Ecology Survey Calendar

Ecology survey work can be constrained by season, below is a simple calendar showing the standard times to conduct survey work for each species. In order to reduce the risk of delays to your project this should be taken into account when scheduling your work.

It should be noted that Ecology by Design always strives to work with its clients to agree an acceptable survey approach and therefore please call us for more information. 

Phase 1 habitat survey

This survey can be carried out at any time of the year and involves collecting baseline data on a site, including what habitats and vegetation are present and the suitability a site has to support protected species. The time of year the survey is carried out will affect the amount of data collected as there are many more species of plants visible and identifiable during the spring and summer than there is in winter, however this should not affect the overall outcome of the survey.



Preliminary Roost Assessments

A preliminary roost assessment (PRA) is the only bat survey which is not seasonally constrained and can be carried out at any time of the year. The survey consists of a building being assessed for its potential to support roosting bats. Although the likelihood of finding live bats varies seasonally, it is still possible to see other evidence of bat presence such as droppings, scratching or staining. If a building is considered to have the potential for roosts, for example, missing or broken tiles, gaps under soffits, gaps under hanging tiles then activity surveys are usually recommended. Trees can also be inspected for their potential to support roosting bats at any time of the year, although potential roosting features (PRF’s) such as cracks, rot holes and woodpecker holes are often easier to see when foliage is sparse during the winter months.


Emergence and Activity Surveys

Bats hibernate and therefore these surveys are constrained to when bats are active, between May and September. The size and type of site being affected determines which survey is carried out. For work on individual buildings up to three emergence/re-entry surveys are carried out, surveyors will focus on particular features, such as a missing tile to see if bats emerge or return after foraging, therefore indicating a roost is present. For larger sites where woodlands or hedgerows are to be affected then it may be necessary to undertake transects which involves walking specific routes around the site to identify bats and also installing static monitors to collect bat activity data over a period of several days.


Great Crested Newt

Presence / absence and population estimate survey

Great crested newts spend time both on land and in water and therefore this restricts when surveys can be undertaken. Pond surveys can be carried out between mid-march and the end of June, an initial four survey visits are undertaken to establish presence or absence and then if newts are present a further two survey visits are carried out to determine population size. Half of the visits must be undertaken in the optimal period between mid-April and mid-May.


eDNA Survey

This survey is strictly time controlled and can only be carried out between 15th April to the 30th June. However the earlier this survey is carried out the better, this is because if the results come back positive a full six survey visits (as above for a population estimate) will need to be carried out on the pond to determine population size before the end of June. This survey must be planned carefully to avoid running out of time and having to continue the following year.


HSI Assessment

This assessment can be carried out at any time during the year and gives a score of how suitable a pond is for great crested newt. The score takes into account various factors, such as shade, water quality, terrestrial habitat, and aquatic vegetation. Although a useful survey for scoping survey requirements it cannot indicate whether or not great crested newts are present or absent from a particular pond.


Hazel Dormouse

Dormice hibernate and therefore nest tube surveys are restricted to between April and November, and involve installing nest tubes in suitable habitat and checking them periodically over the season for dormice. Nut surveys can be undertaken during the autumn and winter months. Dormice open the outer shells of hazelnuts with their teeth leaving specific characteristic markings in the shell and therefore if these are found they can confirm presence but no absence if no nuts are found.


Water Vole

Water voles are most active during mid-April to September. They do not hibernate during the winter but they are less active spending most of their time within their burrows, leaving less signs in the form of footprints, droppings and feeding remains, making them more difficult to detect. Two survey visits are recommended during the season.



Otter surveys can be carried out throughout the year as otters remain active and do not hibernate. The survey involves searching along river banks for otter spraints, slides and holts. These surveys are often undertaken at the same time as water vole surveys as they inhabit the same types of environment.



Badger surveys can be undertaken throughout the year and involve searching for badger setts, latrines, tracks and footprints. Sometimes it is not clear whether a badger sett is active and in these instances camera traps can be installed to check for badger activity over a period of a few weeks. During the summer it can be difficult to search for signs if there is a lot of vegetation and undergrowth and therefore it may be easier during the spring or autumn months. On large sites where there are multiple badger setts a bait marking survey may be necessary to determine the territorial boundaries of each badger colony.



Reptiles are active between March and October, although April, May and September are optimal periods for survey. This is because temperatures can still be cool and reptiles are more likely to be detected basking. Surveys involve placing artificial refugia (usually squares of corrugated tin or bitumen felt) in areas of suitable reptile habitat and carrying out seven separate visits to check for the presence of reptiles above and beneath them and also in the general area. The surveys are constrained by temperature and weather and can only be carried out when it is dry and between 9 and 18 degrees Celsius.


Breeding and Wintering bird

The optimal period for most species for undertaking a wintering bird survey is November to February, and March to August for breeding bird surveys.  Bird surveys involve assessing the species and numbers of birds present within a site. The field survey method and number of visits depends on the site and objectives. Birds which are present during the spring and summer months often leave a site and migrate elsewhere and different species move in to the site for the wintering months therefore it is often necessary to undertake two differen