Duerden Cormack – resident ecologist at Hope farm - reflects on 25 years of wildlife monitoring on farm.
By now you will hopefully know that here at Hope Farm we are celebrating 25 years of demonstrating nature-friendly arable farming. Following the Farm Wildlife Six Key Actions we have implemented changes to benefit wildlife whilst producing food and maintaining a profitable farm business. Farm manager Georgie Bray has summarised what to look out for this year here and, in this blog, I’m going to explain how we know nature-friendly farming works for wildlife.
The first step
Before we set about making changes, we needed to know what we were starting with. In our first year, cropping continued as normal, but habitats were mapped, and a comprehensive set of baseline surveys was conducted covering birds, several invertebrate groups, vascular plants, bryophytes, and fungi. Only then could we target our management, implementing the first Farm Wildlife Six Key Action – enhance existing habitats and begin to assess change.
These baseline surveys have been repeated at more or less regular intervals over the last 25 years, however, the real value of Hope Farm has been in the standardised, annual monitoring of a few select groups, particularly its birds.
Standardised monitoring
We use the British Trust for Ornithology’s Common Bird Census methodology to monitor breeding bird populations which allows us to calculate the number of territories held by each species in a consistent manner. In contrast, to deal with the huge numbers, we survey wintering birds using a team of volunteers so that birds using each field are counted roughly simultaneously. For butterflies, we walk three UK Butterfly Monitoring Scheme transects each week throughout the summer, April to September, recording all butterflies seen.
Although across all surveys we record all individuals of all species, we restrict our analysis to DEFRA’s farmland bird index and farmland butterfly indicators. These are a suite of species that rely on farmland for at least part of their lifecycle and includes specialists and generalists. By taking the year 2000 as a baseline, we produce indices that allow comparisons to be made against the national trend.
The results
In the first ten years of the Hope Farm project we saw incredible changes including;
Since then, the index has levelled off and fluctuated around what appears to be the farm’s new carrying capacity, around 160% greater than the baseline. Relatively simple changes to farmland management have produced immediate gains and delivered resilient populations of farmland birds despite a background of continued decrease at the national scale.
For Hope Farm’s wintering bird populations, it is much harder to suggest drivers of change although the trend is undeniably one of huge increase. The index has increased by an overall average of 1631% - note the difference in scale between the wintering and breeding bird indices. Impressive peak counts include 723 Yellowhammers in February 2016, 128 Corn Buntings in December 2022, and 1076 Linnets in January 2024. In contrast to breeding populations, wintering bird numbers are influenced by food availability and the climate on a much broader, often continental scale. The increasingly large fluctuations observed in the index in recent years likely reflect the influence of uncontrollable factors such as these. However, some of the habitat changes we have implemented are likely to have contributed to the overall increase such as maintaining thicker hedgerows which are cut less frequently; retaining overwinter stubbles, reducing tillage, using cover crops and providing winter bird seed mixes, unharvested headlands and supplementary feed.
Hope Farm’s butterfly populations have also shown strong gains – the index has increased by an overall average of 348%. Once again however there are factors at play beyond increased habitat provision. Butterflies have complex, population-level relationships with parasites and are particularly vulnerable to extreme weather events. Across the country, the 2024 season was especially bad with several cold, wet snaps occurring at critical stages in many species’ lifecycles. Looking more closely at the trends for individual species there are also some clear climate related impacts. Ringlet, for example, was almost lost from the farm following the drought and heatwaves in 2022 whereas Small Heath has seen an inexorable increase in number over the last 10 years. Despite these fluctuations and individual differences, the overall trend is clear - relatively simple habitat changes to support not just pollen and nectar provision but the needs of the whole lifecycle, stopping use of insecticides and reducing other pesticide use have delivered strong, positive changes.
Image: Whitethroat brood at RSPB Hope Farm (c) Duerden Cormack, RSPB
Notable wildlife
As well as the standardised monitoring efforts, large amounts of incidental recording occurs at Hope Farm and many interesting records are generated by one-off surveys or visiting specialists. Well over 2000 species have been recorded here including several of significance for the county and country.
Although clay soils tend to have a poorer arable flora than lighter land, there are some plants of interest. Rare arable specialists include Broad-leaved Spurge, Slender Tare, and recently discovered Shepherd’s-needle. We also participated in a Natural England project with Plantlife called ‘Colour the Margins’ to reintroduce the critically endangered Corn Buttercup which now survives in a dedicated plot.
Images - Corn Buttercup, Slender Tare and Shepherd's Needle (c) Duerden Cormack, RSPB
We are lucky that the landscape Hope Farm sits in is rich with surviving old elm trees. We host uncommon elm specialists such as White-letter Hairstreak, the weevil Anthonomus ulmi, the gall-forming aphid Kaltenbachiella pallida, and the moths White-spotted Pinion and Dusky-lemon Sallow. Wrinkled Peach mushrooms are a common sight in autumn on dead elm and were noted several times by the Huntingdonshire Fungus Group on the baseline survey in 2000 and 2001. In total they recorded 491 species including a first for Britain - Eutypa crustata!
Images: Grey Partridge and Wrinkled Peach (c) Duerden Cormack, RSPB
Conclusion
The results of the wildlife monitoring at Hope Farm are clear – with considered application of the Farm Wildlife six key actions, including relatively targeted habitat provision and sympathetic farming practices, productive arable farms can be sustainable, profitable, biodiverse, and produce food. However, some species need a more joined up, landscape-scale approach if they are to recover; Turtle Doves, for example, have not been recorded here for several years now. Even after 25 years of monitoring work here it still feels like we have hardly scratched the surface – we’re looking forward to the next 25 and will of course share our findings along the way!