This article was downloaded by: [213.122.178.99]On: 21 March 2014, At: 18:35Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Bird StudyPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/tbis20

Disturbance of overwinteringwildfowl by anglers at two reservoirsites in South WalesMartin Cryer a , Nigel W. Linley a , Robin M. Ward a , JonathanO. Stratford a & Peter F. Randerson aa Department of Applied Biology , University of WalesInstitute of Science and Technology , PO Box 13, Cardiff, CF13XF, UKPublished online: 24 Jun 2009.

To cite this article: Martin Cryer , Nigel W. Linley , Robin M. Ward , Jonathan O. Stratford &Peter F. Randerson (1987) Disturbance of overwintering wildfowl by anglers at two reservoirsites in South Wales, Bird Study, 34:3, 191-199, DOI: 10.1080/00063658709476961

To link to this article: http://dx.doi.org/10.1080/00063658709476961

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoeveras to the accuracy, completeness, or suitability for any purpose of the Content. Anyopinions and views expressed in this publication are the opinions and views of theauthors, and are not the views of or endorsed by Taylor & Francis. The accuracyof the Content should not be relied upon and should be independently verifiedwith primary sources of information. Taylor and Francis shall not be liable for anylosses, actions, claims, proceedings, demands, costs, expenses, damages, and otherliabilities whatsoever or howsoever caused arising directly or indirectly in connectionwith, in relation to or arising out of the use of the Content.

This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden.

Terms & Conditions of access and use can be found at http://www.tandfonline.com/page/terms-and-conditions

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

Bird Study (1987) 34, 191-199

Disturbance of overwintering wildfowl by anglers attwo reservoir sites in South Wales

MARTIN CRYER, NIGEL W. LINLEY, ROBIN M. WARD,JONATHAN 0. STRATFORDand PETER F. RANDERSONDepartment of Applied Biology, University of Wales Institute of Science andTechnology, PO Box 13, Cardiff CF1 3XF, UK

Studies of bird distribution and behaviour at 2 reservoir sites in South Walesshowed different degrees of disturbance by anglers. During October and Marchat Llandegfedd Reservoir, the distributions of Wigeon, Pochard and Mallardwere strongly influenced by the presence of anglers. At the Llanishen/Lisvanecomplex, small numbers of anglers throughout the winter on Llanishen hadrelatively little impact on either Tufted Duck or Coot. The impact of game-fishingon birds on reservoirs in the winter seems to be determined by the distributionof anglers as well as by their total number.

The reclamation of natural wetlands foragricultural and urban development in

recent years has decreased the feeding areasavailable for wildfowl, causing them to congre-gate on remaining natural sites and reservoirsin increasing numbers (Owen, Atkinson-Willes & Salmon 1986). These aggregations canresult in potential conflict between conserva-tion and recreational interests (Matthews 1982)but Tuite, Owen & Paynter (1983) concludethat local factors make generalization imposs-ible. In particular, sympathetic managementby zoning and the provision of a wildfowlrefuge appears to reduce the long-term impactof disturbance.

There has been recent pressure to extendthe traditional fly-fishing season (April toOctober) on reservoirs and by 1983 it had beenbrought forward by up to a month on overhalf of all British reservoirs offering troutfishing (Bell & Austin 1985). Fishing through-out the winter for rainbow trout is also allowedin some instances (e.g. Rutland Water, AnglingTimes 1985). The arrival of anglers at the water-side during winter and early spring maydisturb waterfowl: in March, angling at Llan-degfedd Reservoir resulted in a marked re-

distribution of birds and the prema in redeparture of some species (Bell & Austin 1985),whereas at Grafham Water a traditional startin late April had a relatively minor impact onthe birds present (Cooke 1974). Furthermore,recent studies have indicated that the combi-nation of angling and sailing at LlandegfeddReservoir can result in disturbance severeenough to cause entire populations to desert(Edwards & Bell, 1987).

