Scottish Natural Heritage Commissioned Report 369 Whooper swan (Cygnus cygnus) distribution and habitat use in the Black Cart flood plain during winter 2008/2009

COMMISSIONED REPORT

Commissioned Report No. 369 Whooper swan (Cygnus cygnus) distribution and habitat use in the Black Cart flood plain during winter 2008/2009 (Contract No. 266539)

For further information on this report please contact: Dave Lang Scottish Natural Heritage Caspian House Mariner Court Clydebank Business Park CLYDEBANK G81 2NR Telephone: 0141 951 4488 E-mail: [email protected]

This report should be quoted as:

Harding, N. (2010). Whooper swan (Cygnus cygnus) distribution and habitat use in the Black Cart flood plain during winter 2008/2009. Scottish Natural Heritage Commissioned Report No. 369 (Contract No. 266539).

This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage. This permission will not be withheld unreasonably. The views expressed by the author(s) of this report should not be taken as the views and policies of Scottish Natural Heritage.

© Scottish Natural Heritage 2010.

COMMISSIONED REPORT Summary

Whooper swan (Cygnus cygnus) distribution and habitat use in the Black Cart flood plain during winter 2008/2009 Commissioned Report No. 369 (Contract No. 266539) Contractor: Scottish Natural Heritage Year of publication: 2010

Background The purpose of this project is to determine the distribution, habitat use, abundance, and behaviour of whooper swans wintering on the Black Cart flood plain during the 2008/2009 winter. Whooper swans are listed for special conservation measures on Annex 1 of the EC Birds Directive and the core part of the whooper swan range at the Black Cart was notified as an SSSI in 1999 and a SPA in 2000. This study builds upon earlier work to improve understanding of long term patterns of behaviour and population trends. Such information is of vital importance to SNH in discharging its duties with regard to securing favourable conservation status for the swan population and in its role in ensuring the sustainability of future development in the area.

Main findings

 Up to 183 whooper swans were recorded in the Black Cart study area during the winter. This is the greatest number of wintering birds recorded since 2001/2002, and contrasts with the steady decline in numbers of recent years.

 The percentage of juveniles in the flock was 26% which compares favourably with estimates of breeding success from other parts of Britain and from the most recent international whooper swan census.

 In November, the three most abundant habitats in the study area were improved pasture, stubble and winter cereal with 36%, 20% and 10% cover respectively. All other habitats had less than 5% cover. The area of improved pasture and winter cereal remained unchanged through the winter. However, the cover of stubble declined from 22% to 6% as it was ploughed.

 Up to the 29th January birds fed almost wholly on stubble and after this date they fed almost wholly on improved pasture. This switch occurred much later than during the 2007/2008 winter. The switch from stubble was not due to its physical loss, but was probably due to deterioration in its quality as feeding habitat.

 Birds roosted in five locations: the Black Cart and nearby fields, Linwood Pond, Newshot Wetland, Linwood Moss Pond and field 178A at Auchans. The peak counts were 163 for the Black Cart, 16 for Linwood Pond, 57 for Newshot Wetland, 72 for field 178A and 5 for Linwood Moss Pond. The Black Cart was regularly used as the main roost throughout the winter. The other roosts acted as satellites, and were used less regularly, by smaller numbers of birds, at particular times of year.

 In December 2008 birds were regularly feeding in the fields to the east of the airfield and flying directly over the main runway to the Black Cart. To prevent an incident proactive management must be employed to deter birds from feeding in these fields.

 From the previous winter there were major changes in population size, feeding distribution, roost usage, habitat use and flight lines. These changes were not predictable, indicating that in the short term at least annual monitoring may be required to provide the information necessary for SNH to respond effectively to the development pressures and agricultural changes which could potentially threaten the favourable conservation status of these birds, whilst ensuring air safety is not compromised.

For further information on this project contact:

Dave Lang, Scottish Natural Heritage, Caspian House, Mariner Court, Clydebank Business Park, Clydebank, G81 2NR Tel. 0141 951 4488 e-mail: [email protected]

Acknowledgements

Many thanks to all the farmers and landowners who provided access to their land.

Table of Contents Page

1 INTRODUCTION ...... 9

2 METHODS ...... 9 2.1 Overview ...... 9 2.2 Roost surveys...... 10 2.3 Feeding surveys ...... 10 2.3.1 Overview...... 10 2.3.2 Survey routes and field numbering...... 10 2.3.3 Habitat recording ...... 12

3 RESULTS ...... 13 3.1 Data management and analysis environment ...... 13 3.2 Population ...... 13 3.3 Feeding distribution ...... 15 3.3.1 Data issues...... 15 3.3.2 Chronology ...... 15 3.3.3 Changes in feeding distribution between the 2007/2008 and 2008/2009 winters 18 3.3.4 Field usage...... 19 3.3.5 Habitat availability...... 20 3.3.6 Habitat use...... 20 3.4 Roost use...... 22 3.4.1 Introduction...... 22 3.4.2 Black Cart...... 23 3.4.3 Linwood Pond...... 24 3.4.4 Newshot Wetland...... 24 3.4.5 Linwood Moss Pond ...... 25 3.4.6 Field 178a...... 25 3.4.7 Auchans Pool...... 25 3.4.8 Field 52...... 26 3.4.9 Other possible roosts...... 26 3.4.10 Use of sub roosts within the Black Cart site ...... 26 3.5 Flight lines ...... 26 3.6 Colour ringed birds ...... 27 3.7 Disturbance ...... 27

4 DISCUSSION...... 27

5 REFERENCES...... 28

List of Figures

Figure 1: Field numbering and feeding survey route for the 2007/2008 winter.

Figure 2: Field numbering used in the 2008/2009 winter.

Figure 3: Survey route followed from the 26 November 2009 till the 29 January 2010 inclusive

Figure 4: Survey route followed from the 6 to the 19 February 2010 inclusive.

Figure 5: Survey route followed from the 26 February till the 10 April 2010 inclusive.

Figure 6: Best estimates of total numbers of whooper swans within the Black Cart study area on different dates within the 2008/2009 winter.

Figure 7: Percentage of aged birds which were juveniles on each date

Figure 8: All feeding records within the Black Cart Study Area for the 2008/2009 winter.

Figure 9: All feeding records within the Black Cart Study Area for the 2007/2008 winter.

Figure 10: Feeding records for November 2008

Figure 11: Feeding records for December 2008

Figure 12: Feeding records for January 2009

Figure 13: Feeding records for February 2009

Figure 14: Feeding records for March 2009

Figure 15: Feeding records for April 2009

Figure 16: The number of dates on which whooper swans were present during formal feeding surveys for fields where birds were present at least once during the 2008/2009 winter.

Figure 17: The total number of birds recorded during formal feeding surveys for fields where birds were present at least once during the 2008/2009 winter.

Figure 18: The maximum number of whooper swans recorded during formal feeding surveys for fields where birds were present at least once during the 2008/2009 winter.

Figure 19: Relationship between total number of birds recorded and maximum number of birds recorded for fields holding birds at least once during the 2008/2009 winter

Figure 20: Relationship between no of dates birds present and total numbers of birds recorded for fields holding birds at least once during the 2008/2009 winter

Figure 21: Relationship between no of dates birds present and maximum number of birds recorded for fields holding birds at least once during the 2008/2009 winter.

Figure 22: Relationship between number of dates birds present in the 2007/2008 winter and the number of dates they were present in the 2008/2009 for fields where birds present in at least one of the winters.

Figure 23: Relationship between the total number of birds recorded in the 2007/2008 winter and the total number recorded in the 2008/2009 winter for fields where birds present in at least one of the winters.

Figure 24: Relationship between maximum number of birds present in the 2007/2008 winter and the maximum number of birds present in the 2008/2009 winter for fields where birds present in at least one of the winters.

Figure 25: Distribution of habitats across numbered fields in the Black Cart study area on the 26 November 2008.

Figure 26: Distribution of habitats across numbered fields in the Black Cart study area on the 10 April 2009.

Figure 27: Distribution of habitats across numbered fields in the Black Cart study area on the 25 November 2007.

Figure 28: Change in cover of selected habitats during the 2008/2009 and 2007/2008 winters, for just those fields recorded in both surveys

Figure 29: Number of whooper swans recorded in each foraging habitat on each formal feeding survey during the 2008/2009 winter based upon the maximum number of birds recorded in each field.

Figure 30: Number of whooper swans recorded in each foraging habitat on each formal feeding survey during the 2007/2008 winter based upon the maximum number of birds recorded in each field.

Figure 31: Roosts and potential roosts in the 2007/2008 and 2008/2009 winters.

Figure 32: Flight lines by time of day for the 2008/2009 winter

Figure 33: Flight lines during the 2008/2009 winter classified according to estimated maximum height achieved.

Figure 34: Flight lines by time of day for the 2007/2008 winter

Figure 35: The cumulative percentage of flights and birds on flight lines below given altitudes (metres) for the 2007/2008 and 2008/2009 winters.

List of Tables

Table 1: Details of routes covered in each feeding survey, along with start and end times

Table 2: Fields covered from the Auchans circuits and the revised route across Blackstoun Farm.

Table 3: Fields for which the boundaries have been revised since the 2007/2008 survey.

Table 4: Fields for which the habitat classification recorded in 2007/2008 has been revised.

Table 5: Minimum, maximum and best estimates of the numbers of whooper swans present in the Black Cart Study area on different dates in the 2008/2009 winter

Table 6: Peak monthly whole site counts, together with counts of adults, juveniles and unaged birds on the same dates.

Table 7: Casual records of whooper swans in the Auchans area outside the existing study area prior to its extension to include these fields in February 2009.

Table 8: Total area of each habitat on 26 November 2008 and 10 April 2009, along with the maximum area recorded during the winter.

Table 9: Comparison of habitat cover between 25 November 2007 and 26 November 2008, for fields within the Black Cart study area covered in both winters

Table 10: Summary of use of Black Cart roost during the 2008/2009 winter

Table 11: Summary of use of roosts other than the Black Cart during the 2008/2009 winter

Table 12: Summary of use of Black Cart roost east and west of Barnsford Bridge

Table 13: Summary of use of subroosts within Black Cart East of Barnsford Bridge.

Table 14: Illustration of conventions used in recording roost usage in tables 10 to 13.

Table 15: Roost movement times at dawn

Table 16: Roost movement times at dusk

Table 17: Colour ring observations

Table 18: Recorded instances of disturbance

Table 19: Recorded instances of potential disturbance

1 INTRODUCTION

The purpose of this project is to determine the distribution, habitat use, abundance, and behaviour of whooper swans wintering on the Black Cart flood plain during the 2008/2009 winter. Whooper swans are listed for special conservation measures on Annex 1 of the EC Birds Directive and the core part of whooper swan range at the Black Cart was notified as a SSSI in 1999 and a SPA in 2000. This study will build upon earlier work to improve understanding of long term patterns of behaviour and population trends. Such information is of vital importance to SNH in discharging its duties with regard to securing favourable conservation status for the swan population and in its role in ensuring the sustainability of future development in the area.

The objectives for this project are:

 To gain an understanding of the number of whooper swans within this year’s Black Cart flock, how this changes throughout the wintering season, and to establish the peak wintering population size.

 To study whooper swan use of the Black Cart flood plain to determine which areas are most used and which areas are avoided.

 To identify the habitats and type of agricultural management in areas used by whooper swans. In particular to take note of which areas are used under particular conditions – e.g. high rainfall with flooding, or severely cold weather where water bodies or field are frozen.

 To identify the regular routes taken by the whooper swans between significant areas such as feeding and roosting sites, including an assessment of heights. Also to note any consistency in flight routes taken when whooper swans are disturbed.

 To assess the traditional field usage with reference to previous studies in this area (1994/95 to 2003/04 inclusive) to understand which areas are of most importance and what alterations in conditions provoke a change in usage of particular sites.

 To assess how disturbance affects site usage both when feeding and roosting.

 To note any swans tagged with rings or collars.

