Table 3.
Results of GLMMs of the variation in the acoustic properties of soundscapes.
| Fixed effects | North America | Europe | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Estimate (SE) | χ2 | DF | p | Estimate (SE) | χ2 | DF | p | ||
| (a) ADI | Latitude | 0.00002 (0.00088) | 0.03 | 1 | 0.856 | −0.0004 (0.0005) | 0.78 | 1 | 0.376 |
| Longitude | 0.00002 (0.00035) | 0.19 | 1 | 0.659 | 0.0005 (0.0003) | 3.57 | 1 | 0.059 | |
| Year | −0.00198 (0.00068) | 8.46 | 1 | 0.004 | −0.0073 (0.0030) | 5.98 | 1 | 0.014 | |
| (b) AEI | Latitude | −0.00001 (0.00009) | 0.01 | 1 | 0.949 | −0.0005 (0.0005) | 1.25 | 1 | 0.263 |
| Longitude | −0.00009 (0.00003) | 0.08 | 1 | 0.782 | −0.0005 (0.0003) | 2.84 | 1 | 0.092 | |
| Year | 0.00144 (0.00057) | 6.47 | 1 | 0.011 | 0.0053 (0.0030) | 3.08 | 1 | 0.079 | |
| (c) BI | Latitude | 0.00004 (0.00009) | 0.16 | 1 | 0.691 | −0.0002 (0.0005) | 0.25 | 1 | 0.621 |
| Longitude | 0.00002 (0.00003) | 0.44 | 1 | 0.508 | 0.0004 (0.0003) | 2.26 | 1 | 0.132 | |
| Year | −0.00217 (0.00088) | 6.08 | 1 | 0.014 | −0.0056 (0.0021) | 6.91 | 1 | 0.009 | |
| (d) H | Latitude | 0.00010 (0.00009) | 1.38 | 1 | 0.239 | −0.0004 (0.0005) | 0.86 | 1 | 0.353 |
| Longitude | 0.00006 (0.00004) | 3.19 | 1 | 0.074 | 0.0006 (0.0003) | 4.65 | 1 | 0.031 | |
| Year | −0.00625 (0.00175) | 12.79 | 1 | <0.001 | −0.0095 (0.0030) | 10.01 | 1 | 0.002 | |
Annual values for each acoustic index were standardised at the site-level prior to analyses.
(a) Acoustic Diversity Index (ADI), (b) Acoustic Evenness Index (AEI), (c) Bioacoustic Index (BI) and (d) Acoustic Entropy (H) in 202737 NA-BBS sites across North America between 1996 and 2017 and in 16524 PECBMS sites across Europe between 1998 and 2018.