Bats respond negatively to increases in the amount and homogenization of agricultural land cover
Agricultural intensification has led to widespread declines in biodiversity. An important component of agricultural intensification in many regions, including eastern Ontario, is the shift from grazing lands and perennial forage crops to annual row crops, with associated increases in use of pesticides.
We predicted that bat abundance and diversity would be lower in sites surrounded by landscapes with more agriculture and where the agriculture was dominated by annual row crops rather than perennial forage crops.
We assessed bat occurrence and relative bat abundance with acoustic bat recorders at the centres of 32 landscapes that varied in (1) the proportion of agriculture and (2) the proportion of agriculture that is in annual row crops versus perennial forages (pasture and hay).
Consistent with our first prediction, the abundance or presence of four bat species, total bat abundance and bat species richness declined with increasing agricultural cover in the surrounding landscape. Inconsistent with our second prediction, the abundance of three bat species, total bat abundance and bat species richness were greatest where the proportion of agriculture in annual crops was about equal to the proportion in perennial forage in the surrounding landscape.
Based on these results, bat abundance and richness can be increased in agricultural landscapes by reducing the conversion of natural areas to agriculture and by maintaining a balance of perennial forage and annual crop types. We speculate that farmlands with a diversity of crop types provide a more temporally stable supply of insect food for bats.
KeywordsChiroptera Landscape context Landscape composition Scale of effect Agricultural intensification Multi-scale analysis
We would like to thank Kevin Hannah, Elyse Howat, and Russ Weeber at the Canadian Wildlife Service (CWS) for performing the landscape selection work that provided us with candidate sites to choose from. We are also grateful to Laurens Put and Michelle Vala for their assistance with fieldwork, Charles Francis (CWS, ECCC) for his constructive comments and access to the bat recorders, Scott Wilson (WRD, ECCC) for his role in developing the project, and Dan Bert for logistical support. Thanks to Kevin Ethier and Liv Monck-Whipp for their advice on acoustic bat sampling, and again to Kevin for allowing us to use his QDFA model. We also acknowledge Amanda Adams, Lauren Hooton and Brock Fenton for providing the reference bat passes that the QDFA model uses. This work was supported by Natural Sciences and Engineering Council of Canada (NSERC) grants to LF and by Environment and Climate Change Canada.
- Adams AM (2013) Assessing and analyzing bat activity with acoustic monitoring: challenges and interpretations. Dissertation, The University of Western OntarioGoogle Scholar
- Agriculture and Agri-Food Canada (AAFC) (2013) Annual crop inventory 2013. Government of Canada. http://open.canada.ca/data/en/dataset/4b1d45b0-5bfe-4c6d-bcd3-96c9d821ad3b. Accessed 5 May 2016
- Agriculture and Agri-Food Canada (AAFC) (2017) Annual crop inventory 2016. Government of Canada. http://open.canada.ca/data/en/dataset/b8e4da73-fb5f-4e6e-93a4-8b1f40d95b51. Accessed 1 Mar 2017
- Barton K (2014) Package “MuMIn”: multi-model inference. R package. Version 1.9.13. https://CRAN.R-project.org/package=MuMIn
- Bruinsma J (2009) The resource outlook to 2050: by how much do land, water and crop yields need to increase by 2050. In: Proceedings of a technical meeting of experts, Rome, Italy, 24–26 June 2009, Food and Agriculture Organization of the United Nations (FAO), pp 1–33Google Scholar
- Fahrig L, Arroyo-Rodríguez V, Bennett JR, Boucher-Lalonde V, Cazetta E, Currie DJ, Eigenbrod F, Ford AT, Harrison SP, Jaeger JAG, Koper N, Martin AE, Martin J-L, Metzger JP, Morrison P, Rhodes JR, Saunders DA, Simberloff D, Smith AC, Tischendorf L, Vellend M, Watling JI (2019) Is habitat fragmentation bad for biodiversity? Biol Conserv 230:179–186CrossRefGoogle Scholar
- Farm & Food Care Ontario (2015) Survey of pesticide use in Ontario, 2013/2014 estimates of pesticides used on field crops and fruit and vegetable crops. Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), GuelphGoogle Scholar
- Harvey MJ, Altenbach JS, Best TL (2011) Bats of the United States and Canada. John Hopkins University Press, BaltimoreGoogle Scholar
- Hooton LA (2010) Identifying critical stopover sites for migratory bats. Dissertation, The University of Western OntarioGoogle Scholar
- Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) (2017) http://www.omafra.gov.on.ca/english/stats/agriculture_summary.htm#area. Accessed 1 Aug 2017
- Put JE, Fahrig L, Mitchell GW (2017) Data from: bats respond negatively to increases in the amount and homogenization of agricultural land cover. Mendeley Data, v1. https://doi.org/10.17632/b2mfw6fgyy.1
- R Core Team (2017) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. https://www.R-project.org/
- Skaug H, Fournier D, Bolker B, Magnusson A, Nielsen A (2016) Generalized linear mixed models using “AD Model Builder.” R package version 0.8.4Google Scholar
- Werling BP, Dickson TL, Isaacs R, Gaines H, Gratton C, Gross KL, Liere H, Malmstrom CM, Meehan TD, Ruan L, Robertson BA, Robertson GP, Schmidt TM, Schrotenboer AC, Teal TK, Wilson JK, Landis DA (2014) Perennial grasslands enhance biodiversity and multiple ecosystem services in bioenergy landscapes. Proc Natl Acad Sci USA 111:1652–1657CrossRefGoogle Scholar