2 METHODS

2.1 Overview

Between 26th November 2008 and 10th April 2009, 19 full visits to the site were made. Each full visit consisted of three components.

9

1. Observations at dawn of birds departing a roost. 2. A feeding survey following a systematic route to record the feeding locations of birds.

3. Observations at dusk either of the departure of birds from a feeding location towards a roost, or of their arrival at a roost.

On some dates roosts were also visited after dark to determine the presence or absence of birds.

During each visit any observations of disturbance or flights between feeding areas were also recorded.

2.2 Roost surveys

The purpose of roost surveys was to determine the number of birds using individual roosts, and also to record the flight lines used by birds. Observations at dawn were made of birds departing their roosts and at dusk of either birds arriving at their roosts or of birds departing their feeding grounds for the roost. As well as potentially providing information on the probable use of known roosts, observations at dusk of birds departing their feeding ground also potentially allow the identification of new, previously unidentified, roosts.

On some days, roosts were also visited after dark. Although poor visibility prevents accurate counts the presence or absence of whooper swans can often be established, and sometimes an absolute minimum of the number of birds present can also be determined.

2.3 Feeding surveys

2.3.1 Overview

During feeding surveys, the number of swans present in each field was recorded (where possible distinguishing between adults and juveniles), along with the habitat within that field.

As in previous years, where possible, feeding surveys were carried out by bicycle, as this allowed the observer to scan continuously, stopping safely as required and also allowed parts of the route inaccessible by car to be covered rapidly. Occasionally, in icy conditions, a car was used initially until the ice had thawed sufficiently to allow cycling to be resumed safely.

2.3.2 Survey routes and field numbering

As recommended in Harding (2008), the recording of flooding and livestock was discontinued this year. This considerably reduced the time required to complete the formal feeding survey, so that all the extensions to the route developed during the 2007/2008 season (Figure 1) could to be completed on all visits (Figures 3-5), providing full coverage, even on the shortest days of mid-winter.

In previous surveys, some fields within the study area have been excluded from habitat recording (Figure 1), presumably because no birds had ever been recorded in

10 them. However, to obtain unbiased estimates of habitat selection it is necessary to include all fields within the broad foraging area used by the birds irrespective of whether birds have been recorded in them previously. Thus, for this winter’s survey, all fields within the study area have been numbered (Figure 2), and habitats and birds present in them recorded on each visit. This closes the “gaps” in previous coverage, reducing the potential for bias in assessments of habitat selection.

The outer boundaries of the study area are defined so as to encompass all locations where birds have been recorded feeding in the past. This results in irregular study area boundaries (Figure 2). The alternative approach of defining the study area as all fields within a fixed radius of the Black Cart Roost, although superficially attractive, would increase the survey effort required to achieve full coverage beyond what was practical to achieve in a single day, and also introduce alternative biases as areas never frequented by the birds would be included; thus we believe the current approach is a good compromise.

To allow the gap in coverage to the north of Portnauld farm to be filled, the return route from the Newshot fields was revised so as to complete a circuit via Old Mains and Portnauld rather than retrace the original route. A small section of the route along the Greenock road immediately north of the Inchinnan industrial estate was dropped as this area can be adequately surveyed from the nearby hilltop vantage point introduced last year (Figure 3).

Between the 26th November 2008 and the 29th January 2009 the farmer at Blackstoun farm, Mr Ritchie, refused access over his land because of concerns about biosecurity. Therefore, over this period, the route was diverted via Linwood (Figure 3). A New survey route (Figure 4) and associated protocols were agreed with the farmer to satisfy his concerns and access across Blackstoun Farm was possible from the 6th February 2009 onwards, although following a different route to that followed in previous surveys. The new survey route visits the main farm buildings before proceeding onto the farm so that the farmer can be notified of the observer’s presence and, the observer can wash and disinfect their footwear and bicycle at a disinfection point, prior to proceeding onto the land.

During both the 2007/2008 and 2008/2009 winters small numbers of birds were recorded feeding in the Auchans area during casual observations, outside the standardized feeding surveys (Table 7; 11 birds in total on the 03/12/2008 was the maximum recorded). However, as the area was outside the area traditionally used for feeding by birds roosting on the Black Cart SPA, and as there was no evidence linking the birds recorded feeding in the area to the Black Cart population, the assumption was made that the birds present were probably not part of the Black Cart population and these observations have been excluded from both population estimates and formal analyses of foraging behaviour. However, on the 19th February 2009, approximately 127 birds were located feeding in this area outside the existing study area (see section 3.3.2). To allow this area to be adequately covered, from the 26th February 2009 till the end of the season, the route was extended so as to include a circuit across Linwood Moss and along Auchans Road (Figure 5). In subsequent feeding surveys up to 99 birds were recorded feeding in these Auchans fields outside the previous study area (see section 3.3.2). Thus, during this season three survey routes were followed (Table 1):

1) From the 26th November till the 29th January inclusive, the route on Figure 3 was followed which diverts through Linwood to avoid crossing Blackstoun Farm.

11 2) From the 6th February till the 19th February inclusive the route in Figure 4 was followed, which includes the revised route across Blackstoun Farm, but does not include the Auchans circuit.

3) From the 26th February till the 10th April inclusive, both the revised route across Blackstoun farm and the Auchans circuit were followed (Figure 5).

Coverage of field 228 is assumed to have started a week earlier than other fields covered by the Auchans circuit, on the 19th February 2009, as this was the field were birds were first recorded outside the study area, prompting the route extension the following week. Although not formally covered until the commencement of the Auchans circuit on the 26th February, field 234 is assumed to have been covered throughout the season as this field was very clearly visible from existing route, and had remained under winter cereal, and free of birds, throughout the season.

The revised route across Blackstoun farm is considerably longer than the old route. During the short days of mid-winter it is unlikely that an observer following this revised route would be able to complete all other components of the survey route. So, in any future surveys further prioritisation of different elements of the survey route is likely to be necessary.

As in 2007/2008, the fields near Linwood south of the A736 are not visible from the survey route (Figure 1), and have been excluded from all analyses of habitat selection by foraging whooper swans. This area consists largely of derelict ground and developments such as car parks which are unlikely to be used as foraging habitat by whooper swans, although there is one field (field 140) of improved grassland which could potentially be used.

An additional 73 new fields (fields 183-254, plus field N182, a field near Auchans where birds were recorded outside formal surveys on one occasion last year, but which was not included in subsequent feeding surveys) were covered by formal feeding surveys this year but not last year. Of these 73 additional fields, 50 were added so as to provide complete coverage within the existing study area, and 23 were added so as to extend the study area in the Auchans area. Table 2 identifies the 23 additional fields added to extend the study area in the Auchans area; these were not formally surveyed prior to the 26th February this year, and have not been formally surveyed in previous winters. Table 2 also identifies the 17 fields only clearly visible from the revised route across Blackstoun Farm, and thus not covered this year until the 6th February. Of these 17 fields, 12 were covered last year, but five (fields 229-233) are new fields introduced so as to provide complete coverage.

The changes in coverage which have taken place this winter (c.f. Figures 1 and 2, Tables 1 and 2) needs to be fully taken into account when analysing changes in the recorded distribution of birds and habitats both between last winter and this, and also within this winter. Furthermore, when comparing last winter and this, consideration also needs to be given to the small number of fields for which last year’s boundaries or habitat classification have subsequently been revised (Tables 3 and 4). The database associated with the project has been updated accordingly.

2.3.3 Habitat recording

To provide an initial baseline, the habitat within each field was recorded (e.g. turf, improved pasture, stubble, setaside, game crop) at the start of the season. To allow the recording of more than one habitat within a field, each field is assumed to consist

12 of one or more patches, and the habitat is recorded for each patch, along with the estimated (by eye) percentage of the total field area occupied by that patch. Subsequently, during each feeding survey, any change in habitat since the previous visit (e.g. as a result of ploughing) was recorded.

Also, when birds where encountered in a field the actual habitat they were feeding in was recorded, so that where a field includes a mosaic of several potentially suitable feeding habitats, it is possible to determine the actual feeding habitat(s) used by the birds within the field. This extends the methodology used previously. 3 RESULTS

3.1 Data management and analysis environment

All analyses were undertaken using R version 2.9.2 (Crawley 2009, R Development Core Team 2009) and ESRI Arcview 9.3. The data was entered in the combined Microsoft Access database / ESRI Arcview Personal Geodatabase created last winter as a common repository for data from future and past surveys of the Black Cart Whooper Swans. The latest version of this database has been deposited with Scottish Natural Heritage.

3.2 Population

Table 5 and Figure show the total numbers of whooper swans recorded within the Black Cart study throughout the 2008/2009 winter. For each date there is a minimum estimate, a maximum estimate and a best estimate for the number of birds present. Full details of the derivation of each of these population estimates are provided within the appropriate table within the accompanying Microsoft Access database. Unless otherwise stated the best estimates for each date form the basis for the following analyses. Peak monthly whole site counts are given in table 6. The 18 formal population estimates in Table 5 and Figure 6 can be summarised into four natural groups  The first 3 formal counts of the field season between the 26th November and the 17th December 2008 which varied between 165 and 183.  Two counts of 170 and 171 respectively which occurred in consecutive weeks on the 12th and 19th February respectively.  Two unusually low counts on the 8th January 2009 and the 6th February respectively of 85+ birds and 121 birds, both based on the numbers of birds recorded departing the Black Cart roost at dawn, with less birds being recorded during the subsequent feeding surveys.  The 6 remaining counts between the 22nd December 2008 and the 5th March 2009 inclusive of 140 to 152 birds.  The series of 5 rapidly declining counts from the 13th March to the 10th April, as birds departed for their breeding grounds, with only five birds remaining by the 10th April.

As this contract did not start until late November, the arrival of birds from their breeding grounds was not covered. This winter’s numbers follow a different pattern to that observed in the 2007/2008 winter, where numbers tended to increase through the winter, peaking on the 21st March, and then declining very rapidly (Harding 2008).

Considerable caution is required in interpreting the population estimates shown in Table 5 and Figure 6. This is because on the 19th February 2009 a new feeding area

13 outside the existing study area was discovered which on occasion was subsequently used by large numbers of birds apparently from the Black Cart population (see section 3.3.2). These are the fields between Linwood and Craigends, in the vicinity of Auchans Farm. Birds earlier in the season could potentially have foraged in these fields and gone undetected. The problem is exacerbated because although there is evidence suggesting that the birds feeding in the area are part of the population centred on the Black Cart roost, they would sometimes roost locally in the fields rather than return to the Black Cart roost (see section 3.4). Thus, birds using this area prior to the 19th February could potentially have been missed in both roost counts and feeding surveys.

Therefore, it is unclear to what extent the fluctuations in numbers visible in Table 5 and Figure 6 represent genuine fluctuations in numbers rather than birds being missed because they were feeding undetected, and/or being missed during roost counts. In particular, the low population counts for the 08/01/2009, when only 85 birds were recorded, and the 06/02/2009 when only 121 birds were recorded, could potentially be due to birds both feeding and roosting in the Auchans area, and thus going undetected.

The peak count this winter was 183 birds on the 26th November 2009. The British whooper swan population has been increasing steadily since the late 1980s (Holt et al. 2009). However, from the winter of 2000/2001 until the winter of 2006/2007, the peak number of whooper swans recorded wintering on the Black Cart declined steadily from 299 birds to 78 birds (Holt et al. 2008, Collier et al. 2005). Last winter, 2007/2008, the peak counted increased slightly to 99 birds (Harding 2008), and the peak count of 183 birds recorded during the 2008/2009 winter is the greatest number of wintering birds recorded since 2001/2002, when 238 birds were recorded (Collier et al. 2005). This is encouraging with respect to the favourable conservation status of this population.

For whooper swan, 57 birds and 210 birds are the thresholds for national and international importance respectively (Holt et al. 2009). This suggests that the number of whooper swans recorded during the 2008/2009 winter around the Black Cart is of national but not international importance. However since whooper swans are on Annex 1 of the bird’s directive, this still potentially satisfies the qualifying criteria for the associated SPA (Stroud et al. 2001).

