PARTRIDGE habitat mapping
To monitor our progress towards this goal we utilized digital habitat maps, collected twice a year (once in the summer and winter) from cropping plans and site visits (see full report). In total we created 240 individual habitat maps, equivalent to approximately 120,000 hectares of habitat data. We assessed the benefits provided by each habitat type recorded on these maps using expert knowledge. We were therefore able to measure exactly how much area these features occupied on our demonstration sites.
Our analysis of this habitat data has revealed that, except for two sites, by the end of the project almost every demonstration site had achieved this target of 7% beneficial habitat coverage. In fact, many demonstration sites began the project above this 7% target, with an average coverage of 8.8% (Figure 1) in 2017 – an unintended consequence of our initial demonstration site selection criteria which required sites to have recent grey partridge records and farmers willing to engage with our project. As a result, our demonstration sites were either managed by farmers already predisposed towards wildlife-friendly farming and thus had already established beneficial habitat or were sites where we had worked before, and therefore already had some of our beneficial measures in place.
Figure 1. The percentage of demonstration and reference sites occupied by beneficial summer
habitat over the six years of the PARTRIDGE project. The 7% target is provided for comparison.
Despite these high initial values, by 2021 we succeeded in significantly increasing coverage by almost 5%, raising this average to an incredible 13.7% of our project areas covered by beneficial habitat (Figure 1). On top of this new habitat, we refined and improved those measures already established on our demonstration sites, further benefitting wildlife at these sites. Looking at the specific benefits these habitats provided, we found that our demonstration sites had more than double the minimum amount of nesting and brood-rearing habitat required to recover grey partridge populations. Conversely, we found that our reference sites, representing typical farming systems within their respective reasons, saw no increase in the amount of beneficial habitat across the project duration.
Furthermore, the range of different habitat types we established at our demonstration sites was significantly more diverse than those few beneficial habitat types present at our reference sites, thereby benefitting a wider range of farmland species. This is reflected in our monitoring data, which showed that the abundance of breeding territories and the richness of farmland birds was greater at our demonstration sites than our unenhanced reference sites.
Establishing all this additional habitat was far from easy. Because of the size of our demonstration sites and the farming systems of our partner countries, we often ended up working with dozens of farmers – making it difficult to ensure an even distribution of habitat across the landscape. Each individual farmer will have different preferences as to where on their land any new habitat is established - or may even elect not to engage in the project whatsoever and not establish any habitat. Similarly, some farmers on our demonstration sites were dairy and/or cattle farmers who found it more difficult to give up their pastureland for wildlife, while others offered up large fields of several hectares in a ‘have it all or leave it altogether’ manner. Consequently, we found that our beneficial habitat was being established in highly aggregated clusters (Figure 2) at our demonstration sites. Whilst the consequences of this at our demonstration sites have yet to be investigated, we suspect that had we achieved a more even distribution of habitat across our demonstration sites we may have achieved a larger increase in biodiversity.
Figure 2. Maps of less aggregated beneficial habitat at Whitburgh, SC (A) compared to more
aggregated habitat at Ramskapelle, BE (B) and Burghsluis, NL (C). The gaps between habitats
in the latter two sites indicates where it has not been possible to establish beneficial habitat.
The unintentional aggregation of our habitat also had positive effects – by combining several smaller adjoining habitats, and in combination with our focus on establishing large (> 0.5 hectare) blocks of wild-bird mixes (Figure 3), we greatly increased the amount of ‘core’ (> 20 meters in width; Gottschalk and Beeke, 2014) beneficial habitat across our demonstration sites. These ‘core’ areas provide grey partridge and other ground-nesting birds with areas to nest and forage with a significantly reduced risk of predation. Our project was able to double the amount of ‘core’ habitat at our demonstration sites over the course of the project – with the final levels at our demonstration sites ten times greater than that at our reference sites, making them far more suitable for the recovery of our study species.
Figure 3. An example of a 2nd (on the left of the photo) and 3rd (on the right of the photo) year
PARTRIDGE wild-bird mix. We aimed to ensure this measure was at least 0.5 ha in size, and therefore
would have been considered ‘core habitat’, thereby reducing predation risk. © Francis Buner
In conclusion, the PARTRIDGE project succeeded in meeting our goal of establishing significant levels of additional beneficial habitat at our demonstration sites. Despite complications with positioning of these habitats, we were able to provide a great deal of nesting, brood rearing and overwinter cover habitat across our demonstration sites, with a large proportion of these habitats having a significantly reduced risk of predation.
Written by Cameron Hubbard, GIS & Biometrics Analyst, The Game and Wildlife Conservation Trust