DOI: 10.5061/dryad.7wm37pvzs
title: Data from: Winter game crop plots for gamebirds retain hedgerow breeding songbirds in an improved grassland landscape

description: The cause of recent population declines in some farmland / hedgerow
 breeding bird species in the UK is related to a lack of cover and food
 resources in winter.  In improved grassland areas some of those
 declines have been particularly acute and some have been shown to be
 related to the availability of grass and weed seed in winter. 
 The provision of seed-bearing crops as part of AES options has been shown
 to benefit some of these birds.  Game crop plots sown on shooting
 estates for holding and driving gamebirds in autumn and winter have been
 shown to hold relatively high densities of farmland and wood-edge birds
 during the winter. We studied breeding songbirds in hedges in a primarily
 improved grassland area in the SW of England where there are some large
 shooting estates that sow relatively large game crop plots (1 - 5 ha) in
 the landscape.  In this study we found that otherwise similar
 hedges in terms of size and density near to those winter game crop plots,
 had between 1.5 and 2 times as many breeding resident songbirds per unit
 length the following spring compared to hedges further away from game crop
 plots. This was despite game management in these plots being wound down
 during February and in many cases, the crops themselves being removed by
 mid-March. Hedges within approximately 350m from game crop plots had more
 breeding birds. We discuss possible mechanisms and suggest that some
 passerines preferentially establish breeding territories in hedges near to
 game crops in late winter. We suggest how to distribute game crop plots to
 maximise any benefit in an improved grassland landscape.
description: This dataset was collected on Exmoor by two researchers. They
 undertook bird surveys along hedges at differing distances from wild bird
 cover plots. The data is the number of birds recorded on each survey and
 measurements of the hedges such as height, density and width
 etc.  The data is a csv file and analysis has been
 performed in R. 
description: # Winter game crop plots for gamebirds retain hedgerow breeding songbirds
 in an improved grassland landscape Authors: Rufus Sage (lead author),
 Maureen Woodburn, Sam McCready, Jenny Coomes (processed the data and did
 the analysis). Sage, Rufus; Woodburn, Maureen; McCready, Sam; Coomes,
 Jenny (2023), Winter game crop plots for gamebirds retain hedgerow
 breeding songbirds in an improved grassland landscape, Dryad, Dataset,
 Files uploaded: * R code
 for analysis: Exmoor data - for upload.R * CSV of data: exmoordatafull.csv
 The dataset contains information about the hedges and game cover, as well
 as the number of birds seen per survey. Column headings in dataset: ID:
 unique to all rows site: 1, 2 or 3 site.new: categorical version of site
 (a, b or c) transect.orig: the original transect number transect.code:
 unique transect number for each different cover plot, with five hedges
 within it. distance: five bands: 1 to 5. (changed to categorical in the
 code). 0-50m, 75-150m, 200-350m, 500-800, 1.1km+ visit: early spring or
 late spring, 1 or 2. date: numbers. Starting 1st April. covertype1: main
 plant species in the cover plot covertype2: secondary plant species in the
 cover plot coverarea.map: measured area of the cover plot from a map.
 Metres squared. coverarea.keeper: the area that the gamekeeper gave for
 the cover plot cover.manage: how the cover plot was managed weather time
 length: length of the hedge in metres num.hedge.types: number of distinct
 hedge types in the hedge line. status: category of how 'good'
 the hedge seems to be for birds (only recorded on second visit).
 hedge.den: hedge density: category of 1 (least dense), 2 or 3 (most
 dense). cut: If recently cut in the preceding winter, put a 1. If not, put
 a zero. bank.height: height of bank that the hedge is on. width: hedge
 width - bottom part of tall hedges hedge.height: height of hedge (without
 the bank) standards: presence/absence of standard (tall) trees in the
 hedge. 0 = no standards to 2 = lots of standards. gaps: 0 (no gaps), 1 or
 2 (many gaps). crop1: In adjacent field. Improved permanent grass (0),
 unimproved permanent grass, grazed areas and moorland (1), leys (2), game
 cover (3), arable (4), track or road (5), scrub (6) crop2: In adjacent
 field. Improved permanent grass (0), unimproved permanent grass, grazed
 areas and moorland (1), leys (2), game cover (3), arable (4), track or
 road (5), scrub (6) double.hedge: 1 if both sides were included in survey.
 0 if not. road: 1 = road, 0 = grassy track plant.spp: Dominant plant
 species in the hedge. Hz – hazel, Ok- oak, Wil – willow, Bt – blackthorn,
 Be – beech, Hw – hawthorn, Eld – elder, Bir – birch, Syc – sycamore, Gor -
 gorse The following are all the bird species recorded: Robin, Wren,
 Chaffinch, Blue Tit, Blackbird, Great tit, Goldfinch, Dunnock, Linnet,
 Yellowhammer, Chiffchaff, Willow warbler, Blackcap, Wood Pigeon, Magpie,
 Spotted Flycatcher, Stonechat, Carrion Crow, Bullfinch, Goldcrest,
 Buzzard, Meadow Pipit, Osprey, Wheatear, Green Finch, Siskin, Redstart,
 Pied Wagtail, Long Tailed Tit, Coal Tit, Whitethroat, Sparrowhawk, House
 Sparrow, Garden Warbler, Jackdaw, Stock Dove, Swallow, GS Woodpecker,
 Raven, Lesser Redpol, Jay, Grasshopper Warbler, Skylark, Nuthatch, Song
 Thrush, and Mistle Thrush. Some of these species were not used in analysis
 - see main text. The birds that were used in analysis were split into
 resident and migrant - see R code for these calculations. Cells containing
 NA are missing data either because the survey was not undertaken or
 because the data was not known.