The WWT/JNCC Goose & Swan Monitoring Programme (GSMP) recommends that age assessment for whooper swans should take place between October and January, with the focus on December and January (WWT 2009a). In December and January, the estimated proportion of juveniles varied between 22% and 32% with a mean of 27% and a median of 26 (Table 1, Figure 7). The estimated percentage of juveniles on the 17th December 2008, when the maximum number of individuals (179) were aged during this period, was 26%. During the previous (2007/2008) winter the median percentage of young over December and January (excluding one obvious extreme outlier) was 20% and the mean was 20.8%, with the maximum count of 95 birds (all aged) recorded during this period on the 27th January including 20% of juveniles. These estimates suggest that the proportion of young in the Black Cart flock increased from c.20% during the 2007/2008 winter to c.26% during the 2008/2009 winter.

Amongst 5,844 birds across 6 regions of Britain and Ireland aged by the WWT/JNCC Goose & Swan Monitoring Programme (GSMP) during the 2008/2009 winter the overall percentage of young was 16.8%, with the highest percentages recorded in the Republic of Ireland (19.8%) and Southwest Scotland (19.0%) (WWT 2009b). During

14 the previous 2007/2008 winter the same survey found the overall percentage of young across four regions of Britain was 20.7% (Holt et al. 2009). Thus whereas during the 2007 breeding season the breeding success of birds wintering on the Black Cart was apparently similar to that of birds wintering across other areas of Britain and Ireland, during the 2008 summer they were apparently more successful. Breeding success estimates for the Black Cart population in both winters compare favourably with both long term national averages (Holt et al. 2009, Robinson et al. 2004, WWT 2009b), and the breeding success recorded during the most recent international whooper swan census, made in January 2005 when 19.2% young were recorded (Worden et al. 2009).

Between the 2007/2008 and 2008/2009 winters the maximum number of juveniles recorded increased from 22 to 49, and the maximum number of adults recorded increased from 79 to 135. Thus, the overall increase in the number of birds recorded this winter is the result of an increase in both the number of adults and juveniles present; it does not simply represent the result of increased breeding success.

3.3 Feeding distribution

3.3.1 Data issues

A small number of records of either injured birds or of birds which had moved from another field because of disturbance by myself have been excluded from all analyses, as their presence in particular fields does reflect underlying patterns of field or habitat selection. For the purposes of creating maps showing the distribution of feeding birds (Section 3.3.2, Figures 8-15), all other records of foraging birds have been used, including casual records and those made during the course of dawn and dusk roost counts, although the different types of records are differentiated within the figures. However, for the formal statistical analyses of field usage and habitat selection only records collected during the formal feeding survey have been used. This is to avoid any potential biases which might arise as a result of survey effort for dawn, dusk and casual observations being concentrated in particular areas. Where there were multiple counts for the same field within a single formal feeding survey (as can occur when numbers change through the day), the largest count has been used.

3.3.2 Chronology

Figures 10 to 15 show the distribution of feeding birds in each month.

November (Figure 10)

 The contract started in late November. On the 25th November, during habitat recording, 168 birds were recorded on stubble in field 51 at Candrens.

 On the following day, the 26th November, during the month’s only formal feeding survey, 162 birds were recorded in the same field and 20 birds were recorded also on stubble in field 129 at Inchinnan. Eleven birds flew in for a short stay on the turf in field 43 at Blackstoun, before, probably, returning to join the main flock of birds in field 51 at Candrens. At dawn on the 26th, 35 birds flew from roosting on the Black Cart to feeding on stubble in the nearby field 122.

15 December (Figure 11)

 On the 3rd December, birds were again feeding on stubble in field 51 at Candrens although no accurate count of the number of birds present was possible as the birds were departing to roost at the time they were being counted. Twelve birds were also recorded feeding on stubble in field 137 near Netherton farm, to the east of the airport.

 On the 9th December, 41 birds were recorded feeding on stubble in field 133, again to the east of the airport near Netherton farm. Also, 126 birds were recorded feeding on stubble in field 128 at Inchinnan.

 On the 17th December, birds were again feeding on stubble to the east of the airport, with 130 birds present in field 133. Forty seven birds were reported again on stubble in field 51 at Candrens, with 3 birds on stubble in the adjoining field 48.

 On the 22nd December, 146 birds were again feeding to the east of the airport in field 133, on stubble, whilst 6 birds were recorded on stubble in field 48 at Candrens.

January (Figure 12)

 On the 6th January, 11 birds were recorded (casually) on improved pasture in the adjoining fields 61 and 62, by the Broomhill roundabout.

 On the 7th January, 82 whooper swans were recorded (casually) at Candrens, in the adjoining stubble fields 48 and 51.

 The following day, 75 whooper swans were again recorded on stubble in field 48.

 During the remaining three feeding surveys during January (on the 16th, 22nd and 29th) nearly all birds (148 to 152) were consistently recorded on stubble in field 130 at Inchinnan, which is immediately next to the main road. The only exception to this was 2 birds recorded at Candrens on improved pasture in field N47 on the 29th.

February (Figure 13)

 On the 6th February, 21 birds flew directly from the Black Cart roost at dawn to feed on improved pasture in the nearby riverside field N114, remaining there for much of the day. Later in the day 6 of these birds moved to the adjoining field 113, again feeding on improved pasture. However, the majority of the population, 87 birds, were at Candrens, feeding on the improved pasture in field N47. Four additional birds were recorded feeding on improved pasture in field 61 near the Broomhill roundabout.

 On the 12th February, 134 birds flew directly from the Black Cart roost to feed on pasture in the nearby riverside field N114 again, with c. 123 of these birds remaining in this field throughout the day. No other birds were recorded during the formal feeding survey, although c. 160 birds departed Black Cart at dawn, and 163-170 birds returned at dusk; thus the feeding location of the 44- 47 birds returning from the west of Barnsford Bridge at dusk to the Black Cart

16 roost remains unknown, although the preceding feeding survey was believed to be thorough.

 At dawn on the 19th February, 27 birds flew directly from the Black Cart roost onto the improved pasture in the nearby riverside fields N114 and N118, with 25 birds remaining in field N118 during the formal feeding survey. An additional 19 birds were recorded feeding at Candrens, on improved pasture in field N47. However, the majority of the population, 75 birds, were found feeding on improved pasture at Auchans. Although 11 of these 75 birds were in field 178A within the existing study area boundaries, 64 of the birds were in a new adjoining field, field 228, which lay beyond these boundaries. Furthermore, at dusk, an additional 52 birds were recorded flying to roost at dusk from hidden fields further to the west.

 On the 26th February, the feeding survey route was extended to include additional fields at Auchans, and 53 birds were recorded on improved pasture in “new” fields 228 and 239, outside the previous study area boundary. In addition to these birds, 73 birds remained in the vicinity of the Black Cart throughout the day, feeding on improved pasture in the riverside fields N81A, N83, 113, and N79A, 15 birds were recorded on improved pasture in field 61 by the Broomhill roundabout, and 5 birds were recorded on improved pasture in field N47at Candrens.

March (Figure 14)

 On the 5tth March, 99 birds were recorded feeding on improved pasture at Auchans, in the “new” field 239. The remaining birds recorded on this date were all recorded in the fields to the south west of the Broomhill roundabout, with 27 birds feeding on improved pasture in the adjoining fields 61 and 62, and 26 birds feeding on stubble in the nearby field N54.

 On the 13th March again the vast majority of birds were recorded in the Auchans fields, with 99 birds in field 228. As on the 5th March, the remaining birds were again recorded in the fields to the south-west of the Broomhill roundabout, with 17 and 29 birds feeding on improved pasture in fields 61 and N168 respectively, and up to 19 birds feeding on stubble in field N54. Furthermore, at dawn 2 birds had been seen flying from their roost on the Newshot wetland to feed on improved pasture in the immediately adjoining field 177, although these birds had disappeared from this field by the time they were covered during the formal feeding survey.

 On the 19th March again the vast majority of birds were feeding on improved pasture at Auchans, with 96 birds distributed across fields 178A, 228 and 239. In addition 35 birds were feeding on improved pasture in fields 61 and 62 near the Broomhill roundabout, 6 birds were feeding on improved pasture in the vicinity of the Black Cart roost, with birds in fields RIV3 and N118, and 3 birds were feeding on improved pasture in field 177 which immediately adjoins the Newshot wetland, the same field were 2 birds were recorded at dawn the previous week.

 On the 27th March, 72 birds remained on improved pasture in field 178A throughout the whole day, roosting in the same field on the preceding and following nights. In addition, 27 birds were recorded on improved pasture in field N114, immediately adjoining the Black Cart roost, and 3 birds were again

17 recorded on improved pasture in field 177 immediately adjoining the Newshot wetland roost.

April (Figure 15)

 On the 3rd April, 14 birds were recorded on improved pasture in field 178A at Auchans, with 3 birds across fields 113, N118 and RIV3 in the immediate vicinity of the Black Cart roost, and 3 birds again on improved pasture in field 177 immediately adjoining the Newshot wetland.

 On the 10th April, 3 birds flew at dawn from the Black Cart roost to feed on improved pasture in the nearby riverside field N118; it was probably the same three birds subsequently located feeding in the nearby field 122, which had been ploughed and harrowed. Two additional birds were located feeding in improved pasture at Candrens in field N47.

3.3.3 Changes in feeding distribution between the 2007/2008 and 2008/2009 winters

There were major differences between the foraging distribution of the Black Cart whooper swans in the 2008/2009 and 2007/2008 winters (Figures 8 and 9):

 During the 2007/2008 winter, the only birds recorded at Auchans during formal feeding surveys were 11 birds on the last visit of the season (10/04/2008). During the 2008/2009 winter, from the 19th February onwards, possibly earlier, the fields around Auchans were regularly used by large numbers of birds, with up to 99 birds recorded in the area during feeding surveys. This included the use of new fields, beyond the previous study area boundaries.

 During December 2008 up to 130 birds were regularly recorded feeding in the fields around Netherton to the east of the airfield. No birds were recorded feeding in these fields during the 2007/2008 winter.

 Fields 174 and 176 at Newshot were regularly used during the 2007/2008 winter, but were not used at all during the 2008/2009 winter.

 During the 2007/2008 winter, a common pattern was for birds departing from the Black Cart roost to first move to the fields immediately adjoining the river and feed before moving on their eventual feeding locations. In contrast during the 2008/2009 winter, birds generally flew directly to their final feeding locations, without feeding in the vicinity of the roost first.

 Although in February 2009, up to 134 birds were regularly recorded in the riverside fields immediately adjoining the Black Cart roost, generally during the 2008/2009 winter much less use was made of these fields than during the previous winter. In particular, during the 2008/2009 winter there was no use of the fields to the west of Barnsford Bridge, although at times during the previous winter these fields had been heavily used.

 The fields to the south west of Broomhill roundabout, particularly fields 61 and 62 were regularly used by small numbers of birds (maximum 47) throughout

18 the 2008/2009 winter but were only used once, by 19 birds on the 2nd April 2008, during the previous winter.

 Field 10 at Selvieland was used by up to 79 birds in late November and early December 2007 but was apparently not used at all during the 2008/2009 winter. However, it should be borne in mind that as surveys did not start until late November, if birds had used this field slightly earlier in the latter winter, their presence could potentially have been missed.

3.3.4 Field usage

During formal feeding surveys, birds where recorded feeding in a total of 23 different fields, excluding the arbitrary river “fields”. For each field in which birds were recorded Figures 16, 17 and 18 show respectively:

 The number of dates on which birds were present.

 The total number of birds recorded for each field, calculated by summing the maximum count for each field on each date as recorded during formal feeding surveys- this has the same dimensions as bird-days.

 The maximum number of birds recorded.

