CNPA 2020 Deer Population Dynamics Report

A stra­tegic over­view of wild deer pop­u­la­tion dynam­ics in the Cairngorms Nation­al Park

Report to the Cairngorms Nation­al Park Author­ity 4^th Feb­ru­ary 2021

Strath Caulaidh

CON­TENTS

REPORT PRE­PAR­A­TION 3 ACKNOW­LEDGE­MENTS 4 INTRO­DUC­TION 5 METH­ODS 6 HELI­COPTER DEER COUNTS 6 HIS­TOR­IC DEER COUNT DATA 9 OTH­ER DEER COUNT DATA 11 DEER CULL RECORDS 11 SPA­TIAL ANA­LYS­IS 12 DEER POP­U­LA­TION MOD­ELS 13 IMPACT DATA: HIA 15 IMPACT DATA: OTH­ER FORMS 18 KEY FIND­INGS 19 LAND CHAR­AC­TER­IST­ICS 19 CON­TEM­POR­ARY DEER COUNTS 24 DUNG COUNTS & ASSO­CI­ATED SUR­VEYS 34 CULL RECORDS 38 HIS­TOR­IC DEER COUNT DATA 46 POP­U­LA­TION MOD­EL­LING 54 IMPACT SUR­VEYS 60 INTER­PRET­A­TION 67 CON­TEM­POR­ARY DEER COUNTS 67 HIS­TOR­IC POP­U­LA­TION TRENDS 72 IMPACTS OF DEER ON OPEN RANGE HAB­IT­ATS 74 CON­CLU­SIONS 75 RECOM­MEND­A­TIONS 77 APPENDIX 1 – SNH HIA 82

REPORT PRE­PAR­A­TION

Con­trib­ut­ors • Douglas Camp­bell • Mel Marchbank

Draft by / date DC 19/7/20 Checked / date MM 20/7/21 Final by / date DC 04/02/21 Checked/​date MM 04/02/21

Stand­ard caveats • SCL have exer­cised reas­on­able skill, care and dili­gence in the pre­par­a­tion of this doc­u­ment, in accord­ance with the stand­ards of a qual­i­fied and com­pet­ent per­son exper­i­enced in car­ry­ing out work of a sim­il­ar scope and com­plex­ity to the agreed ser­vices and cur­rent at the time when the ser­vices were per­formed. • SCL have per­formed the agreed ser­vices gen­er­ally in accord­ance with our pro­pos­al doc­u­ment or oth­er­wise accord­ing to the cli­ents spe­cific­a­tion, but have in places added to and var­ied the scope where it appeared to us neces­sary and reas­on­able to do so. • SCL have taken all reas­on­able pre­cau­tions to avoid dam­age to prop­erty belong­ing to the cli­ent and any third party. • The ser­vices and the ser­vice products delivered to date can­not neces­sar­ily reveal all adverse or oth­er mater­i­al con­di­tions at the site that could oth­er­wise be iden­ti­fied either through a dif­fer­ent for­mu­la­tion of the ser­vices or through more detailed work being car­ried out by SCL.

Spe­cif­ic caveats • The report in places uses data sets cre­ated by oth­er organ­isa­tions and we can­not be held respons­ible for their accur­acy. • A range of oth­er data avail­able from private sec­tor, third sec­tor or oth­er gov­ern­ment organ­isa­tions may be avail­able to help the CNPA expand upon the find­ings of this pro­ject, but the scope of the pro­ject and timeline pre­cluded con­tact being made.

ACKNOW­LEDGE­MENTS

• Mike Cot­tam and Pete May­hew of CNPA iden­ti­fied the funds needed for the pro­ject. • Jimmy Irvine of NatureScot, and the GiG team who deal with digit­al data, provided his­tor­ic deer count data and his­tor­ic cull data along with inform­a­tion held on deer fencelines. We are immensely grate­ful to them for provid­ing these data (and sup­port­ing notes) in a very timely manner.

INTRO­DUC­TION

1. The Cairngorms Nation­al Park (CNP) cov­ers ~ 452,800ha of moun­tain, moor­land, wood­land and farm­land in the north east of Scot­land. A total of 18,000 people live with­in its loc­al com­munit­ies, and a wide range of busi­nesses oper­ate with­in its boundaries.

2. The Cairngorms Nation­al Park Author­ity (CNPA) has stat­utory duties in rela­tion to plan­ning and out­door access with­in the park, but also provides a range of ser­vices to sup­port busi­ness own­ers, landown­ers and loc­al communities.

3. The CNPA also has an import­ant stra­tegic part to play in rela­tion to land man­age­ment¹. Policies and sup­port pack­ages are in place to encour­age act­ive con­ser­va­tion of the park’s icon­ic land­scapes and val­ued semi-nat­ur­al hab­it­ats, at the same time as pro­mot­ing sus­tain­able rur­al devel­op­ment through tour­ism and oth­er forms of busi­ness activ­ity (e.g. farm­ing, forestry) where appro­pri­ate. The author­ity there­fore has a par­tic­u­larly import­ant role to play in rela­tion to land­scape-scale plan­ning and co-ordin­a­tion of land man­age­ment activity.

