Copulation Phenology of Ornate Box Turtles (Terrapene ornata)

Abstract

Many organisms respond to environmental change by altering the timing of various life-cycle events. Understanding an organism's phenology, therefore, is crucial for predicting the effects of anthropogenic impacts such as climate change. Nevertheless, collecting adequate data to test hypotheses in secretive species is difficult, especially for rare behaviors. We integrated data from online citizen science platforms, published literature, and unpublished studies to clarify the seasonal timing of copulation in Terrapene ornata, a behavior that is rarely observed. We identified 132 copulation events involving an estimated 256 individual turtles: 19 instances from 5,465 photo-vouchered observations, 78 from 11 publications, and 35 from radiotracking 267 turtles for 8 yr across five sites. Copulations in T. ornata occurred in every month from April to October, with the fewest records in April and October. We found no copulation records in two months of purported aboveground activity (March and November), suggesting that mating in the wild may not occur at any time during the active season. The frequency of reproductive events exhibited multimodality with evident peaks in May and September. Records from the northern portion of the species' range were most frequent in the spring, whereas southern records were most frequent in the fall. Our approach generated a large number of empirical records for a rare behavior in a secretive species across vast spatial scales, which would not have been possible using any of the individual data sources alone.