These figures show that there is considerable variation between fields in both the frequency of use (Figure 16) and the total (Figure 17) and maximum (Figure 18) number of birds recorded. Figures 19 to 21 plot these potential measures of importance against one another to show to what extent fields are rated consistently according across the different measures. From these figures it can be seen that field N47,48,51, N114, 128, 130,133, 178A, 228 and 239 all held birds on 3 or more dates, had maximum counts of more than 70 birds and total counts of more than 80 birds. However, other fields were rated very differently according to the measures of importance used. For example, although 128 only held birds on one date, on this date it held 126 birds (Figure 21), and so it is rated relatively highly on both the total number and maximum number metrics (Figure 19). Conversely although field 61 held birds on 5 dates, it never held more than 31 birds (Figure 21), and so is not particularly highly rated on either the total numbers (Figure 20) or maximum numbers (Figure 20, Figure 19) metrics.

Figures 22 to 24 shows each of these metrics for fields holding birds in the 2008/2009 winter plotted against the corresponding metric for fields holding birds in the 2007/2008 winter. For any of the metrics there is very little relationship between the ratings of fields in the two winters. In particular for both the total number (Figure 23) and maximum number metrics (Figure 24), points are clustered along the axes, indicating that fields which were highly rated in one winter were not highly rated in the other, and vice versa. For example, fields 87, N109, 10 and 73 which on occasion held over 60 birds in the 2007/2008 winter, had no birds recorded in them in the 2008/2009 winter (Figure 24). Conversely, fields N114 and 133 which on occasion held over 100 birds in the 2008/2009 winter had no birds recorded in them during the 2008/2009 winter (Figure 24). On the maximum numbers metric, the only fields rated consistently highly in both winters are fields N47, 128, 51 and 130 (Figure 24). The same picture emerges from considering the total number of birds metric (Figure 23) and number of dates birds present metrics (Figure 22). In summary, the fields that where important in the 2008/2009 winter tended not to be important in the 2007/2008 winter, and vice versa.

19 3.3.5 Habitat availability

Table 8 presents the total area of different habitats within the study area at the beginning and end of the winter, along with the maximum area of each habitat recorded during the winter. The phase 1 habitat code (Joint Nature Conservation Committee 2004) for each habitat is also given, along with the broader habitat categories used for mapping the distributions of habitats at the start and end of the season in Figures 25 and 26 respectively. At the beginning of the season, the three most important habitats by far were improved pasture, stubble and winter cereal, at 36%, 20% and 10% of the total area respectively (Table 8, Figure 25). All other habitats had less than 5% cover. The area of improved pasture and winter cereal remained unchanged through the winter. However, the cover of stubble declined from 22% to 6% as it was ploughed to make way for new crops, with the area of ploughed increasing correspondingly from 2 to 20%. It is the ploughing of stubble and areas previously stripped of turf which dominates the changes in habitats over the winter (Figures 25, 26).

Considering fields covered in both winters, the principal change between the 2007/2008 and 2008/2009 winters is the much larger area of stubble present at the expense of winter cereals and setaside (Table 9, Figures 25 and 27). There was a smaller area of turf present in the second winter, as c.50% of the area used for growing turf had already been stripped before fieldwork began at the end of November. Between the two winters, the Moss Road landfill site was also largely restored to improved grassland.

During the 2008/2009 winter the spring ploughing of stubble started in late December, continuing at a reasonably steady rate through January, February and the Early part of March, before accelerating in late March and early April (Figures 28a and 28b). In the 2007/2008 winter, the spring ploughing of the much smaller area of stubble present did not start until mid-February, and mainly took place from the end of March onwards. Less stripping of turf was recorded over the 2008/2009 winter than over the 2007/2008 winter, although more stripping may have taken place in the autumn of the second winter before fieldwork began (Figure 28c). Compared to the 2007/2008 winter, much less setaside was present in the 2008/2009 winter, and was left unploughed throughout the duration of the winter (Figure 28d)

3.3.6 Habitat use

Figure 29 presents the total number of whooper swans recorded in each habitat for each formal feeding survey of the 2008/2009 winter. Birds recorded outside the formal feeding surveys have been ignored so as to avoid bias due to uneven coverage. The maximum number of birds recorded in each field during the formal feeding survey has been used to calculate these totals. There has been no attempt to control for double counting due to birds moving between fields, because of the difficulty of avoiding subjective judgements during this process, potentially leading to bias.

Figure 29 shows a very clear change in feeding behaviour during the season. Up to the 29th January birds fed almost wholly on stubble and after this date they fed almost wholly on improved pasture. The physical loss of stubble is not thought to be the reason for the change in foraging behaviour because at the beginning of February when the birds switched foraging behaviour large areas of stubble still remained. Furthermore, the main stubble fields used by birds for feeding invariably remain

20 unploughed long after they were abandoned by the birds (birds last recorded feeding in field 130 at Inchinnan on the 29th January but field not ploughed until after the 27th March; birds last recorded feeding in field 133 at Netherton to the east of the airfield on the 22nd December but field not ploughed until after the 19th February; birds last recorded in field 48 at Candrens on the 8th January but this field still unploughed on the 10th April). Thus, the switch from stubble to grass is probably triggered due to the loss of cereal from the stubble fields as it rots or is consumed by swans, wildfowl and other beasts. The switch is probably too early for fresh grass growth on the improved pasture to be a contributory factor.

Figure 30 shows the same information for the 2007/2008 winter. During the 2008/2009 winter in addition to recording which field birds where feeding in the habitat they were using was also recorded. For fields consisting of a mosaic of potentially suitable habitats, this allows the number of birds using each element of the mosaic to be accurately recorded. However, during the 2007/2008 winter, only the field birds were present in was recorded. In one field, field 122, birds fed on both stubble and rotovated ground, but the numbers using each habitat was not recorded. Within the field both habitats covered approximately equal areas, and the assumption has been made that equal numbers of birds used each habitat. Making the extreme assumptions that in fact either all birds fed in the rotovated ground, or no birds fed in the rotovated ground would have little impact on the overall conclusions given the number of birds involved. Providing both feeding habitat and field are recorded for future surveys this problem should not recur.

During the 2007/2008 winter, the switch from foraging on stubble to foraging on pasture was less marked and took place earlier in the season (Figure 29). Both across the season and within particular dates the birds exploited a wider range of habitats. During the 2007/2008 winter birds feeding in winter cereals used just two fields, fields 174 and 176 near Newshot. No other fields of winter cereal were used. No birds were recorded feeding on winter cereal during the 2008/2009 winter. Fields 174 and 176 were not used during the 2008/2009 winter, although they were under stubble, and thus might have been expected to provide better feeding habitat.

The large increase in the area of stubble in the study area between the 2007/2008 winter and the 2008/2009 winter may have contributed to the increase in the number of birds wintering, and also to their greater concentration within stubble fields. The increased area of stubble might also help explain some of the observed changes in the distribution of feeding birds since last winter. For example, during the 2007/2008 winter all of the agricultural fields to the east of the airfield around Netherton farm were either under setaside or improved pasture (Figure 27). During the 2008/2009 winter all of these fields were under stubble. This may explain why whereas during the 2007/2008 winter no birds were recorded in these fields (Figure 8), in December 2008, large numbers of birds were recorded (Figures 8 and 11).

The use of stubble fields continued much longer during the 2008/2009 winter than during the 2007/2008 winter. During the 2007/2008 winter the last date upon which birds were recorded feeding in stubble was the 13th November at Inchinnan and the 27th December at Candrens. During the 2008/2009 winter birds fed on stubble at Inchinnan until the 29th January. One possible explanation for this pattern would be that during 2008/2009 the greater area of stubble meant that whooper swans (and other birds and animals) depleted individual fields more slowly, so that were able to exploit stubble fields for a longer period. Although feeding was concentrated in only a small proportion of the stubble fields available, if stubble fields varied greatly in their suitability as foraging habitat (e.g. in the quality of spilt grain present) then the area of suitable stubble fields could still potentially be limiting. Alternative potential

21 explanations, which are not mutually exclusive, are that a wet harvest meant more grain was spilt initially during the latter winter, or that colder conditions reduced the speed at which spilt grain decomposed, so that it persisted for longer. More grain within stubble fields either as a result of more being spilt initially or because it has decomposed more slowly might also contribute to a greater concentration of birds in stubble habitats compared to other habitats, irrespective of any increase in area.

The increase in the area of stubble alone does not adequately explain all the changes in feeding distribution observed between the two winters. In particular, the conversion of fields 174 and 176 at Newshot from winter cereal to stubble between the two winters might have been expected to increase their use, whereas the opposite has occurred: whereas these fields where regularly used during the 2007/2008 winter, they were used at all during the 2008/2009 winter. This suggests that differences in aspects of habitat quality which are not obvious (e.g. the quantity of spilt grain present) may have an equal or greater influence on field selection than the more obvious differences in habitat type (e.g. winter cereal versus stubble). The increased area of stubble also does not explain those changes in feeding distribution which took place later in the season after the switch to feeding on improved pasture had taken place, including the much greater use of the Auchans area, and the regular use of fields 61 and 62 to the south west of the Broomhill roundabout.

3.4 Roost use

3.4.1 Introduction Tables 10, 11, 12 and 13 summarise observations of roost use for the 2008/2009 winter. These tables summarise:

1) Observations at dusk of birds departing from feeding fields towards their roost.

2) Observations at dusk of birds arriving at their roost.

3) Observations after dusk of the number of birds present. Although still useful, without night sights, such observations are likely to yield at best a gross underestimate of the actual numbers present.

4) Observations of the number of birds departing a roost at dawn – this is defined as the number of birds estimated to have been present before any recorded movements took place.

5) Observations of the number of birds using a roost during the dawn departure. Sometimes during departures birds will fly into a roost from elsewhere, so that the total number of birds departing the roost is greater than the number present before any recorded movements.

Table 10 summarises the use of the Black Cart roost, and table 11 summarises the use of roosts other than the Black Cart. Table 12 identifies as far as possible whether birds roosting on or near the Black Cart where roosting to the east or the west of Barnsford Bridge. Table 13 provides more detailed information for those birds recorded roosting to the east of Barnsford Bridge, where possible reporting which particularly subroost they were using. Table 14 explains by example the conventions used in recording roost usage in tables 10 to 13.

22 It should be noted that observations of birds departing from a field towards a roost suggest rather than prove usage. Also, as generally only part of the flock is under observation at any one time, such methods can only provide a partial estimate of the number of birds using a particular roost.

During the 2008/2009 winter birds were recorded roosting in five locations (Tables 10 and 11, Figure 31):

 In or near the Black Cart River SPA.

 Linwood Pond.

 Newshot wetland.

 Linwood Moss Pond.

 Field 178A at Auchans

Linwood Moss Pond and field 178A were not recorded as roosts during the 2007/2008 winter, but the other three roosts were (Harding 2008). Field 178A has been used for roosting previously (Rees and White 2001). Field 52 at Candrens was used as a roost last year, but not this year. Auchans Pool was identified as a potential roost last year, and additional observations were conducted there this year.

3.4.2 Black Cart

As in 2007/2008 and in previous years, the Black Cart is clearly the most important roost, regularly being used by a high proportion of the flock throughout the winter (Tables 10 and 11). The Black Cart (Table 10) appears to be the main roost, used regularly by large numbers of birds throughout the year, with the other roosts (Table 11) acting as satellite roosts, used by birds from the same Black Cart flock but only at particular times of year, and usually by smaller numbers of birds.

The peak number of birds using the Black Cart roost was at least 163 birds. As noted in Harding (2008) the number of birds using the Black Cart roost is likely to be under estimated because a single observer operating from a single vantage point cannot see all parts of the site, nor within the areas which are visible be certain of recording all movements when birds are departing from several widely separated locations simultaneously.

