DEVELOPMENT OF INDIVIDUAL-BASED MODELS IN SHOREBIRDS

High Water MarkLow Water MarkWASH1972-75Intertidal mudflats and sandflatsProposed fresh-water reservoir

HOW WE THOUGHT ABOUT THE ISSUEDecreasing area Increasing densityIncreasing competitionPercentage starving over winter

EMPIRICAL APPROACH?Increasing densityPercentage starving over winterXX X X X X X X XX??(i) It would be technically very difficult 0 0 0 0 0 00 0 0

Increasing densityPercentage starving over winterHabitat of above average quality is lostHabitat of average quality is lost..and (ii) the function would probably change after habitat loss

THE QUESTION: HOW TO DESCRIBE THE DENSITY-DEPENDENT STARVATION FUNCTION - NOT ONLY AS IT IS AT PRESENT BUT HOW IT WOULD BE IF THE FEEDING ENVIRONMENT WAS CHANGED BY:Habitat loss Disturbance ShellfishingSea-level rise Mitigation measuresetc etc

EVENTUAL ANSWER: develop and test individual-based models using oystercatchers eating mussels on the Exe estuary

MUSSELSLOCAL ISSUE: WOULD HARVESTING MUSSELS AFFECT THE BIRDS?

NO EFFECT EFFECTIncreasing harvest/Decreasing food supply Percentage starving

Before After

DEVELOPMENT OF THE MODEL1976-1996Field work on interference and exploitation competition between oystercatchers for mussels

HOW THE MODEL WORKSMORE DETAILS AT:http://www.dorset.ceh.ac.uk/shorebirds/

Each bird decides each tide where, when and on what prey species it is best to feedhttp://www.dorset.ceh.ac.uk/shorebirds/

Each of the three displaced birds will choose the next best place in which to feedPRINCIPLE: birds in model use optimality decision rules (= fitness maximising) to decide how to respond to a change in their feeding environment just as real birds do

Calibration period for overwinter mortality of adult mussel-feeding oystercatchers on the Exe

Sept 1976 Mar 1980

MORE NATURAL HISTORY WAS NEEDED: eg. feeding in fields over high tide

Predicted (retrospective) and observed increase in mortality 1980 - 1999Calibration period:

CONCLUSION

Winter mortality was density-dependent and the model postdicted it quite well

NO LONGER SO!Applying the model to species other than Oystercatchers: some say that they take too long to parameteriseThe models can usually be built, tested and applied within the time typically taken to conduct an EIA: i.e. 1 3 years

Bird energetics Prey energy content Functional responses Interference functions Food supply, exposure time, weather Human activities eg. fisheryObtained for the site being modelledBuilt into model allometric functionsMODELS CAN NOW BE BUILT AND TESTED VERY QUICKLY AS MOST PARAMETERS ARE IN THE LITERATURE:

Applications to other species: whatwe need to know

Bird energetics Prey energy content Functional response Interference function Food supply, exposure time and weatherAPPLICATION TO OTHER SPECIES - 1

Functional responses of oystercatchers eating musselsA

Chart2

1.303330.0259768502

1.796670.0514028388

1.710.1006708652

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1.91.6584876327

2.203331.7703009661

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2.3693121054

2.3800498379

2.3872625606

2.3924413284

2.3963401736

2.3993814053

2.4018199543

Data

Fit

Biomass density of mussels > 30mm long(gAFDM/sq m)

Intake rate (mgAFDM/s)

Sheet1

vh=2 dh=1 st=0Site AFDM IR (mgAFDM/s)Days since August 1stMussels >30mm per sq.mSite biomass >30mm (gAFDM30mm (gAFDM/sqm)c6c7fitsc6c7residsc2c5fitsc2c5residsc2c4fitsc2c4residsFMFitBiomc2c5fitFitNumberc2c4fit

01.63333144.226.314.21.5633312.811.6751753361-0.11184533611.60292477030.03040522971.638729524-0.00539952400.11.60291889720.11.638729524