4. Wild deer are present through­out the park. Red deer are thought to be the most abund­ant spe­cies, fol­lowed by roe deer. Sika deer and fal­low deer are also present loc­ally. Wild deer pro­duce a range of impacts, both pos­it­ive and neg­at­ive, on the land and loc­al com­munit­ies present with­in the park. The two forms of impact need to be bal­anced, accord­ing to loc­al and region­al pri­or­it­ies. The CNPA there­fore has a poten­tially import­ant and use­ful stra­tegic role to play in help­ing achieve this aim at region­al scale.

5. A vari­ety of data are cur­rently avail­able to under­pin the CNPA’s abil­ity to deliv­er on its stra­tegic deer man­age­ment remit. This includes (i) heli­copter count data of deer man­age­ment group (DMG) areas sup­plied by NatureScot (NS), (ii) stat­utory cull returns provided annu­ally to NS from landown­ers, (iii) hab­it­at impact mon­it­or­ing data gathered by NS or landown­ers and (iv) a range of mon­it­or­ing data from wood­land deer pop­u­la­tions (e.g. dung counts, crop impact sur­veys). How­ever, these data sets cur­rently exist in mul­tiple loc­a­tions and in a vari­ety of formats. As a con­sequence, there is no robust estim­ate of how many wild deer live with­in the Cairngorms Nation­al Park as a whole. Cru­cially, the CNPA has no stra­tegic over­view of their con­tem­por­ary dis­tri­bu­tion — or their pop­u­la­tion dens­ity — in dif­fer­ent areas and hab­it­at types. Moreover, the CNPA also lacks a land­scape-scale data set show­ing how hab­it­at impacts vary across the park.

1 The Nation­al Parks (Scot­land) Act 2000 states that the aims of Nation­al Parks are to: (1) con­serve and enhance the nat­ur­al and cul­tur­al her­it­age of the area, (2) pro­mote sus­tain­able use of the nat­ur­al resources of the area, (3) pro­mote under­stand­ing and enjoy­ment (includ­ing enjoy­ment in the form of recre­ation) of the spe­cial qual­it­ies of the area by the pub­lic and (4) pro­mote sus­tain­able eco­nom­ic and social devel­op­ment of the areas’ com­munit­ies. How­ever, where these aims con­flict, the rel­ev­ant Nation­al Park author­ity must pri­or­it­ise the first of these aims.

1. The cur­rent absence of a stra­tegic-scale over­view of deer pop­u­la­tion dynam­ics means the CNPA’s lead­er­ship team and staff face chal­lenges in:

a) Demon­strat­ing clearly what pro­gress has been made, to date, in deliv­er­ing on key CNPA policies relat­ing to deer man­age­ment across the park.

b) Estab­lish­ing wheth­er, based on the most up-to-date sets of data, the CNPA’s policies on deer man­age­ment and related issues seem likely to be fully deliv­er­able in the near term.

c) Determ­in­ing wheth­er their cur­rent deliv­ery mod­el (e.g. avail­able CNPA sup­port pack­ages, cur­rent staff num­bers etc) is suf­fi­cient to ensure that these policies will oth­er­wise be suc­cess­fully delivered in the longer-term.

d) Under­stand­ing how con­tem­por­ary deer dis­tri­bu­tion and dens­it­ies at region­al and loc­al scale might impact on the cur­rent and future deliv­ery of oth­er key CNPA policies (e.g. on wood­land expan­sion, on peat­land res­tor­a­tion, on biod­iversity, on sup­port­ing the fra­gile rur­al eco­nomy of the area).

1. It is pos­sible, in prin­cip­al, to bring avail­able data sets togeth­er and ana­lyse them to obtain the stra­tegic over­view needed by the CNPA. How­ever, in prac­tice there are tech­nic­al chal­lenges involved in ensur­ing the pro­cess is robust. In addi­tion, a con­sid­er­able amount of intern­al staff time would need to be employed in com­plet­ing the task.

2. There­fore, in March 2020, the CNPA com­mis­sioned Strath Caulaidh Ltd (SCL) to com­pile and ana­lyse avail­able deer count and deer cull data, to help devel­op an improved stra­tegic under­stand­ing of deer pop­u­la­tion dynam­ics in the Cairngorms Nation­al Park. In late 2020 the scope for the study was expan­ded to include com­pil­a­tion and review of con­tem­por­ary herb­i­vore impact sur­vey data on open range habitats.

METH­ODS

HELI­COPTER DEER COUNTS

1. Records of heli­copter deer counts under­taken by NS were down­loaded from ​‘Nat­ur­al Spaces’. This included an ESRI-com­pat­ible shapefile of the loc­a­tions, sizes and com­pos­i­tions of deer groups coun­ted over the peri­od 2004 – 2019 and a Microsoft Excel table con­tain­ing data on the tim­ing of each count.