From the 12th February 2009 onwards, a set procedure was adopted for monitoring departures at dawn from the Black Cart roost which it is thought, for a single observer, provides the best balance with respect to recording birds roosting on all parts of the site, both east and west of Barnsford Bridge. On arrival c. 1 hour before sunrise, the observer moved to quickly to Barnsford Bridge to check whether birds were roosting west of the bridge on RIV1, or in the nearby field 113. The observer would then quickly move c. 100m north along Barnsford Road till a vantage point is gained (by the road sign) which provides a view of more distant parts of RIV1. Then the observer would quickly return to a vantage point on Inchinnan Drive, just west of the entrance to M& Co, on the river side of the hedge (NS 47049 67492), This provides a vantage point over the Black Cart east of Barnsford bridge from which birds can be seen departing from both nearby RIV2 and RIV3 and the more distant RIV4 and field 125.

23 3.4.3 Linwood Pond

The maximum number of birds using the Linwood Pond roost during the 2008/2009 winter was 16, but on most nights birds were either absent, or present in low numbers (<10). More birds used this roost during the 2007/2008 winter with 19 or more birds present on at least 3 occasions (Harding 2008).

Part of the reason for the lighter use is likely to be the colder conditions during the 2008/2009 winter, which resulted in the pond being frozen for much of the winter. On the night of the 3rd December six birds were clearly seen departing from the nearby field 51 towards Linwood Pond, and descending as if preparing to land. However, a subsequent visit to the pond after dark found no birds present, with the pond frozen solid. On the night of the 8th January, 5 birds landed on a frozen Linwood pond at dusk, and then departed almost immediately. If the same had happened on the 3rd December, this would explain why birds were seen departing to the pond at dusk, but no birds were found there subsequently.

3.4.4 Newshot Wetland

On all five dates when the Newshot wetland was visited this winter between the 2nd December 2008 and the 12th March 2009 it was used as a roost, with the number of birds present varying between 2 and 57-63.

In addition on the 29th January at 9:28 2 whooper swans flew into field 130 from the direction of Newshot wetland. As observations only began two minutes before this observation was made, more birds could potentially have arrived earlier (although this movement was 71 minutes after sunrise, during a previous dawn watch on the Newshot wetland on the 3rd December roosting birds were still present 72 minutes after sunrise).

On the 13th March the two birds roosting on the wetland flew to the adjoining field 177 to feed. During the next three feeding surveys (19th March to 3rd April 2009) 2-3 adult whooper swans were consistently recorded feeding in this same field. This is consistent with 2-3 birds roosting on the Newshot wetland over this period, and feeding in the nearby fields.

The maximum count of 57-63 birds was recorded on the 21st December 2008, when the feeding survey suggested that 152 birds were present on the Black Cart flood plain. Fifty seven birds represents 38% of this population estimate, or 31% of the peak population estimate (183 birds) for the winter.

Thus the evidence suggests regular use of the Newshot wetland throughout the winter, with a significant proportion of the Black Cart flood plain flock sometimes present.

The maximum number of birds using this roost during the 2008/2009 winter, 57+, is considerably higher than the maximum number of 15 birds recorded during the previous winter. However, as the previous winter’s counts are based upon on just two visits it is unclear to what extent this represents a genuine increase in the number of birds using the site rather than additional sampling effort.

As noted in the previous report (Harding 2008) the existing use of a roost at Newshot suggests that the further creation of a pond in the area may be of little value in terms

24 of providing an alternative roosting site for the Black Cart population of Whooper Swans (Land Use Consultants 2007).

Last year the birds roosting on the wetland flew to feed on winter cereal in fields 174 and 176. This year, the birds did not feed in these nearby fields but continued on to more distant feeding grounds. As this year these fields were under stubble rather than winter cereal this is perhaps surprising.

3.4.5 Linwood Moss Pond

At dusk on the 19th February five whooper swans flew to roost on Linwood Moss Pond (Table 11, Figure 31), a new roost not identified previously. However, on two subsequent dates (19th March, 26th March) checks found no evidence of this roost being used.

3.4.6 Field 178a

During late March and early April, up to 72 birds regularly roosted on a pool in field 178A, having fed locally (Table 11, Figure 31).

At dusk on the 19th February, none of the c. 127 birds feeding in the Auchans area apparently roosted locally, with the vast majority of birds departing towards the Black Cart. However, at dusk on the 19th March, of the 96 birds in field 178a at dusk 22 remained to roost in field 178A whilst 74 departed in the direction of the Black Cart. On the consecutive nights of the 26th and 27th March, 72 birds roosted in field 178A on both nights, having remained in the field throughout the day. On the evening of the 3rd April 2009, 14 whooper swans roosted in field 178A, having fed in the field during the previous day.

In conclusion, birds feeding within the Auchans area both roosted locally and also departed westwards, to more distant roosts, probably the Black Cart. On the same night, some birds will roost locally whilst others depart toward the Black Cart. On some nights whereas most birds apparently departed towards the Black Cart, on other nights most birds apparently roosted locally. As noted previously on the evening of the 3rd April 2009 14 birds roosted in field 178A, have fed in the same field during the preceding day. Exactly this same number of birds had departed westwards from the Black Cart roost the previous dawn. These observations are consistent with birds roosting on the Black Cart one night and in field 178A the next night. On the 05/03/2009 a (distinctive) family of colour ringed birds (2 adults: 1 yellow left, other yellow right, 3 juveniles: all yellow left) was observed in field 239, in the Auchans area. A similar family was recorded in field 113 immediately adjoining the Black Cart roost on the 26/02/2009. Although the birds were too distant to allow individual ring combinations to be read, this observation provides further supporting evidence for the case that the birds feeding around Auchans belong to the Black Cart population. Thus, at present the available evidence strongly suggests that the birds feeding in the Auchans area are part of the Black Cart population, but as yet we do not have conclusive proof.

3.4.7 Auchans Pool

Birds roosting in field 178A during the 2008/2009 winter concentrated around a pool at the field’s northern end (Figure 31). There was no evidence that they used the Auchans pool which occurs in the south-eastern corner of the same field. The 8 birds seen at dusk on the evening of the 7th November 2007 , “departing from the

25 Candrens Area and apparently landing in the vicinity of Auchans Pool” (Harding 2008) could equally well have been used this field at the northern end of field 178A, or the Linwood Moss pond.

3.4.8 Field 52

The 2008/2009 winter was drier than the 2007/2008, so that field 52 did not flood as in 2007/2008, and was not used as a roost.

3.4.9 Other possible roosts

On the night of the 22nd December, 4 of the 146 birds feeding in field 133, which lies near Netherton Farm to the east of the airfield, departed eastwards toward an unknown roost, possibly Hogganfield Loch.

On the night of 19th February, 48 of the birds departing from the Auchans fields departed towards Linwood Pond, although a subsequent post dusk check located only two birds there. Also although 11 birds departed towards the Linwood Moss Pond, only five birds were subsequently found roosting there. Thus, 52-54 birds remain unaccounted for. On the same evening 62 birds departed directly towards the Black Cart and it is thought that these other 52-54 birds also probably returned to the Black Cart via a more circuitous route. However, the possibility exists of an additional as yet to be discovered roost.

3.4.10 Use of sub roosts within the Black Cart site

During the 2007/2008 winter birds regularly roosted on RIV1 to the west of Barnsford Bridge, with up 88 birds present, and then flew to the surrounding fields to feed (Harding 2008). In contrast, during the 2008/2009 winter, birds were only recorded roosting to the east of Barnsford Bridge, with no evidence of birds roosting on section RIV1 to the west of the bridge (Table 12). There was also no evidence of birds feeding in the fields to the west of Barnsford Bridge.

During the 2008/2009 winter all three river sections to the east of the bridge (RIV2, RIV3 and RIV4) were heavily used by roosting birds (Table 13). In addition the pond in field 125 was heavily used, particularly during January when, when all or most of the Black Cart flood plain flock regularly roosted there, and then flew to the nearby field 130 at Inchinnan to feed. On the night of the 16th January over 100 birds flew initially to field 125 to roost, but were disturbed by wildfowlers discharging shots in the immediate vicinity of the roost, and then moved to RIV3 to roost. It should be noted that this field lies just outside the SPA boundary.

In contrast to the 2007/2008 winter (Harding 2008), there was no evidence during the 2008/2009 winter of birds being present in fields 113 and 122 before dawn (Table 13).

3.5 Flight lines

During the 2008/2009 winter, 339 flight lines were recorded and fully characterised in terms of numbers of birds, maximum height achieved, time, date, origin and destination (Figures 32 and 33). In the 2008/2009 as in 2007/2008 (Figure 34, Harding 2008) again the vast majority of flight did not pass over the airfield, nor pose a threat to aircraft. However, during December up to 146 birds fed on stubble in the fields to the east of the airfield and flew directly over the main runway when en route

26 to and from their roost on the Black Cart. These flights mainly occurred at dusk and dawn, often in very poor visibility and with heavy air traffic. Although the recorded flight lines across the airfield were at altitudes of less than 60m (Figure 7), as aircraft are landing or taking off this does not yield vertical separation between aircraft and the birds.

All recorded flights during the 2008/2009 winter were altitudes of less than 60m (Figure 33, 35), with a similar distribution to that observed in the 2007/2008 winter (Figure 35). Apart from those flights noted above which passed directly over the main runway in December, flights at such altitude are unlikely to pose a risk to approaching and departing aircraft.

At dawn (Table 15), roost departure flights began an average of 1 minute before sunrise and ended on average 38 minutes after sunrise, although movement could begin as early as 50 minutes before sunrise and end as late as 139 minutes after. The average duration of movements was 39 minutes, although it could be as little as 0 (i.e. a single flight at a particular time), to as long as 95 minutes.

At dusk (Table 16), roost arrival flights began an average of 27 minutes after sunset and ended an average of 43 minutes after sunset, although movement could begin as early as 1 minute before sunset and end up to 69 minutes after. The average duration of movements was 17 minutes, although it could be as little as 0 (i.e. a single flight at a particular time), to as long as 46 minutes.

Comparing departure times between the 2007/2008 and 2008/2009 winters, although the duration of dawn movements is similar in the two winters (on average 39 minutes in 2008/2009 compared to 35 minutes in 2007/2008), birds in the latter winter apparently departed the roost later with departures starting 14 minutes later with respect to sunrise in the 2008/2009 winter. At dusk, again there is little difference between the winters in the average duration of movements (17 minutes in 2008/2009 compared to 14 minutes in 2007/2008), but also there is little difference in departure times, with birds in 2008/2009 apparently departing on average just 1 minute later than in 2007/2008. Thus, because birds in 2008/2009 were apparently departing their roosts approximately 15 minutes later than in 2007/2008, but returning to their roosts at about the same time, this suggests that their were spend less time feeding in the fields during the later winter. This fits the hypothesis of the greater area of stubble in the 2008/2009 providing easier feeding conditions.

3.6 Colour ringed birds

Four individual colour ringed whooper swans, A59, IS3, 5H(N or A) and VXL? were recorded during the winter (Table 17). 5H(N or A) was also recorded during the 2007/2008 winter.

3.7 Disturbance

Tables 18 and 19 catalogue recorded instances of actual and potential disturbance.

4 DISCUSSION

In December 2008 birds were regularly feeding in the fields to the east of the airfield and at dawn and dusk flying directly over the main runway to and from the Black Cart

27 roost, in conditions of poor visibility and at times in the day when flights are frequent. Such behaviour must greatly increase the risk of collision between swans and aircraft at the point when the aircraft are either in the late stages of landing or the early stages of taking off. To adequately manage the risks to air safety that such flights represent, proactive management must be employed to deter birds from feeding in the fields to the east of the airfield.

Between the 2007/2008 and 2008/2009 winters there were large changes in the distribution, abundance and ecology of the wintering whooper swans which are the sole qualifying interest of the Black Cart SPA, with major changes in population size, feeding distribution, roost usage, habitat use and flight lines. These changes were not predictable, indicating that for the near future at least annual monitoring may be required to provide the information necessary to allow SNH to respond effectively to the development pressures and agricultural changes which could potentially threaten the favourable conservation status of this population, whilst ensuring air safety is not compromised

5 REFERENCES

Collier, M.P., Banks, A.N., Austin, G.E., Girling,T., Hearn, R.D. & Musgrove, A.J. 2005. Waterbirds in the UK 2003/04: The Wetland Bird Survey. BTO/WWT/RSPB/JNCC, Thetford. Crawley, M.J. 2009. The R book. John Wiley and Sons Limited, England.

