DOI: 10.5061/dryad.2v6wwpzkn
title: Climate effects on nesting phenology in Nebraska turtles

description: A frequent response of organisms to climate change is altering the timing
 of reproduction. In particular, advancement of reproductive timing has
 been a common response to warming temperatures in temperate regions. Over
 the past three decades in Nebraska, USA, the timing of nesting of the
 Common Snapping Turtle (Chelydra serpentina) was negatively correlated
 with mean December maximum temperatures of the preceding year and mean May
 minimum and maximum temperatures in the nesting year, and positively
 correlated with precipitation in July of the previous year. Increased
 temperatures during the late winter and spring likely permit earlier
 emergence from hibernation, increased metabolic rates and feeding
 opportunities, and accelerated vitellogenesis, ovulation, and egg
 shelling, all of which could drive earlier nesting. However, for the
 Painted Turtle (Chrysemys picta), the timing of nesting was positively
 correlated with mean minimum temperatures in September, October, December
 of the previous year, February of the nesting year, and April
 precipitation. These results suggest warmer fall and winter temperature
 may impose an increased metabolic cost to painted turtles that impedes
 fall vitellogenesis, and April rains may slow the completion of
 vitellogenesis through decreased basking opportunities. For both species,
 nest deposition was highly correlated with body size, where larger females
 nested earlier in the season. Although average annual environmental
 temperatures have increased over the last four decades at our study site,
 spring temperatures have not yet increased, and hence, nesting phenology
 has not advanced at our site for Chelydra. While Chrysemys exhibited a
 weak trend toward later nesting, this response was likely due to increased
 recruitment of smaller females into the population due to nest protection
 and predator control (Procyon lotor) in the early 2000s. Should climate
 change result in an increase in spring temperatures, nesting phenology
 would presumably respond accordingly, conditional on body size variation
 within these populations.
description: Three data sets are included: 1) climate data during study period
 at field site; 2) nesting phenology and associated data for painted
 turtles; and 3) nesting phenology and associated data for snapping
 turtles.  Raw data for each data set are included here.
description: Climate Data set: Weather data from July of the
 previous year through May of the year of turtle nesting were obtained from
 the NOAA weather station located immediately adjacent to the turtle
 nesting area (&lt; 100 m).   We tabulated monthly mean maximum (max)
 and monthly mean minimum (Min) temperatures and monthly rain for each
 month (3-letter abbreviations) for each year of the study (33 total
 variables).  We did not include data from June since that is the primary
 month of nesting.  All data are in °F or  inches of rain, as downloaded
 from the weather station. Nesting
 phenology data sets:  Abbreviations include CL (carapace length in mm), PL
 (plastron length in mm), BM (body mass in grams), CS (clutch size), and EM
 (egg mass in grams).