Disturbance Distances in selected Scottish Bird Species – NatureScot Guidance

This document is intended for anyone involved with assessing disturbance to birds (e.g. developers and their ecological consultants, NatureScot staff and those within consenting authorities). This guidance note and the research report which underpins it replaces the Ruddock & Whitfield 2007 review on disturbance distances. This document primarily relates to terrestrial ecosystems and further guidance should be sought for those assessing disturbance in a marine context or for offshore renewable activities.

1. Summary

The avoidance of humans or human activities by birds can have significant adverse effects on both bird distribution and abundance. As a result, we regularly provide advice on suitable buffers to reduce the likelihood of disturbance to protected bird species.

Since 2007, the Ruddock & Whitfield Review of Disturbance Distances in Selected Bird species report has underpinned NatureScot advice and guidance for casework relating to disturbance. Since the publication of that review, new disturbance response information and data has become available furthering our understanding of disturbance for species presented in the 2007 review and for additional species that regularly feature in casework. As a result, NatureScot commissioned an updated literature review of disturbance distances for selected bird species. This guidance note provides a summary of the recommended buffers for a number of key species, based on information in the updated review Research Report 1283 - Disturbance Distances Review: An updated literature review of disturbance distances of selected bird species. This guidance note, and the research report which underpins it, now replaces the Ruddock & Whitfield 2007 review.

2. Assessing buffer zone ranges

The buffer zones recommended in this guidance are the range of suggested protection distances for a particular species, that can be used to protect each presented bird species from human disturbance during the breeding and nonbreeding seasons. The buffers are based on a range of studies and types of disturbance for different times of year.

The report that underpins this guidance has taken into account previously published buffers/ disturbance distances as part of drawing up the revised buffers. Buffer zones have also been estimated, where possible, from quantitative studies that have recorded Alert Distance (AD), Flight Initiation Distance (FID) and Minimum Alert Distance (MAD) during the breeding and non-breeding seasons. For species which lack quantitative data, buffers were estimated from non-quantitative studies. For species which lack data for a specified season (i.e. breeding or non-breeding), or where buffers are considered to be similar between both seasons, a single buffer has been provided to include both breeding and nonbreeding seasons. Please see our website for details of bird breeding season dates in Scotland.

Disturbance activities are likely to differ in their significance depending on several factors, such as; the species, the habitat requirements of the species, time of year, time of day and topography. The potential type/ source of disturbance is also a factor, although the distances at which birds of the same species will respond to differing disturbance sources often overlap. Therefore, the buffer zones in this guidance are not differentiated in terms of the source of disturbance and, in general, a precautionary approach has been used to estimate the zones.

Although buffer zones are convenient for quantification of bird responses to human disturbance, it should be recognised that bird heart rate may be increased by exposure to human disturbance before alert behaviour or flight initiation responses are evident. Increased heart rate and increased levels of stress hormones have physiological costs and so disturbance may have subtle impacts even on birds that are not clearly showing behavioural responses to disturbance. Therefore, the upper limit of the disturbance buffer should be used unless it can be demonstrated that a lower buffer is sufficient.  This is intended to provide a precautionary approach, however it is noted that in certain circumstances lower buffers will be appropriate. Factors influencing whether a lower buffer would be considered sufficient include, but are not limited to, type of disturbing activity, duration, topography and known levels of habituation. We also recognise the importance of incorporating site-specific factors into our consideration when applying buffers.

We also recommend that this guidance is used in conjunction with the detailed assessment in the species account within the MacArthur Green report and interpreted alongside other industry guidance such as forestry guidance.  

For more detailed information on the disturbance distances of each of the species listed in the table below, please refer to the species accounts in the report by MacArthur Green (2022). We acknowledge that the list of species for which buffers are presented is not exhaustive, for species not covered NatureScot should be contacted for advice.

3. Recommended disturbance buffers

Please note that these disturbance buffers are guidance only, and observing maximum or minimum buffers does not guarantee that birds will not be disturbed. Those species listed on Schedules A1 and 1A are afforded additional protection under the Wildlife and Countryside Act. Further details of the implications of this protection can be found on our website.

In addition, please note that some of the buffers listed here differ from the underlying report. In those cases, the buffers described in this guidance should be used. This is the case where NatureScot has found additional impetus for alterations. Further details for the justification for each species is listed below the table.

Table 1: Summary of appropriate disturbance distance buffers in the breeding and non-breeding season. (*) Denotes species listed on schedule 1A and A1. (†) Denotes species with altered buffer distances. (§) Denotes species for which buffers have changed since the Ruddock and Whitfield review.