Harding, N. 2008. Whooper Swan (Cygnus Cygnus) Distribution and Habitat Use in the Black Cart Floodplain During Winter 2007/2008. Scottish Natural Heritage Commissioned Report No.310 (ROAME No. R07LI08).

Holt, C.A., Austin, G.E., Calbrade, N.A., Mellan, H. Thewlis, R.M., Hall, C., Stroud, D.A., Wotton, S.R. & Musgrove, A.J. 2009. Waterbirds in the UK 2007/08: The Wetland Bird Survey. BTO/WWT/RSPB/JNCC, Thetford.

Joint Nature Conservation Committee 2004. Handbook for Phase 1 Habitat Survey: A Technique for Environmental Audit. JNCC, Peterborough.

Land Use Consultants 2007. Analysis of Alternative Roosting Sites for Whooper Swans in the Black Cart Valley. Report prepared for Mountgrange (Linwood) Ltd by Land Use Consultants with Ove Arup and Partners Limited.

R Development Core Team 2009. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3- 900051-07-0, URL http://www.R-project.org.

Rees, E.C. and White, G.T. 2001. Whooper Swans wintering in the Black Cart Floodplain Winter 2000-2001. Report prepared for Glasgow Airport Ltd. by WWT Wetlands Advisory Service.

Robinson, J.A., Colhoun, K., McElwaine J.G. & Rees E.C. 2004. Whooper Swan Cygnus cygnus (Iceland population) in Britain and Ireland 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee, Slimbridge.

28 Stroud, D.A., Chambers, D., Cook, S., Buxton, N., Fraser, B., Clement, P., Lewis, P., McLean, I., Baker, H. & Whitehead, S. (eds). 2001. The UK SPA network: its scope and content. JNCC, Peterborough.

Worden, J. Crowe, O., Einarsson, O., Gardarsson, A., McElwaine, G. & Rees, E.C. 2009. Population size and breeding success of the Icelandic Whooper Swan Cygnus cygnus: results of the January 2005 International Census. Wildfowl 59:17-40.

WWT 2009a. http://www.wwt.org.uk/research/monitoring/surveys/age_assess.asp. Downloaded 24/03/2010.

WWT 2009b. http://www.wwt.org.uk/research/monitoring/species/2009/whooper_latest2009.asp#2 008/09 Downloaded 24/03/2010

29 Table 1: Details of routes covered in each feeding survey, along with start and end times

Routes covered Across End Blackstoun Auchans Date Start Time Time Farm circuit 26/11/2008 09:47 15:30 no no 03/12/2008 10:14 16:15 no no 09/12/2008 09:53 15:42 no no 17/12/2008 09:30 15:30 no no 22/12/2008 09:45 15:00 no no 08/01/2009 10:08 15:40 no no 16/01/2009 10:15 15:28 no no 22/01/2009 10:33 15:20 no no 29/01/2009 10:28 15:36 no no 06/02/2009 11:24 17:09 yes no 12/02/2009 09:55 16:15 yes no 19/02/2009 09:32 16:12 yes no 26/02/2009 08:36 16:06 yes yes 05/03/2009 09:22 16:50 yes yes 13/03/2009 09:02 15:45 yes yes 19/03/2009 08:32 16:33 yes yes 27/03/2009 09:18 16:30 yes yes 03/04/2009 09:13 15:44 yes yes 10/04/2009 09:00 14:14 yes yes

Table 2: Fields covered from the Auchans circuits and the revised route across Blackstoun Farm.

N182 237 242 247 252 Fields 228 238 243 248 253 covered from Auchans 234 239 244 249 254 Circuit 235 240 245 250 236 241 246 251 Fields 22A 30B1 34 232 covered by 22B 30B2 35 233 Revised 29A 32 229 Blackstoun 29B 33A 230 route 30A 33B 231

30

Table 3: Fields for which the boundaries have been revised since the 2007/2008 survey.

2007/2008 2008/2009 Field field Revision N15A Electric fence separating fields N15A and N15B last year not N15 N15B present this year 30B1 30B 30B divided by wire fence. Fence present last year 30B2 99A 99 99 divided by wire fence. Fence probably present last year 99B 173A 173 divided into 3 by boundaries, including small patch of 173 173B woodland, all of which would have present last year 173C

N178A N178A Field boundary modified; same boundary should have been used last year.

31 Table 4: Fields for which the habitat classification recorded in 2007/2008 has been revised.

Original 2007/2008 Field classification Reclassification Comments Improved N15 Pasture Rushy pasture Ungrazed Improved Ungrazed Rushy 41 Pasture pasture Poorly visible field, but presence of stubble this winter makes me suspect last winter’s classification (But note fields 171/172 definitely improved Improved pasture last winter, and stubble this 60 Pasture Unknown winter). Improved N78 Pasture Rushy pasture Poorly visible field, but presence of stubble this year makes me suspect last winter's classification (But note Ungrazed fields 171/172 definitely improved Improved pasture last winter, and stubble this 129 Pasture Unknown winter). Uncut Damp Improved Hay 140 Meadow Improved Grassland Reclassified as Improved grassland rather than pasture, as appearance Improved suggests previous arable cropping, and 144 Pasture Improved Grassland boundaries not stock proof. Tall Ruderal/Rough Neutral Grassland 155 Tall Ruderal mosaic

32 Table 5: Minimum, maximum and best estimates of the numbers of whooper swans present in the Black Cart Study area on different dates in the 2008/2009 winter

Minimum Maximum Best juvs. as % of Casual aged Date estimate? Total Adults Juvs. Unaged Total Adults Juvs. Unaged Total Adults Juvs. Unaged birds 25/11/2008 yes 168 119 49 0 168 119 49 0 29% 26/11/2008 no 162 122 37 3 206 135 45 26 183 135 45 3 25% 03/12/2008 no 31 09/12/2008 no 165 121 44 0 173 121 44 8 165 121 44 0 27% 17/12/2008 no 180 132 47 1 180 132 47 1 180 132 47 1 26% 22/12/2008 no 152 119 33 0 152 119 33 0 22% 07/01/2009 yes 82 32 15 35 82 32 15 35 32% 08/01/2009 no 85 55 20 10 85 55 20 10 27% 16/01/2009 no 152 106 46 0 152 106 46 0 152 106 46 0 30% 22/01/2009 no 150 112 38 0 151 113 38 0 150 112 38 0 25% 29/01/2009 no 148 110 38 0 150 112 38 0 150 112 38 0 25% 06/02/2009 no 121 70 23 28 121 70 23 28 25% 12/02/2009 no 163 104 30 29 170 104 30 36 170 104 30 36 22% 19/02/2009 no 124 84 33 7 171 84 33 54 171 84 33 54 28% 26/02/2009 no 146 106 40 0 150 106 40 4 146 106 40 0 27% 05/03/2009 no 152 111 41 0 152 111 41 0 152 111 41 0 27% 13/03/2009 no 146 113 33 0 146 113 33 0 146 113 33 0 23% 19/03/2009 no 140 88 27 25 140 88 27 25 140 88 27 25 23% 27/03/2009 no 102 72 30 0 102 72 30 0 102 72 30 0 29% 03/04/2009 no 17 10 7 0 17 10 7 0 17 10 7 0 41% 10/04/2009 no 5 4 1 0 5 4 1 0 5 4 1 0 20%

33 Table 6: Peak monthly whole site counts, together with counts of adults, juveniles and unaged birds on the same dates. Bracketed counts are monthly peak counts of adults or juveniles when these are higher.

Month Total Adults Juvs. Unaged November 183 135 45 (49) 3 December 180 132 47 1 January 152 106 (112) 46 0 February 171 84 (106) 33 (40) 54 March 152 111 (113) 41 0 April 17 10 7 0

Table 7: Casual records of whooper swans in the Auchans area outside the existing study area prior to its extension to include these fields in February 2009.

Date Time Field Habitat Total Adult Juvenile Unaged 30/10/2007 15:37 N182 Stubble 5 2 3 0 03/12/2008 15:22 247 Stubble 5 2 3 0 Improved 03/12/2008 15:27 254 Pasture 6 3 3 0 29/01/2009 14:57 247 Stubble 5 0 0 5

34 Table 8: Total area of each habitat on 26th November 2008 and 10th April 2009, along with the maximum area recorded during the winter. Area (hectares) As % of total area Phase 1 code Mapping habitat Habitat 26/11/2008 10/04/2009 Maximum 26/11/2008 10/04/2009 Maximum A1 Woodland and scattered scrub Woodland 28.5 28.5 28.5 2% 2% 2% A2.2 Woodland and scattered scrub Scattered Scrub 3.3 3.3 3.3 0% 0% 0% B4 Improved Pasture Improved Pasture 533.9 533.9 533.9 36% 36% 36% B4 Other grassland Improved Grassland 40.2 40.2 40.2 3% 3% 3% B4 Other grassland Ungrazed Improved Pasture 22.9 22.9 22.9 2% 2% 2% B4 Other grassland Mown Improved Grassland 6.8 6.8 6.8 0% 0% 0% B4 Other grassland Rough Improved Pasture 5.0 5.0 5.0 0% 0% 0% B4 Other grassland Rank Wet Neutral Grassland 4.0 4.0 4.0 0% 0% 0% B4 Other grassland Rough Neutral Grassland 1.9 1.9 1.9 0% 0% 0% B5 Other grassland Rushy Pasture 31.6 31.6 31.6 2% 2% 2% B5 Other grassland Ungrazed Rushy Pasture 4.4 4.4 4.4 0% 0% 0% C3.1 Derelict ground Tall Ruderal 1.4 1.4 1.4 0% 0% 0% Tall Ruderal / Rough Neutral Grassland C3.1 / B4 Derelict ground Mosaic 7.1 7.1 7.1 0% 0% 0% C3.1 / B4 Tall Ruderal / Rough Neutral Grassland / / A2.2 Derelict ground Scattered Scrub Mosaic 60.7 60.7 60.7 4% 4% 4% G1 Rivers and ponds Pond 0.4 0.4 0.4 0% 0% 0% G1.6 Tidal pond and mudflats Tidal Pond 8.8 8.8 8.8 1% 1% 1% G2 Rivers and ponds River 15.0 15.0 15.0 1% 1% 1% H1.1 Tidal pond and mudflats Tidal Mudflats 9.5 9.5 9.5 1% 1% 1% J1.1 Stubble Stubble 330.2 91.9 330.2 22% 6% 22% J1.1 Ploughed Ploughed 22.5 300.7 300.7 2% 20% 20% J1.1 Winter Cereal Winter Cereal 153.8 152.8 153.8 10% 10% 10% J1.1 Rhubarb Rhubarb 55.2 55.2 55.2 4% 4% 4% J1.1 Turf Turf 47.7 42.9 47.7 3% 3% 3% J1.1 Other arable bare ground Stripped 47.7 13.7 47.7 3% 1% 3% J1.1 Arable Bare Ground Bare Ground 4.2 4.2 4.2 0% 0% 0% J1.1 Fruit Canes Fruit Canes 3.2 3.2 3.2 0% 0% 0% J1.1 Strawberries Strawberries 3.2 3.2 3.2 0% 0% 0% J1.1 Setaside Setaside 2.7 2.7 2.7 0% 0% 0% J1.2 Amenity grassland Playing Field 8.3 8.3 8.3 1% 1% 1% J1.2 Amenity grassland Amenity grassland 3.0 3.0 3.0 0% 0% 0% J3 Industrial Car Park 6.7 6.7 6.7 0% 0% 0% J3 Industrial Hard core / Bare Ground 1.3 1.3 1.3 0% 0% 0% Total 1475.2 100% 100% 100% 35 Table 9: Comparison of habitat cover between 25/11/2007 and 26/11/2008, for fields within the Black Cart study area covered in both winters Area (hectares) As % of total area Phase 1 25 Nov 26 Nov 25 Nov 26 Nov code Mapping habitat Habitat 2007 2008 2007 2008 Woodland and A1 scattered scrub Woodland 27.9 28.5 2% 3% Woodland and A2.2 scattered scrub Scattered Scrub 0.3 0.3 0% 0% B4 Improved Pasture Improved Pasture 393.9 367.1 35% 33% B4 Other grassland Improved Grassland 15.9 30.8 1% 3%

