Consistent oviposition preferences of the Duke of Burgundy butterfly over 14 years on a chalk grassland reserve in Bedfordshire, UK

The Duke of Burgundy butterfly (Hamearis lucina) is known to have specific habitat requirements for its larval foodplants. However, no studies have yet investigated whether these preferences vary over time or in relation to climate, and there is a paucity of data on whether management on reserves can replicate preferred conditions. Here, we build upon existing research to confirm which characteristics Duke of Burgundy prefer for their larval foodplants, whether preferences remain consistent across years, and whether conservation management on reserves can replicate these conditions. Fieldwork was carried out at Totternhoe Quarry Reserve, a chalk grassland site in Bedfordshire, UK. Confirming previous research, we found that large Primula plants in dense patches were chosen for oviposition, but that once chosen there was no preference to lay eggs on a plant’s largest leaf. Chosen foodplants were also more sheltered and in closer proximity to scrub than their controls. However, at a finer scale, we found little evidence for any preference based on differences in microclimate, or vegetation height immediately surrounding the plants. This suggests features that alter microclimatic conditions at a larger scale are relatively more important for determining the suitability of oviposition sites. Nearly all preferences remained consistent over time and did not vary between years. Management of scrub on the reserve was able to reproduce some preferred habitat features (high plant density), but not others (large plant size). Implications for insect conservation The consistency of findings across years, despite inter-annual variation in temperature, rainfall and number of adults, indicates that the Duke of Burgundy is conservative in its foodplant choice, highlighting its need for specific habitat management. Targeted management for foodplants could form part of a tractable set of tools to support Duke of Burgundy numbers on reserves, but a careful balance is needed to avoid scrub clearance leaving plants in sub-optimal conditions.

Geographical patterns in the flora of Cambridgeshire (v.c.29)

Cambridgeshire data collected for the BSBI’s Atlas 2020 project include 347,496 records at monad (1 km) or finer resolution. We used these data to cluster taxa by spherical k-means to produce 21 clusters of taxa with similar patterns of distribution. Some of the clusters correspond to well-defined habitats such as chalk grassland, ancient woodland, traditional fenland, and saline riversides and roadsides. Other clusters were less expected, corresponding to arable clayland, washland (the Ouse and Nene washes), waste ground and garden escapes. There was a cluster of ubiquitous species and another of common arable weeds. The distributions of the clusters are displayed as coincidence maps. Some species are intermediate between two clusters. These can be recognised by their relatively poor goodness of fit to any one cluster. The clusters differ markedly in ecological attributes and whether they include rare or threatened species. We interpret these differences using Ellenberg values and the vascular plant Red List for England.

Long-term monitoring for adders: an evolving methodology

Currently, there is no recommended methodology for long-term population monitoring of European adders (Vipera berus). To open a debate on a preferred methodology, we describe an approach based on 10-years’ experience of monitoring in a chalk grassland reserve. The main elements are: 1) selection of a site with areas offering contrasting environmental conditions; 2) detection of adders along standard survey paths (transects) combined with paired artificial refuges of corrugated iron and roofing felt that are essential for detecting immature stages; 3) recognition of individual adders based on head-scale and neck patterns; 4) frequent site visits throughout the reptile active season; and 5) adoption of an Encounter Index (E.I.) that combines data from standard paths and refuges and normalises them for variations in survey effort and for shifts between years in the encounter rates along paths and at refuges. E.I. values correlate strongly with the numbers of known adders in the reserve but in some years E.I. values have been disproportionally high. Future objectives of the project are to explain variations in detectability and to estimate adder detectability associated with the current monitoring approach. Effective long-term monitoring is achievable by deploying “sufficient” refuges and, within practical limits, maximising path lengths and site visits. Future analysis of our own results will likely confirm our methodology as a “rule of thumb” for adder monitoring on, at least, chalk grassland.