01.70333192.688.42721.8157.1971.73216208640.07783791361.60292480380.10040519621.6387295240.06460047600.21.60292185460.21.638729524

01.34667222361.3120.71.93667172.51.74360420310.19306579691.6029248071-0.25625480711.638729524-0.29205952400.41.60292333330.41.638729524

01.45333226415.3121.81.92157.31.74305228350.17694771651.6029248071-0.14959480711.638729524-0.18539952400.61.60292382620.61.638729524

02.0186.3274.9127.92.03333129.61.74171499470.29161500531.60292480740.40707519261.6387295240.37127047600.81.60292407270.81.638729524

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01.76667115279.8155.71.75158.51.74309969110.00690030891.60292480820.16374519181.6387295240.127940476031.602924614831.638729524

01.84118.8260.7166.31.563331371.7421249667-0.17879496671.60292480840.23707519161.6387295240.201270476041.602924664141.638729524

01.5433392.9406.8188.81.773332141.74471288960.02861711041.6029248089-0.05959480891.638729524-0.095399524051.602924693751.638729524

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11.94667142.24591452.62333177.92.39645467390.22687532612.2789065281-0.33223652812.3195753292-0.37290532920751.6029248041751.638729524

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12.26667104.6412.5184.22.69333212.32.41445853030.27887146972.3083089522-0.04163895222.3135251163-0.04685511630851.602924805851.638729524

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12.47333154.9858.9304.22.42297.12.4415336094-0.02153360942.3525992450.1207307552.34490334620.12842665380951.6029248058951.638729524

12.5134673.8306.62.74333337.62.44978419050.29354580952.3531417580.1468582422.33685768640.163142313601001.60292480612001.638729524

12.5153.3669.1319.92.60667318.12.44606705190.16060294812.35600477390.15399522612.33659637190.173403628102001.6029248094001.638729524

12.81101.4566.2367.82.44667323.82.447198712-0.0005287122.36464222110.44535777892.3298085560.48019144403001.602924816001.638729524

13.03667153768.8397.12.70333351.22.4521381490.2511918512.36892185320.66774814682.34146418190.695205818104001.60292481058001.638729524

12.29667159.61011.1553.22.01552.12.4736079268-0.46360792682.3842062977-0.08753629772.3493355486-0.052665548605001.602924810810001.638729524

11.9194.71362.5667.82.15333761.52.4840629876-0.33073298762.3909407601-0.49094076012.3558163582-0.455816358206001.60292481112001.638729524

12.20333155.41438.9685.71.77688.42.4811269455-0.71112694552.3917920921-0.18846209212.3568096202-0.153479620207001.602924811214001.638729524

11.51190.71452.5796.31.51787.72.4849840749-0.97498407492.3962131621-0.88621316212.3569755572-0.846975557208001.602924811316001.638729524

13.12333151.81888.9869.13.07333884.12.48790766670.58542233332.39851559590.72481440412.36103895660.762291043409001.602924811318001.638729524

22.27146.914.29.442.136677.751.81105407780.32561592221.99980396820.27019603182.00000000120.2699999988010001.602924811420001.638729524

21.41667104.726.314.21.3533312.831.9111934414-0.55786344141.9998039778-0.58313397782.0000000015-0.583330001510.10.02597685020.10.0215855242

22.40667147.422.520.71.7814.431.9292381927-0.14923819271.99980398390.40686601612.00000000150.406669998510.20.05140283880.20.0427821617

21.8566711052.856.32.6633336.92.02248071750.64084928251.9998039922-0.14313399222.0000000018-0.143330001810.40.10067086520.40.0840500704

21.93194.888.42721.81557.1972.0450046561-0.23000465611.9998039932-0.06980399322.0000000019-0.070000001910.60.14793436510.60.1238827223

21.69333188.1273.799.82.32667152.12.07116966360.25550033641.9998039943-0.30647399432.000000002-0.30667000210.80.19331323420.80.1623537129

