A guide to optimal and limited survey windows for protected species and habitats in Scotland. Use this calendar during project planning to ensure survey requirements are identified before seasonal windows are missed.
⚑ Highlands & Islands note: Survey windows in the Scottish Highlands and Islands are typically 2–4 weeks later than lowland Scotland or England. Spring comes later, breeding seasons are delayed, and weather can restrict access significantly. Treat all dates as approximate and always seek site-specific advice.
| Species / Habitat | Month | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
| Habitats & Vegetation | ||||||||||||
| Phase 1 Habitat SurveyWalkover / PEA | Sub-optimal | Sub-optimal | Sub-optimal | Sub-optimal | Sub-optimal | Sub-optimal | ||||||
| UKHab SurveyUK Habitat Classification | Sub-optimal | Sub-optimal | Sub-optimal | Sub-optimal | Sub-optimal | Sub-optimal | ||||||
| NVC SurveyNational Vegetation Classification | – | – | – | Mosses & lichens only | Mosses & lichens only | – | – | – | ||||
| Mammals | ||||||||||||
| BadgerSett surveys & bait marking | Sett survey | Sett survey | Limited bait marking | Limited | Sett survey | |||||||
| BatsRoost surveys & activity† Not a Purple Plover service | Hibernation roost inspection | Hibernation roost inspection | Hibernation roost inspection ▲ | Low activity | Summer roost surveys ▲ | Summer roost surveys | Summer roost surveys | Summer roost surveys | Mating begins | Low activity | Hibernation roost inspection | Hibernation roost inspection |
| OtterPresence / absence & activity | ||||||||||||
| Pine MartenField signs & den surveys | Den surveys begin | Den surveys | Den surveys | |||||||||
| Red SquirrelField signs & activity | Breeding female surveys | |||||||||||
| Water VoleField signs & habitat assessment | – | Habitat survey | Initial habitat survey ▲ | ▲ | Habitat survey | – | ||||||
| Birds | ||||||||||||
| Wintering BirdsWaders, wildfowl, raptors | – | – | – | – | – | Migrants arriving | ||||||
| Breeding BirdsBBS, territory mapping | – | – | Early migrants ▲ | ▲ | Low activity | – | – | – | – | |||
| RaptorsNest monitoring (Schedule 1 licence required) | Territory checks | Courtship display | Incubation begins ▲ | Incubation | Chick rearing | Chick rearing | Fledging | Post-fledging | Territory checks | Territory checks | Territory checks | Territory checks |
| Wading BirdsCurlew, lapwing, golden plover etc. | Wintering counts | Wintering counts | Arrival on breeding grounds ▲ | Breeding surveys ▲ | Breeding surveys | Breeding surveys | Post-breeding | Departing | Migrants arriving | Wintering counts | Wintering counts | Wintering counts |
| Aquatic/Reptile Species | ||||||||||||
| Freshwater Pearl MusselPresence / population surveys† Not a Purple Plover service | – | – | – | – | – | |||||||
| Great Crested NewtHSI assessments & eDNA surveys | – | – | Pond surveys begin | Egg surveys | Egg & larvae surveys | Larvae surveys | Terrestrial only | Terrestrial only | Terrestrial only | Terrestrial only | – | – |
| FishTiming varies by species & migration† Not a Purple Plover service | ||||||||||||
| ReptilesAdder, slow worm, common lizard | – | – | Basking surveys ▲ | Peak ▲ | Peak | Reduced basking | Reduced basking | Peak | Limited activity | – | – | |
Species Notes & Highland Timing
Otters Otters can be surveyed year-round in Scotland. Survey windows are limited more by weather conditions and vegetation cover than by season. Winter surveys benefit from lower vegetation but can be restricted by high water levels and flood conditions on upland burns.
Bats † In the Highlands and Islands, emergence surveys are typically 2–3 weeks later in spring than in lowland Scotland. On the islands, species diversity is lower — common pipistrelle and brown long-eared are most frequently recorded. Maternity roosts tend to form from late May in the Highlands. Purple Plover does not provide bat surveys — we recommend engaging a specialist bat ecologist.
Breeding Birds (Highland timing) In the Highlands, the breeding season for many species is delayed by 2–4 weeks compared to lowland Scotland. Curlew and lapwing begin territory establishment in March–April in the north, while upland species such as dotterel may not arrive on breeding grounds until late April or May.
Raptors & Schedule 1 species Survey work within the disturbance zone of an active Schedule 1 nest requires a licence from NatureScot. Licence applications should be submitted well in advance of the survey season. Nest monitoring in the Highlands typically runs from February (courtship) through to August (post-fledging checks). Key species in the Highlands and Islands include golden eagle, white-tailed eagle, peregrine, red kite, and hen harrier.
Water Voles Scotland holds a significant proportion of the UK’s water vole population, particularly in upland areas. Highland surveys are best conducted from late April through September when field signs are most visible. Winter surveys are not practical above 200m due to snow cover and inaccessibility.
Freshwater Pearl Mussel † Scotland holds the majority of the world’s remaining freshwater pearl mussel population. Surveys require qualified specialists and are strictly regulated. Water clarity is essential — surveys are not possible in spate or high turbidity conditions, which can be frequent in Highland rivers throughout the year. Purple Plover does not provide freshwater pearl mussel surveys — we recommend engaging a specialist.
Red Squirrel Present year-round across much of the Highlands. Sign surveys (stripped cones, dreys, footprints) are possible throughout the year but are most productive in autumn and winter when vegetation is lower. Surveys for breeding females should be carried out from December through September.
Great Crested Newt GCN have a very restricted range in Scotland, mainly in the Scottish Borders,Central belt and Tayside. However, there are pockets around the Moray Firth and Inverness so don’t assume you are GCN-free. If your project is in the Highlands or Islands, GCN surveys are unlikely to be required — but a desk study will confirm this. Purple Plover can undertake Habitat Suitability Index (HSI) assessments to determine survey need, and eDNA surveys where required. Full pond surveys should be conducted between mid-March and mid-June.
▲ Highland & Islands flag: Cells marked with this symbol have timing that is typically delayed by 2–4 weeks in the Scottish Highlands and Islands compared to lowland Scotland. Always confirm timing with a local ecologist before finalising survey programmes.
This calendar is intended as a planning guide only. Survey timing may vary depending on site conditions, elevation, aspect, and the specific requirements of the project. Advice from a qualified ecologist should always be sought before finalising any survey programme. Source data adapted from the NatureScot Ecological Survey Calendar. Purple Plover Consulting Ltd, Inverness. purpleplover.com