B4 Other grassland Ungrazed Improved Pasture 9.9 13.4 1% 1%

B4 Other grassland Rough Improved Pasture 5.0 5.0 0% 0% B4 Other grassland Rank Wet Neutral Grassland 4.0 4.0 0% 0% B4 Landfill Landfill 12.2 0.0 1% 0% B5 Other grassland Rushy Pasture 23.1 22.9 2% 2%

B5 Other grassland Ungrazed Rushy Pasture 4.4 4.4 0% 0% C3.1 Derelict ground Tall Ruderal 0.9 1.4 0% 0% C3.1 / Tall Ruderal / Rough Neutral B4 Derelict ground Grassland Mosaic 5.5 5.9 0% 1% C3.1 / Tall Ruderal / Rough Neutral B4 / Grassland / Scattered Scrub A2.2 Derelict ground Mosaic 43.1 41.8 4% 4% G1 Rivers and ponds Pond 0.4 0.4 0% 0% Tidal pond and G1.6 mudflats Tidal Pond 8.8 8.8 1% 1% G2 Rivers and ponds River 15.0 15.0 1% 1% Tidal pond and H1.1 mudflats Tidal Mudflats 9.5 9.5 1% 1% J1.1 Stubble Stubble 65.4 250.5 6% 22% J1.1 Winter Cereal Winter Cereal 248.2 116.2 22% 10% J1.1 Rhubarb Rhubarb 54.2 52.3 5% 5% J1.1 Turf Turf 82.7 47.7 7% 4% Other arable bare J1.1 ground Stripped 0.0 47.7 0% 4% J1.1 Ploughed Ploughed 7.1 21.2 1% 2% Arable Bare J1.1 Ground Bare Ground 5.6 4.2 1% 0% J1.1 Fruit Canes Fruit Canes 3.9 3.2 0% 0% J1.1 Strawberries Strawberries 3.2 3.2 0% 0% J1.1 Setaside Setaside 40.4 2.7 4% 0% J1.1 Game Crop/WBC Game Crop/WBC 6.9 0.0 1% 0% Other arable bare J1.1 ground Rotovated Ground 2.8 0.0 0% 0%

J1.2 Amenity grassland Playing Field 8.3 8.3 1% 1% J3 Industrial Car Park 6.7 6.7 1% 1% J3 Industrial Hard core / Bare Ground 0.0 1.3 0% 0% Unknown Unknown 9.4 0.0 1% 0% Total Area 1124.4 1124.4 100% 100%

36 Table 10: Summary of use of Black Cart roost during the 2008/2009 winter

No Field Of No No No No Birds Birds Departing Arriving Present No Present Departing In Towards At After Departing During Roost Evening From Field Roost Roost Dark Roost Departure Morning 25-Nov 143-165 26-Nov 26-Nov 51 162+ (162-185) 27-Nov 03-Dec 51 30++(24++) 04-Dec 08-Dec 83++ 88++09-Dec 16-Dec 75++ 17-Dec 17-Dec 133 NC(76--130) 18-Dec ((131- 22-Dec 133 146 142)) 23-Dec 07-Jan 85+ 08-Jan 15-Jan 148+ 16-Jan 133- 16-Jan 152 17-Jan 21-Jan 123-125 22-Jan 28-Jan 99+ 29-Jan 05-Feb 121+ 06-Feb Black 06-Feb N47 87+ (87+) 07-Feb Cart 11-Feb c.160 12-Feb 163- 12-Feb N114 119 170 13-Feb 18-Feb 124+ 19-Feb 228 & 19-Feb 178A 75 ((62+)) 20-Feb N79A, N81A, 123- 26-Feb N83 71+ 130 27-Feb 04-Mar 109+ 05-Mar 12-Mar 90+ 13-Mar 18-Mar 113++ 19-Mar 19-Mar 178A 96 74 20-Mar 02-Apr 15+ 03-Apr 09-Apr (3) 10-Apr

37 Table 11: Summary of use of roosts other than the Black Cart during the 2008/2009 winter

No Field Of No No No No Birds Birds Departing Arriving Present No Present Departing In Towards At After Departing During Roost Evening From Field Roost Roost Dark Roost Departure Morning 26-Nov 3 27-Nov 03-Dec 51 30++(6++) 0 04-Dec 08-Jan 5 0 09-Jan Linwood Pond 19-Feb 2 20-Feb 25-Feb 8 26-Feb 05-Mar 16 06-Mar 10-Apr N47 2 2 11-Apr 02-Dec 20 03-Dec 21-Dec 57-63 22-Dec Newshot 21-Jan 24 22-Jan Wetland 28-Jan (2++) 29-Jan 29-Jan 13 30-Jan 12-Mar 2 13-Mar 19-Mar 178A 96 22 20-Mar 26-Mar 178A 72 27-Mar 178A 27-Mar 178A 72 72 28-Mar 03-Apr 178A 14 14+ 04-Apr 228 & Linwood 19-Feb 178A 75 5 5 20-Feb Moss Pond 19-Mar 178A 96 0 20-Mar 26-Mar 0 27-Mar Auchans Pool 19-Feb 0 20-Feb 22-Dec 133 146 ((4)) 23-Dec 228 & 19-Feb 178A 75 ((52-54)) 20-Feb Unknown N79A, N81A, 26-Feb N83 71+ ((1)) 27-Feb

38 Table 12: Summary of use of Black Cart roost east and west of Barnsford Bridge

No Of No No No No Field Birds Birds Departing Arriving Present No Present Departing In Towards At After Departing During Roost Evening From Field Roost Roost Dark Roost Departure Morning 25-Nov 143-165 26-Nov 08-Dec 83++ 88++ 09-Dec 16-Dec 75++ 17-Dec 17-Dec 133 NC (76--130) 18-Dec ((131- 22-Dec 133 146 142)) 23-Dec 07-Jan 85+ 08-Jan 15-Jan 148-149 16-Jan 133- 16-Jan 152 17-Jan 21-Jan 123-125 22-Jan 28-Jan 99+ 29-Jan East BC 05-Feb 121 06-Feb 11-Feb c.160 12-Feb 163- 12-Feb N114 119 170 13-Feb 18-Feb 124+ 19-Feb

N79A, N81A, 123- 26-Feb N83 71+ 130 27-Feb 04-Mar 109+ 05-Mar 12-Mar 90+ 13-Mar 18-Mar 113++ 02-Apr 15+ 03-Apr 09-Apr (3) 10-Apr 11-Feb 0 12-Feb 18-Feb 0 19-Feb 04-Mar 0+ 05-Mar West BC 18-Mar 0+ 19-Mar 02-Apr 0+ 03-Apr 09-Apr 0 10-Apr

39 Table 13: Summary of use of subroosts within Black Cart East of Barnsford Bridge.

No Of No No No Field Birds Birds Departing Present No Present Departing In Towards No Arriving After Departing During Roost Evening From Field Roost At Roost Dark Roost Departure Morning 25-Nov 49+ 26-Nov 07-Jan 79+ 08-Jan 05-Feb c.94 99 06-Feb 11-Feb c.97 c.99 12-Feb 12-Feb N114 119 57++ 13-Feb RIV2 18-Feb 103+ 104+ 19-Feb N79A, 26-Feb N81A, N83 71+ 104-111 27-Feb 04-Mar 99+ 05-Mar 12-Mar 40+ 13-Mar 02-Apr 15 03-Apr 08-Dec 43++ 09-Dec 16-Dec 2++ 17-Dec 07-Jan 2++ 08-Jan 16-Jan 133-152 17-Jan 05-Feb c.27 22 06-Feb RIV3 11-Feb c.60 c.60 12-Feb 12-Feb N114 119 44++ 13-Feb 18-Feb 18+ 19-Feb 04-Mar 25++ 05-Mar 12-Mar 27+ 13-Mar 09-Apr (3) 10-Apr 08-Dec 71++ 09-Dec 16-Dec 57++ 17-Dec RIV4 28-Jan (5+) 29-Jan 05-Feb 0 06-Feb 12-Mar 19+ 13-Mar 11-Feb 0 12-Feb 18-Feb 0 19-Feb 04-Mar 0 05-Mar 113 18-Mar 0 19-Mar 02-Apr 0 03-Apr 09-Apr 0 10-Apr 16-Dec 16++ 17-Dec 15-Jan 148-149 16-Jan 16-Jan 100-119 17-Jan 125 21-Jan 123-125 22-Jan 28-Jan 94+ 29-Jan 05-Feb 0 06-Feb 12-Mar 4+ 13-Mar 25-Nov 101+ 26-Nov RIV2, RIV3 18-Feb 124+ 19-Feb 04-Mar 109+ 05-Mar RIV3, RIV4 08-Dec 83++ 88++ 09-Dec RIV3, RIV4,125 07-Jan 6+ 08-Jan RIV2,RIV3, RIV4,125 25-Nov 143-165 26-Nov 40 Table 14: Illustration of conventions used in recording roost usage in tables 10 to 13.

Example Interpretation Definite 10 10 birds definitely using roost Certainty of record Probable (10) 10 birds probably using roost Possible ((10)) 10 birds possibly using roost Accurate 10 accurate count of 10 birds approximate count of 10 Approximate c.10 birds Minimum 10+ Minimum count of 10 birds Floor count of 10 birds - actual count potentially much Floor 10++ higher Count type and Maximum <10 Up to 10 birds accuracy Range between minimum and maximum 10-20 Count of 10 to 20 birds Count of 10 to 20 birds, but minimum count a floor, so Range between actual count potentially much floor and maximum 10--20 higher.

41 Table 15: Roost movement times at dawn

Minutes Minutes after after sunrise sunrise Duration of movement movement movements Date Sunset started ended (minutes) 26/11/2008 08:16 -30 24 54 03/12/2008 08:28 0 54 54 09/12/2008 08:36 -29 42 71 17/12/2008 08:44 -50 -7 43 22/12/2008 08:47 -5 0 5 08/01/2009 08:45 -41 32 73 16/01/2009 08:37 -25 -3 22 22/01/2009 08:29 -2 24 26 29/01/2009 08:17 9 43 34 06/02/2009 08:02 44 139 95 12/02/2009 07:49 -8 49 57 19/02/2009 07:33 -17 34 51 26/02/2009 07:16 12 14 2 05/03/2009 06:59 16 63 47 13/03/2009 06:38 43 43 0 13/03/2009 18:17 -4 28 32 27/03/2009 06:01 33 69 36 03/04/2009 06:43 26 65 39 10/04/2009 06:25 16 16 0 Mean -0.6 38.4 39.0 Median -2 34 39 Minimum -50 -7 0 Maximum 44 139 95

42 Table 16: Roost movement times at dusk

Minutes Minutes after after sunset sunset Duration of movement movement movements Date Watch type Sunset started ended (minutes) 26/11/2008 Field 15:54 37 54 17 03/12/2008 Field 15:47 28 17/12/2008 Field 15:44 13 24 11 22/12/2008 Field 15:46 -1 24 25 08/01/2009 Roost 16:05 44 45 1 16/01/2009 Roost 16:19 -1 45 46 21/01/2009 Roost 16:30 44 47 3 29/01/2009 Roost 16:45 13 20 7 06/02/2009 Field 17:02 38 48 10 Field and 12/02/2009 Roost 17:16 14 29 15 19/02/2009 Field 17:31 23 43 20 Field and 26/02/2009 Roost 17:46 2 42 40 05/03/2009 Roost 18:01 57 67 10 Field and 19/03/2009 Roost 18:30 34 69 35 Field and 27/03/2009 Roost 18:46 59 69 10 10/04/2009 Field 20:14 34 34 0 Mean 27.3 43.0 16.7 Median 34 44 11 Minimum -1 20 0 Maximum 59 69 46