22.84*411.9263.32.31217.52.0759831770.2340168231.9998039960.8401960042.0000000020.839999998110.236917993410.1995316904

22.12105.4462342.61.75275.42.0783449069-0.32834490691.99980399620.12019600382.0000000020.119999998120.431647310320.3681310932

21.83333143.71011.1553.21.90333552.12.0828058563-0.17947585631.9998039965-0.16647399652.000000002-0.166670002130.594535621430.5124736692

21.641851362.5667.81.91761.52.0840301207-0.17403012071.9998039966-0.35980399662.000000002-0.360000002140.732802370240.6374429526

22.29333150.11438.9685.72.28667688.42.08368721350.20298278651.99980399660.29352600342.0000000020.293329998150.851637834650.7466940076

21.77667186.11452.5796.31.9787.72.0841375528-0.18413755281.9998039967-0.22313399672.000000002-0.223330002160.954869241960.8430168555

21.90333145.31888.9869.12.23884.12.08447809580.14552190421.9998039967-0.09647399672.000000002-0.096670002171.045380650170.9285780906

181.125386626881.0050857978

191.196615858491.0739047487

1101.2604374753101.1361385296

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1251.7703009661251.6536114961

1301.8536132869301.7417572713

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1602.1007753086602.0095557361

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1702.1415693476702.054686

1752.1583340465752.0733108259

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1852.1865261446852.1047342231

1902.1984914081902.118110216

1952.2093087192952.1302231455

11002.21913571842002.2519217914

12002.31704469964002.3116651852

13002.35162958396002.3322903749

14002.36931210548002.3427416051

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20.11.99980127730.11.999999882

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20.61.99980354370.61.999999982

20.81.9998036570.81.999999987

211.99980372511.99999999

221.99980386121.999999996

231.999803906331.999999998

241.99980392941.999999999

251.999803942651.9999999996

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271.999803958172.0000000003

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Sheet1

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Data

Fit

Biomass density of mussels > 30mm long(gAFDM/sq m)

Intake rate (mgAFDM/s)

Sheet2

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(b)

Data

Fit

Biomass density of mussels > 30mm long(gAFDM/sq m)

Intake rate (mgAFDM/s)

Sheet3

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(c)

Data

Fit

Biomass density of mussels > 30mm long(gAFDM/sq m)

Intake rate (mgAFDM/s)

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(a)

Data

Fit

Numerical density of mussels > 30mm long(no./sq m)

Intake rate (mgAFDM/s)

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(b)

Data

Fit

Numerical density of mussels > 30mm long(no./sq m)

Intake rate (mgAFDM/s)

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(c)

Data

Fit

Numerical density of mussels > 30mm long(no./sq m)

Intake rate (mgAFDM/s)

Predicting the asymptote of the functional response in shorebirds from 486 spot estimates of intake rate

Intake rate (i.e. asymptote) depends on:

Body mass of bird Mass of prey

R2 = 75.5% (log transformed data)

Curlew sandpiperKnotRedshankGrey ploverCurlewOystercatcherTEST OF PREDICTIONS FOR ASYMPTOTEy = x

Test of predictions for asymptotes

Observed asymptotes

Predicted asymptote (mgAFDM/s)

Applications to other species: whatwe need to know

Bird energetics Prey energy content Functional response Interference function Food supply, exposure time and weatherAPPLICATION TO OTHER SPECIES - 2

Interference function for stabbing oystercatchers: intake rate (mgAFDM/s) against density of birds

Prey sizeBird sizeHandling timeRunning speedPredicting interference parameters from Stillmans state-dependent behavioural model Interference function

Test of Stillmans behaviour-based model: cockle-eating oystercatchers on the baie de Somme

Predicted and observed interference functions in cereal-feeding cranes. Predictions from Stillmans model. Data: L. M. Bautista, J. C. Alonso & J. Alonso.

