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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
These bats were observed both foraging and drinking over the Gallinas River in northern New 
Mexico (Geluso and Studier, 1979). Although they are typically found in areas near permanent 
water (Findley et al., 1975), near Las Vegas, New Mexico they showed a much greater urine con¬ 
centrating ability after feeding in captivity than little brown myotis from the more humid environ¬ 
ment of Indiana (Geluso, 1975; Bassett and Wiebers, 1979). 
Arizona myotis ranked ninth in relative abundance (a total of 66) among 1,595 bats of 20 
species taken over water in the Mogollon Mountains of western New Mexico and adjacent Arizona, 
where they were found in both xeric shrub grassland and evergreen forest habitats (Jones, 1965). 
In a separate analysis limited to three sites over water in western New Mexico and including addi¬ 
tional years of sampling, Arizona myotis also ranked ninth of 19 species (32 captures among 1,004 
individuals) and were taken at a single streamside site at 2,500 meters elevation in pine-spruce-fir 
forest (Jones and Suttkus, 1972). Geluso and Geluso (2012) reported that this species was the least 
abundant bat (one capture among 1,390 bats and 11 species) taken over a 34-year period at a pond 
in coniferous forest at 2,573 meters elevation in the San Mateo Mountains of New Mexico. Some¬ 
what farther south, Jones (2016) documented bats captured during surveys of the Greater Gila 
region of Catron, Grant, and Sierra Counties of New Mexico; this species ranked low in abundance, 
ranking twelfth, with three captures among 282 captures of 16-17 species (Jones, 2016; including 
data from unpublished reports of others). A survey that took place at 37 sites across several habi¬ 
tat types in much of New Mexico in 2006 yielded 1,752 bats of 21 species with 110 Arizona myotis, 
ranking fifth in relative abundance (Geluso, 2006, 2017). 
Foraging and Dietary Analysis. — Diets of Arizona myotis vary by location, and this is 
reflected in cranial morphology. Food habits were analyzed from three populations, one from 
southern Colorado, one from central New Mexico, and one from southern New Mexico; discrimi¬ 
nant function analyses of 24 cranial measurements also were conducted for specimens from these 
three populations (Valdez and Bogan, 2009). Specimens from southern Colorado were least robust 
in cranial and dental morphology, with thinner jaws, lower coronoid processes, and narrower width 
of individual molars when compared to bats from central or southern New Mexico. The diets of 
bats from southern Colorado consisted mainly of smaller, softer bodied insects, primarily 
hymenopterans (wasps, bees, and ants) and dipterans (midges), consistent with their less robust cra¬ 
nial morphology, whereas bats from central New Mexico ate significantly more hard-bodied bee¬ 
tles and fewer soft-bodied hymenopterans. Diets of individuals from southern New Mexico were 
not collected following the same procedures as in the other two populations, but composition was 
similar to the diet in central New Mexico, with coleopterans predominant and hymenopterans low, 
but with greater representation of lepidopterans (Valdez and Bogan, 2009). The relationship 
between regional dietary differences and cranial robustness was speculated to be a reflection of the 
length of the growing season, which may have impacted abundances of different types of available 
prey (Valdez, 2006; Valdez and Bogan, 2009). Overall the diet included seven orders of insects as 
well as minor numbers of arachnids, with insect orders identified to 18 families (Valdez and Bogan, 
2009). Eight orders of insects were reported in Arizona myotis diets from ponderosa pine forests 
in northern Arizona at 2,600 meters elevation, with lepidopterans at the highest frequency of occur¬ 
rence followed by coleopterans and dipterans (Warner, 1985). 
Roosting Habits. — Winter Roosts: Little is known about winter hibernation sites of Ari¬ 
zona myotis, although it is suspected that hibemacula are not far from summer sites (for example, 
Findley et al., 1975; Geluso, 2007). Unpublished records exist for small numbers of individuals 
hibernating in a mine in southeastern California and in a mine in Sonora, Mexico (Arizona Game 
and Fish Department, 2011). Mist netting of bats during winter months in central and southern New 
Mexico yielded only one individual (in late March), although intermittent activity of 11 other 
