DOI: 10.5061/dryad.9cnp5hqhg
title: Data and code from: Opposite, but insufficient, phenological responses to climate in two circumpolar seabirds: relative roles of phenotypic plasticity and selection

description: The magnitude of climate change has been greatest in the Arctic,
 accelerating climate-induced shifts in phenology, but wildlife responses
 vary. Variation may be due to the relative importance of phenotypic
 plasticity or phenotypic selection. Here, we examine and contrast the
 environmental drivers of plasticity in breeding phenology of two
 circumpolar seabirds at their receding summer range limit using unique
 datasets of marked individuals covering 25 and 30 years. Based on prior
 knowledge of the local ecosystems, we predicted that climate would
 generate opposing patterns of plasticity in the two populations. Laying
 phenology of kittiwakes in the Gulf of Alaska was associated with a
 large-scale climate oscillation (Pacific Decadal Oscillation) while the
 Arctic-breeding murres adjusted laying to sea-ice conditions. Kittiwakes
 laid earlier after experiencing colder climate about two years prior and
 laying dates did not advance over the study, but murres laid earlier when
 warmer climate led to earlier spring sea-ice break-up, and murre laying
 dates advanced by one week since 1990. Selection favoured earlier laying
 in both species. Both populations adjusted breeding phenology to
 environmental variation, but we anticipate opposing effects on phenology
 with continued climate change. Ice-constrained species can likely adapt to
 some extent because plasticity can provide the necessary shift to this
 physical barrier, although individuals were only able to adjust by ~one
 week while ice conditions advanced by over a month. In more temperate
 regions, where phenology is driven by bottom-up effects, plasticity and
 selection counteract one another leading to limited adaptability. We
 provide insights into the likely adjustments by Arctic marine animals to
 an increasingly warmer and ice-less summer.
description: Black-legged kittiwake laying phenology and breeding
 success data were collected on Middleton Island, Alaska
 Thick-billed murre laying phenology and breeding success data
 were collected on Coats Island, Nunavut Middleton
 Island climate/environmental data, collated to monthly
 resolution Coats Island climate/environmental data,
 collated to monthly resolution Detailed
 methods are described in: Whelan, S., Hatch, S.A., Gaston, A.J.,
 Gilchrist, H.G., & K.H. Elliott. Opposite, but insufficient,
 phenological responses to climate in two circumpolar seabirds: relative
 roles of phenotypic plasticity and selection. <em>Functional
 Ecology.</em>
description: For both species, we included complete data for first
 breeding attempts only Each excel workbork includes a
 sheet that describes each variable Code used for
 analysis is also included; the code relies on the variable names used in
 the workbook Detailed methods are
 described in: Whelan, S., Hatch, S.A., Gaston, A.J., Gilchrist, H.G.,
 & K.H. Elliott. Opposite, but insufficient, phenological responses
 to climate in two circumpolar seabirds: relative roles of phenotypic
 plasticity and
 selection. <em>Functional Ecology</em>.