Expected distributional shifts in warming regions are poleward and upward range
shifts. Studies on these shifts fall mainly into two types: (a) those that infer large-scale
range shifts from small-scale observations across sections of a range boundary (with
the total study area often determined by a political boundary such as state, province, or
country lines) and (b) those that infer range shifts from changes in species’ composition
(abundances) in a local community. Studies encompassing the entire range of a species,
or at least the northern and southern (or lower and upper) extremes, are few and have
been concentrated on amphibians (Pounds et al. 1999, 2006), a mammal (Beever
et al. 2003), and butterflies (Parmesan 1996, Parmesan et al. 1999). The paucity of
whole-range studies likely stems from the difficulties of gathering data on the scale
of a species’ range—often covering much of a continent.