The present study considers 2 reservoir sitesof considerable importance to wildfowl inSouth Wales where angling for trout is per-mitted throughout the traditional season. Theeffects of extensions of this season by 2 weeksat Llandegfedd and over most of the winterat Llanishen are discussed.

SITE DESCRIPTIONS

Llandegfedd Reservoir is one of the largeststill water bodies in Wales (Table 1). Itsshoreline is convoluted, being steep andwooded around much of the southern end ofthe basin, and bordered by gently slopinggrassland to the north. Since its establishmentin 1963, it has become the most important

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

Open grazed gross

Wood

Stone bark

n.t Rough grass

Bracken

• Buoys on penme`erot sound area

5OOn

192 M. Cryer et al.

Table 1. Site locations and descriptions

SiteGridreference

Area(ha)

Conservationstatus

Winteractivities

Llandegfedd ST 333995 174 SSSI (1971) Bird watchingLlanisheri ST 187817 24 None Angling

SailingBird watching

Lisvane ST 187817 7 SSSI (1972) Bird watching

inland site for overwintering wildfowl in SouthWales (RSPB 1977; NCC 1981; Owen et al.1986), the numbers of Wigeon, Pochard, andMallard recently having peaked at above 1%of the total British wintering population. Sail-ing on the central deepwater areas is permittedfrom 1 March to 31 October, whereas anglingfrom the shore and from rowing boats is con-ducted around most of the perimeter from thespring opening to 17 October. In 1981 theWelsh Water Authority changed the start ofthe fishing season from 4 April to the 20 March,the date for other reservoir fly fisheries inWales.

Llanishen and Lisvane Reservoirs lie withinCardiff City boundaries (Table 1). They areseparated only by a causeway and are both ofuniform artificial construction. Fly-fishing isavailable on both reservoirs during the sum-mer season and, since 1981, on Llanishen dur-ing the winter (18 October-29 February). Thefishery is one of the most heavily used in SouthWales (Mawle 1983). The site supports locallysignificant overwintering populations ofTufted Duck and Coot, and recently Lisvanehas increased in local importance as a summermoulting ground for Tufted Duck (Odin 1984).

METHODS

Investigations were carried out during winter1985 and spring 1986. Observations were madeapproximately weekly at Llanishen and Lis-vane, and approximately monthly at Llandeg-fedd, where intense periods of observation ofseveral consecutive days were also carried outat the end of the 1985 and at the start of the1986 fly-fishing seasons.

Counts were made at hourly intervals from

dawn to dusk, by 1 (Llanishen) or 3 (Llandeg-fedd) observers equipped with telescope andbinoculars and positioned at appropriatepoints around the site (Figs 1 and 2). Theobservers remained at their positions through-out the day to minimize disturbance. At eachcount, the location of all birds present and anestimate of the proportion feeding were re-corded on an outline map of the site. Thepositions of anglers, sailing boats, walkers,birdwatchers, dogs and other potentially dis-turbing influences were also recorded.

Bird distribution data were analysed bycalculating an electivity index for each species

Figure 1. Llandegledd Reservoir showing banksidecharacteristics and sectors used to quantify bird andangler distribution. The positions of observers areindicated by crosses.

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

Figure 2. Llanishen and Lisvane Reservoirs showingsectors used to quantify bird and angler distribution.The position of the observer is indicated by a cross.

on each sampling occasion for each of severalsectors within the two sites (Figs 1 and 2). Theindex selected for this purpose was Jacobs'(1974) modification of Ivlev's (1961) index:

D = (r- p)/(r+p - 2rp)

where: D is the electivity index;r is the fraction of a given species ina given sector;p is the fraction of a total site areawithin a sector.

Possible values of the index range from -1 to+1. Positive values indicate a larger numberof birds than would be expected if they wereevenly distributed over the whole site, nega-tive values a smaller number, and a value of0.0 indicates that birds are present in numbersexactly proportional to the size of the sector.

