The purpose of this document is to provide a species account of the Grey Partridge (Perdix perdix) of Holyrood Park, Edinburgh for the summer 2006 season. As such it provides information on the distribution of the species, based on the methods documented in ‘Bird Monitoring Methods’ (Gilbert, Gibbons and Evans, 1998). It is a summarised version of the original, excluding as it does the recommendations for further work, detailed references, appendices and the maps showing the survey routes followed. An electronic copy of the full length original version can be obtained from the author.
Background
The Grey Partridge is a Edinburgh Biodiversity Action Plan priority species (EBP, 2004), and its management within Holyrood Park is included as part of the Seed Eating Birds Species Action Plan.
It is a resident game bird of open farmland and meadows, particularly where cereal and pasture are present, and has been identified as a priority species as a result of the dramatic decline in its UK population over the last forty years (Gilbert, Gibbons and Evans, 1998). While, once adult, the birds can live up to 5 years (RSPB, 2006) they are, as young, highly dependent on insect-rich brood rearing habitat (Aebischer, 2003).
The Historic Scotland Ranger Service (HSRS) established a log of casual wildlife sightings in January 2000 and since then has regularly recorded the presence of Grey Partridge within the Park, the observed locations being detailed in Appendix One. Prior to this at least three pairs were noted as breeding in 1993, and a covey count of 17 was noted in 1982 (SWT, 1993).
As the 1993 survey represents the last systematic study of the species within the Park it was decided, following discussions with Natalie Taylor and Jenny Hargreaves of HSRS, to carry out a breeding season survey of the population in March 2006.
Aims
To determine the distribution of Grey Partridge within Holyrood Park at the start of the summer 2006 season.
Objectives
To undertake a survey of Grey Partridge within Holyrood Park in support of the above aim.
Methodology
Prior knowledge acquisition
The field observers should familiarise themselves with the description and illustrations of Grey Partridge in ‘Collins Bird Guide’ (Svensson and Grant, 1999). The call and alarm call of the species are available in ‘Collins Bird Songs and Calls’ (Sample, 1996).
The description, illustrations and call of potential confusion species Red-legged Partridge (Alectoris rufa) and female Pheasant (Phasianus colchicus) should also be noted.
Examples of alternative publications providing descriptions and illustrations are ‘Birds of Europe’ (Jonsson, 2003) and ‘RSPB Birds o Britain and Europe’ (Hume, 2002).
Survey Areas
The areas surveyed were:
Duddingston cultivation terraces
Dunsapie Crag
Whinny Hill (entire)
Crow Hill
Nether Hill
The Dry Dam
Slopes east of Salisbury Crags
The proposed and actual survey routes are shown as maps in Appendices Two and Three of the full length version, the proposed routes being based on an analysis of the location of previous incidental records shown in Appendix One of the original.
Exclusions
Time constraints did not allow the Wells o’ Wearie or the area to the west of Samson’s Ribs to be surveyed in 2006. The area north of the Hunter’s Bog water body was not surveyed as it had been short mown.
Methods and equipment
The timing and underlying methodology of the survey was based on the Grey Partridge survey methodology for pre-breeding season population, as documented in ‘Bird Monitoring Methods’ (Gilbert, Gibbons and Evans, 1998).
Two survey teams were employed, working in parallel to cover the Arthur’s Seat (team of 3 plus dog) and Salisbury Crags (team of 4) routes within the two hour time window spanning the half hour before and the hour and a half after sunrise.
The following equipment was used by the survey location team leaders:
Survey maps (See Appendix Two and Three of the full length version)
Pencil and eraser
Binoculars (of the binoculars available to the HSRS the Viking 8x40 ZCF were deemed the most suitable)
Motorola GP340 two-way radio
The following counting methods were employed:
Survey location - Arthur’s Seat
Counting method employed
Slow zig-zag transect (circa 1-2mph).
Starting from Duddingston Village car park ascended to the High Road via the cultivation terraces.
Traversed to the top of Jacobs Lader and then traversed the slopes up and over Dunsapie Crag.
Ascended the south side of Whinny Hill then descended to the lower east side of Crow Hill.
Ascended the east side of Crow Hill to its summit and then traversed the summit of Nether Hill.
Descended via the grassy area between Crow Hill and Arthur’s Seat to the bottom of the chain link fence.
Two team members descended via the Dry Dam to St Margaret’s Loch. One team member, plus dog, descended to St Margaret’s Loch via the north end of Whinny Hill
Survey location - Salisbury Crags (Hunter’s Bog)
Counting method employed
Entered Hunter’s Bog via the Hawse and traversed the length of the east slope of Salisbury Crags, repeating the traverse until the east slope of the crags and Hunter’s Bog had been surveyed.
