Spatial and temporal activity patterns of threatened Kansas bats

Abstract

Insectivorous bats benefit human well-being and save the American farmer billions of dollars (U.S.) in annual pesticide costs through control of insect populations. Bats constitute essential wildlife providing significant ecological services in states with agriculture-based economies, such as Kansas. Recently, many bat species have experienced significant population declines due to factors such as climate change, disease, and wind turbine strikes. Among these bats, four species distributed across the Great Plains were recently identified as species of conservation concern. My thesis research focuses on these species, including the Northern Long-eared Myotis (Myotis septentrionalis), Tri-colored bat (Perimyotis subflavus), Little Brown Myotis (Myotis lucifugus) and Hoary bat (Lasiurus cinereus). These species all occur within Kansas; however, little is known about their spatial and temporal distribution and activity across Kansas. My thesis contributes greater understanding of their biology towards future conservation and management. Using an economic brand of passive acoustic recorders, I surveyed six sites across the course of a summer (May-Aug 2025) focusing on spatial distribution by randomly placing 10 recorders at each site. To assess landscape-level distribution of focal bat species, I used occupancy models based on detection histories collected from 14 nights of surveys from each detector. I found a negative relationship between number of recordings of M. lucifugus and proportion of grassland ([beta]grassland = -2.38, SE = 0.81, n = 143) within 1km; a positive relationship between number of P. subflavus recordings and proportion of woodland ([beta]woodland = 4.78, SE = 1.73, n = 77) within 1 km; and a positive relationship between number of recordings of L. cinereus and the Shannon diversity index ([beta]SHDI = 2.80, SE = 0.63, n = 380) within 1 km. No recordings were positively identified as M. septentrionalis. These results indicate the need for managed native woodlands and landscape heterogeneity across Kansas. Native woodlands are used as roosting and foraging habitat for each imperiled bat species while landscape heterogeneity provides foraging pathways for larger, less maneuverable species, such as L. cinereus. To assess temporal activity, I used a more sensitive passive acoustic recorder across three sites for 10 months (Mar-Dec 2025). I used negative binomial generalized linear models to assess bat activity related to different temporal variables. Day of year with a quadratic term was the best supported model for all species tested except P. subflavus. For this latter species, the top-ranked model was an additive effect between minimum daily temperature and average wind speed ([beta]Tmin = 0.084, SE = 0.022; [beta]wind = -0.359, SE = 0.094, n = 55). When day of year was removed from the model sets, I found temperature was the best supported model for L. cinereus ([beta]Tmin = 0.085, SE = 0.013, n = 401), M. lucifugus ([beta]Tmax = 0.099, SE = 0.013, n = 595), and overall bat activity ([beta]Tmax = 0.191, SE = 0.008, n = 99,577). I again found no recordings that were positively identified as M. septentrionalis. These results can be used to identify when bats arrived and when they were active on the landscape. Refraining from cutting down potential maternity roosts and stopping wind turbine blades during times of high activity can help ensure the continued fitness of threatened bat species within Kansas.