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Effects of Management and Configuration of Uncropped Land on the Winter Habitat Use of Birds on Arable Farm Systems - BD1642

Uncropped farmland, typically in the form of set-side, field margins or wildbird strips, has apparent benefits at the field scale for birds, by often holding greater diversity and sometimes abundance than equivalent areas of crop (e.g. Henderson et al. 2000 & 2004, Stoate et al. 2004). However, for birds at least, the evidence that the introduction of uncropped land has had impacts on declining bird populations is weaker, for example at a national or regional level – and at best population declines of some species may have been slowed (Vickery et al. 2004, Defra: BD1640). There are two reasons why benefits at the population level may not have been as great as expected. First, management, in terms of habitat composition, of uncropped areas may not always have been carried out in the most beneficial way. Second, the scale at which uncropped land has existed in time and space, and its configuration (e.g. strips or blocks) may have affected its value. Small areas of uncropped land may have increased biodiversity at a field level, but overall resources at a larger scale may not have been increased enough to make an impact at the population level.

The LINK-funded project ‘Farm4BIO: managing uncropped land in order to enhance biodiversity benefits of the arable farmed landscape’ (LK0971) has been set-up to address the above two topics by varying the quality and quantity of uncropped areas alongside the configuration (margin or block). The project takes an experimental approach with variable-scale treatments and two management treatments, compliance-managed uncropped land including organic and novel-managed uncropped land (land managed with novel treatments specifically to promote biodiversity). All uncropped land and other arable crops within the surrounding area are being surveyed at a relatively large scale (1-km2) with four replicates to each treatment. Breeding birds, bees, hoverflies, carabid beetles and arable weeds have been sampled in a baseline year (prior to the introduction of the novel management treatment) and for three subsequent years following the introduction of novel management. Two arable farming regions are considered: East Anglia (2 replicates) and Wessex (2 replicates).

The LINK project’s unique design offers a great opportunity for further intensive research into configuration and scale effects of uncropped land. A key aspect not included in the current project is a consideration of the relative effects of different treatments of uncropped land on winter bird habitat use. All of the novel treatments will provide seed but especially the wild bird and insect-rich covers. Winter feeding habitat in particular is likely to be an important factor affecting populations of granivorous species (Siriwardena et al. 1999). Effects of winter food provision on bird abundance were considered by the BTO under the Defra-funded project ‘Winter Feeding of Farmland Birds’ (BD1616) with evidence to suggest that local breeding numbers may be enhanced by improved winter foraging habitat (Siriwardena et al. (2005), also Gillings et al. (2005). During the winter itself, however, most farmland birds (and in particular Farmland Bird Indicator species) are not territorial in the winter, so they are more likely to distribute themselves according to resources, than in summer, as there is no behavioural exclusion and in this way, bird abundance in winter is more likely than in summer to show effects of the presence of uncropped land on their distribution.

The present proposed research would provide a complimentary assessment of habitat use, scale and configuration to the summer work on Farm4BIO, through repeated winter surveys of bird abundance (all species) in each study 1 km square used in that same project. As with the summer work, the data would compare between treatments, taking into account the context of the surrounding farmland.
Overall objective:
To provide evidence of the effects of the presence and management of uncropped land on bird abundance distributions during the later winter, so called ‘hunger gap’ (late January to March) with special attention being given to key indicator species on the Defra farmland bird index.

Specific objectives:
1 To determine, whether the presence, configuration and/or management of uncropped land affects the abundance of birds in winter at both the field scale and the farm scale;
2 To determine whether there is any evidence of differential depletion (i.e. differing within-seasonal patterns in habitat) according to treatment of uncropped land or related affects on bird numbers.

Project Documents
• FRP - Final Report : Effects of Management and Configuration of Uncropped Land on the Winter Habitat Use of Birds on Arable Farm Systems   (310k)
Time-Scale and Cost
From: 2009

To: 2009

Cost: £45,268
Contractor / Funded Organisations
British Trust For Ornithology, The Game & Wildlife Conservation Trust