DOI: 10.5061/dryad.bnzs7h48k
title: Data from: First records of complete annual cycles in water rails Rallus aquaticus show evidence of itinerant breeding and a complex migration system

description: In water rails Rallus aquaticus, northern and eastern populations are
 migratory while southern and western populations are sedentary. Few
 details are known about the annual cycle of this elusive species. We
 studied movements and breeding in water rails from southernmost Norway
 where the species occurs year-round. Colour-ringed wintering birds
 occurred only occasionally at the study site in summer, and vice versa.
 Geolocator tracks revealed that wintering birds (n = 10) migrated
 eastwards in spring to breed on both sides of the Baltic Sea, whereas a
 single breeding bird from the study site wintered in north Italy. Ambient
 light records of geolocator birds further indicated that all but one
 incubated 2–4 clutches per season. By combining information on incubation
 and movement, we found evidence for itinerant breeding in three individual
 birds: After a first breeding attempt (one did not incubate), all moved
 129–721 km to breed again. This behaviour is rarely recorded in birds and
 was unexpected because the water rail is described as monogamous with both
 parents caring for eggs and chicks. The study greatly improves our
 knowledge about the annual cycle and reproduction in water rails. However,
 more studies are warranted to evaluate the generality of our findings and
 causes of breeding itinerancy.
description: The table includes data on the migration (timing of
 departure/arrival, estimated stationary periods and estimated coordinates
 of stationary sites) and timing of incubation (first to fourth clutch; one
 individual did not show any signs of incubating eggs) for 11 individual
 water rails. This information was estimated from light-level data
 collected by geolocators and processed in R package ‘TwGeos’ and using the
 ‘invChanges’ function from the R package ‘GeoLight’, ver. 2.0.1. For more
 details about methods, please see Lislevand et al. 2020: doi:
 10.1111/jav.02595.
description: Cells without information are filled with "na", except
 for the incubation data where there is only a single line of information
 per nest (at the same line as info for site a). Description of
 columns: 
 Column header Description Ring # Ring number (Stavanger Museum, Norway) Bird ID Letters A-K followed by year of tracking (2014 or 2015) to separate individuals Sex M = male; F = female Age 2y = second calendar year; 3y = third calendar year; 3y+ = third calendar year or older  Mass body mass in g Wing wing length in mm Site different letters to separate stationary sites (unique within individuals but not between)  arrival Timing of arrival at the site departure Timing of departure from the site Stationary duration Duration of the stationary period Movement duration Duration of the movement period (time between stationary periods) Long, median Longitude, median calculated from data Lon.2.5% Longitude, lower limit of 95% CI Lon.97.5% Longitude, upper limit of 95% CI Lat, median Latitude, median calculated from data Lat.2.5% Longitude, lower limit of 95% CI Lat.97.5% Longitude, upper limit of 95% CI GC distance from breeding site Great circle distance from breeding site in km. GC distance from previous site Great circle distance from previous site in km. Total GC migration distance Total great circle distance travelled, in km Incubation onset I First date of recorded incubation, first nest Incubation finish I Last date of recorded incubation, first nest Incubation onset II First date of recorded incubation, second nest Incubation finish II Last date of recorded incubation, second nest Incubation onset III First date of recorded incubation, third nest Incubation finish III Last date of recorded incubation, third nest Incubation onset IV First date of recorded incubation, fourth nest Incubation finish IV Last date of recorded incubation, fourth nest