Species	Buffer zone (m) suggestions during the breeding (BR) and nonbreeding (NBR) seasons	Overall likely sensitivity to disturbance
Whooper swan, Cygnus cygnus	NBR = 200-600m	Medium
White-fronted goose, Anser albifrons	NBR = 200-600m	Medium
Bean goose, Anser fabalis	NBR = 200-600m	Medium
Pink-footed goose, Anser brachyrhynchus	BR ≤1000m NBR = 200-600m	Medium
Greylag goose, Anser anser	BR and NBR = 200-600m	Medium
Barnacle goose, Branta leucopsis	BR = 50-200m NBR = 200-600m	Medium
Common shelduck, Tadorna tadorna	BR and NBR = 100-400m	High
Mallard, Anas platyrhynchos	BR = 50-100m NBR ≥ 100m	Low/Medium
Gadwall, Anas strepera	BR and NBR = 100-200m	Medium
Pintail, Anas acuta	BR and NBR = 100-200m	Medium
Shoveler, Anas clypeata	BR and NBR = 100-200m	Medium
Eurasian wigeon, Anas penelope	BR = 100-200m NBR = 200-500m	High
Greater scaup, Aythya marila	NBR = 150-450m	High
Common eider, Somateria mollissima	BR = 100-200m NBR = 200-500m	Medium/High
Common scoter, Melanitta nigra	BR = 300-500m	High
Common goldeneye, Bucephala clangula §	BR = 100-150m NBR = 150-800m	High
Capercaillie, Tetrao urogallus †, §	BR (nesting females) and NBR = 100-150m   BR (lekking males) = 1000m   NBR = 100m	Medium/High
Black grouse, Tetrao tetrix	BR (nesting females) and NBR = 100-150m   BR (lekking males) = 500-750m   NBR = 100m	Medium
Red-throated diver, Gavia stellata	BR = 500-750m NBR = ≤1000m	High
Black-throated diver, Gavia arctica	BR = 500-750m NBR = ≤1000m	High
Great northern diver, Gavia immer	NBR = 100-350m	Medium/High
Slavonian grebe, Podiceps auritus §	BR and NBR = 150-350m	Medium
White-tailed eagle, Haliaeetus albicilla *, †, §	BR and NBR = 250-500m	High
Osprey, Pandion haliaetus §	BR = 350-750m	Medium/High
Golden eagle, Aquila chrysaetos *	BR = 750-1000m NBR = 250-500m	High
Red kite, Milvus milvus *	BR and NBR = 150-300m	Medium
Marsh harrier, Circus aeruginosus	BR and NBR = 300-500m	Medium
Hen harrier, Circus cyaneus *, §	BR and NBR = 300-750m	Medium
Common buzzard, Buteo Buteo	BR and NBR = 100-200m	Low/Medium
Honey buzzard, Pernis apivorus	BR = 100-200m	Medium
Northern goshawk, Accipiter gentilis	BR = 300-500m	Medium
Kestrel, Falco tinnunculus	BR = 100-200m NBR = ≤50m	Low/Medium
Eurasian hobby, Falco subbuteo	BR = 200-450m	Medium
Peregrine falcon, Falco peregrinus	BR = 500-750m NBR = ≤200m	Medium
Merlin, Falco columbarius	BR = 300-500m NBR = ≤200m	Medium
Eurasian oystercatcher, Haematopus ostralegus	BR = 50-100m NBR = 150-300m	Medium
Ringed plover, Charadrius hiaticula	BR = 100-200m NBR = 100-300m	High
Grey plover, Pluvialis squatarola	NBR = 150-300m	Medium
Golden plover, Pluvialis apricaria	BR and NBR = 200-500m	Medium
Dunlin, Calidris alpina	BR = 100-200m NBR = 150-300m	Medium
Red knot, Calidris canutus	NBR = 100-300m	Medium
Purple sandpiper, Calidris maritima	BR and NBR <300m	Low/Medium
Wood sandpiper, Tringa glareola	BR = 150-300m	Medium
Common redshank, Tringa totanus	BR = 100-200m NBR = 200-300m	Medium
Greenshank, Tringa nebularia	BR and NBR = 300-500m	Medium/High
Black-tailed godwit, Limosa limosa	BR and NBR = 100-200m	Medium
Bar-tailed godwit, Limosa lapponica	NBR = 200-300m	Medium
Eurasian curlew, Numenius arquata	BR = 200-300m NBR = 200-650m	High
Whimbrel, Numenius phaeopus	BR and NBR = 100-300m	Medium
Red-necked phalarope, Phalaropus lobatus	BR <50m	Low
Little tern, Sternula albifrons	BR = 100-300m	Medium
Sandwich tern, Thalasseus sandvicensis	BR ≥200m	High
Common tern, Sterna hirundo	BR = 200-400m	Medium/High
Arctic tern, Sterna paradisaea	BR ≥200m	Medium
Roseate tern, Sterna dougallii	BR ≥200m	High
Snowy owl, Bubo scandiacus	NBR = 150-500m	Medium
Long-eared owl, Asio otus §	BR and NBR = 100-300m	Medium
Short-eared owl, Asio flammeus	BR and NBR = 300-500m	Medium/High
Tawny owl, Strix aluco	BR = 50-200m NBR ≥50m	Low/Medium
Barn owl, Tyto alba	BR = 50-100m NBR ≥50m	Low
Corncrake, Crex Crex	BR ≥100m	Medium
European nightjar, Caprimulgus europaeus §	BR = 150-500m	Medium/High
Kingfisher, Alcedo atthis	BR and NBR = 50-100m	Low/Medium
Crested tit, Lophophanes cristatus §	BR and NBR = 10-50m	Low
Crossbill species, Loxia spp §	BR and NBR = 50-200m	Low

 

4. References

Goodship, N.M. and Furness, R.W. 2022. Disturbance Distances Review: An updated literature review of disturbance distances of selected bird species. A report from MacArthur Green to NatureScot.

Ruddock, M. and Whitfield, D.P. 2007. A review of disturbance distances in selected bird species. A report from Natural Research (Projects) Ltd to Scottish Natural Heritage.