DOI: 10.5061/dryad.m905qfvc6
title: Sex-specific selection of agricultural farmland by a partially migratory ungulate

description: Large herbivores at northern latitudes often forage on agricultural
 farmland. In these populations, presence of both resident and migrant
 individuals (termed partial migration) is common, but how migrants and
 residents differ in their selection of farmland is not well understood.
 Higher access to farmland may provide benefits to residents compensating
 for not following the ‘green wave’ of emerging vegetation like migrants.
 According to sexual segregation theory, males and females differ in
 body-size related nutritional needs and risk-sensitivity associated with
 farmland. Yet, how the sexes differ in selection of farmland through an
 annual cycle remains unclear. We quantified seasonal variation in the
 selection of farmland by partially migratory red deer (Cervus elaphus) at
 broad, landscape scale and at fine, within-home range scale using 16 years
 of data (2005-2020) from 329 females and 115 males in Norway. We tested
 predictions related to the partial migration and sexual segregation
 theories using resource selection functions. We predicted higher selection
 for farmland by residents than migrants, and higher selection by females
 than males due to higher nutritional needs, but that higher perceived
 predation risk would impact their diurnal selection patterns. The time
 spent on farmland was higher in winter (14-18%) than summer (8-14%).
 Residents selected farmland more than migrants mainly at broad, landscape
 scale, while differences were smaller and less consistent at fine,
 within-home range scale. Females showed higher broad-scale selection for
 farmland in winter, and males higher in summer. At fine, within-home range
 scale, females selected farmland more in summer during darkness, whereas
 sex-differences were small otherwise. The fine-scale selection of farmland
 was markedly higher during low-light conditions than during daylight. High
 population density was correlated with high broad-scale selection of
 farmland, i.e., high farmland availability in the home ranges, whereas the
 effect of density was weak at fine, within-home range scale. Our study
 emphasises how hypotheses deriving from the theories of partial migration
 and sexual segregation can improve our understanding of selection of
 farmland by ungulates. The higher selection by residents during summer
 highlights the importance of retaining landscape connectivity allowing for
 migration, reducing pressure on local resources. 
description: The methods comprise fitting research selection functions using
 use-availability data for red deer (<em>Cervus elaphus</em>)
 to analyse their selection of farmland on broad landscape scale (second
 order selection; Johnson, 1980) and on finer, within-home range scale. The
 data of used locations is collected using GPS collars (Followit, Sweden,
 and Vectronic, Germany) on male and female adult red deer. The available
 locations were randomly sampled within each individual's available
 range (for the second order selection analysis) and seasonal home range
 (for the third order selection analysis), respectively. The RSF's
 were fitted using generalised linear mixed-effects models (GLMMs) for the
 second order selection analysis, and generalised linear models (GLMs) for
 the third order selection analysis.
description: # Sex-specific selection of agricultural farmland by a partially migratory
 ungulate
 [https://doi.org/10.5061/dryad.m905qfvc6](https://doi.org/10.5061/dryad.m905qfvc6) ## Description of the data and file structure **Description of the data variables:** * use_avail: Marks whether the data is a "used" or "available" location, based on the definition following the level of selection of the research selection function. 1 = used, 0 = available. * hab2: Habitat variable with the habitats counted as available habitat for the red deer. Four levels; forest, marsh, mountain, and aafarmland (= farmland). * sex: Sex of the red deer individual. m = male, f = female. * visual.assignment: Movement category, with the levels "migratory" and "stationary". * dens: Red deer population density index. Shot red deer per km2. * log.dens: The log_e of the variable dens (see above). * elevation: Altitude of the location, given in metres above sea level. * log.elevation: The log_w og the variable elevation (see above). * lightlevel: The light level for the given date and time of the location (specific for the used locations, randon within the season for the available locations). Three levels; light, dark, twilight. * prop.pasture: Proportion available farmland habitat within the individual home range. * asin.pasture: The prop.pasture variable (see above) arcsine square root transformed. * region: Region of Norway where the individual is located. Levels: SoF (Sogn & Fjordane), Tr (Trondelag), MoR (More & Romsdal), and SW (Hordaland). * yr: Year * id: Individual ID ### Data files #### File: summer\_within\_HR.RData **Description:** Data used to fit the research selection function (RSF) for the summer season on the within-home range level (third order of selection).  #### File: summer\_within\_landscape.RData **Description:** Data used to fit the RSF for the summer season on the landscape level (broad-scale, second order of selection).  #### File: winter\_within\_HR.RData **Description:** Data used to fit the RSF for the winter season on the within-home range level (third order of selection).  #### File: winter\_within\_landscape.RData **Description:** Data used to fit the RSF for the winter season on the landscape level (broad-scale, second order of selection).  ## Code/software R version 4.3.0 was used for the computation.  Separate scripts are available per season and per selection level:  #### Script: Mod\_fit\_and\_sel\_summer\_within\_HR.R **Description:** Script for model fitting and selection for the analysis of the summer season on the within-home range level (fine-scale, third order of selection, data file called summer_within_HR.RData).  #### Script: Mod\_fit\_and\_sel\_summer\_within\_landscape.R **Description:** Script for model fitting and selection for the analysis of the summer season on the landscape level (broad-scale, second order of selection, data file called summer_within_landscape.RData).   #### Script: Mod\_fit\_and\_sel\_winter\_within\_HR.R **Description:** Script for model fitting and selection for the analysis of the winter season on the within-home range level (fine-scale, third order of selection, data file called winter_within_HR.RData).  #### Script: Mod\_fit\_and\_sel\_winter\_within\_landscape.R **Description:** Script for model fitting and selection for the analysis of the winter season on the landscape level (broad-scale, second order of selection, data file called winter_within_landscape.RData).  Versions of the packages used in the scripts:  * lme4: version 1.1-33 * MUMIn: version 1.47.5 * ggplot2: version 3.5.1