Sophie Burry, Dorset LNP Assistant
The heath tiger beetle (Cicindela sylvatica) is a species that is often overlooked in Dorset. Often because they are incredibly tricky to spot in the wild (as well as being incredibly rare, they are also very agile hunters!) but also because they can be overshadowed by their “more attractive” relative – the iridescent green tiger beetle (Cicindela campestris).
Globally, the heath tiger beetle is distributed across the Palaearctic realm but is often found in small, isolated populations. In England, remaining individuals have been confined to the South in the counties of Surrey, Sussex and Hampshire with Dorset also being a traditional stronghold for populations.
Heath tiger beetle vs Green tiger beetle © Steven Falk / Charles J. Sharp
Why is the species so rare?
It’s estimated that more than half of England’s heath tiger beetle populations have disappeared over the last 25 years! This dramatic decline means that the species is now classed as ‘nationally scarce’. It’s thought that fragmentation and degradation of their characteristic lowland heath habitat are associated with their absence, a trend that’s also thought to have impacted the species in other European countries [1]. In Dorset, 75% of heathland has been lost over the last century due to development, agricultural intensification and afforestation. Sadly, this has had a lasting impact on many of our heathland species.
What do we know about the species?
Much of the information we have on the species, such as their biology and life cycle, has been informed from similar species that are in greater abundance such as the green tiger beetle. Past studies have also given us an insight into the species habitat requirements and the potential management techniques required to increase their presence. However, there are still questions that have been left unanswered, with some contradictory research. For example, they are thought to exhibit limited powers of dispersal. However, distance between two populations has been observed over a greater distance, meaning that the species may be capable of dispersing further [2]. Studies have also seen an expansion in their geographic range, in seemingly uncharacteristic habitats [3 & 4]. This highlights the potential need for further surveys to be conducted outside of the species known geographic range in Dorset, as the presence of rare or cryptic species can often be missed [5].
Why should the species be conserved?
The heath tiger beetle has previously been thought of as a suitable candidate as an umbrella species (a species which can, when protected, indirectly protect multiple others) as they can occur with other rare, specialist heathland species [6]. This means that implementation of appropriate management could also benefit other species of lowland heath. This includes our six native UK reptile species and various bird species like nightjars and Dartford warblers. It has also been argued that tiger beetles in general make good indicator species for biodiversity conservation because of their obvious appearance and often specialist association to early successional and threatened habitat.
What’s being done to conserve the species in Dorset?
The heath tiger beetle was a chosen species for the Back from the Brink project (Dorset’s Heathland Heart) in 2022. This project involved the creation of new microhabitats to benefit 19 target species. For the heath tiger beetle, artificial scrapes were created by scraping the ground free of vegetation, creating suitable bare ground habitat. The species prefer bare ground for several reasons e.g., adults have open areas to hunt for prey and larvae are able to dig vertical burrows for ambush hunting and development [7]. An increase in adult individuals was recorded on new scrapes at the 3 key sites where management was undertaken (Slepe Heath, Sopley Heath and Great Ovens), suggesting that the creation of sandy scrapes had been successful for the species. However, due to a lack of adequate baseline data, it was difficult to assess whether the scrapes had led to a species recovery at population level. Sopley Common nature reserve has one of the largest populations of heath tiger beetles in the South of England. Dorset Wildlife Trust, who manage the reserve, have been actively working towards creating 15% more bare ground on the site than 10 years ago – watch this space!
Distribution records for the heath tiger beetle within Dorset heathland. Red dots show previous records post 1990 and blue dots show Back From The Brink records between 2018-2021 © Footprint Ecology and DERC
What’s being done to conserve the species elsewhere?
The Species Recovery Trust and Sparsholt College have jointly set up a captive breeding programme to breed large numbers of individuals for reintroduction (this has shown to be a success so far!). Surrey Wildlife Trust have been carrying out heathland restoration work for the species at a county level. This includes reintroductions and the deliberate creation of bare, compacted sandy areas for nesting burrows. This could be a great opportunity for all three counties to collaborate!
The next time you are out and about on one of their heathland haunts (adults emerge from late April to early September), keep an eye out for this evasive beetle as well as our other incredible Dorset heathland species. The Species Recovery Trust have put together a helpful handbook which gives information on how to identify and survey the species.
References
[1] – Kotze, D.J., Brandmayr, P., Casale, A., Dauffy-Richard, E., Dekoninck, W., Koivula, M.J., Lövei, G.L., Mossakowski, D., Noordijk, J., Paarmann, W. and Pizzolotto, R., 2011. Forty years of carabid beetle research in Europe–from taxonomy, biology, ecology and population studies to bioindication, habitat assessment and conservation. ZooKeys, (100), p.55.
[2] – Dodd, S.G., 2011. Population size and dispersal of the Tiger Beetles Cicindela sylvatica Linnaeus, 1758 (Heath Tiger Beetle) and Cicindela campestris Linnaeus, 1758 (Green Tiger Beetle) (Coleoptera: Carabidae: Cicindelidae) within a Surrey heathland mosaic. Master of Science Dissertation. University of Birmingham.
[3] – Dudko, R.Y., Matalin, A.V. and Fedorenko, D.N., 2010. The ground beetle fauna (Coleoptera, Carabidae) of southeastern Altai. Entomological Review, 90, pp.968-988.
[4] – Puchkov, A.V., Martynov, A.V., Shyshkina, M.G. and Markina, T.Y., 2021. Rare and protected species of Caraboidea (Coleoptera) of the Steppe zone of Ukraine. Ecologica Montenegrina, 48, 62-70.
[5] – Loehle, C., 2020. Quantifying species’ geographic range changes: conceptual and statistical issues. Ecosphere, 11(3), e03070.
[6] – Berglind, S.Å., 2004. Area-Sensitivity of the Sand Lizard and Spider Wasps in Sandy Pine Heath Forests: Umbrella Species for Early Successional Biodiversity Conservation? Ecological Bulletins, 189-207.
[7] – Offer, D., Edwards, M. and Edgar, P., 2003. Grazing heathland: a guide to impact assessment for insects and reptiles: English Nature Research Reports. Natural England. 497.