O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
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in a southern Arizona cliff swallow nest in September (Hayward, 1970). They also have been found 
roosting in nests of cave swallows (Petrochelidon fulva ) in twos and threes during December in 
central Texas (Ritzi et al., 1998). 
Night Roosts: Cave myotis often utilize night roosts, which may differ in location from diur¬ 
nal roosts, after filling their stomachs early in the night. Night roosts may be in caves, mines or 
buildings, and bats may night roost as singletons or in smaller clusters than they usually form in 
the daytime. They also may rest in trees for brief periods at night (Caire et al., 1984). This species 
will share night roosts with other species of bats (Barbour and Davis, 1969; Easterla, 1973). 
Population Ecology. — Litter Size, Natality, and Female Reproduction: Copulation 
occurs in autumn and winter, with sperm storage followed by ovulation and fertilization in spring. 
Single embryos were found in each of 36 pregnant females sampled in Arizona (Hayward, 1961, 
1970) and 39 females sampled from locations in Texas and Arizona (Krutzsch, 2009). One young 
is born annually in early summer in Kansas (based on 43 dissections with single embryos), with 
most females giving birth fairly synchronously over a compressed period of about two weeks 
(Kunz, 1973). In Oklahoma, the parturition period lasts about four weeks, from approximately the 
second week of June through the second week of July, with the majority of births occurring in the 
middle two-week period, similar to Kansas populations (Loucks and Caire, 2007). Two pregnant 
females brought into captivity in Kansas each produced singletons (Twente, 1955b), and four 
females from Kansas each had single embryos (Dunnigan and Fitch, 1967). Two females from Ari¬ 
zona each had single embryos (Cockrum, 1955), as well as one female taken in Jalisco, one taken 
in Chihuahua, one taken in Sinaloa, and nine taken in Durango, Mexico (Jones et al., 1962; Jones, 
1963; Bradley and Mauer, 1965; Watkins et al., 1972). Twinning also can occur, with five of seven 
females examined in southern New Mexico having a single fetus and two females having twins 
(Geluso and Geluso, 2004). Females become sexually mature in their first year of life in Texas 
(Krutzsch 2009), and all of 39 females banded as juveniles were found to be pregnant or lactating 
the subsequent year at a maternity roost in Kansas (Kunz, 1973). The sex ratio of 474 volant young 
at an Oklahoma maternity roost was 1:1 (Loucks and Caire, 2007). 
Natality at maternity colonies was nearly 100% in a Kansas study (Kunz, 1973) and 96% in 
Oklahoma (Humphrey and Oli, 2015). Seven bats were reproductive in a sample of 10 females 
(70%) mostly taken over water at Big Bend National Park in Texas (Easterla, 1973). Nine of ten 
females (90%) collected at unspecified locations in Durango, Mexico, were reproductive (Jones, 
1963). Four of six females examined in Kansas in 1964 were pregnant (Dunnigan and Fitch, 1967). 
Survival: In a metapopulation covering multiple caves in a 186-square-kilometer core area 
studied in northwestern Oklahoma during the 1960s and 1970s, estimated apparent survival was 
lowest the first six months post-weaning (Humphrey and Oli, 2015), a pattern similar to that seen 
in other species of bats (for examples see reviews in O’Shea et al., 2004, 2010). Survival increased 
over the first half of the lifespan, then declined (Humphrey and Oli, 2015). Apparent survival esti¬ 
mates for the northwestern Oklahoma population studied by Humphrey and Oli (2015) varied by 
sex and time, with females having higher apparent survival than males, and annual rates ranging 
between about 0.5 and greater than 0.70 in unknown-age females, depending on year. 
Minimum-number-alive survival rates (biased by banding effects in a declining population) in 
a northwestern Texas study conducted during 1957-1963 suggested a maximum mortality of about 
80% in the first year of life, annual survival of 0.47, and that most bats in the population were less 
than three years old with a maximum age of six years (Tinkle and Patterson, 1965). These survival 
estimates appear unsustainable (see review in O’Shea et al., 2011c) but possibly may include per¬ 
manent emigration, banding-caused mortality (Hitchcock, 1965; O’Shea et al., 2004), or other 