Please note that while Holyrood Park is a site of Special Scientific Interest this does not guarantee unrestricted access to any of the areas mentioned.
For both routes surveyors walked a line abreast at approximately 20 metre intervals. The dog with the Arthur’s Seat team was allowed to run free as long as visible to its owner, allowing any birds that it flushed to be positively identified by the survey team.
Particular care had to be taken when surveying Hunter’s Bog due to the drainage ditches present, and during the descent of the Dry Dam due to the gradient of the slopes at the south end.
The following details were recorded:
detailed transect line taken on the ground
location, time, count, behaviour and flight direction (if any) of Grey Partridge seen
areas which were considered to receive insufficient coverage and noted reasons
Notation methods are detailed in Appendix Four of the full length version.
Survey date and conditions
Due to adverse weather conditions on the 14th March the survey was rescheduled for the 21st March 2006 between 0615 and 0815. The weather conditions on the day were 0/10 cloud, 5mph N wind, temperature 3°C, therefore within the “calm and preferably dry” conditions specified in the Grey Partridge survey methodology (Gilbert, Gibbons and Evans, 1998). This methodology specifies mid-March for the survey as the birds will have paired by then. Therefore, the delay of one week was not considered to be significant.
Analysis methods employed
No analysis of the data was necessary as the survey recorded only a simple presence/absence.
Results
Grey Partridge count by location:
Count – 2
Location - East top of Crow Hill (NT279728)
Comments - Flushed by dog at 0715, flew south
Discussion
Methods
In order to carry out the survey within the required time window a third survey team should be employed to cover the Wells o’ Wearie and the area to the west of Samson’s Ribs. Their survey direction should still be east to west in order to avoid potential double counting of any birds flushed by the ‘Arthur’s Seat’ team from Crow or Nether Hill that fly into Wells o’ Wearie area. This is on the basis that the third survey team will have completed their survey of the Wells o’ Wearie before the ‘Arthur’s Seat’ team reach Crow or Nether Hill, a fact that could be confirmed by radio communication at an appropriate point.
A dog per team would be a useful addition, as the experience of the ‘Arthur’s Seat’ team indicated that dogs were useful in flushing birds from areas of deep grass, where they would otherwise be out of sight to the surveyors.
Species account
The noted decline in incidental observations since 2001 (See Appendix One of the full length version) fits in with the observation of only one pair of birds during the survey. Also, the number of birds seen is at the low end of the average number of birds per sighting shown in that appendix. Nonetheless a casual record of two young birds at the same location in August (HSRS, 2006) does suggest that breeding is still taking place within the Park.
This decline appears to fit with the national decline of the species noted by the British Trust for Ornithology (BTO, 2000). The BTO have noted a marked decline in the UK Grey Partridge population over the period 1978 to 2000 (last date), the species now being placed on the priority species list due to its “rapid decline”.
Factors that have been blamed for the national decline in Grey Partridge are:
1) Loss of nest sites (such as hedge bottoms) to farm intensification
2) Reduced food supplies and sources for chick food through the use of pesticides and herbicides, as well as the loss of winter stubble feeding grounds for over-wintering birds
3) Vulnerability of nests to predators in farmland with poor cover
4) Nest destruction caused by early mowing and other farm operations
(UK Biodiversity Partnership, 2006)
No evidence has been found supporting the suggestion that a factor in the decline in Grey Partridge numbers is competition from Red-legged Partridge (British Garden Birds, 2006).
While many of the above factors do not directly affect Holyrood Park it has been suggested that the decline in the reserve population outside of the park may now be weakening the resident gene pool, simply in terms of making it more difficult to replace losses with birds from outside the park (pers. comm.). Also, if the accumulation of rank grasses in certain areas of the Park since the end of sheep grazing in 1978 has reduced insect-rich brood-rearing habitat, this could, where a critical factor, adversely affect chick survival rate (Aebischer, 2003).
Further Study/Work
While it would be possible to continue to monitor the species through miscellaneous wildlife records the experience to date suggests that a more systematic approach is required. While the Grey Partridge survey methodology (Gilbert, Gibbons and Evans, 1998) suggests an annual survey a reduced frequency may need to be considered against the other conservation priorities for the Park.
Conclusions
The 2006 survey of Grey Partridge in Holyrood Park, Edinburgh established the presence of at least one breeding pair for that season. The Park population of this species appears to have been declining since 2001, possibly reflecting the general UK decline of this species.