Applications to other species: whatwe need to know

Bird energetics Prey energy content Functional response Interference function Food supply, exposure time and weather Human activitiesAPPLICATION TO OTHER SPECIES and SYSTEMS What do we need to measure?

RECENT DEVELOPMENTS Risk of being killed by predators: trade-off between foraging and safety

Multi-species models:up to 9 species in one estuary

Multi-site models:several estuaries across several countries

SOME EXAMPLES OF RECENT APPLICATIONS IN SHOREBIRDSOystercatchersShellfishing, disturbance 8 estuaries 4 countries

Other shorebirds: Disturbance, habitat loss,12 speciesbait-digging, Spartina 10 estuariesencroachment, hunting 4 countriessea-level rise, monitoringestuary quality, mitigation

WildfowlHunting, farming, wind4 speciesfarms >25 estuaries 4 countriesBlue - examples used here

1. OYSTERCATCHERS and SHELLFISHINGHow much shellfish should we leave after shellfish harvesting to ensure that the birds fitness is not reduced?

EXE: oystercatchers eating musselsPrey biomass/bird left over after shellfish harvesting

Mortality Fail to reach target body mass

%%With disturbanceNo disturbanceRange 1976-19990 55 110 165 kg/bird0 55 110 165 kg/bird

CRITICAL THRESHOLD or ECOLOGICAL FOOD REQUIREMENT (food/bird)Critical threshold = 61kgAFDM/birdPercentage starvingEXE ESTUARY

Ecological requirement Multiples of (threshold)kgAFDM/bird Exe Mussel 61 9.13 7.74

Bangor Mussel 50 9.62 6.42 Burry Cockle 44 9.27 5.58

Wash Cockle 20 7.93 2.52

Somme Cockle 33 6.56 5.03

* Taking into account wastage of shellfish flesh (stolen from the birds; winter loss of flesh from the shellfish themselves) Critical threshold or Ecological requirement (E) Physiological requirement (P)kgAFDM/bird kgAFDM/bird * E/P

Because of interference and individual variation in efficiency, just leaving enough shellfish for oystercatchers after harvesting is not enough to ensure they survive in good condition - as Dutch experience confirmsCONCLUSION: ecological requirements are 3-8 times larger than physiological requirements

2.DISTURBANCE: people and raptors

SOMME : DISTURBANCE IN OYSTERCATCHERSACTUAL AMOUNT:1994-951996-971997-981997-98 including raptors

DISTURBANCES PER HOURPERCENTAGE STARVINGSevere winterMild winter

POLICY ADVICE:

IN SEVERE WINTERS, DO NOT ALLOW OYSTERCATCHERS TO BE DISTURBEDBUTIN MILD WINTERS, THEY CAN BE DISTURBED but only up to about ONE disturbance/hour - including raptors

3.SPREAD OF THE GRASS Spartina ON TO UPSHORE MUDFLATS

SOMME: Spartina spreads downshore at 20-40m per year into the feeding areas of dunlin

High Water mark

0ha 100ha 200ha 0 years 5 years 10 yearsDunlin with Spartina spreading at 40m/yearMortality over winter %POLICY ADVICE: get rid of it!

4.HABITAT LOSS and MITIGATION for it

English ChannelR. SeinePORT (105 ha of mudflats)MITIGATION: Convert reed beds into 50 or 100 ha of mudflatsHigh Water MarkPORT DEVELOPMENT: SEINE ESTUARY

5%

0%Mortality %Before PortAfter Port50ha mitigation 100ha mitigationFailing to reach 75% body mass %15%0%DUNLIN in SEINE ESTUARY: Port development and proposed mitigationScenarioScenario

POLICY ADVICE:

The mitigation is needed but should be 100ha if it is to fully effective

TESTS of model predictions:

Distribution and prey choiceImpact on food supplyHours feeding per daylight tide4Mortality of oystercatchers

CONFIDENCE IN MODEL PREDICTIONS?

