5.4.3.1.2. Changes in timing (phenology)
Invertebrates: Warmer conditions during autumn and spring adversely affect
the phenology of some cold-hardy species. Experimental work on spittlebugs (Philaenus
spumarius) found that they hatched earlier in winter-warmed (3°C above ambient)
grassland plots (Masters et al., 1998).
Amphibians: Two frog species, at their northern range limit in the UK, spawned
2-3 weeks earlier in 1994 than in 1978 (Beebee, 1995). These changes were
correlated with temperature, which also showed increasing trends over the same
period.
Birds: Changes in phenology, or links between phenology and climate, have been
noted for earlier breeding of some birds in Europe, North America, and Latin
America (see Table 5-3). Changes in migration also
have been noted, with earlier arrival dates of spring migrants in the United
States (Ball, 1983; Bradley et al., 1999), later autumn departure dates (Bezzel
and Jetz, 1995), and changes in migratory patterns in Europe (Gatter, 1992).
5.4.3.1.3. Changes in morphology, physiology, and behavior
Amphibians and Reptiles: Correlations between temperature and calling rates
have been found in Egyptian frogs (Akef Mamdouh and Schneider, 1995). Indian
tree frogs show differences in behaviors that depend on their level of hydration
(Lillywhite et al., 1998). Painted turtles grew larger in warmer years, and
during warm sets of years turtles reached sexual maturity faster (Frazer et
al., 1993). Physiological effects of temperature, primarily sex determination,
also can occur while reptiles are still within their eggs (Gutzke and Crews,
1988).
Birds: Spring and summer temperatures have been linked to variations in the
size of eggs of the Pied Flycatcher (Ficedula hypoleuca). Early summer mean
temperatures explain ~34% of the annual variation in egg size between the years
1975 and 1994 (see Figures 5-3 to 5-5;
Jarvinen, 1996).
Mammals: Body size is correlated with many life-history traits, including reproduction,
diet, and size of home ranges. North American wood rat (Neotoma spp.) body weight
has shown a significant decline that is inversely correlated with a significant
increase in temperature over the past 8 years (Smith et al., 1998). Juvenile
red deer (Cervus elaphus) in Scotland grew faster in warm springs, leading to
increases in adult body size (Albon and Clutton-Brock, 1988).
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