DOI: 10.5061/dryad.1zcrjdg24
title: Data from: Factors influencing nest site selection in a rapidly declining shorebird, the Eurasian curlew

description: In this period of rapid human-induced environmental change, it is vital
 that influences of habitat on the distribution and productivity of
 threatened species are understood. Ground-nesting birds are declining more
 rapidly across Europe than any other group, with large-bodied birds at the
 greatest risk of extinction. Productivity and adult survival cannot both
 be maximised concurrently, and individuals will make decisions during the
 nest-placement phase which will favour one outcome or the other, however
 under conditions of accelerating change, these decision processes may
 become decoupled from positive fitness outcomes. The Eurasian curlew
 (Numenius arquata) is Europe’s largest wader and is showing steep declines
 in breeding productivity. Curlews are known to use a diverse range of
 habitats for nesting, where anthropogenic or natural features may
 influence distribution. There is an urgent need to understand the spatial
 scales of these impacts, and whether habitat characteristics have a
 positive or negative impact on nest survival. In our study site in
 Southern England, curlew showed a marked preference for nesting in wetter
 habitats, primarily mire, and a weaker selection of dry heathland. Nest
 survival improved in wetter habitats, and the area of mire round a nest
 site was positively associated with increased levels of nesting success,
 whilst area of scrub had a negative association. These both point to
 likely modulation of predator behaviour. Woodland significantly excluded
 curlew from potentially suitable breeding habitat, with an impact observed
 up to 2km from the nest site, but nest survival did not improve with
 distance from woodland. Curlews strongly avoided nesting near a major road
 passing through the study site, despite seemingly suitable habitat nearby.
 Understanding landscape effects will assist in planning future habitat
 management for curlew, impacts of forestry and avoidance of additional
 pressures on a species of high conservation concern.
description: # Eurasian curlew nest site selection: Open source data \[Access this
 dataset on Dryad]DOI:10.5061/dryad.1zcrjdg24 Contained here is the raw
 data we used in our analysis. (**allyearsdata.csv**), all nest location
 data gathered over 3 yr period and used to compare against randomly
 generated locations, (**allyearsdataRMark**), the raw datafile of nest
 locations, found date, visits and fate set up as per RMark protocol,
 (**2022_detection_history**) containing data for analysis of the
 detectability of curlews on each survey visit, and folder (**home
 ranges**) containing csv's exported from Movebank of location data
 taken from the GPS-tagged adult curlews included in the study. ##
 Descriptions ### **allyearsdata.csv** * *year *: the year the data was
 collected * *Lat* & *Long *: latitude and longitude coordinates of
 nest site, reduced in accuracy to 0.1 decimal place to preserve safety of
 a declining species. ### **allyearsdataRMark** * *Year *: the year the
 data was collected. * *Lat* & *Long *: latitude and longitude
 coordinates of nest site, reduced in accuracy to 0.1 decimal place as
 above. * *nocc :* 'number of capture occasions', in this case
 the number of times the nest was visited during the recorded incubation
 period. * *FirstFound *: days are numbered from 1-54, 1 being the first
 day of the season when a nest was found, and 54 being the last day of the
 season when a bird in the study population was actively incubating.
 FirstFound is the number of day within this range when that particular
 nest was discovered. * *LastPresent *: the number of the day when the nest
 was last visited and the bird was still incubating. * *LastChecked *: the
 number of the day when the nest was last checked for signs of activity or
 a continuing nesting attempt. * *Fate *: whether the nesting attempt
 failed or hatched successfully. 0 = hatched, 1 = failed. * *Freq *:
 denotes whether the day numbers associated with that nesting attempt are
 unique, or whether they appear in a separate attempt. Therefore 1 = unique
 dates, 2 = 2nd attempt with the same dates. ###
 **2022\_detection\_history** * *first column (blank) *: unique identifiers
 for each site included in the analysis. * *detection *: whether a curlew
 was detected during the visit. * *survey number *: which visit number it
 was. * *effort level *: due to having the involvement of a number of
 different agencies and volunteers, the surveys were conducted by various
 different individuals who did not have equal experience or time capacity
 as each other. Their individual search intensity was ranked numerically in
 'effort level' to capture this and control as much as possible
 for the inter-individual differences. \[variables which were tested for
 effect on curlew detectability below] * *habitat *: which habitat was the
 nest located in, of the four utilized by curlew in the New Forest. *
 *nest *: distance in metres to the next nearest curlew nest. * *carpark *:
 distance in metres to the nearest car park, and so on for the remaining
 variables listed in the columns. *a31* and *a35* are the names of the
 trunk roads crossing the National Park. *settlement* was any town, village
 or hamlet. ### **home ranges** The column names in the csvs included here
 were generated by the Movebank system when they were exported, and they
 vary slightly depending on the age of the GPS tag or the manufacturer.
 Each csv represents a unique bird. In the case of some older models of GPS
 tag not so many fields of information are available as with the newer
 tags, so there are blank areas under some of the headers - these have been
 infilled with N/A for clarity that it was expected for that information to
 be missing.  The column headers in each file are as follows: * timestamp -
 The date and time corresponding to a sensor measurement or an estimate
 derived from sensor measurements. Containing the full date (day, month,
 year) and time (hours, minutes, seconds) * location-long - The geographic
 longitude of the location as estimated by the sensor. Positive values are
 east of the Greenwich Meridian, negative values are west of it. In decimal
 degrees using the WGS84 reference system. * location-lat - The geographic
 latitude of the location as estimated by the sensor. In decimal degrees
 using the WGS84 reference system. * acceleration-raw-x - Raw acceleration
 values provided by the tag for the X axis. Range and units may vary by
 provider, tag, and orientation of the sensor on the animal. *
 acceleration-raw-y - Raw acceleration values provided by the tag for the Y
 axis. Range and units may vary by provider, tag, and orientation of the
 sensor on the animal. * acceleration-raw-z - Raw acceleration values
 provided by the tag for the Z axis. Range and units may vary by provider,
 tag, and orientation of the sensor on the animal. * gps:hdop - horizontal
 dilution of precision, a measure of accuracy of location data *
 gps:satellite-count - The number of GPS satellites used to estimate the
 location. * ground-speed - The estimated ground speed provided by the
 sensor or calculated between consecutive locations, in metres/second *
 heading - The direction in which the tag is moving, in decimal degrees
 clockwise from north, as provided by the sensor or calculated between
 consecutive locations. Values range from 0-360: 0 = north, 90 = east, 180
 = south, 270 = west. * sensor-type - the type of sensor which was used to
 collect the positions * individual-local-identifier - An individual
 identifier for the animal, provided by the data owner. Values are unique
 within the study. * study-name - The unique name of the overall study *
 utm-easting - The easting of the location as estimated by the sensor, in
 metres using the WGS84 reference system * utm-northing - The northing of
 the location as estimated by the sensor, in metres using the WGS84
 reference system * utm-zone - The UTM zone used to convert locations from
 decimal degrees to UTM. Selected based on the location of each event *
 study-timezone - The time zone at the study reference location, determined
 using the IANA Time Zone Database and a shapefile of these zones provided
 by efele.net * study-local-timestamp - The date and time a sensor
 measurement was taken, converted from the values in 'timestamp'
 to the time zone of the study reference location. The time zone for the
 study reference location is determined using the IANA Time Zone Database
 and a shapefile of these zones provided by efele.net The files contained
 within the home ranges folder are as follows: * 887.csv, 892.csv,
 1103.csv, 15573.csv, 220568.csv, 220916.csv, DHS22.csv, DHS23.csv,
 HN23.csv, HS23.csv