Protected Species Survey Calendar 2025

For anybody looking to conduct an ecology survey in 2025, they will need to consider the ecology survey calendar. Due to the nature of what is involved in an ecological survey, there are often certain times of year or certain seasons where they must be conducted.

At Ecology by Design, we offer a range of ecology services for various species throughout the year.

On this page you will find guidance on ecological survey calendar periods for 2024, detailing the optimum time to survey for each species.

What affects the ecology survey calendar?

• Weather conditions

• Species behaviour

• Location of survey

Phase 1 habitat survey

During a phase 1 habitat survey an ecologist conducts a walkover of a site and habitats are identified, classified and mapped. This survey can be undertaken at any time of year, but classification of habitats can be more detailed between late March and mid-October when rarer flowering plants can be more easily identified.

Extended Phase 1 habitat survey

An extended phase 1 habitat survey, also known as a Preliminary Ecological Appraisal (PEA) begins with the same process as the Phase 1 survey but also considers the potential of the site for protected species. An extended Phase 1 can be conducted all year round but completing the survey during protected species’ active months can provide better information regarding their presence on the site.

NVC survey

Late March – Mid October

An NVC (National Vegetation Classification) survey is a comprehensive botanical survey. The best time to conduct this survey is late March to mid-October but this varies with habitat type.

Ecology survey calendar by species

Below are details of the best time to conduct ecology surveys depending on the animal species in questions. Factors affecting the time period include the weather, behavioural patterns and habitat of the animal in question.

Bat survey calendar

A bat survey consists of several key stages to determine the presence of bats, and follow up assessments throughout the year.

You can read more about bat surveys and what is involved by reading our blog post What to Expect from a Bat Survey.

Preliminary Roost Assessment

At any time

An inspection to determine the potential of a building to support roosting bats can be conducted at any time, but in winter the chances of finding a roost is reduced. Evidence is often still present, and the surveyor will look for potential access and roost features. If a building has roost potential, follow up emergence/ re-entry surveys (see below) will be required.

Emergence/ Re-entry survey

May – September

Emergence/ Re-entry surveys can only be completed from May to September, the months that bats are most active. These surveys involve monitoring bat activity around a building using bat detectors that convert echolocation into audible sound.

Activity Transect survey

April – October

An activity transect survey assesses foraging behaviour, flight paths and foraging habitat of bats on a site. Surveyors walk a transect route with multiple stopping points and monitor bat species present using a bat detector. These surveys can be conducted between April and October.

Tree Roosts

Any time of year

This survey identifies the potential of a tree to support bat roosts, the surveyor will look for potential roost features and evidence of bats. These surveys can be conducted at any time of year but during winter, the lack of foliage enables surveyors to clearly see any roost features such as cracks and knot holes.

Hibernation Roosts

December – March

Hibernation roost surveys can be carried out from December to March. If potential is found after an initial inspection, static bat detectors are deployed for a minimum of two weeks in each winter month (December to February) to monitor activity and establish if the site is being used by hibernating bats.

Bird survey calendar

Breeding Bird survey

March to June

A breeding bird survey requires multiple visits by surveyors during the nesting season (March to June). There are several methods used, walking a transect route with stopping points or using vantage points to monitor bird activity on a site.

Wintering Bird survey

Mid October – Mid March

A wintering bird survey follows similar methodology to a breeding bird survey but is conducted between mid-October and mid-March. Bird surveys timings depend on the habitat and species being monitored.

Water Vole survey

Mid March – October

Water vole surveys should be conducted when the species is most active, between mid-March and October. Presence of water vole and evidence (including latrines, faeces and footprint) is recorded. Two survey visits are usually required and are often done at the same time as otter surveys.

Otter Survey

All year round

Otter surveys can be conducted all year, but Spring is optimal. Otter surveys follow similar methodology to water vole surveys.

Reptile Survey

March – October

Reptile surveys require multiple visits during the active months of March to October, although June to August is sub optimal due to warmer weather making reptiles less likely to be found basking. Walkover surveys are conducted, during which the surveyor looks for basking reptiles, artificial refugia is often used.

You can find out more in our reptile survey guide.

Great Crested Newt Survey

You can find out everything you need to know about great crested newts in our detailed guide, What is a Great Crested Newt Survey?

There are various stages involved in a great crested newt survey, which require assessments throughout the year.

Habitat Suitability Index (HSI) Assessment

All year round

This survey can be conducted all year and assesses the suitability of a pond for great crested newt using a scoring system.

eDNA survey

Mid April – late June

An eDNA survey involves testing pond water samples for great crested newt DNA, if DNA is found to be present, further surveys may be required, as described below. eDNA surveys can only be carried out between mid-April and late June.

Presence/ Likely Absence and Population estimates

Mid March – June

These surveys can only be conducted from mid-March to June, surveyors visit ponds over multiple visits to establish presence/likely absence and if necessary, population density using methods such as netting, torch searching, trapping and egg searching.

Badger survey

February – April

Badger surveys involve searching for evidence of badgers, and can involve walkover surveys, bait-marking and hair traps. These surveys can be conducted at any time of year, but bait-marking is optimal from February to April when territory marking is most frequent.

You can find out more in our blog post, What is a Badger Survey?

Hazel Dormouse survey

April – November

A hazel dormouse survey involves both hand surveys and monitoring nests. The presence or likely absence of hazel dormice can be determined by multiple monitoring visits to previously installed nest tubes or boxes, between April and November. Hand searches for feeding evidence can be done all year round.

White-Clawed Crayfish survey

Mid June – Mid September

White-clawed crayfish surveys should be conducted after the breeding season, from mid-July to mid-September. Methods include manual searching when the water allows visibility, hand-netting, overnight torch searching and trapping.

Invertebrates survey

Varies depending on species

The optimal period for conducting terrestrial invertebrate surveys is May to September, when adults are most likely to be present. Techniques such as sweep netting, beating and pit fall trapping is used. Freshwater invertebrate surveys are conducted from mid-March to April or September to mid-October if the water is flowing and between June and August if the water is standing.

Roman Snail survey

May – August – Daytime

April – June – Night time

There is no standard survey technique for roman snails, daytime hand searches can be conducted from May to August and overnight torch surveys from late April to early June following or during periods of rain.

Red Squirrel survey

All year round

Red squirrel surveys can be conducted all year round, survey methods include checking nest boxes, counting dreys (nests), feeding sign surveys, visual surveys and trail cameras.

You can head to ecology resources blog for more about ecological surveys and species surveys. For more information about Ecology by Design, contact us, arrange a free quote, or give us a ring on 01865 893 346.