DOI: 10.5061/dryad.ghx3ffbxj
title: Data from: Year-round carryover effects are driven by migration phenology for Hirundo rustica (Barn Swallow) wintering in West Africa

description: Recently, population declines have been reported for many migratory birds.
 Because of complex life cycles, determining the causes for such declines
 is often difficult. Thus, migratory birds are of special conservation
 interest. We studied the migratory behavior of barn swallows Hirundo
 rustica tagged with solar geolocators and determined carryover effects
 during the entire annual cycle from one breeding season to the next. We
 used a Partial Least Square Path Model (PLS-PM) to disentangle migratory
 and breeding events that occur in chronological order. In addition, we
 controlled for broad environmental conditions in the wintering grounds
 (NDVI and latitude) and the specific moulting habitat (δ13C). We did not
 find a carryover effect from reproduction investment in the attachment
 year to breeding success in the subsequent year. Individuals which
 invested more in reproduction departed earlier from the breeding colonies,
 but this in turn did not affect the onset of autumn migration. Thus, the
 pre-migratory period should be acting as a buffer stage counteracting any
 previous carryover effects from reproduction investment. On the other
 hand, we found a long-lasting domino effect from the onset of autumn
 migration to subsequent breeding success, consistent with the notion of a
 migratory race. Specifically, individuals which started earlier the autumn
 migration, arrived earlier to the wintering grounds, started earlier the
 spring migration, arrived earlier to the breeding colonies and had a
 higher breeding success. We highlight that the pre-migratory period (i.e.,
 the time elapsed between departure from breeding areas and the onset of
 autumn migration) should be important for the lifecycle of migratory
 species, but it has been frequently overlooked.
description: This data corresponded to 35 individuals wintering in West Africa
 (22 females and 13 males) and breeding in southern Spain (Seville and
 Badajoz). Key dates in migration behavior were obtained after
 reconstructing the migratory route for each individual.
description: # Year-round carryover effects are driven by migration phenology for
 Hirundo rustica (Barn Swallow) wintering in West Africa
 [https://doi.org/10.5061/dryad.ghx3ffbxj](https://doi.org/10.5061/dryad.ghx3ffbxj) ### Description of the data and file structure An Excel file with the variables described below. This dataset correspondeds to 35 individuals wintering in West Africa (22 females and 13 males) and breeding in southern Spain (Seville and Badajoz). Key dates in migration behavior were obtained after reconstructing the migratory route for each individual. The variables provided here are: (1) 'Departure date from breeding colony’, (2) 'Onset of autumn migration’, (3) 'Arrival date at wintering area', (4) “Onset of spring migration” and (5) 'Arrival date at breeding colony'. This data was associated with reproduction data at the individual level. Breeding pairs in our study colonies laid up to three clutches during the breeding season. Thus, we used the number of clutches, the total number of eggs and the total number of fledglings (age &gt;18 days) across all clutches as indices of reproductive success. For males, total number of eggs was assigned from their female mate. We evaluated broad environmental conditions at the wintering areas by extracting Normalized Difference Vegetation Index values (hereafter: NDVI) within the core area used by each geolocator-tagged individual during the winter period. We used δ13C as a proxy of habitat type occupied during the wintering period, measured in tail feathers captured at breeding site and molted the previous winter. Not available data (i.e, NA) was due to lack of input information on reproductive events of some geo-tagged swallows in either year because we could not link these individuals to their target nests. No changes made last requirement.