Interpretation of distribution maps

The vast majority of distribution maps on this site show the results of records made by or verified by specialists or accepted as reliable. However like all distribution maps they need to be interpreted with caution - the presence of a dot is no guarantee that the record is proof of a viable population of the species or that the site or habitat still occurs. A record shown on a map may be the result of a single individual or a numerous population. The presence of an old dot may indicate that the area has not been visited more recently or that the species has not been looked for subsequently. However the changes to the Essex countryside over the last century and losses and changes that continue today mean that many species are declining, sites and habitats have been lost and many species are more difficult to locate than previously.

Records depend enormously on what level of survey was undertaken and how taxonomically wide ranging it was, the skills and experience of the recorder, what recording techniques were employed, whether it was undertaken throughout the season and in favourable weather conditions etc. In addition recording a species can simply depend on good luck, being in the right place at the right time.

Maps may seem to suggest that a species is widespread and common in the region and unlikely to be under any threat - but there are huge pressures in the county on both farmland and semi-natural habitats within the wider countryside and in particular there are major development threats around the larger conurbations. This is nowhere more pronounced than in the Thames Gateway, but applies equally to other important areas for nature conservation in the county such as around Colchester, Chelmsford, Maldon, Braintree, Great Dunmow etc.

An example of a map that appears to show a species that is widespread and common in the Thames Gateway and under no threat is one for the UKBAP (UK Biodiversity Action Plan) bumblebee Bombus humilis (Brown-banded Carder Bee). When sites known to be destroyed or under imminent threat of destruction by developments are shown in red, the picture is very different - and since the status of many other sites is unknown the true situation may be much worse. In addition to this, bumblebees are known to require landscape scale habitats for their survival.