43 Table 17: Colour ring observations

Date Time Field Age Leg Background Lettering Combination Comments Observer 26/02/2009 12:26 61 Adult yellow Black A59 Nigel Harding 27/03/2009 17:58 178A Adult right yellow black IS3 Above right knee Nigel Harding 08/01/2009 14:36 48 Adult Left yellow Black 5H(N or A) Above left knee Nigel Harding 29/01/2009 09:51 130 Adult Left yellow Black 5H(N or A) Above left knee Nigel Harding 27/03/2009 11:50 N114 Adult left yellow Black 5H? Above left knee Nigel Harding 29/01/2009 09:51 130 Adult Right yellow Black VXL? Colour ringed family in field 113 at 11:07. 2 adults (1 yellow left, other Unable to yellow right), 3 juveniles 26/02/2009 11:07 113 Family yellow Black read (all yellow left) Nigel Harding Colour ringed family in field 239 at 15:09. 2 adults (1 yellow left, other yellow right), 3 juveniles (all yellow left). Probably same birds recorded in field 113 on the 26/02/2009. Strengthens case for Auchans birds Unable to being part of the Black 05/03/2009 15:09 239 Family yellow Black read Cart population Nigel Harding Unable to 17/12/2008 10:04 133 Adult Left yellow Black read Nigel Harding

44 Table 18: Recorded instances of disturbance

Distance from birds Distance Total disturbance Flight birds no of occurred Cause of height displaced Date Time Field birds Adults Juveniles (m) disturbance Outcome (m) (m) Observer Birds flew directly over airport, apparently landing in vicinity of field 122, although no birds recorded in Disturbed by this field, or nearby observer during during subsequent Nigel 03/12/2008 10:50 137 12 170 feeding survey feeding survey 30 1000 Harding Disturbed by shot discharged by wildfowlers. (4 wildfowlers and dog observed c.100 birds moving into intending to roost position near field on field 125 Nigel 16/01/2009 17:13 125 100 c.100m 125 at 16:20). displaced to RIV3. 20 600 Harding

45 Table 19: Recorded instances of potential disturbance

Date Details Observer Rubbish being burnt in old field 120 (N118) near river at 11:20. Being attended by 12/02/2009 man on quad bike. Nigel Harding Pile of rubble and (unlit) bonfire present in field 120 27/03/2009 (N118) near river. Nigel Harding

46 Figure 1: Field numbering and feeding survey route for the 2007/2008 winter, showing standard route (red) and extensions (blue) with colour coding of fields indicating whether they are visible from the standard route (light green) or one of the extensions (various colours).

47 Figure 2: Field numbering used in the 2008/2009 winter.

48 Figure 3: Survey route followed from the 26th November 2009 till the 29th January 2010 inclusive

49 Figure 4: Survey route followed from the 6th to the 19th February 2010 inclusive.

50 Figure 5: Survey route followed from the 26th February till the 10th April 2010 inclusive.

51 Figure 6: Best estimates of total numbers of whooper swans within the Black Cart study area on different dates within the 2008/2009 winter.

Total Adults Juveniles Unaged nos 0 20 40 60 80 100 120 140 160 180

01/12/2008 01/01/2009 01/02/2009 01/03/2009 01/04/2009

Date

52 Figure 7: Percentage of aged birds which were juveniles on each date 40 35 30 % juveniles% 25 20

01/12/2008 01/01/2009 01/02/2009 01/03/2009 01/04/2009

date

53 Figure 8: All feeding records within the Black Cart Study Area for the 2008/2009 winter. For fields with multiple records, records with higher precedence are plotted on top of, and can potentially hide records of lower precedence. Order of precedence is a follows: records from formal feeding survey > records from dawn roost counts > records from dusk roost counts > casual records.

54 Figure 9: All feeding records within the Black Cart Study Area for the 2007/2008 winter.

55 Figure 10: Feeding records for November 2008

56 Figure 11: Feeding records for December 2008

57 Figure 12: Feeding records for January 2009

58 Figure 13: Feeding records for February 2009

59 Figure 14: Feeding records for March 2009

60 Figure 15: Feeding records for April 2009

61 Figure 16: The number of dates on which whooper swans were present during formal feeding surveys for fields where birds were present at least once during the 2008/2009 winter.

No of dates birdsNo present dates of 012345

61 N47 178A 228 RIV3 130 133 177 239 48 51 N114 N118 RIV2 113 62 N54 122 128 129 137 43 N168 N81A N83 RIV4

Field

62 Figure 17: The total number of birds recorded during formal feeding surveys for fields where birds were present at least once during the 2008/2009 winter. 400 300 200 total number of birds recorded birds of number total 100 0

130 133 51 228 178A N114 239 128 N47 61 48 N54 113 N83 N81A N118 N168 129 62 RIV3 137 43 RIV4 177 RIV2 122

Field

63 Figure 18: The maximum number of whooper swans recorded during formal feeding surveys for fields where birds were present at least once during the 2008/2009 winter.

150 100 Max nos of birds nos recorded of Max 50 0

51 130 133 128 N114 228 239 N47 178A 48 113 N83 N81A 61 N168 N54 N118 129 137 43 62 RIV4 RIV3 122 177 RIV2

Field

64 Figure 19: Relationship between total number of birds recorded and maximum number of birds recorded for fields holding birds at least once during the 2008/2009 winter

51

0 130 5

133 128 N114 01

0 239 228

N47 178A

48 01 maximum number of birds recorded birds of number maximum

113 N83 N81A 61 N168 N118 N54 129

13743 RIV4 62 RIV3 RIV2122177 05

0 100 200 300 400

total number of birds recorded

65 Figure 20: Relationship between no of dates birds present and total numbers of birds recorded for fields holding birds at least once during the 2008/2009 winter

130 400

300 133

51 228 200 178A N114 239 total number of birds recorded birds of number total

128 N47 100 48 61

N54113 N81AN168N83 N118 129 62 RIV3 RIV413743 RIV2177

0 122

12345

no dates birds present

66 Figure 21: Relationship between no of dates birds present and maximum number of birds recorded for fields holding birds at least once during the 2008/2009 winter

51

130 150

133 128 N114

239 228 100

N47 178A

48 maximum number of birds recorded of number maximum 50

113 N83 N81A 61 N168 N54 N118 129

13743 RIV4 62 RIV3 122 RIV2177 0

12345

no dates birds present

67 Figure 22: Relationship between number of dates birds present in the 2007/2008 winter and the number of dates they were present in the 2008/2009 for fields where birds present in at least one of the winters.

61 N47

228 178A RIV3

N114133177239 130 51 48 RIV2 N118

N54 62 113 no dates birds present 2008/2009 winter birds present no dates

N16813712943 N83128 RIV4 N81A122

012345 N77AN78N79ARIV111712514450734046 N109 1744952 87 10 176

02468

no dates birds present 2007/2008 winter

68 Figure 23: Relationship between the total number of birds recorded in the 2007/2008 winter and the total number recorded in the 2008/2009 winter for fields where birds present in at least one of the winters.

130 400

300 133

51 228 200 178A N114 239

128 N47 total number of birds recorded 2008/2009 winter 2008/2009 recorded birds of number total 100 61 48

N54 113 N168 N83 N81A N118 129 RIV362 13743 RIV4 177 RIV2 0 N7811740 N77A 125144 N79A RIV150 17446 52 73122 49N109 10 176 87

0 50 100 150 200

total number of birds recorded 2007/2008 winter

69 Figure 24: Relationship between maximum number of birds present in the 2007/2008 winter and the maximum number of birds present in the 2008/2009 winter for fields where birds present in at least one of the winters.

51

0 130 5

133 128 N114 01

0 228239

N47 178A

48 maximum nos 2008/2009 winter 2008/2009 nos maximum 01

113 N83 61 N81A N168 N54 N118 129

13743 RIV4 62 RIV3 177 RIV2 122 05 N7811740 N77A 125144 N79A 174RIV1 17650 46 4952 7310 N109 87

0 20406080

maximum nos 2007/2008 winter

70 Figure 25: Distribution of habitats across numbered fields in the Black Cart study area on the 26th November 2008. Mosaics indicated by double white crossing hatching over background indicating habitat with highest cover.

71 Figure 26: Distribution of habitats across numbered fields in the Black Cart study area on the 10th April 2009. Mosaics indicated by double white crossing hatching over background indicating habitat with highest cover.

72 Figure 27: Distribution of habitats across numbered fields in the Black Cart study area on the 25th November 2007. Mosaics indicated by double white crossing hatching over background indicating habitat with highest cover.

73 Figure 28: Change in cover of selected habitats during the 2008/2009 and 2007/2008 winters, for just those fields recorded in both surveys

Figure28a: Stubble Area (ha) Area

2007/2008 2008/2009 0 50 100 150 200 250

01/10 01/11 01/12 01/01 01/02 01/03 01/04

Date

Figure 28b: Ploughed ground

2007/2008 2008/2009 Area (ha) Area 0 50 100 150 200 250

01/10 01/11 01/12 01/01 01/02 01/03 01/04

Date

74 Figure 28c: Turf Area (ha) Area

2007/2008 2008/2009 0 20406080

01/10 01/11 01/12 01/01 01/02 01/03 01/04

Date

Figure 28d: Setaside 0 04 03 Area (ha) Area

2007/2008 2008/2009 02 0 1

01/10 01/11 01/12 01/01 01/02 01/03 01/04

Date

75 Figure 29: Number of whooper swans recorded in each foraging habitat on each formal feeding survey during the 2008/2009 winter based upon the maximum number of birds recorded in each field.

200 River Ploughed Stubble Turf Improved Pasture 150 100 no of birds recorded in each habitat in each recorded birds of no 50 0

26/11 3/12 9/12 17/12 22/12 8/1 16/1 22/1 29/1 6/2 12/2 19/2 26/2 5/3 13/3 19/3 27/3 3/4 10/4

Date

76 Figure 30: Number of whooper swans recorded in each foraging habitat on each formal feeding survey during the 2007/2008 winter based upon the maximum number of birds recorded in each field.

River Rotovated Ground Stubble Winter Cereal Turf Rushy Pasture Improved Grassland Improved Pasture no of birds recorded in each habitat in each recorded birds of no 0 20 40 60 80 100 120 140

19/10 25/10 30/10 7/11 13/11 25/11 1/12 9/12 13/12 23/12 27/12 6/1 11/1 21/1 27/1 3/2 10/2 21/2 25/2 4/3 14/3 21/3 2/4 8/4 14/4

Date

77 Figure 31: Roosts and potential roosts in the 2007/2008 and 2008/2009 winters.

78 Figure 32: Flight lines by time of day for the 2008/2009 winter

79 Figure 33: Flight lines during the 2008/2009 winter classified according to estimated maximum height achieved.

80 Figure 34: Flight lines by time of day for the 2007/2008 winter

81 Figure 35: The cumulative percentage of flights and birds on flight lines below given altitudes (metres) for the 2007/2008 and 2008/2009 winters Cumulative % below % Cumulative

2007/2008 Flights 2008/2009 Flights 2007/2008 Birds 2008/2009 Birds 0 20406080100

020406080100

Max height (m)

82 Scottish Natural Heritage is a government body responsible to the Scottish Government.

Statement of principles:

Scottish Natural Heritage – the government body that looks after all of Scotland’s nature and landscapes, across all of Scotland, for everyone. Our 5 strategic priorities are:

– Caring for Scotland’s nature and landscapes – Helping to address climate change – Delivering health and well being – Supporting the Scottish economy – Delivering a high quality public service

Find out more at www.snh.gov.uk

Policy and Advice Directorate, Great Glen House, Leachkin Road, Inverness IV3 8NW www.snh.gov.uk