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PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
Survival: Adult survival is a key demographic parameter in bat population dynamics. Some 
form of survival estimation has been applied in studies of six species of concern: Townsend’s big- 
eared bat, southeastern myotis, eastern small-footed myotis, Arizona myotis, cave myotis, and 
Yuma myotis. Four studies conducted during the late 1940s to the early 1960s on Townsend’s big- 
eared bats in California, southeastern myotis in Florida, and cave myotis in the western Great 
Plains calculated simple return rates (which do not account for capture probability) and are of his¬ 
torical interest in understanding likely survival requirements to maintain stable populations of bats. 
A study of eastern small-footed myotis banded at a hibemaculum in Ontario from 1941-1962 was 
the first to use survival estimation techniques that adjusted for capture probability (Cormack-Jolly- 
Seber approaches) on a species of concern. Findings from that analysis showed differential survival 
of males, but estimates for females seem unsustainable and likely were biased by factors such as 
permanent emigration and banding-caused mortality. Use of standard Cormack-Jolly-Seber mod¬ 
els that do not explicitly account for emigration may not be appropriate for monitoring situations 
in which sampling is limited in spatial scope, and such approaches have not been used with species 
of concern. Two studies calculated survival rates retrospectively without estimating emigration. 
One was based on historic records of Townsend’s big-eared bats banded in 1965-1974 and recap¬ 
tured through 1980 in Washington hibemacula, and the second on cave myotis banded at multiple 
caves in Oklahoma during the 1960s and 1970s. Townsend’s big-eared bats in the Washington 
study showed likely differences in survival and capture probabilities by sex as well as time trends, 
with estimates likely influenced by permanent emigration due to disturbance and banding-related 
injury or mortality. The study of cave myotis indicated variable capture probabilities with time, 
higher survival in females, lower survival during the first six months of life, as well as increasing 
survival over the first half of the lifespan, and then declining survival thereafter. Survival estimates 
seemed low in cave myotis, perhaps due to documented major catastrophic flooding of caves and 
freezing events, as well as possible permanent emigration or banding-related mortality. 
Two studies used modem estimation and analytical techniques on more recently marked pop¬ 
ulations of species of concern but without estimation of emigration bias. Survival of banded Ari¬ 
zona myotis roosting in bat boxes in ponderosa pine forests in Arizona was estimated over a seven- 
year period ending 2012. Survival and capture probabilities in Arizona myotis varied by sex and 
year, with female estimates higher than in males. Survival in Yuma myotis populations were esti¬ 
mated in colonies roosting in four bridges in California, two in an area subject to a contaminant 
spill. Apparent survival of adults was unaffected in the spill area and increased at all four roosts 
over the study period (1992-1996), coinciding with increasing habitat recovery from a prolonged 
regional drought; juvenile survival in the area not subject to the spill also increased but was always 
lower than adult survival and was lower in the area of the spill. Survival estimates indicated a 
growing population when incorporated in a stage-based population model. In general, studies are 
lacking that explicitly account for the emigration process when estimating bat survival. Well-estab¬ 
lished, capture-mark-recapture models that model temporary emigration separately from the sur¬ 
vival process can provide more unbiased estimates of survival (for example, Kendall et al., 1997), 
and more complex sampling designs and models have been used to estimate permanent emigration 
(for example, Lindberg et al., 2001; Kendall et al., 2013). To our knowledge, no survival estima¬ 
tion studies have used such models and designs with a focus on contemporary populations of the 
bat species of concern. 
Mortality Factors: Direct mortality factors impact species of concern, but documentation is 
largely anecdotal. Weather events probably have the greatest but highly intermittent effects. Flood¬ 
ing of caves used by southeastern myotis has resulted in deaths of tens of thousands of these bats 
in Florida, as well as of cave myotis in the Great Plains. Deaths of the latter species due to freez- 
