DOI: 10.5066/p134reo7
title: Results and Code From the North American Bat Monitoring Program's (NABat) Integrated Species Distribution and Trend Models for Hoary Bat and Silver-Haired Bat

description: These data contain results and model code from the North American Bat Monitoring Program's (NABat) integrated species distribution and trend models for the hoary bat (Lasiurus cinereus) and silver-haired bat (Lasionycteris noctivagans). These results document population status and trends based on the first continental-scale, comprehensive analysis of NABat data for tree bats (2012–2023), integrating stationary acoustic, mobile transect acoustic, and live-capture data using a web-supported analytical pipeline that applies Bayesian hierarchical modeling and a multi-scale integrated species distribution modeling (MS-iSDM) framework to account for imperfect detection and species misclassification. Results show strong evidence of declines in hoary bat relative abundance (-24% [-46% to -1%] total change), and less severe, more uncertain declines in silver-haired bat (-10% [-39% to 20%] total change) from 2012-2023. Trends in relative abundance (reported as total proportional change and average annual proportional change) were variable across space for both species, spanning a range from substantial declines to substantial increases. The provided tabular data include predictions (with uncertainty) for each species' summer distributions and trends (relative abundance and occupancy probability) based on data from the entire summer season (May 1–Aug 31), for each from 2012-2023. Predictions represent relative abundances and occupancy probabilities in the 'core' pre-volancy season in the summer (June 15 – July 15), i.e., the period of time before juveniles can fly and become detectable. Results are summarized at 4 different spatial scales (Range-wide, state- or province-level, 50 kilometer (km) x 50 km grid-cells, and 5 km x 5 km sub-units (NABat 'quads'). At the 50km grid-cell level, predictions (with uncertainty) are provided for relative abundance each year (2012-2023), and the overall proportional change in relative abundance between 2012-2023. At the sub-unit (5km) level, predictions (with uncertainty) are provided for occupancy probabilities (i.e., probability of presence) each year (2012-2023), and for the overall proportional change in occupancy probability between 2012-2023. At the state- or province-level, average relative abundance (across all grid cells) and average occupancy probability (across all sub-units [i.e., 'quads']) is provided for each state or each province and year. Trend estimates for total proportional change between 2012-2023 are also provided for each state and province for average relative abundance and average occupancy probability, while additional trend metrics (absolute difference of change) between 2012-2023 are provided for average occupancy probability. At the range-wide scale, average relative abundance (across all grid cells) and average occupancy probability (across all sub-units) is provided for each year, along with the overall trends in both metrics from 2012-2023. Predictions at the grid cell (50km x 50km) and sub-unit (5km x 5km, i.e., 'quad') can be cross-referenced to the NABat knitted grid (50km or 5km scales) for analytical or visualization purposes (see related products). Model code was provided to document the JAGS model used to produce the results. Parameter estimates from the final models are also provided for each species.