Table 4. Comparison of acoustic characteristics of solo songs between two periods of time (2011 – 2012, 2018 – 2022) in four populations, and their interaction of white-eared ground-sparrow Melozone leucotis , based on linear mixed-effects models. PC1 correlates with the duration and number of elements, PC2 correlates with the minimum and maximum frequency, and PC3 correlates withthe frequency of maximum amplitude.