DOI: 10.5061/dryad.5p251
title: Data from: Eggs brought in from afar: Svalbard-breeding pink-footed geese can fly their eggs across the Barents Sea

description: Many Arctic-breeding waterbirds are thought to bring nutrients for egg
 production from southern latitudes to allow early breeding. It has proved
 problematic to quantify the extent of such capital breeding and identify
 whether nutrients for egg production are brought in from nearby or from
 afar. Before reaching their breeding grounds on Svalbard, pink-footed
 geese Anser brachyrhynchus fly ∼ 1100 km across the Barents Sea from
 Norway. Using abdominal profile indexing (API) we scored body stores in
 individually marked geese just prior to migration from the northernmost
 staging area in Norway to Svalbard, followed by their breeding success on
 their non-breeding grounds in autumn. In productive breeding years leading
 to a high (&gt; 13.8%) proportion of juveniles in the autumn
 population, there was a positive relationship between female API and
 number of young produced, suggesting that the geese are at least partial
 capital breeders. Moreover, focusing on the geographic origin of proteins
 used in egg synthesis and measuring nitrogen stable isotope ratios in
 pink-footed geese's eggs and food sources in Norway and Svalbard, we
 identified that capital breeding in this species is ∼ 50% on average but
 may potentially amount to as much as 100%, notably in females laying
 early. About 60% of this protein capital is carried in well-developed
 follicles across the Barents Sea, the remainder likely being stored in
 muscle tissues. Conditions on the wintering grounds and migratory stopover
 sites can have profound effects on an individual's fitness but the
 here presented link between the use of migratory stopover sites and
 breeding performance is particularly noteworthy. Apparently, some
 individuals accept the putative costs of carrying body stores over large
 distances to the breeding grounds. The data also highlights considerable
 variation in the reliance on capital for breeding, suggesting substantial
 individual scope to adjust breeding strategy to changing environmental
 conditions.
description: Figure 1
 dataData underlying figure 1
 including for each individual female (femaleID), the year in which it was
 observed, its API score upon departure from Vesterålen (APIdepart), the
 number of young it was observed with during the following autumn (#young)
 and the average percentage of juveniles in the population in that specific
 year of observation (PercJuvInPop).Figure
 1.csvFigure 2
 dataData underlying figure
 2, including the average, standard deviation and sample size of the
 Nitrogen isotope ratios (dN_mean, dN_SD and dN_n, respectively) of three
 different tissues (item). The data file also contains the year in which
 the samples were collected as well as the site
 (where_whom).Figure
 2.csvFigure 3
 dataData underlying the two
 panels in Figure 3. The nitrogen isotope ratio (dN) of both yolk and
 albumen (item) in eggs is provided. For each egg the year of collection,
 the nest from which it was collected (nest) and its identity within the
 nest (egg; coded A-E, the coding not necessarily reflecting laying order)
 are provided.Figure
 3.csv