All five tree species expressed unique patterns of phenology, but generally phenological traits were positively correlated (Fig. 1; all leaf-all flower: Pearson26 = 0·809, P < 0·001; all leaf-all fruit: Pearson26 = 0·583, P = 0·002; all flower-all fruit: Pearson26 = 0·499, P = 0·009). Migrant diversity and abundance were positively correlated with the combined flower phenology of all tree species (Fig. 1; diversity: all flower: F1,26 = 13·049, P = 0·02; date F1,26 = 0·035, P = 0·853; year: F3,26 = 4·693, P = 0·012; abundance: all flower: F1,26 = 8·024, P = 0·010; date F1,26 = 0·406, P = 0·531; year: F3,26 = 1·998, P = 0·147). However, when examined independently, only the flowering phenology of honey mesquite correlated with both diversity and abundance of migrants (Fig. 1; diversity: HOME flower: F1,26 = 18·447, P < 0·001; date F1,26 = 0·566, P = 0·461; year: F3,26 = 5·099, P = 0·009; abundance: HOME flower: F1,26 = 9·622, P = 0·006; date F1,26 = 0·085, P = 0·773; year: F3,26 = 1·916, P = 0·159), although the flowering phenology of screwbean mesquite did correlate with diversity (diversity: SCME flower: F1,26 = 13·418, P = 0·002; date F1,26 = 2·131, P = 0·161; year: F3,26 = 2·741, P = 0·072).
Figure 1. Tree phenology and migrant diversity and abundance change in concert. Tree species expressed diverse phenological patterns, but generally, leaf, flower, and fruit development were highly correlated (b–g). While migrant diversity and abundance (a) correlated with the average leaf and flower phenology of all tree species (b), only the flowering phenology of honey mesquite (f) predicted migrant diversity and abundance independently. For ease of comparison, graphs present mean phenology and migrant diversity and abundance of eight periods throughout the spring, but analyses were conducted on raw data. Error bars indicate SEM across years.
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