I’m very pleased to have been involved with an invertebrate study with practical conservation value, as these are still vanishingly rare in a (conservation) world dominated by cuddly vertebrate. A few years back I had the pleasure to supervise a field project on the Oxford University Department for Continuing Education’s PgCert in Ecological Survey Techniques looking at habitat preferences of the Greater Bermudan Land Snail (Poecilozonites bermudensis) on a small island (Port’s Island) off Bermuda. The student, Alison Copeland, conducted an excellent study on the habitat preferences of these snails, which were thought to be extinct at some point before a small population were found in Stanley, Bermuda’s capital city. A large breeding programme was in the meantime established, and the need for more information on the snail’s habitat requirements were urgently required. Alison made use of the recent discovery of another free-living population of the snail on Port’s Island to investigate to what extent they could be found near a range of habitat features, but the good news is that they are less demanding in their requirements than previously thought in terms of elevation, vegetation and distance to the sea (although they tend to avoid an invasive tree species and needs to be close to limestone features).
You can read a very interesting blogpost on the study written by Alison here.
The study has now, in a condensed form, been published in Oryx.
Copeland, A. and Hesselberg, T. (2021). Habitat preferences of the critically endangered greater Bermuda land snail Poecilozonites bermudensis in the wild. Oryx 1-4. doi:10.1017/S0030605320000836.
Abstract
The endemic, Critically Endangered greater Bermuda land snail Poecilozonites bermudensis is known from only two relict subpopulations. Little is known of its habitat preferences in the wild. Observations of released zoo-reared P. bermudensis suggested an affinity for limestone, which we investigated on Port’s Island. Previous qualitative observations on Port’s Island suggested an aversion to the litter of the invasive tree Casuarina equisetifolia, which we examined. Additionally, we hypothesized that snail abundance would increase with elevation, distance from the sea, and with increased plant species diversity. During 2 May–14 June 2018, we found 558 live P. bermudensis at 70 sites across Port’s Island. We found no correlation between the number of live snails at a site and either the number of plant species, elevation or distance from the shoreline, but snails were significantly less abundant at sites dominated by C. equisetifolia. Significantly more snails were found around limestone features, indicating future reintroductions and searches for any undiscovered subpopulations should focus on limestone features where C. equisetifolia is absent.
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