2. The shapefile data were sum­mar­ised by year and by DMG area in Arc­GIS, and ana­lysed to assess:

a) Which parts of the CNPA area had deer count data avail­able? b) When each avail­able count data set had been obtained?

c) To what extent it was war­ran­ted to ​‘join’ select data sets togeth­er, and treat them as a single uni­fied data set, for the pur­pose of deriv­ing a robust con­tem­por­ary estim­ate of deer num­bers across the CNP?

1. Ini­tial inspec­tion of the avail­able data from Nat­ur­al Spaces revealed a num­ber of poten­tial issues with obtain­ing a con­tem­por­ary over­view of deer abund­ance, deer dens­ity and deer dis­tri­bu­tion across the CNP area:

a) NS heli­copter count records relate to red deer only, where­as there are in fact four spe­cies of deer present in the CNPA area (roe, fal­low, sika and red deer). Any estim­ate of the deer pop­u­la­tion using the park based on heli­copter count data will be an under-estim­ate for this reas­on alone.

b) Heli­copter count data do not cov­er wood­lands, as they are unre­li­able when under­taken in dense tree cov­er (Map 1). The lack of avail­ab­il­ity of cor­res­pond­ing, con­tem­por­an­eous wood­land count data from NS means there is fur­ther poten­tial for bias in any deer abund­ance or dens­ity estim­ates derived for the CNP as a whole. Firstly, deer liv­ing per­man­ently in these wood­lands were unlikely to have been coun­ted. Secondly, as the counts are often under­taken in snowy weath­er any open hill deer shel­ter­ing tem­por­ar­ily in the trees might be missed dur­ing heli­copter counts.

c) Counts ten­ded not to cov­er the major areas of farm­land in low­land set­tings (e.g. the Spey­side sec­tion labelled ​‘Part of Cairngorms’; Map 1). This is in part because DMG’s do not always include such places with­in their bound­ar­ies, but also in part as they are often partly wooded (Map 1).

d) Sig­ni­fic­ant areas of open range land in the CNPA area have no heli­copter count data avail­able at all (see Map 1), even though in prin­cip­al they could be coun­ted. These include:

i) Areas out with an offi­cial DMG but coin­cid­ing with his­tor­ic Deer Com­mis­sion for Scot­land zones used to record deer cull return data (e.g. Mor­ven, Cabrach/​Glenbuchat, Moray) (Map 1).

ii) Areas not cur­rently covered by DMG’s.

(1) These areas were often included with­in older DCS count areas, mainly under the ​‘Cairngorms’ head­ing and hence included under the label ​‘Part of Cairngorms’ (Map 1).

(2) Anoth­er area was nev­er his­tor­ic­ally included in a DCS count area but does fall with­in the CNPA bound­ary (referred to as Unas­signed; Map 1).

iii) A frag­ment of the Birse Par­ish DMG is included with­in the CNPA bound­ary (approx. 10ha).

e) Some areas had a very recent count under­taken, but the area covered was rel­at­ively small in com­par­is­on with the size of the CNP (see Map 1). Examples included:

i) Places which are cent­rally-loc­ated with­in the CNPA area, but where deer move­ments between the count areas and adja­cent land could be sig­ni­fic­ant. The issue in using such data to syn­thes­ise a con­tem­por­ary estim­ate of over­all deer abund­ance or dens­ity is that adja­cent areas were coun­ted at markedly dif­fer­ent times. Examples of these recently coun­ted areas include East Grampi­an Sub-Group 1 DMG² coun­ted in 2019 (as part of the cur­rent Caen­lochan Sec­tion 7 Agree­ment) and parts of the East Grampi­an Upper Deeside & Don­side DMG (coun­ted vari­ously in 2019 and 2020) (Map 1).

ii) Places on the peri­phery of the park, where only a small part of a much lar­ger DMG is included in the CNPA area (e.g. Mon­adh­liath, Mid-West Asso­ci­ation, East Loch Ericht).

1. Hav­ing reviewed the avail­able heli­copter count data sets, the fol­low­ing con­clu­sions were reached on which heli­copter data sets to include in the CNPA- wide ana­lys­is of con­tem­por­ary deer abund­ance and density:

a) The major­ity of the open range land in CNPA was covered by one of two land­scape-scale deer counts. These data sets, which were gathered with­in a ~ 12 month peri­od albeit over two win­ters, covered a major­ity of the CNPA area in the nar­row­est time win­dow available:

i) Janu­ary 2016: East Grampi­ans South Deeside — North Angus DMG, East Grampi­ans SG1 DMG.

ii) Feb­ru­ary 2017: East Grampi­ans Upper Deeside & Don­side, West Grampi­ans DMG and Cairngorms & Spey­side DMG.