Percentage of birds1. DISTRIBUTION and PREY CHOICE: proportion of birds eating cockles or mussels in the Burry InletObserved = Predicted =

2. IMPACT ON FOOD: Mussel consumption by oystercatchers on the ExeObservedPredictedPercentExclosure Survey

Chart3

12.1

12.1

11.4

Deadbirds

BirdBirdName$AgeClFeedMethFightAbPropDomPatTypeIFIRBirdAliveIntDay1FESTI

103+S3113.020.13021109.331000.08354350-0.2668136238

132S2117.650.1765152.451300.058772565-0.2052213001

143+S3131.590.3159189.19140-0.015806585-0.1230982019

163+S3132.340.3234182.76160-0.0198191250.0411479945

252S2139.340.3934177.32250-0.0572691450.1232710927

293+S3114.530.14531122.522900.0754645

362S210.850.0085184.883600.1486525

423+S3115.120.1512197.114200.072308

522S216.470.06471101.255200.1185855

553+S310.240.0024186.245500.151916

563+S319.630.09631100.085600.1016795

573+S310.90.009183.25700.148385

593+S312.650.0265187.955900.1390225

623+S3124.120.2412180.296200.024158

701S1134.580.3458185.42700-0.031803

773+S3124.250.24251105.457700.0234625

783+S3132.960.3296195.41780-0.023136

793+S317.620.07621129.37900.112433

802S2111.530.11531100.478000.0915145

923+S3143.340.4334178.92920-0.078669

942S2143.830.4383172.77940-0.0812905

953+S3145.330.4533186.64950-0.0893155

1042S2137.70.377173.411040-0.048495

1073+S319.040.09041103.410700.104836

1253+S313.880.0388190.3412500.132442

1272S2122.240.22241105.1812700.034216

1283+S314.170.0417189.5712800.1308905

1343+S318.160.0816195.9113400.109544

1403+S3113.120.13121108.0214000.083008

1443+S3138.120.3812168.121440-0.050742

1473+S3143.920.4392190.951470-0.081772

1503+S315.560.0556193.7115000.123454

1523+S313.020.0302172.0515200.137043

1633+S319.370.09371104.9316300.1030705

1703+S3129.360.2936189.571700-0.003876

1733+S31530.53176.011730-0.13035

1792S2115.340.15341117.7817900.071131

1883+S3114.130.14131102.2518800.0776045

1893+S3120.110.20111105.318900.0456115

1963+S313.620.0362197.8119600.133833

1993+S3141.540.4154183.171990-0.069039

2103+S3114.150.14151106.9821000.0774975

2193+S3130.170.3017181.662190-0.0082095

2343+S3146.210.4621172.862340-0.0940235

2411S111.760.01761106.7824100.143784

2423+S3140.150.4015159.262420-0.0616025

2453+S319.480.0948183.7224500.102482

2463+S3121.070.21071100.9124600.0404755

2511S1122.330.2233110525100.0337345

2603+S3114.80.1481101.0126000.07402

2653+S311.380.01381103.9226500.145817

2692S2119.920.1992183.0726900.046628

2813+S3113.380.1338194.9228100.081617

2901S1124.330.2433189.6529000.0230345

2943+S3129.690.2969176.952940-0.0056415

2992S2136.420.3642189.472990-0.041647

3003+S3110.80.1081112.9630000.09542

3103+S3115.650.1565172.0731000.0694725

3173+S3124.280.2428188.2231700.023302

3183+S315.860.05861136.4431800.121849

3303+S3114.150.14151107.8333000.0774975

3512S2111.430.1143194.5935100.0920495

3552S2131.780.3178173.683550-0.016823

3883+S3110.770.10771104.0138800.0955805

3932S2143.060.4306181.813930-0.077171

3983+S3130.170.30171113.783980-0.0082095

4093+S3135.480.3548189.124090-0.036618

4133+S3111.40.1141105.2441300.09221