RESULTS

The presence of anglers on Llandegfedd Reser-voir at the start and finish of our study perioddoes not appear to have influenced thenumber of wildfowl using the site, changes inbird numbers being typical seasonal fluc-tuations (Owen et al. 1986). However, theproportion of Wigeon (Fig. 3), Pochard (Fig.

Disturbance of wildfowl by anglers 193

4), and Mallard (Fig. 5) feeding during the dayincreased markedly at the start of the closedseason in October. The distribution of all 3species changed following the cessation ofangling: Wigeon in particular used the opengrassy shores (sectors C, D, and E) most fre-quently, whereas during the open season theytended to use the centre of the reservoir (sectorA). Pochard and Mallard showed similar,though less marked, redistributions at the startof the closed season. The start of fishing inMarch saw Wigeon returning to the centre ofthe reservoir and Mallard moving away froma small favoured bay (sector L). Numbers ofPochard on the reservoir at this time were verylow.

The number of anglers using Llandegfeddat the start of the 1986 season was similar tothat for the 1984 season (Table 2) (Bell & Austin1985). In 1984 83% of bank anglers used thenorthern area of open grassland frequentlyfavoured by wildfowl (sectors D,E, & F, Fig.1), whereas in 1986 the proportion was only26% (Table 2), leading to a density of bankanglers nearly 3 times higher in these a reas in

1984 compared with 1986 (mean ngler

Table 2. Mean number of anglers using given sector.,of Llandegfedd Reservoir (Fig. I) during the first 4days of the fly-fishing seasons of 1984 and 1986.Asterisks denote sectors strongly preferred bywildfowl. 1984 counts from Bell & Austin (1985).C.V. is coefficient of variation. Total numbers of allanglers are not significantly different between the 2years (t44 = 1.17, P > 0.10)

Bank anglers Boat anglers

Sector 1984 1986 1984 1986

A 0.00 0.00 0.26 0.17B 0.94 2.75 0.46 0.50C 0.73 1.92 0.20 0.33D" 2.43 1.50 0.34 0.13E* 3.16 2.29 0.66 0.21P 10.52 1.96 0.14 0.13G 0.45 0.25 0.34 0.67H 0.55 3.79 0.14 0.58I 0.50 6.75 0.06 0.25

J 0.11 0.54 0.14 0.92K 0.05 0.00 4.78 4.58L 0.00 0.00 0.00 0.21

Total 19.44 21.75 7.52 8.68

C.V. 183.5% 109.6% 210.7% 171.4%

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

194 M. Cryer et al.

densities 16.1±9.0 and 5.7±- 6.1; t = 3.70,P < 0.01).

Sailing occurred on Llandegfedd on twodates after the close of fishing. On both oc-casions (marked by arrows on Figs 3 to 5), theproportion of birds feeding decreased for allspecies, particularly for Pochard, which werestill using the centre of the reservoir at thistime.

Counts of Tufted Duck (Fig. 6) and Coot(Fig. 7) using Llanishen and Lisvane showedno fluctuations that could not be attributed toseasonal changes. Tufted Duck preferredLisvane to Llanishen Reservoir throughout thestudy period, and indeed tended to avoid theside of Lisvane adjacent to Llanishen (Fig. 8).Llanishen Reservoir was used briefly by TuftedDuck, however, when Lisvane was frozen

20 20 30

i9 21 23

Dc

Noe Dec Jac 'et Mar

Figure 3. The total number and number feeding diurnally (upper panel) and the distribution(lower panels) of Wigeon on Llandegfedd Reservoir during the study. The lower panels indicatethe electivity of Wigeon for four sectors of the reservoir (A,C,D,E). Flectiyities greater than 0.0indicate positive selection and values less than 0.0 indicate avoidance. Sectors not shown herewere not used by Wigeon during the study. Vertical lines on 17 October and 20 March indicatethe close and opening of fly-fishing. Pecked lines on 31 October oncl 1 March (upper panel)indicate the close and opening of sailing and arrows indicate the occurrence of sailing duringthe closed fishing season.

