Going on night-time safari to spot brown hares: Why did we do it and what did we find?
In order to understand the impact of these habitat improvements on overall farmland biodiversity, we embarked on an extensive monitoring programme. Over the course of seven years, various species, including the brown hare, were closely monitored at our 10 demonstration and paired reference sites across our five project countries Belgium, The Netherlands, Germany, Scotland and England.
The brown hare holds a special place in our agricultural landscape, cherished by nature enthusiasts, farmers, small game hunters, and the general public alike. Through our monitoring efforts, we aimed to find out whether the habitat improvements positively affected the number of hares at our demonstration sites.
This required an incredible effort spanning the seven-year project period. Each year, three to four night-time counting sessions were scheduled per site. Equipped with the line-transect spotlight method, we set out on thrilling night-time safaris, spending countless hours driving along the fixed transects, meticulously counting hares illuminated by the spotlight. The scale of this monitoring endeavour was truly astonishing. Across 453 separate nocturnal monitoring sessions, we covered an expansive area of over 127,000 hectares and counted approximately 34,000 hares! It was quite an adventure, and we invite you to check out our factsheet and monitoring blog to learn more about the monitoring method and our first hand experiences.
Mapping hare counts at night
Now, let’s delve into our findings.
Upon comparing the numbers of hares counted by the end of the project between the demonstration and reference sites, we discovered a significant difference. On average, our demonstration sites had an additional 11 hares more per 100 hectares compared to the reference sites! This result provides compelling evidence that the improved habitat quality at our demonstration sites had a positive influence on local hare populations. Moreover, it demonstrates that the habitat measures, tailored to the grey partridge, were equally beneficial for the brown hare, talk about a win-win situation.
Figure 1 Comparing Index (number of hares seen/100 ha) between reference and demonstration sites (2021-2023); in background: model fit per site; in blue: point estimate and 95% confidence interval for reference sites; in green: point estimate and 95% confidence interval for demonstration sites. Note that the Belgian sites are not shown due to the confidentiality of this data.
But, as the world of science often reveals, the full picture is more nuanced. Detailed habitat mapping showed that while we successfully increased good quality habitat coverage in our demonstration sites by an average of around 4% through the implementation of our habitat improvements, many of these sites were already in good shape at the start of the project, with good quality habitat coverage close to or exceeding the targeted 7% in 2017.
To disentangle the impact of the additional 4% of habitat improvements on local hare numbers from the effect of the pre-existing good quality habitat, we took a closer look at the trend in hare numbers over the project’s duration. In other words, whether the number of hares increased faster in the demonstration sites with our habitat improvements than in the paired reference sites.
Somewhat unexpectedly, the results of this trend analysis showed no overall difference in the trend and outcomes varied substantially between different sites.
Figure 2 – Percentage difference in trend between demonstration and reference sites for all site-couples separately and combined (OVERALL);
point estimate and 95% confidence interval; naming based on the abbreviated country name followed by the name of the demonstration site; 0%: no difference; 30% project's target
This suggests that, while our habitat improvements were undoubtedly valuable, they might not have had a substantial enough impact on the population trend to be noticeable through our monitoring efforts. Trend analyses are notoriously challenging, requiring huge amounts of effort and time. As biological populations fluctuate naturally, long time series are needed in order to separate the year-to-year and site-to-site variation from the overall change in trend. Although the seven years of monitoring provided valuable insights, more time might be needed to accurately assess population trends and their response to habitat improvements.
Furthermore, we must recognize that habitat quality is just one of many factors influencing local hare numbers. Each site has its unique story, with local conditions such as weather, hunting pressure, poaching, predation, diseases, and potential methodological errors, all potentially influencing the number of hares recorded. These additional influences make it even more challenging to establish a straightforward cause-and-effect relationship between habitat improvements and hare populations.
In conclusion, our results provide evidence that increased habitat quality results in higher number of hares and that the habitat improvements, tailored to the grey partridge, also benefitted the local brown hare populations. Nevertheless, they also demonstrate the complexity of the interaction between habitat improvements and local hare dynamics. Clearly, there’s more to the storythan meets the eye.
By sharing our experiences and the things we learned along the way, we aim to provide evidence that active management can boost local farmland biodiversity and reinforce the role of effective agro-environmental schemes in preserving farmland biodiversity.
Hopefully you enjoyed this exciting journey into the world of brown hares and habitat improvements. Stay tuned for more updates from our PARTRIDGE monitoring adventures!
Written by Fleur Petersen, data analyst at INBO, Belgium and PARTRIDGE
Edited by Francis Buner, Senior Conservation Scientist at GWCT and Head of PARTRIDGE