Population variability
For all three groups, we found a significant negative relationship
between the log-transformed detrended variability in population change
and years to extinction (Table 2; Fig. 2), showing that year-to-year
population variability does indeed increase as extinction is approached.
In relation to body size, all our models suggest that the magnitude of
annual population variability is higher as body size decreases (Table 2;
Fig. 2). An interaction between body size and years to extinction was
included in the best fitting models, or those within two AIC units
thereof (Table 2). This interaction was significant and negative in the
non-avian subset (Table 2), suggesting a greater increase in variability
in larger-bodied taxa.