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

Nov Dec Jon Feb

1 2 19 21 23

Mar

over in February. Coot were found on Lisvane(especially the northern side) throughoutOctober and November, but from Decemberonwards tended to use Llanishen (especiallythe eastern side) more frequently (Fig. 9).These patterns of distribution and abundanceare typical for the site (N. Odin, P. Bristowpers. comm.).

On 4 of the observation days (11.10, 16.12,19.12 & 20.12.85), the mean number of anglersusing the complex was greater than 3.0; oneach of the other 14 days, it was less than 1.0.These differences in intensity of angling werenot associated with decreases in the number

Disturbance of wildfowl by anglers 195

of birds present or in the proportion feeding.Furthermore, the mean distributions of birdsbetween the 26 sectors of Llanishen and Lis-vane reservoirs (Fig. 2) did not differ signifi-cantly between times of relatively high andlow angling pressure, (mean angler densitiesgreater than 3.0 and less than 1.0, respectively;x22 , 26 = 9.0 for Tufted Duck and 26.8 for Coot,P > 0.10 in each case).

DISCUSSION

The close of fishing at Llandegfedd in October1985 had a profound influence on the

Figure 4. The total number and number feeding diurnally (upper panel) and the distribution(lower panels) of Mallard on Llandegfedd Reservoir during the study. Conventions as in Fig. 3.

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

- •

• • • O OOOO

196 M. Cryer et al.

behaviour of the 3 commonest species ofwildfowl present on the reservoir. Whilstfishing was underway, Wigeon, Pochard andMallard concentrated in the central sector ofthe reservoir, whereas from the first day ofthe closed season and throughout most of thewinter, all 3 species mainly used one or moreof the sectors towards the northern end of thereservoir. Mallard also moved into a small baynear the dam in the latter half of the winter.After the start of the 1986 season the numberof birds using the site did not greatly change,but Wigeon used the central sector of thereservoir more and Mallard stopped using thesmall bay near the dam.

These changes in distribution and abun-dance were much less marked than thoserecorded by Bell & Austin (1985) at the startof the 1984 season at Llandegfedd, when all 3species were driven completely from their pre-ferred sectors and apparently left the reservoirprematurely as a result of disturbance. Differ-ences between the 2 years in weather con-ditions and angling pressure may explain thelesser impact of the opening of the 1986season. The weather during February andMarch 1986 was extremely severe: the reser-voir margins and bays and the pastures andfeeding grounds around Llandegfedd werefrozen for long periods. This probably caused

1 000

100

+ 1

A

15 20 25 30

1 2 19 21 23Oct

Nov

Dec Jar Feb

Mar

Figure 5. The total number and number feeding diurnally (upper panel) and the distribution(lower panels) of Pochard on Llandegfedd Reservoir during the study. Conventions as in Fig. 3.

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

IOct Nov Dec Jan Feb Mar

Figure 6. The total number of Tufted Duck usingLlanishen and Lisvane Reservoirs during the studyand the numbers feeding diurnally.

the observed decrease in bird density beforethe start of the fishing season, leaving rela-tively few individuals to be disturbed whenangling started. The number of Pochard in par-ticular had decreased to very low levels bythen.

The impact of anglers in 1986 was probablysmall compared with 1984 because of differ-ences in angler distribution caused by windyweather and a concentration of easily caughttrout in Sor Bay (sectors H and I) in 1986.Anglers preferred the northern grassy sectorsin 1984, areas also favoured by wildfowl. Boat

Disturbance of wildfowl by anglers 197

500- Total Number feeding

• • • •

100-

t= 50-m

10Oct Nov Dec Jan Feb Mar

Figure 7. The total number of Coot using Llanishenand Lisvane Reservoirs during the study and thenumbers feeding diurnally.

anglers were very scarce in this area in bothyears.

