GECCO: Forest proximity enhances bat activity in Midwestern agricultural fields

Study Purpose
This dataset supports a study investigating how agricultural field size, field isolation, and insect density influence bat acoustic activity patterns in the Midwest United States. The primary hypothesis was that overall bat activity decreases with distance from the nearest tree line, but that the rate of decrease varies among phonic groups.

Study Area and Sampling Design
Fieldwork was conducted across 20 agricultural fields located in Vigo, Vermillion, Owen, and Sullivan counties, Indiana, between June 6 and September 15, 2018. Sampling was divided into two seasonal sets (early and late season) based on historical local temperature trends. Each set contained seven sampling periods, with three fields sampled during each period over four consecutive nights.

Data Collection Methods
At each field, two Anabat SD2 bat detectors and two passive blacklight insect traps were deployed: one at the tree line and one at the most isolated point in the field (farthest from woody vegetation). Each bat detector was paired with an insect trap.
Bat calls were classified into phonic groups (Low, Mid, Myotis) using BCID Eastern USA version 4.7d (Bat Call Identification, Inc., Kansas City, Missouri). Insect samples were manually identified to the order level.

Environmental Data Collection
Temperature data were recorded using HOBO Pendant® Temperature/Light 8K loggers placed at the tree line. If a logger malfunctioned (one logger failed after August 24, 2018), temperature records from the nearest weather station (wunderground.com) were substituted.

Landscape Analysis
Land cover within a 0.5-kilometer radius of each bat detector was classified using the LAND_COVER_2011_USGS_IN dataset (30-meter resolution; a subset of the 2011 USGS National Land Cover Database). Spatial analyses, including buffer creation and landscape extraction, were conducted in ArcMap version 10.1 (Esri, Redlands, California).

Data Analysis
Generalized linear mixed models (GLMMs) were developed using bat acoustic activity as the response variable and landscape features, abiotic conditions (temperature), and biotic factors (insect abundance) as explanatory variables. The study found that proximity to the nearest tree line significantly influenced bat activity across phonic groups, with Low, Mid, and Myotis bats all showing a strong preference for tree-adjacent areas.