Farmland birds in the UK prefer PARTRIDGE measures in winter
Farmland birds are in decline in Europe and measures are needed to halt and reverse this decline. During the European Interreg PARTRIDGE-project (2016-2023) we improved the area of our 10 farmland demonstration sites - two each in Flanders, The Netherlands, Germany (Lower Saxony), Scotland and England - by enhancing existing and creating new high-quality wildlife habitats such as flower blocks and beetle banks to levels above 7% of the farmed areas. How to do this is covered in detail in our press releases and described in our fact sheets. This habitat improvement provided more and improved breeding habitat in the summer, and additional food and shelter for wintering birds. The main target species, of course, was the partridge, but other farmland birds are believed to benefit as well.
Rotherfield demonstration area during winter
Balgonie in early winter with the PARTRIDGE partner looking at measures that benefit wintering birds
To demonstrate that wintering birds are indeed using the measures, we conducted point counts in the winters from 2019-2020 to 2022-2023 in the demonstration areas and corresponding reference areas (without those measures) in the Netherlands, Belgium, England and Scotland. In England, the demonstration area and reference area were Rotherfield and Cheriton; in Scotland, they were Balgonie and Balbirnie, respectively. In the demonstration areas, we selected 8-10 points at or near the measures and 7-10 points with no measures. In nearby reference sites, without measures, the points were randomly selected. Each month, from November to February, all birds present in a 100m circle around the points were counted.
Field Set-up
In total, we analysed the data of 27 species from two groups of species commonly found in agricultural areas during winter (see below). The first group of nine species is largely dependent on seeds as a food source in winter [see references 1-3] and species in this group have declined the most due to agricultural intensification. The other 18 species are not primarily dependent on seeds for food in the winter. Abundance and species richness were calculated for both groups in each count circle for each site visit.
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Seed eaters |
Balgonie 9 species: Chaffinch, linnet, tree sparrow, goldfinch, greenfinch, grey partridge, reed bunting, skylark, yellowhammer. Rotherfield 7 species: Chaffinch, linnet, goldfinch, greenfinch, grey partridge, skylark, yellowhammer. |
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Other species |
Balgonie 13 species: Blue tit, wood pigeon, blackbird, jackdaw, magpie, robin, starling, fieldfare, great tit, house sparrow, redwing, ring-necked pheasant, wren. Rotherfield 16 species: Blue tit, wood pigeon, blackbird, jackdaw, magpie, robin, starling, fieldfare, great tit, meadow pipit, redwing, ring-necked pheasant, rook, song thrush, stock dove, wren. |
Abundance
The number of birds from the seed-eater group was six times higher in Balgonie and 70% higher in Rotherfield in the counting circles with measures in the demo areas than in those of the reference areas (Figure 1). For all the European areas combined where winter birds were counted (n = 6), this was slightly more than six times higher on average. For the counting circles without measures, there was no difference in the number of birds between the Scottish demonstration site Balgonie compared to the reference site Balbirnie. The number of seed-eating birds in the circles without measures at the English demonstration site Rotherfield was 80% lower than in the reference site Cheriton. For the European areas combined, this was 13% higher on average.
For the other species which are less dependent on seeds, the results are slightly different. In England, there were respectively 2x and 2.5x more birds in the counting circles with and without measures at Rotherfield compared to the reference site Cheriton. In Scotland, both the counting circles with measures of the Balgonie demonstration site and those of the reference site Balbirnie on average had the same number of birds while there were about 50% less in the counting circles without measures in the demonstration stie. For all the European areas together, the average number of birds in counting circles with measures was on average 29% higher than in the reference areas, for the counting circles without measures there was no difference with the reference areas.
Kestrel on the lookout over winter seedheads
Figure 1: Abundance - Average number of birds observed in the circle around the count point during winter in our demonstration (Demo) and control areas. Demo+ with measures, Demo without measures. The vertical lines show the variation between counts.
Diversity
Compared to bird abundance, bird diversity scored better. The number of seed eating bird species recorded in the counting circles with measures were two times higher compared to the reference area both at Rotherfield and Balgonie (Figure 2). At both sites, there was no difference in species diversity between the counting circles without measures in the demonstration areas and the reference areas. Overall, for the European demonstration sites combined, the number of species per year is slightly higher in the demonstration areas than the reference areas for the seed eaters.
Species diversity for the other birds, those that do not primarily depend on seeds, was 60% higher in the demonstration site Rotherfield compared to the reference site Cheriton for both the circles with and without measures. In Scotland there were only few species of this group, and there was no difference in species diversity between the demonstration site Balgonie and the reference site Balbirnie. The results for all European sites combined show that species richness is 40% (with measures) and 10% (without measures) higher in the demonstration areas than in the control areas, respectively.
Figure 2: Diversity - Average number of birds species observed per count point during winter in our demo and control areas. Demo+ with measures, Demo- without measures. The vertical lines show the variation between counts.
Conclusion
Our results clearly show that birds that rely heavily on seeds in winter benefit the most. This was most likely due to them utilising the PARTRIDGE mix, which contains several plant species that produce seeds that are available in winter. During our winter censuses, large flocks of birds were regularly seen diving into the plots with measures to feed on the seeds. However, other species that do not depend on seeds were also found in larger numbers on or near the measures. These species can also utilise the mix by seeking shelter and/or food there. Although not specifically studied in winter, we were able to show that the PARTRIDGE mix produced more insects for food in summer, and we believe the same is true for seeds during the winter months.
References
- Gillings, S., et al. (2005). Winter availability of cereal stubbles attracts declining farmland birds and positively influences breeding population trends. Proceedings of the Royal Society B: Biological Sciences, 272(1564): p. 733-739.
- Broughton, R.K., et al. (2020). Intensive supplementary feeding improves the performance of wild bird seed plots in provisioning farmland birds throughout the winter: a case study in lowland England. Bird Study, 67(4): p. 409-419.
- Hammers, M., et al. (2015). Ecological contrasts drive responses of wintering farmland birds to conservation management. Ecography, 38(8): p. 813-821.
Written by Luc De Bruyn, senior researcher at INBO and data analyst for PARTRIDGE, Belgium, edited by Francis Buner, Head of Wildlife Recovery at GWCT, Head of PARTRIDGE and Fiona Torrance, researcher and advisor, GWCT Scotland