Low intensity fishing continued throughoutmuch of the 1985/86 winter on LlanishenReservoir but not on the closely associatedLisvane. Our observations show clearly thatthe small numbers of anglers present onLlanishen during the winter did not markedlyalter bird behaviour. Observed fluctuations inTufted Duck numbers were not correlated withthe number of anglers present, and the pro-portion of Tufted Duck feeding, the numberof Coot, and the proportion of Coot teed ingremained fairly stable, apparently una ffectedby the numbers of anglers. Spatial distri-butions of both species were unaffected by thepresence of anglers.

1000

100

Sector

Llanishen L n svane

ABCDEFGH 1 J KLMNOPQRS T UVWXYZ

IM••ME••ME•MUMMUM MN •MMEMMEMMEMMEMEMM••• •MIMMEMEMMEMMEMMEM MOM• MEME••M•MMINI•• •••MOMMEMMEMEMME•M• MEMMEMM• E•EM•MENEMMUMM MIMEOIMEMMIMEMEM••• MEMOEMEMMOMMEMMOME ••• =WM •••E••••••••••M•• •••IMMEMEMMEME•ME••M•• MEMO• MEMEMOMMEIMEEMMEME 11.11=• OMEMEMEMEMMUOMEM =•EEMMEMEME•EMS••M•••• MINIME• MEMINIMMEMEMMEMMEME •M=••MER•MM•••M•EM•M MEM •ME •EMEUMMIMM•MUMMEM•MMMOM •••••••••MM•M•EM••EM••M•••M•MEMMEMEMUM ME=

Figure 8. The distribution of Tufted Duck on Llanishen and Lisvane Reservoirs during thestudy. Day 1 was 11 October. Shaded squares indicate sectors which Tufted Duck preferredon a given day (mean electivity positive). Arrows indicate occasions on which the mean densityof anglers using the Reservoirs over the day was greater than 1.0.

25

4661

67

7071

BB95

102

116124131155

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

198 M. Cryer et al.

Sec Or

Llanishen Lisvane

ABCDEFGH I J KLMNOPORST UVWXYZ

ME MEMEEMEMEME MEMO •• MEMO •MMEN MI •MEM. E•MEN= UM

aM

MEMO ERE•MOM

I• •NI•MME•M•M ME • • IIMM• •EMIMME•MO MO MAME• =•UER ME MI •EM EEO• ••OE OE En MUM •11.• EMEMEMEM REM MEMO• MEMO M MEM • •EM• •E•EM REIM MUM•ER.'• ME MEEEMOOM• M "MEM• MI MEMEMMEMMEOM MIME=• El ME ••NEEMMEE MENME UM •IROMMEMOU MM..=• •INEEMEIMMUMEMEMEMEMMR MEM MMEEM•RE•MEREEME •

• M MUM •IEIMMUMMUMMERES

Figure 9. The distribution of Coot on Llanishen and Lisvane Reservoirs during the study.Conventions as for Fig. 8.

1

18253239

466163

>, 670 70

71

88

95102116

124131155

Although Tuite, Hanson & Owen (1984)concluded that game-fishing had little, if any,impact on overwintering wildfowl, anglerscould disturb wildfowl if they were sharingthe same sites. At Llandegfedd Reservoir, dis-turbance occurs at the start and finish of thefly-fishing season, when wildfowl are presentin considerable numbers, although yearlyvariations in conditions seem also to be import-ant in determining the number of birds andtheir response. The behaviour of sensitivespecies, such as Wigeon, is modified by thepresence of anglers, there being good evidencethat feeding rates can be reduced by disturb-ance (Cramp & Simmons, 1977 and presentstudy). Sailing also has a detrimental effect onwildfowl at Llandegfedd, whether conductedwithin or outside the angling season (Edwards& Bell, 1987), and present study). The exten-sion of fishing by 2 weeks in the spring atLlandegfedd has probably resulted in in-creased disturbance to wildfowl using the site,and this may be sufficient in some years tocause premature desertion. However, atLlanishen and Lisvane Reservoirs there is littleapparent disturbance of overwintering TuftedDuck and Coot by the small number of anglerstaking advantage of the extended winterseason on Llanishen. This is probably partlybecause the anglers used Llanishen and thebirds could use Lisvane. Furthermore, Cootare very tolerant of human disturbance.

