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Abstract Population monitoring and research are essential for conserving wildlife, but these activities may directly impact the populations under study. These activities are often restricted to minimize disturbance, and impacts must be weighed against knowledge gained. However, few studies have quantified the effects of research or census‐related visitation frequency on populations, and low visitation rates have been hypothesized to have little effect. Hibernating bats have been hypothesized to be especially sensitive to visitation because they have limited energetic stores to survive winter, and disturbance may partly deplete these stores. We examined the effect of site visitation frequency on population growth rates of three species of hibernating bats, little brown bats (Myotis lucifugus), Indiana bats (Myotis sodalis) and tri‐colored bats (Perimyotis subflavus), both before and after detection of the disease white‐nose syndrome. We found no evidence that more frequent visits decreased population growth rates for any of these species. Estimated coefficients were either the opposite sign as hypothesized (population growth rates increased with visitation frequency) or were very small (difference in population growth rates 0.067% [SE 2.5%]–1.8% [SE 9.8%]) relative to spatial and temporal variation (5.9–32%). In contrast, white‐nose syndrome impacts on population growth rates were easily detected and well‐characterized statistically (effect sizes 4.4–8.0; severe population declines occurred in the second and third years after pathogen detection) indicating that we had sufficient power to detect effects. These results indicate that visitation frequency (forM. sodalis:annual vs. semi‐annual counts; forM. lucifugusandP. subflavus:1–3 three research visits per year) had undetectable impacts on bat population growth rates both with and without the additional stress of an emerging infectious disease. Knowledge gained from censuses and research may outweigh disturbance due to human visitation if it can be used to understand and conserve the species.
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The Effect of Venipuncture Site on Hematology of Bats: Implications for Comparative Analyses
Synopsis Wildlife health comparisons within and across populations and species are essential for population assessment and surveillance of emerging infectious diseases. Due to low costs and high informational yield, hematology is commonly used in the fields of ecoimmunology and disease ecology, yet consistency and proper reporting of methods within these fields are lacking. Previous investigations on various wildlife taxa have revealed noteworthy impacts of the vein used for blood collection on hematology measures. However, the impacts of venipuncture site on bats, a taxon of increasing interest in ecoimmunology and disease ecology, have not yet been tested. Here, we use a long-term study system in western Oklahoma to test the effect of venipuncture site on hematology parameters of the Mexican free-tailed bat (Tadarida brasiliensis) and cave myotis (Myotis velifer), two abundant and representative bat species from the families Molossidae and Vespertilionidae. Between September 2023 and October 2024, we collected paired peripheral blood from both the propatagial and intrafemoral veins in 25 individuals per species. We then quantified total red and white blood cells, reticulocyte counts, and leukocyte differentials and used generalized linear mixed models to compare parameters among venipuncture sites within and between bat species. Overall, venipuncture site had no effect on any hematology parameters; however, we revealed small differences in neutrophil and lymphocyte proportions between veins among the species. By contrast, we detected significant species-level differences in most cell measurements, which we propose could be explained by life-history strategy and phylogenetic differences. We encourage continued testing of additional venipuncture sites, and of the same venipuncture sites on different species, on hematology and other health metrics used in ecoimmunology and disease ecology. Lastly, we emphasize the importance of thorough method reporting in publications to enable transparent comparisons and accounting for even small sampling-based artifacts. All future efforts are especially important for bats to improve conservation monitoring, ecosystem services estimations, and their association with emerging infectious diseases.
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- Award ID(s):
- 2515340
- PAR ID:
- 10598034
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Integrative And Comparative Biology
- ISSN:
- 1540-7063
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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