b) The most recent avail­able count from each of the peri­pher­al DMG areas (Mon­adh­liath, Mid-West Asso­ci­ation, East Loch Ericht) was also included in the ana­lys­is of con­tem­por­ary deer abund­ance and dens­ity. Des­pite each area being rel­at­ively small, the degree of mix­ing between each (and the oth­er major count DMG’s to the east) will be neg­li­gible. That said, the num­ber of deer coun­ted in each area, with­in the CNPA bound­ary itself, will not neces­sar­ily provide a reli­able meas­ure of abund­ance for the year as a whole:

i) The Mon­adh­liath count was con­duc­ted in a warm spring (April 2019) when many deer had moved to high­er ground. This count may, with all else equal, have under-estim­ated the num­ber of deer that would have oth­er­wise been present dur­ing a snow­i­er winter count of the same sub- area. With deer free to move in and out of the CNPA bound­ary, as there is no deer fence in place at this point, the num­ber of deer present will vary markedly through time.

ii) The oth­er two counts (Mid-West, East Loch Ericht) were winter counts, but were of very small areas where deer num­bers are likely to vary

2 Recently re-named the South Grampi­an DMG, and with its bound­ar­ies now expan­ded, but referred to herein as EG SG1 in line with the his­tor­ic data sets being ana­lysed for this report.

markedly from week to week, in the same way as the por­tion of the Mon­adh­liath included, depend­ing on the weather.

c) The remain­ing areas (Mor­ven, Unas­signed, Cabrach/​Glenbuchat, Moray, Part of Cairngorms) had no red deer heli­copter count data available.

1. For the pur­poses of sim­pli­fy­ing ana­lys­is and present­a­tion, the CNPA area was split into sev­er­al zones reflect­ing the nature of the count data avail­able (Map 1):

a) East Grampi­ans (Upper Deeside & Don­side DMG, South Deeside & North Angus DMG, Sub-Group 1 DMG).

b) West Grampi­ans (cov­er­ing the WG DMG only).

c) Cairngorms (incor­por­at­ing Cairngorms & Spey­side DMG plus the ​‘Part of Cairngorms’ areas pre­vi­ously included in old DCS count maps).

d) Mon­adh­liath / Mid-West Asso­ci­ation /​East Loch Ericht DMG’s (com­bined, as they are peri­pher­al to the core CNPA area).

e) Birse/​Morven/​Cabrach/​Moray/​Unass’ (cov­er­ing all the areas not offi­cially coun­ted which lie on the east and north sides of the CNPA area).

HIS­TOR­IC DEER COUNT DATA

1. SNH made avail­able a range of ​‘archive’ deer counts as part of the pro­ject. The data set covered the peri­od 1966 – 2004 inclus­ive. The data set com­prises ground count data, gathered by the Red Deer Com­mis­sion (RDC) and its suc­cessor Deer Com­mis­sion for Scot­land (DCS), as well as some early heli­copter counts by DCS pri­or to them mer­ging with Scot­tish Nat­ur­al Her­it­age (SNH; later re-named NatureScot).

2. Addi­tion­al ​‘his­tor­ic’ count data, cov­er­ing the peri­od 2005 – 2015, were con­tained in the main file down­loaded from Nat­ur­al Spaces. By sum­mar­ising these two data sets a com­plete record of counts was avail­able for analysis.

3. The two sets of count data (1966−2004, 2005 – 2015) were dis­played on GIS and a search made to identi­fy peri­ods in time (ideally with­in 12 – 24 months) that large parts of the CNP had been coun­ted. These data were ana­lysed and presen­ted in chart form to illus­trate pos­sible trends in deer abund­ance and dens­ity over time, across the CNP area as a whole, from the 1960’s to date.

4. Upon inspec­tion of the data it became appar­ent that only three parts of the CNP had been coun­ted con­sist­ently, and in a man­ner that was worthy of detailed ana­lys­is³: Cairngorms & Spey­side DMG, West Grampi­ans DMG (pre­vi­ously called Tay­side DMG) and the three main East Grampi­ans DMG’s: SDNA, UDD, SG1 (Birse Par­ish was only covered occa­sion­ally and in part).

3 Mon­adh­liath, East Loch Ericht and Mid-West DMG’s were omit­ted because of the high like­li­hood that deer moved in and out of the CNP bound­ary reg­u­larly). All the oth­er areas had little or no count cov­er­age (e.g. Moray, Mor­ven, Cab­rach etc).

Con­fid­en­tial Con­tains Ord­nance Survery Data© Crown copy­right, 2019

MON­ADH­LIATH Mon­adh­liath DMG Mid West Asso­ci­ation DMG Part of Cairngorms Cairngorm/​Speyside DMG Moray Upper Deeside and Don­side DMG Cabrach/​Glenbuchat Part of Cairngorms Mor­ven Unas­signed Birse Par­ish DMG Birse Par­ish DMG South Deeside North Angus DMG ELE DMG West Grampi­ans DMG East Grampi­an SG1 DMG Pos­sible out­er lim­it of cull records Rivers Lochs DMG_SCOTLAND DMG_SCOTLAND DMG’s and oth­er count areas Deer­CountA Birse Par­ish DMG Cabrach/​Glenbuchat Cairngorm/​Speyside DMG ELE DMG East Grampi­an SG1 DMG Mid West Asso­ci­ation DMG Mon­adh­liath DMG Moray Mor­ven Part of Cairngorms South Deeside North Angus DMG Unas­signed Upper Deeside and Don­side DMG West Grampi­ans DMG Cairngorms Nation­al Park 2010 10 20 Kilo­metres Map 1 Map show­ing the areas used for ana­lys­is in this report. DMG’s are shown (heavy black lines), with some parts lying out with the CNPA area.

