DOI: 10.5061/dryad.05qfttf4h
title: Microclimate-driven trends in spring-emergence phenology in a temperate reptile (Vipera berus): Evidence for a potential 'climate trap'?

description: Climate change will increase the exposure of organisms to higher
 temperatures, but can also drive phenological shifts that alter their
 susceptibility to conditions at the onset of breeding cycles. Organisms
 rely on climatic cues to time annual life-cycle events, but the extent to
 which climate change has altered cue reliability remains unclear. Here, we
 examine the risk of a ‘climate trap’ – a climatically-driven
 desynchronisation of the cues that determine life-cycle events and fitness
 later in the season in a temperate reptile, the European adder (Vipera
 berus). During the winter, adders hibernate underground, buffered against
 sub-zero temperatures, and re-emerge in the spring to reproduce. We
 derived annual spring-emergence trends between 1983 and 2017 from
 historical observations in Cornwall, United Kingdom, and related these
 trends to the microclimatic conditions that adders experienced. Using a
 mechanistic microclimate model, estimates of below- and near-ground
 temperatures were used to derive accumulated degree-hour and absolute
 temperature thresholds that predicted annual spring-emergence timing.
 Trends in annual emergence timing and subsequent exposure to ground frost
 were then quantified. We found that adders have advanced their phenology
 towards earlier emergence. Earlier emergence was associated with increased
 exposure to ground frost and, contradicting the expected effects of
 macroclimate warming, increased post-emergence exposure to ground frost at
 some locations. The susceptibility of adders to this ‘climate trap’ was
 related to the rate at which frost risk diminishes relative to advancement
 in phenology, which depends on the seasonality of climate. We emphasise
 the need to consider exposure to changing microclimatic conditions when
 forecasting biological impacts of climate change.
description: This spreadsheet contains
 nine tabs to present the data used in the
 article 'Microclimate-driven trends in spring-emergence phenology in
 a temperate reptile (<em>Vipera berus</em>): Evidence for a
 potential ‘climate trap’?' (Turner & Maclean, 2022;
 <em>Ecology and Evolution</em>). The first tab, labelled
 'Metadata_README', contains metadata for the dataset, including
 identification and affliliations of the authors, a description of the tabs
 in the spreadsheet, and descriptions of data labels used in the
 spreadsheet tabs. The second tab, labelled 'adder_sightings',
 comprises of records of <em>Vipera berus</em> (adder)
 sightings in Cornwall, United Kingdom, sourced from the Environmental
 Records Centre for Cornwall and the Isles of Scilly (www.erccis.org.uk),
 the Record Pool (www.recordpool.org.uk) and the Cornish Biodiversity
 Network (www.cornishbiodiversitynetwork.org). Due to data sensitivities
 and issues associated with the General Data Protection Regulation,
 information pertaining to the locations and dates of adder sightings in
 some instances in the dataset have only be provided at reduced spatial and
 temporal resolutions. A unique identification code for locations has been
 attributed to records. For full-resolution access, contact the data
 custodian and corresponding author. The raw datasets of adder sightings
 were filtered prior to inclusion in the analysis in Turner and Maclean.
 See the main text for all filtering procedures and microclimate modelling.
 The remaining tabs contain data relating to each adder sighting location
 in 'adder_sightings' for each year 1983 - 2017 computed from
 microclimate models using the <em>microclima </em>R package
 (Maclean et al., 2019). The third tab, labelled
 'total_spring_frost', contains annual rates of spring ground
 frost. The fourth, fifth and sixt tabs, labelled 'Cue1(i)',
 "Cue1(ii)', and 'Cue1(iii)', each contain predicted
 annual adder emergence timing and computed rates of post-emergence spring
 ground frost using the 5th, 2.5th and 10th percentile thresholds,
 respectively, of an accumulated (degree-hours) temperature cue for adder
 emergence. The seventh tab, labelled 'Cue2', contains predicted
 annual adder emergence timing and computed rates of post-emergence spring
 ground frost using a sharp rise in accumulated (degree-hours) temperature
 cue for adder emergence. The eighth tab, labelled
 'Cue3', contains predicted annual adder emergence timing and
 computed rates of post-emergence spring ground frost using a below-ground
 temperature gradient collapse cue for adder emergence. Lastly, the ninth
 tab, labelled 'Cue4', contains predicted annual adder emergence
 timing and computed rates of post-emergence spring ground frost using a
 critical air temperature (10°C) cue for adder emergence. The main text
 presents the analysis of adder emergence and spring ground frost data from
 the 'Cue1(i)'. Analysis of data from 'Cue1(ii)',
 'Cue1(iii)', 'Cue2', 'Cue3', and
 'Cue4' are presented in the Supplementary Information for Turner
 and Maclean.