Abstract
<jats:p>Anthropogenic warming is expected to produce smaller bodies and relatively longer appendages in endotherms. We tested these predictions using century spanning museum series of European ground squirrels (Spermophilus citellus) from eastern Austria. Adult head–body length (HBL) was compiled from records; hindfoot, femur, humerus and skull were measured with callipers. Among 18 candidate climate metrics, an eight year moving average of annual maximum temperature with a three year lag best explained morphology. Linear mixed effects models showed HBL declined with increasing temperature (about 2.4% per 1°C). In contrast, appendages tended to lengthen with temperature in absolute terms, and most ratios to HBL increased, with strongest support for hindfoot/HBL and skull/HBL. Skull length also increased with temperature, both absolutely and relative to HBL. Males were larger in absolute measures, but sex differences were weak or not present for ratios. These findings document temperature associated morphological changes consistent with Bergmann’s and Allen’s rules in this endangered rodent.</jats:p>