DOI: 10.5061/dryad.6276d
title: Data from: Plasticity in incubation behavior and shading by king rails (Rallus elegans) in response to temperature

description: King rails experience a wide range of temperatures during the course of
 the breeding season throughout their rapidly contracting geographic range.
 Incubating parent birds are adapted to keep their eggs within a
 temperature range appropriate for embryo development, but king rail
 clutches are at risk of exceeding lethal temperatures in the latter half
 of the nesting season. We investigated whether behavioral plasticity
 during incubation enables parents to maintain clutch temperature within
 tolerable limits for embryo development. Video revealed that king rail
 parents interrupted incubation to stand above and shade their eggs. We
 tested the hypothesis that the onset of shading was a direct response to
 ambient temperature (adaptive plasticity). We monitored clutch temperature
 directly by experimentally adding into clutches a model egg embedded with
 a programmable iButton. We measured ambient temperature at the nest site
 simultaneously. Parents spent proportionately more time shading and less
 time incubating their eggs at higher ambient temperatures. Shading may
 primarily function in cooling the parent. The frequency and duration of
 shading bouts were significantly greater at higher ambient temperatures.
 Parents also took more frequent but shorter recesses in hotter conditions.
 Diurnal recesses exposed eggs to direct sunlight, and the highest clutch
 temperatures were recorded under these conditions. Complete hatching
 failure in at least one nest was attributable to high clutch temperature
 for an extended period. Because mean ambient temperature increases
 throughout the breeding season, we investigated seasonal patterns in onset
 of incubation and its effect on hatching rate. Later in the season,
 parents tended to initiate incubation earlier, and hatching asynchrony
 increased significantly. Together these results suggest that breeding king
 rails may be constrained in their ability to cope with sustained high
 temperatures should seasonal averages continue to rise as predicted.
description: BehaviorTimeBudgets&AmbientandEggTemperatureTime budgets of individual king rail parents attending nests coded by nest number and sex in relation to clutch and ambient temperatures. Behaviors include incubation, shading and nest building.HatchingSuccess&ClutchTemperatureFor king rail clutches in which clutch temperature was measured, hatching success (proportion of eggs hatched) in relation to maximum clutch temperature and time clutch temperature exceeded 43.5ºC.IncubationTiming&HatchingSynchronyHatching rates of king rail nests in relation to Julian first egg date. Over five years at Mackay Island NWR, hatching rates are reported as the number of days during which the eggs hatched and the number of eggs hatched per day. The day of initiation of incubation in relation to first egg date is reported in cases where known.RecessDuration&AmbientTemperatureMultiple measures of recess duration (time when nest unattended) at incubated king rail nests during the incubation period, in relation to the mean ambient temperature during the recess interval.RecessFrequency&AmbientTemperatureMultiple measures per nest of rate of recesses per hour in king rail nests during the incubation period in relation to mean ambient temperature.