Con­fid­en­tial

OTH­ER DEER COUNT DATA

1. A num­ber of stud­ies have been under­taken across the CNPA area using ​‘deer dung count’ tech­niques. The authors of this cur­rent report have been involved in many of them, work­ing on con­tract for the Forestry and Land Scot­land (FLS) / CNPA / NatureScot over the peri­od 2000 – 2019. Oth­er sim­il­ar data sets are thought to have been gathered in the CNPA, on select areas of private land, but the scope and budget of this pro­ject pre­cluded a con­sulta­tion being con­duc­ted with landown­ers to ascer­tain avail­ab­il­ity and nego­ti­ate access.

2. The loc­a­tions dung-coun­ted by SCL for pub­licly fun­ded pro­jects were com­piled and presen­ted on a map in this report to illus­trate the degree of cov­er­age obtained. Ref­er­ence is also made in the report to some of the more note­worthy res­ults obtained from recent stud­ies, as they provide an insight into the pos­sible dynam­ics of wood­land deer pop­u­la­tions in the CNP more widely.

DEER CULL RECORDS

1. SNH was asked by CNPA to provide out­puts from the data­base in which they hold stat­utory annu­al cull return inform­a­tion sent by landown­ers across Scot­land. A run of 30 years of data, stretch­ing back to 1990, was reques­ted for his­tor­ic­al context.

2. The data provided included all four spe­cies of deer culled, and covered all types of land (wood­land, agri­cul­tur­al land, open range).

3. The data­base was quer­ied by SNH with the aim of provid­ing data for the entirety of the CNPA but, in real­ity, the data sets provided have the fol­low­ing issues:

a) Strad­dling of CNPA bound­ar­ies: data can be quer­ied on an estate-by-estate basis. How­ever, many estates straddle the bound­ar­ies of the CNPA area. As a res­ult, the cull records provided cov­er an area of land some­what lar­ger than that of the CNPA area itself.

b) Con­fid­en­ti­al­ity: data were provided at region­al scale and not by estate. This approach was accept­able for the pur­poses of the inten­ded ana­lys­is but did cre­ate some dif­fi­culties in cer­tain areas. For the south­ern-most DMG’s (West Grampi­ans and East Grampi­ans Sub-Group 1) a por­tion of their land lies out with the CNPA but the outly­ing estates were not stripped out of the data sup­plied. The data for these areas there­fore includes land out with the park.

c) Com­plete­ness of cov­er­age: some land­hold­ings do not provide a return at all, although what pro­por­tion of the CNPA this applies could not be con­firmed exactly by SNH. Some land­hold­ings also fail to provide a return in cer­tain years, because they shoot no deer or because they for­get etc.

d) Break­down of data into land types: it appears from the data sets provided by SNH that ​‘agri­cul­ture’ as a cat­egory was only intro­duced in the mid-2000’s as an option on forms. SNH also com­men­ted that the break­down by land type

e) Unre­cor­ded culls: some cull­ing will go unre­cor­ded, for example because it relates to the illeg­al tak­ing of anim­als (poach­ing).

f) Nat­ur­al mor­tal­ity: it is well doc­u­mented that wild deer, and in par­tic­u­lar red deer on open range in winter, die of nat­ur­al causes with­in the CNPA area as well as being culled. There are no reli­able park-wide records for how large the num­bers might be, although anec­dot­ally the num­ber dying in hard win­ters (in the hun­dreds loc­ally, and quite pos­sibly in the thou­sands on a park-wide basis in some very severe win­ters) is suf­fi­cient to sup­press deer num­bers loc­ally in the same way as cull­ing does. The num­ber of deer culled annu­ally, as presen­ted herein, is there­fore likely to be dif­fer­ent to the over­all num­ber of deer dying annually.

g) Deer-Vehicle col­li­sions: sim­il­arly, a num­ber of DVC’s hap­pen each year in the CNPA area. Some are recor­ded (by an SNH-sponsored pro­ject⁴) but many will go un-recor­ded. It is not known wheth­er the num­ber dying each year con­trib­utes sig­ni­fic­antly to sup­pres­sion of the population.

1. The sup­plied cull data were ana­lysed accord­ing to the five main count areas (see pre­vi­ous sub-sec­tion on heli­copter count data), as follows:

a) Data were ana­lysed accord­ing to spe­cies and land use type.

b) For ana­lys­is involving break­downs by land use or deer spe­cies, only data from 2005 onwards was included as this is assumed to be more reliable.

