PARTRIDGE measures attract farmland birds in winter
Farmland birds are in decline in Europe and hence urgent action is needed to halt and reverse this decline. Between 2016 and 2022, the Interreg PARTRIDGE project, improved the area of our 10 farmland demonstration sites - two each in Flanders, The Netherlands, Germany, 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 we did this was already covered in detail in previous blogs and is described in our factsheets. These habitat improvements provide more and better breeding habitats in summer, and more food and shelter for overwintering birds. The main target bird is of course the grey partridge, with other farmland birds also expected to benefit. To show that overwintering birds indeed benefit from the measures, we carried out point count surveys in the demo sites and corresponding control sites (without those measures) at several of our sites in The Netherlands, England, Scotland, and Flanders (Belgium) during the winters of 2019-2020 to 2022-2023. In the demonstration sites we selected points on or nearby our implemented habitat measures (mainly PARTRIDGE flower blocks) and points away from those measures. In nearby control sites, where we did not introduce PARTRIDGE flower blocks, points were randomly located. Each month, from November to February we counted all birds present in a circle around the points.
Overall, we analysed the data obtained for 29 species of two groups. The first group of 10 species (seed eaters – see below) commonly occur in farmland and largely depend on seeds as a source of food in winter [see References 1-4]. Farmland birds from this group have shown the greatest decline across Europe because of agricultural intensification. The other 19 species (other birds below) are also commonly encountered in a farmland environment, but they do not rely primarily on seeds as food during the winter. Bird abundance and species richness were calculated for both groups in each counting circle at each site visit.
Brambling on flower blocks
Brambling, Chaffinch, Linnet, Tree Sparrow, Goldfinch, Greenfinch, Grey Partridge, Reed Bunting, Skylark, Yellowhammer.
Blue Tit, Wood Pigeon, Blackbird, Collared-Dove, Jackdaw, Magpie, Robin, Starling, Fieldfare, Great Tit, House Sparrow, Meadow Pipit, Northern Lapwing, Redwing, Ring-necked Pheasant, Rook, Song Thrush, Stock Dove, Wren.
The average number of birds from the seed-eater group observed in the counting circles around our habitat measures in the demonstration sites was over six-times higher than in the circles on the control sites (Figure 1). For the circles on our demonstration sites without measures, the number of birds was on average 13% higher than in the control sites. A similar picture was obtained for the other birds, but the differences were smaller. For these species, the average number of birds observed in counting circles with measures on demonstration sites was on average 29% higher than in the control sites. For the circles without measures, there was no difference. For both groups of species, the number of birds was highest at the beginning of the winter, decreasing towards the end of the winter.
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.
The effect on the number of bird species (diversity) visiting our areas in winter is more subtle. Overall, the number of species per year is slightly higher in the demonstration areas than the reference areas for the seed eaters. On average, we recorded 7 species within the circles which contained our measures, 6 in circles without measures and 5 in the control sites. There was no difference between the three treatments for the other bird group with 14-15 species per year. However, when we look at the number of species seen simultaneously in a single counting circle, the difference is greater (Figure 2). Then, on average, there are about three times as many seed-eating species in the counting circles with measures on our demonstration areas than in the control areas. For the counting circles without measures at our demo areas, this is 21% more. For the other species, 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.
Our results show clearly that birds that rely heavily on seeds during the winter months benefit the most. The PARTRIDGE mix contains several plant species that produce seeds that are available in winter. During our winter counts, largeflocks of birds were regularly seen diving into our PARTRIDGE blocks, searching for food. Interestingly, species that do not depend on seeds are also found in greater numbers on or near the measures. They may be looking for shelter and food items other than seeds in the PARTRIDGE blocks. Although we did not examine this specifically in winter, we were able to show that the PARTRIDGE mix produced more insect food in summer.
- Hammers, M., et al., Ecological contrasts drive responses of wintering farmland birds to conservation management. Ecography, 2015. 38(8): p. 813-821.
- Dochy, O. and M. Hens, Van de stakkers van de akkers naar de helden van de velden: beschermingsmaatregelen voor akkervogels. 2005, Rapporten van het instituut voor natuurbehoud IN.R.2005.01: Brussel, Belgium.
- Gillings, S., et al., Winter availability of cereal stubbles attracts declining farmland birds and positively influences breeding population trends. Proceedings of the Royal Society B: Biological Sciences, 2005. 272(1564): p. 733-739.
- Broughton, R.K., et al., 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, 2020. 67(4): p. 409-419.
Written by Luc De Bruyn, senior researcher at INBO and data analyst for PARTRIDGE, Belgium, edited by Francis Buner, Senior Conservation Scientist at GWCT, Head of PARTRIDGE