexico during 
December (Jones, 2016). Mist netting of bats over water during winter months in central and south¬ 
ern New Mexico yielded only one (during March), although intermittent activity of 11 other species 
was detected from November to March including captures of 401 individuals (Geluso, 2007). Indi¬ 
viduals roosting in a northwestern Arizona mine tunnel during mid- to late September were 
described as “sluggish” and “extremely fat” but did not use this roost during winter (Cockrum and 
Musgrove, 1964a:473). 
Warm Season Roosts: The first roost of Allen’s big-eared bats found in the U.S. was located 
among boulder and rubble piles within a cave in the Chiricahua Mountains of southeastern Arizona 
(Commissaris, 1961). About 30 individuals were observed in this situation during August 1958, 
along with fringed myotis and Townsend’s big-eared bats; 14 Allen’s big-eared bats were captured, 
all females and volant juveniles, indicating that the roost housed a small maternity colony. Visits 
to the site the subsequent year during February, May, and late August failed to find this species 