SPA­TIAL ANALYSIS

1. A Geo­graph­ic Inform­a­tion Sys­tem (GIS) was built in ArcMap cov­er­ing the CNPA area and its environs.

2. A wide range of data was input to the GIS including:

a) CNPA bound­ary and DMG bound­ar­ies from SNH.

b) DCS count area bound­ar­ies (where neces­sary to fill in gaps in DMG shapefile cov­er­age; sketched from a PDF sup­plied by SNH so not guar­an­teed accur­ate) and sketched bound­ar­ies for remain­ing areas not covered by SNH.

c) Heli­copter deer count data from SNH (clas­si­fied by deer group size and com­pos­i­tion — stags, hinds & calves).

d) Alti­tude and topo­graphy (Ord­nance Sur­vey Pan­or­ama), with the land area divided into 100m alti­tude bands for analysis.

4 https://www.nature.scot/professional-advice/land-and-sea-management/managing- wild­life/­man­aging-deer­/deer-vehicle-col­li­sions

e) Roads, rivers, lochs etc (OS Meridian)

f) Sites of Spe­cial Sci­entif­ic Interest (SSSI) from SNH.

g) Land Cov­er Scot­land (LCS) from James Hut­ton Insti­tute (JHI), which describes the extent and types of hab­it­at present across Scotland.

h) Soils (1: 250,000 scale) from Scot­tish Gov­ern­ment, a data set describ­ing the vari­ous types of soil present.

i) Land Cap­ab­il­ity for Agri­cul­ture (LCA) from James Hut­ton Insti­tute (JHI), which iden­ti­fies the vari­ous types of land across Scot­land and its suit­ab­il­ity for dif­fer­ent agri­cul­tur­al activities.

j) Nation­al Forest Invent­ory (NFI) from Scot­tish Gov­ern­ment, describ­ing the extent and nature of wood­land cov­er (all types).

k) Nat­ive Wood­land Sur­vey of Scot­land (NWSS) from Scot­tish Forestry, describ­ing the extent and nature of nat­ive wood­land cov­er present and its condition.

1. Stat­ist­ics were derived from the GIS to help:

a) Char­ac­ter­ise the nature of the land present with­in the CNPA area

b) Show where deer had been coun­ted in recent times, as well as which areas had no count data available.

DEER POP­U­LA­TION MODELS

1. Records of the num­bers of open range red deer coun­ted in the West Grampi­an DMG, Cairngorms and Spey­side DMG and East Grampi­ans DMG’s were avail­able at reg­u­lar inter­vals span­ning sev­er­al dec­ades. In addi­tion, cull records were avail­able over an exten­ded peri­od from SNH’s his­tor­ic records. Pop­u­la­tion mod­els were built using a selec­tion of these data to estab­lish wheth­er con­tem­por­ary pop­u­la­tions could be pre­dicted from a pre­vi­ous start­ing point. The fol­low­ing approach was employed:

a) Only a ​‘core area’ was ana­lysed, with two spa­tial scales being investigated:

i) Entire area: a single mod­el includ­ing the records, and suit­able para­met­ers, for the com­bined land area of the Cairngorms & Spey­side DMG, West Grampi­ans DMG and East Grampi­ans DMG’s.

ii) Indi­vidu­al mod­els: Cairngorms & Spey­side DMG, West Grampi­ans DMG and East Grampi­ans DMG’s.

b) Heli­copter-count based data are only avail­able from Feb­ru­ary 2005 onwards, so these data were used as the start point for the mod­els. Two sets of repeat count data are avail­able for each of the three regions also. These are both embed­ded with­in the mod­el out­puts for read­er ref­er­ence, as they were used

when attempt­ing to bal­ance the mod­el by vary­ing its para­met­ers (see com­ments later­in this section).

c) All count out­puts are for sum­mer deer num­bers and dens­it­ies (i.e. spring counts plus recruit­ment). There­fore, the num­bers included in the mod­els will dif­fer from the spring count data provided by SNH as an input to the models.

d) The mod­els related to all land in each DMG with the excep­tion of wood­land. Land areas include any land lying out with the CNP, because cull data were sup­plied only at DMG scale.

e) Cull records relate only to open range and agri­cul­tur­al land (i.e. have wood­land culls excluded).

f) Cull records should in gen­er­al be con­sidered a min­im­um giv­en that SNH stated some smal­ler prop­er­ties do not always sub­mit records.

g) No allow­ance was made for poach­ing, as we assume the vast major­ity of the land (and there­fore deer pop­u­la­tion) included in the mod­els is unlikely to be affected.

