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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
all occupancy estimates were 0.586 ± 0.10 (SE) using the highest-ranking model. This was the low¬ 
est model-averaged occupancy estimate of eight species sampled. Point estimates of occupancy 
tended to be higher in reserve habitat, but greater precision and model certainty would be useful to 
improve all estimates (Weller, 2008). 
Species dynamic distribution models were constructed using Bayesian hierarchical modeling 
techniques for 12 species of bats in Washington and Oregon. The analysis was based on an eight- 
year monitoring program; bat activity was sampled with mist nets and acoustic detectors, and the 
analysis accounted for detectability and annual turnover in bat occurrence (Rodhouse et al., 2015). 
This species did not show a decline in occurrence probabilities with time (Rodhouse et al., 2015). 
Management Practices and Concerns. — Maternity colonies “are very sensitive and 
quickly abandoned if disturbed” (Schmidly, 1991:78). Intentional disturbances should be avoided 
or timed for periods when individuals are absent from roosting places. Replacement of a bridge 
used by a colony during the early maternity season in New Mexico likely resulted in deaths of thou¬ 
sands of Yuma myotis and Brazilian free-tailed bats (Geluso and Mink, 2009). Past efforts by the 
U.S. Army Corps of Engineers to eliminate colonies in crevices of the Davis Dam on the Colorado 
River near Bullhead City, Arizona were reported by Cockrum et al. (1996). To avoid disturbance 
by unauthorized visitors, the National Park Service has erected a large fence around abandoned 
mine shafts, as well as built other bat-compatible closures at Joshua Tree National Park and Lake 
Mead National Recreation Area to protect colonies of this species (Burghardt, 2000). An aban¬ 
doned mine housing a maternity colony of 300-500 Yuma myotis on Bureau of Land Management 
property in southeastern California also has been successfully gated for protection of these bats, as 
have abandoned mines on Imperial National Wildlife Refuge lands in southern Arizona and south¬ 
eastern California (Henry, 2002). However, counts at one mine on the refuge declined substantial¬ 
ly following installation of additional cupolas and gates on upper shafts (Brown, 2013). Knowing 
locations of Yuma myotis maternity colonies in cliffs at Colorado National Monument has helped 
resource management staff there determine the need for seasonal closure of recreational climbing 
routes that intersect or closely approach those sites (Neubaum, 2017). 
Evelyn et al. (2004) noted that size of available roosting trees could be a limiting factor in 
some areas if this species generally prefers roosting in especially large trees, as found in their study 
on the San Francisco Bay peninsula. 
Yuma myotis seem strongly associated with river canyons and may be particularly vulnerable 
to habitat loss from large-scale water impoundments such as reservoirs. Major water development 
projects have the potential to not only reduce productive foraging habitat through submersion but 
also eliminate adjacent roost habitat in rock crevices of canyon walls. 
Nyctinomops macrotis — Big free-tailed bat (Family Molossidae) 
Conservation Status.— National and International Designations: U.S. Fish and Wildlife 
Service (1994, 1996a,b): Species of Concern (inactive, former Category 2 candidate for listing 
under the U.S. Endangered Species Act). Bureau of Land Management (2009a, 2010c, 2011b): 
Sensitive Species (Colorado, Nevada, and Utah state offices). International Union for the Conser¬ 
vation of Nature (2017): Least Concern. NatureServe (2017): Species Rounded Global Ranking 
G5, Secure. 
State Designations: California Department of Fish and Wildlife (2015b, 2017): Special Ani¬ 
mals List, Species of Special Concern. Colorado Parks and Wildlife (2015b): Species of Greatest 
Conservation Need, Tier 2. New Mexico Department of Game and Fish, 2015: Sensitive taxa 
(informal). Texas Parks and Wildlife (2012): Species of Greatest Conservation Need. Utah Divi- 