ACKNOWLEDGMENTS

J. Corbett, G. Whittle, M. Farooqi, C. Regoand M. Winterbotham assisted in the field.Professor R.W. Edwards, Dr P.N. Ferns andDr S. Ormerod commented on the script. MrT.C. Iles advised on aspects of data analysis.The Welsh Water Authority gave permissionto use reservoir sites and provided generalsupport to the investigation which was fundedby Manpower Services Commission under theCommunity Programme scheme.

REFERENCES

Angling Times (1985) Trout tonic: Rutland Watersport extended. Issue No. 1689. EMAP PursuitPublishing, Peterborough.

Bell, D.V. & Austin, L.W. (1985) The game fishingseason and its effects on oyerwintering wildfowl.Biol. Conserv. 33, 65-80.

Cooke, A. (1974) The effects of fishing on waterfowlat Grafham Water. Camb. Bird Rept. 48, 40-46.

Cramp, S. & Simmons, K.E.L. (1977) The Birds of theWestern Palearctic, Vol. I. Oxford University Press,Oxford.

Edwards, R.W. & Bell D. (1987) The Impact of Angl-ing on Wildlife. Proc. 4th Brit. Freshwater FisheriesConf. 1-3 April 1985. University of Liverpool,161-166.

Iylev, V.S. (1961) Experimental Ecology of the Feedingof Fishes. (Transl. D. Scott). Yale University Press,New Ha von.

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014

Disturbance of wildfowl by anglers 199

Jacobs, J. (1974) Quantitative measurement of foodselection—a modification of the forage ratio andIvlev's electivity index. Oecologia, 14, 413-417.

Matthews, G.V.T. (1982) The control of recreationaldisturbance. In Managing Wetlands and theirBirds (Ed. D.A. Scott), pp. 325-330. Inter-national Waterfowl Research Bureau, Slimbridge,Gloucester.

Mawle, G.W. (1983) Angling in South Wales. Unpubl.Rept. UWIST, Cardiff. 193 pp.

Nature Conservancy Council. (1981) LlandegfeddReservoir Site of Special Scientific Interest; a natureconservation appraisal. Consultation report, N.C.C.South Wales Region, Cardiff.

Odin, N. (1984) The importance of Lisvane Reservoir toSummering/moulting Tufted Ducks. Glamorgan Bird

Rept. 1984, 9-11.Owen, M., Atkinson-Willes, G.L. & Salmon, D.G.

(1986) Wildfowl in Great Britain (Second edition).Cambridge University Press, Cambridge.

Royal Society for the Protection of Birds. (1977)Inland waters of ornithological importance in Wales.R.S.P.B. Internal Rept. Newtown, Powys. 18pp.

Tuite, C.H., Hanson, P.R. & Owen, M. (1984) Someecological factors affecting winter wildfowl dis-tribution in inland waters in England and Wales,and the influence of water based recreation. J.appl. Ecol. 21, 41-62.

Tuite, C.H., Owen, M. & Paynter, D. (1983) Interac-tion between wildfowl and recreation at LlangorseLake and Talybont Reservoir, South Wales.Wildfowl, 34, 48-63.

(MS received 9 November 1986; revised MS received 14 April 1987)

Dow

nloa

ded

by [

213.

122.

178.

99]

at 1

8:35

21

Mar

ch 2

014