h) Mod­el out­puts are run and presen­ted to show the impact of a small over- and under-count, at the out­set of the mod­el­ling peri­od, in order to reflect poten­tial uncer­tainty in input pop­u­la­tion size:

i) Read­ers should note that the wood­lands of the Cairngorms & Spey­side DMG are entirely open to deer (no deer fences). Some of the wood­lands in oth­er DMG areas are also open to deer, either due to absence of fences or poros­ity of fences loc­ally. Heli­copter counts used as mod­el inputs may, on bal­ance, be under­es­tim­ates of the true num­ber of open hill red deer present dur­ing the main part of the year (e.g. some may have been shel­ter­ing in wood­land at the time of the counts).

ii) Sim­il­arly, some deer will have died of nat­ur­al causes in the spring, after the count but before sum­mer recruit­ment. Also, some deer may have been culled in the same inter­ven­ing peri­od. Both out­comes would have reduced the size of the input count used in the mod­el, but no reli­able records were avail­able to make these adjust­ments for indi­vidu­al areas.

iii) Evid­ently, these ​‘over-count­ing’ biases may to some extent coun­ter­act biases arising due to the afore­men­tioned poten­tial for ​‘under-count­ing’.

i) The adult sex ratio for the start point of each mod­el is gen­er­ated from the Feb­ru­ary 2005 count data (with merged val­ues used for the East Grampi­ans DMG’s mod­el, as mul­tiple DMG’s are included in this).

j) Sum­mer recruit­ment rates are estim­ated from long-term data obtained from spring counts, with a dif­fer­ent value used for each region and a weighted value used for the over­all mod­el. The rate employed in mod­els is the long- term % calves at foot in spring, but with 10% added on to the rate (e.g. 35% becomes 38.5%) to reflect the fact that sum­mer calv­ing rates are likely to be

high­er than the rate evid­enced by spring counts. The rate is held steady in each mod­el, rather than vary­ing annu­ally. Whilst weath­er and changes in dens­ity are known to cause vari­ations in rate, there are insuf­fi­cient loc­al data to derive such para­met­ers with cer­tainty for all areas and years. The mod­elled pop­u­la­tion tra­ject­ory over time may, as a con­sequence, be less vari­able than the real tra­ject­ory (i.e. nat­ur­al per­turb­a­tions would cause more vari­ation between years; inter­ac­tions between year and rate will not there­fore be accur­ately represented).

k) No adult nat­ur­al mor­tal­ity is expli­citly ​‘allowed for’ in the mod­els as insuf­fi­cient records were avail­able to derive reli­able loc­al para­met­ers. Giv­en this, the recruit­ment rates employed in the mod­el can be con­sidered ​‘net rates’ (i.e. not gross rates, with mor­tal­ity of juven­iles and adults later deducted).

l) Mod­els are run con­cur­rently for stags, for hinds and for calves as well as for deer num­bers over­all. The out­puts from the mod­els reflect this, as do any repeat counts included for ref­er­ence purposes.

m) When the mod­el for the entire core area (all DMG’s com­bined) was first run it failed to bal­ance using the above para­met­ers. Skew­ing sur­viv­or­ship appeared to improve the mod­el­ling out­comes. In the mod­el­ling frame­work employed herein, we achieved this by vary­ing the’sex ratio at birth’ para­met­er (53% female and 47% male, rather than 50: 50) to reflect dif­fer­en­tial sur­viv­or­ship. That does not mean the actu­al ratio at birth was skewed as no records are avail­able to ascer­tain this. Rather, it is used as a proxy to ensure male mor­tal­ity rates are high­er than females over­all in the mod­el. It may also be taken to reflect broad­er dif­fer­ences in the way male and female pop­u­la­tions oper­ate more gen­er­ally in the mod­elled area (e.g. some male deer may be ​‘lost’ from the sys­tem due to emig­ra­tion which could con­ceiv­ably arise from stag move­ment out of the mod­elled area dur­ing the rut, and sub­sequent cull­ing on a dis­tant area).

n) In bal­an­cing the mod­el for the entire core area, the key under­pin­ning assump­tion was that the ini­tial count and sub­sequent counts were accur­ate both in terms of over­all num­bers of deer present and break­down into sex and age classes. Should num­bers in fact have been high­er or lower, then a dif­fer­ent suite of para­met­ers may res­ult in mod­el balance.

IMPACT DATA: HIA

1. The meth­ods of Mac­Don­ald et al (1998)5 have long been used by NS (and pre­vi­ously by SNH/DCS) to mon­it­or the level of herb­i­vore impacts on des­ig­nated open range sites across Scot­land. The meth­od, based around the ​‘small-scale indic­at­ors’ of Mac­Don­ald et al, is referred to as Herb­i­vore Impact Assess­ment (HIA). DCS/SNH typ­ic­ally designed the sur­veys and iden­ti­fied plot loc­a­tions then

5 https://www.nature.scot/guide-upland-habitats-surveying-land-management-impacts-volumes-1- and‑2.

asked inde­pend­ent con­tract­ors to under­take the work. Appendix 1 provides an over­view of the method.

