Demographic traits of an Eastern Gartersnake, <i>Thamnophis sirtalis sirtalis</i>, population in two different habitats

Abstract

We examined life history traits in Eastern Gartersnakes (Thamnophis sirtalis sirtalis) from two locationsin an urban park in south-central Pennsylvania from 2015 to 2019. The combined sample differed most noticeablyfrom other Pennsylvania populations only in mean clutch size and seasonal activity patterns. Within the park, however,many demographic traits differed between proximate sites. Population size, survivorship, and juvenile recruitment werelower, and catchability and likelihood of entry were higher on a xeric slope that leads to a highway than in a meadow.Variance in mean litter size was higher on the slope and only females from the slope exhibited a positive relationshipbetween maternal body size and litter size. Broadly speaking, individuals from the park fit within many of the patternsassociated with life history traits examined elsewhere in Pennsylvania, but the differences between sites reveal substantialvariation in natural history responses in what otherwise might have been considered a single homogeneous site.