In addition to dBZ, bird counts were estimated from radar, for which a time series can be found in Figure 15 of the supplemental section. While difficult to verify, a baseline of about 100 birds was found in the study area, with night time peaks regularly reaching 700 - 2500 birds. As birds cannot be tracked and there not summed over time, this does give a preliminary view into the number of birds affected. Peaks are especially high in this time series due to the log nature of dbZ, with spikes in night time migration that are not unreasonably high given large bird estimates in other studies (Van Doren, 2017).
Next, bird density vs. brightness across space were correlated, at each time step. This helps answer the question of whether at any given instant in time, brighter areas are more (or less) likely to have more birds.