4223+S3119.960.1996192.5842200.046414

4293+S313.860.0386190.3642900.132549

4303+S316.740.06741116.8243000.117141

4352S2129.280.2928180.84350-0.003448

4373+S317.890.0789192.0743700.1109885

4503+S3131.110.3111192.254500-0.0132385

4623+S3137.530.3753190.164620-0.0475855

4663+S3121.720.2172197.3346600.036998

4693+S3156.120.5612165.154690-0.147042

4873+S3125.890.25891104.3648700.0146885

4892S2124.390.2439164.148900.0227135

4923+S3120.880.20881101.949200.041492

4941S1110.650.1065189.9649400.0962225

4973+S3139.760.3976180.134970-0.059516

5003+S319.230.0923181.8650000.1038195

13+S3171.520.7152199.2511-0.229432

62S2136.930.36931109.2161-0.0443755

83+S3161.650.6165183.1881-0.1766275

122S2166.170.6617194.49121-0.2008095

193+S3129.630.29631120.65191-0.0053205

202S2156.810.56811114.96201-0.1507335

213+S3176.420.76421122.28211-0.255647

223+S3150.90.5091117.62221-0.119115

243+S3145.610.45611115.16241-0.0908135

303+S3170.960.7096190.9301-0.226436

323+S3160.420.6042195.5321-0.170047

343+S3124.870.24871126.173410.0201455

353+S3188.850.88851109.98351-0.3221475

373+S3192.750.92751107.15371-0.3430125

433+S3146.580.46581123.31431-0.096003

453+S3176.070.76071116.32451-0.2537745

493+S3184.480.84481102.03491-0.298768

513+S3132.960.32961100.92511-0.023136

613+S3164.670.64671101.92611-0.1927845

643+S3196.960.96961134.31641-0.365536

652S215.150.0515196.046510.1256475

663+S3168.760.6876181.19661-0.214666

713+S3174.590.74591100.08711-0.2458565

723+S3124.190.24191119.387210.0237835

863+S3192.010.92011114.86861-0.3390535

883+S3194.380.94381106.11881-0.351733

913+S3197.20.9721106.78911-0.36682

1033+S3144.640.44641106.761031-0.085624

1053+S3155.520.5552192.451051-0.143832

1082S2157.30.5731121.931081-0.153355

1093+S3177.290.77291106.111091-0.2603015

1103+S3164.490.64491110.71101-0.1918215

1133+S3195.580.9558177.161131-0.358153

1143+S3178.440.7844195.921141-0.266454

1193+S3172.280.72281105.91191-0.233498

1203+S3162.850.62851103.011201-0.1830475

1223+S3144.80.448178.731221-0.08648

1243+S3146.890.4689180.81241-0.0976615

1303+S3187.410.8741187.931301-0.3144435

1313+S3193.580.9358177.291311-0.347453

1323+S3178.450.7845179.81321-0.2665075

1353+S3139.760.3976170.31351-0.059516

1383+S3135.820.35821102.191381-0.038437

1393+S3125.730.25731127.0713910.0155445

1453+S3123.880.23881138.3414510.025442

1573+S3157.980.57981117.281571-0.156993

1663+S3167.510.6751187.231661-0.2079785

1683+S3187.460.8746175.291681-0.314711

1693+S3168.220.68221113.151691-0.211777

1713+S31990.991101.671711-0.37645

1783+S3138.230.38231101.531781-0.0513305

1803+S3135.120.35121114.811801-0.034692

1823+S3177.450.7745196.591821-0.2611575

1832S2143.950.4395191.211831-0.0819325

1863+S3160.520.6052192.851861-0.170582

1953+S3177.620.77621115.341951-0.262067

1973+S3162.030.62031113.971971-0.1786605

2013+S31780.78185.892011-0.2641

2073+S3131.740.31741119.962071-0.016609

2143+S3182.980.8298192.732141-0.290743

2163+S3175.450.75451110.152161-0.2504575

2183+S3199.940.9994186.252181-0.381479

