DOI: 10.5061/dryad.2g6v864
title: Data from: Factors influencing plasticity in the arrival-breeding interval in a migratory species reacting to climate change

description: Climate change is profoundly affecting the phenology of many species. In
 migratory birds, there is evidence for advances in their arrival time at
 the breeding ground and their timing of breeding, yet empirical studies
 examining the interdependence between arrival and breeding time are
 lacking. Hence, evidence is scarce regarding how breeding time may be
 adjusted via the arrival-breeding interval to help local populations adapt
 to local conditions or climate change. We used long-term data from an
 intensively monitored population of the northern wheatear (Oenanthe
 oenanthe) to examine the factors related to the length of 734 separate
 arrival-to-breeding events from 549 individual females. From 1993 to 2017
 the mean arrival and egg-laying dates advanced by approximately the same
 amount (~5-6 days), with considerable between-individual variation in the
 arrival-breeding interval. The arrival-breeding interval was shorter for:
 (1) individuals that arrived later in the season compared to early
 arriving birds, (2) for experienced females compared to first-year
 breeders, (3) as spring progressed, and (4) in later years compared to
 earlier ones. The influence of these factors was much larger for birds
 arriving earlier in the season compared to later arriving birds, with most
 effects on variation in the arrival-breeding interval being absent in late
 arriving birds. Thus, in this population it appears that the timing of
 breeding is not constrained by arrival for early- to mid-arriving birds,
 but instead is dependent on local conditions after arrival. For late
 arriving birds, however, the timing of breeding appears to be influenced
 by arrival constraints. Hence, impacts of climate change on arrival dates
 and local conditions are expected to vary for different parts of the
 population, with potential negative impacts associated with these factors
 likely to differ for early- versus late-arriving birds.
description: wheatear timing of
 arrival-breeding dataThe data are contained
 in 6 columns: (1) the ID of the breeding female, (2) the age of the female
 (0 = yearling, 1 = older breeder), (3) the year of the study (3 = 1993, 27
 = 2017), (4) the date of arrival relative to May 1st, (5) the date of egg
 laying relative to May 1st, (6) the interval between arrival and
 egg-layingDRYAD_arrival_breeding_data.csvdata for survival analysesThis is the data used for the Cox proportional hazards modelling and is arranged so that each day after arrival for each individual female is contained in its own row with the start date relative to arrival (cox_start), the stop date relative to arrival (i.e. the following day; cox_stop) and the event outcome during this interval (i.e. whether or not the female initiated egg laying during this time; breed_YN). Also included are the covariates used in the cox modelling for the probability of egg laying after arrival: year (3 = 1993, 27 = 2017), date relative to May 1st, female age (young breeder or older) and the thermal sum for that time period.DRYAD_cox_data.csv