1. A cam­paign of sur­vey­ing over the peri­od 2005 – 2018 yiel­ded a large volume of HIA data, parts of which cov­er the CNP. That said, upon inspec­tion of the data sets avail­able online at Nat­ur­al Spaces and oth­er­wise held dir­ectly, only some parts of the CNP were found to be covered by con­tem­por­ary data (referred to here­on in as SNH HIA): Cairngorms SAC, most recently in 2015, and the Caen­lochan Sec­tion 7 Area, most recently in 2018. Older HIA data are avail­able for the CNP area but are not con­sidered fur­ther in this report due to the restric­ted scope (i.e. to focus on review­ing impact data gathered over a sim­il­ar time frame to con­tem­por­ary counts).

2. Over a dec­ade ago DCS/SNH developed a sim­pli­fied approach to assess­ing herb­i­vore impacts on key open range hab­it­ats, for estate staff and man­agers to use, as part of their Best Prac­tice Guides (BPG) series. These guides are now over­seen by a steer­ing group (https://​www​.best​prac​tice​guides​.org​.uk/) com­pris­ing mem­bers of key industry organ­isa­tions. In recent years the Asso­ci­ation of Deer Man­age­ment Groups (ADMG) has encour­aged DMG’s and their mem­ber estates to use the BPG impact sur­vey pro­to­cols to assess the con­di­tion of dwarf shrub heath (DSH) and blanket bog (BB) hab­it­ats across upland Scotland.

3. CNPA staff con­firmed that a con­sid­er­able num­ber of estates across the East Grampi­an DMG’s areas and West Grampi­an DMG area had recently gathered data using the BPG pro­to­cols for DSH and BB hab­it­at. In autumn 2020 the CNPA input indi­vidu­al estate records into Excel for the pur­poses of this pro­ject. The fol­low­ing data (referred to here­on in as Estates HIA) were provided:

a) West Grampi­an DMG: almost all estates provided data on both DSH and BB.

b) East Grampi­ans DMG’s: a mod­er­ately high pro­por­tion of estates in provided data, but rel­at­ively little BB data were submitted.

c) Cairngorms & Spey­side DMG: some estates provided data, the major­ity of it being for BB.

1. Sev­er­al issues were iden­ti­fied with the Estates HIA data which poten­tially com­plic­ate any analysis:

a) Incom­plete geo­graph­ic cov­er­age means it is more dif­fi­cult to identi­fy spa­tial trends in the data (e.g. in rela­tion to deer dens­ity) across the regions of the CNP. Vari­ab­il­ity in the sup­ply of data from each estate (i.e. DSH only, BB only or both data types) adds to the ana­lyt­ic­al challenge.

b) The sampling strategy for gath­er­ing Estates HIA was not expli­citly stated, but can in large part be inferred from the data provided. Lar­ger estates (and

6 Mon­adh­liath DMG has been gath­er­ing HIA data as part of their Peat­land Action pro­ject but the data are not yet com­piled. Oth­er DMG’s / estates may have gathered HIA data but the park did not provide it and it was not avail­able through SNH online.

oth­er­wise small aggreg­a­tions of estates) appear to have employed a fixed sample size of n=30 ran­dom quad­rats spread across the land mass, but restric­ted to hab­it­at type, for each hab­it­at (DSH, BB). How­ever, many vari­ations on the theme are appar­ent (e.g. some have used n=15 DSH and n=15 BB, some have sampled n=30 in total and plots have fallen at ran­dom in DSH or BB etc).

c) The date of each sur­vey was rarely stated, although it is believed most of the data were gathered in the peri­od 2017 – 2019.

d) The tim­ing of sur­vey was not evid­ent in most of the records provided (e.g. was data gathered in winter, spring, sum­mer or autumn con­di­tions?). This can have implic­a­tions for how sur­veys need to be con­duc­ted to ensure accur­acy of brows­ing data (see below).

e) Moreover, it was not evid­ent from the data which heath­er shoots were assessed dur­ing brows­ing sur­veys: fresh sum­mer growth, or pre­vi­ous years’ growth7. Assess­ing the ​‘brows­ing class’ (Low = < 33% shoots browsed, Mod­er­ate = 33 – 66%, High = > 66%) is the primary focus of the meth­od and so the pre­cise approach used for shoot iden­ti­fic­a­tion dur­ing sur­veys is key.

f) Some sur­veys repor­ted inter­me­di­ate classes of brows­ing (e.g. LM, MH) but it is not clear what the basis for this is.

1. For the pur­poses of the ana­lys­is presen­ted herein, we adop­ted the fol­low­ing approach for ana­lys­is of Estates HIA data:

a) All sup­plied data are assumed to be con­tem­por­ary (i.e. rel­ev­ant to the peri­od of the con­tem­por­ary count analysis).

b) The ana­lys­is focused on brows­ing class, being com­mon to both the BB and DSH sur­vey pro­to­cols, with oth­er vari­ables being omitted8. It was assumed that brows­ing assess­ments were all under­taken at an optim­al time of year (