The cold weather and dropping temperatures mean that several species in the UK hibernate, migrate or reduce their activity levels over the winter months. Mammals such as bats, hedgehogs and dormice, reptiles and amphibians all hibernate during the cold winter months to conserve energy while food is restricted and temperatures drop. This restricts some ecological surveys, such as reptile presence/absence surveys and bat activity surveys, as well as some habitat management and mitigation works during the winter months.
However, there are still a wide variety of ecological surveys that can be undertaken by Ecosulis’ Consultancy Team during the winter months, including extended Phase 1 habitat surveys and protected species surveys. Management and mitigation works, including pond remediation and enhancements works, vegetation clearance and tree planting, can be undertaken by Ecosulis’ Countryside Management Team during the winter months. Ecosulis has over 20 years of experience in ecological surveys, including those specific to the winter months, such as winter bird surveys.
An extended Phase 1 habitat survey can be undertaken at any time of the year. The survey follows a method of habitat classification system developed by the Joint Nature Conservation Committee (JNCC 2007) to map habitats and land use categories. An extended Phase 1 habitat survey is an initial survey to establish the current ecological site conditions, which is used to identify potential constraints and opportunities that ecology may pose to the development plans; and to identify further ecological studies that may be required to ensure that ecology is fully considered within the proposals. This survey can be undertaken at any time of year, including the winter months.
Ecosulis has Environment Agency trained and accredited surveyors who can undertaken River Habitat Surveys and River Corridor Surveys throughout the year. The major habitats, vegetation and physical features of the river corridor are mapped and notes taken on evidence of recreational features, management and observed or potential threats to its conservation value and opportunities for enhancement.
Badger surveys can also be undertaken at any time of year, however are more effective during the winter and spring months when vegetation has died back and setts, tracks, latrines and prints are more visible.
Badger bait marking surveys are used to establish badger territories, and can be useful on larger sites to identify which badger groups are likely to be affected by a development and inform an impact assessment and mitigation. This type of survey is most effective between February and April, when vegetation is at its lowest and activity levels are high. The main setts are identified and badger bait, comprising a peanut and syrup mix with coloured beads, is laid around the sett. Once the uptake of bait has been established, the survey includes visiting previously identified latrines and recording the presence of any coloured beads. The information from these visits can then be used to map the territory of the badger population(s). The survey method follows Delehay et al. (2000) and Design Manual for Roads and Bridges, Highways Agency (1997).
Species of bats in the UK hibernate during the winter months, therefore dusk emergence and activity surveys cannot be undertaken at this time of year. Ecosulis can undertake a daytime bat assessment and survey of buildings and trees at any time of year, including the winter months. Daytime bat assessments of buildings and trees include assessing their suitability to support roosting bats and recording any evidence of bats, including droppings, feeding remains and staining. Ecosulis has recently incorporated the use of DNA analysis of bat droppings collected from a site in Gloucestershire to establish the species of bat using the buildings. This can be used to indicate the species of bats using the structures on site, which in this case was lesser horseshoe bats, which will now be used to inform mitigation measures alongside the results of the summer surveys in 2011. The benefits of the DNA analysis is that mitigation can be considered now and simply validated in the summer when bats are active.
Climb and inspect surveys of trees with bat roosting potential can also be undertaken during the winter months, when vegetation is less likely to restrict the survey. Surveyors inspect features within the trees for their suitability to support roosting bats as well as searching for any evidence of bats, such as droppings and staining.
Although the winter months are suboptimal for dormouse nest tube surveys, they are optimal for hazel nut searches. These should be undertaken before March and include a search for hazel nuts which have been eaten by dormice. Dormice leave a very smooth round opening with tooth marks around the rim of the hole, with very few tooth marks on the nut surface as detailed within the Dormouse Conservation Handbook. Although other small rodents such as mice or voles will gnaw hazel nuts, the above characteristics are distinctive of dormice. Ecosulis has years of experience in undertaking these searches, with experienced and licenced dormice workers within the team.
Otter surveys can be undertaken at any time of year, and evidence of otter activity is usually evident the winter months, including prints in the snow or frost and spraints. Reduced vegetation levels also increase visibility of prints, otter holts and slides. Otter surveys include assessing the waterbody, including rivers, streams and brooks, for suitability to support otters and evidence of otter activity, such as potential holts/lay-up sites, spraint sites and slides.
Ecosulis can undertake surveys of wintering birds between October and March. These surveys include migratory/passage bird surveys and winter farmland bird surveys. Farmland can be particularly important for farmland birds during the winter months, in particular skylarks and yellowhammers. Several sites in Britain also support a large number of migratory bird species, in particular estuary environments and surveys for projects such as wind turbines can require such surveys. Typically wintering bird surveys comprise two visits per month to establish the level of use and areas of the site used by wintering birds, the results of which will inform management prescriptions and mitigation measures.