O’SHEA, CRYAN & BOGAN: UNITED STATES BAT SPECIES OF CONCERN 
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water in 1968 and 1970 (LaVal, 1973), but subsequent work could not confirm the existence of a 
resident colony (Genoways et al., 1979). Easterla (1973) reported a few colonies in cliffs in Big 
Bend National Park in Texas, and at least two colonies were known from New Mexico (Findley et 
al., 1975). As noted above under the section on roosting habits, more-recent studies have confirmed 
the presence of a few maternity colonies in Arizona (Corbett et al., 2008), Colorado (Navo and 
Gore, 2001; Neubaum, 2017), New Mexico (Bogan et al., 1998), and Utah (Mollhagen and Bogan, 
2016). None of these colony sites have been regularly monitored since their discovery. 
Management Practices and Concerns. — In northern Arizona and similar arid areas sub¬ 
ject to drought, maintenance of larger (at least 14 meters diameter) artificial ponds by land man¬ 
agers for grazing livestock is important for provision of water resources for big free-tailed bats 
(Corbett et al., 2008), perhaps especially for lactating females. Similar recommendations are appli¬ 
cable to other areas within the range of this and other species of concern. Too little is known about 
the ecology of this species to predict consequences of various other land management practices on 
their populations. The need for high, steep cliffs for breeding would suggest curtailment of human 
activities that could cause disturbance (such as blasting or recreational climbing) might be consid¬ 
ered near such locations in the known breeding range, especially during summer months when 
maternity colonies are active. Major impoundments could also flood cliff habitats. These bats are 
represented in museum collections from the United States only in small numbers, and requests for 
permits for scientific collecting should be reviewed carefully to insure that the activities do not 
pose a direct threat to colonies. Such was the case in the past. Davis (1974), for example, reported 
acquiring specimens in 1958 by shooting a shotgun several times into the rock crevice occupied by 
female big free-tailed bats in Texas, at the time the only known breeding colony in the United 
States. 
Summary and Highlights 
The amount of information that has been developed about the bat species of concern over the 
past two decades since their informal designation by the U.S. Fish and Wildlife Service (1996a,b) 
is impressive. We believe that several factors have come into play in fostering this increase in 
knowledge. One of the primary factors is the highlighting of these species with this designation by 
state and federal agencies, and by non-govemmental conservation organizations. This focus also 
has benefitted by the general increase in public and scientific interest in bat biology and conserva¬ 
tion, and by advances in research technology available for application to studies of these species of 
concern. Advances include miniaturization of radio transmitters for telemetry, development of field 
acoustic sampling, applications of molecular genetics, and ever-more sophisticated methods of 
quantitative analysis and statistical modeling. It is likely that new technological advances will con¬ 
tinue to be applied toward better understanding of these species. 
Despite advances in knowledge and application of new scientific approaches to research, the 
degree of new information available is unevenly spread among topics and species. As an index to 
recent research, we compiled the numbers of recent papers (2007-2016) we reviewed that were 
based on original data and focused on warm-season roosting habits. Little new information has 
been published about the two bat species of concern in American Samoa and the Caribbean trust 
territories: we found only two papers with original data published on the Samoan flying fox over 
the past decade, and two concerning the red fruit bat. Both of these species roost on tree branches 
in tropical forests. The remaining 18 species of concern in the 50 states were the subjects of about 
320 papers and reports with original data. Even these, however, are unevenly spread among 
species, depending in part on distribution and roosting habits. For example, very little is known 
about western species of concern that roost in high cliffs, and much more is known about hibema- 