2203+S3135.040.35041108.172201-0.034264

2242S2144.750.4475179.482241-0.0862125

2273+S3123.020.23021122.422710.030043

2333+S3187.590.8759198.922331-0.3154065

2353+S3164.110.64111112.362351-0.1897885

2383+S3166.990.66991108.412381-0.2051965

2393+S3182.40.8241119.982391-0.28764

2433+S3125.160.25161118.1924310.018594

2443+S3176.770.7677198.282441-0.2575195

2473+S3194.410.94411106.432471-0.3518935

2543+S3191.060.91061105.952541-0.333971

2573+S3196.460.96461131.912571-0.362861

2593+S3195.30.9531107.842591-0.356655

2613+S3152.060.5206175.062611-0.125321

2623+S3177.580.77581114.172621-0.261853

2661S1151.530.5153196.442661-0.1224855

2673+S3142.860.4286196.762671-0.076101

2733+S3178.790.7879198.22731-0.2683265

2743+S3187.030.87031115.762741-0.3124105

2793+S3167.10.6711109.152791-0.205785

2833+S3170.420.7042199.052831-0.223547

2843+S3182.010.82011105.272841-0.2855535

2871S1134.760.34761121.072871-0.032766

3022S2151.820.51821106.693021-0.124037

3033+S3178.350.7835195.223031-0.2659725

3043+S3188.250.8825187.183041-0.3189375

3063+S3150.60.506194.763061-0.11751

3113+S3189.810.89811114.453111-0.3272835

3193+S3171.440.7144199.553191-0.229004

3203+S3134.110.34111100.73201-0.0292885

3253+S3175.080.7508187.263251-0.248478

3293+S3184.170.8417172.453291-0.2971095

3353+S3166.80.6681118.473351-0.20418

3423+S31950.95187.853421-0.35505

3453+S3179.010.7901195.823451-0.2695035

3463+S317.510.0751199.6834610.1130215

3473+S3156.710.56711111.273471-0.1501985

3493+S3151.840.51841110.973491-0.124144

3523+S3157.940.5794188.73521-0.156779

3533+S3166.940.6694180.263531-0.204929

3603+S3167.440.67441103.63601-0.207604

3622S2156.970.5697186.723621-0.1515895

3652S2120.040.20041111.2236510.045986

3673+S3186.010.86011125.533671-0.3069535

3743+S3152.610.52611120.483741-0.1282635

3783+S3144.630.4463190.513781-0.0855705

3791S1146.470.46471125.33791-0.0954145

3833+S3155.890.5589189.743831-0.1458115

3913+S3193.20.9321103.553911-0.34542

3923+S3135.990.35991117.963921-0.0393465

4013+S3151.390.51391108.34011-0.1217365

4023+S3174.410.7441193.244021-0.2448935

4063+S3112.420.1242198.840610.086753

4103+S3132.440.32441115.144101-0.020354

4113+S3136.70.3671116.494111-0.043145

4143+S3153.990.5399193.694141-0.1356465

4153+S3186.720.8672187.394151-0.310752

4173+S3152.470.5247195.594171-0.1275145

4233+S3191.430.91431115.484231-0.3359505

4243+S3133.520.33521103.634241-0.026132

4273+S3186.880.8688175.424271-0.311608

4323+S3198.270.9827177.854321-0.3725445

4363+S3163.430.6343195.514361-0.1861505

4383+S3123.350.23351119.9643810.0282775

4393+S3162.530.62531116.554391-0.1813355

4403+S3184.520.8452188.254401-0.298982

4443+S3164.750.64751118.924441-0.1932125

4453+S3158.440.5844196.614451-0.159454

4553+S3168.040.6804194.614551-0.210814

4573+S3168.570.68571103.454571-0.2136495

4603+S3141.90.4191112.464601-0.070965

4682S2133.410.33411120.754681-0.0255435

4713+S3190.350.9035197.964711-0.3301725

4743+S3193.350.93351109.774741-0.3462225

4763+S3174.260.7426175.624761-0.244091

4793+S3133.480.33481102.44791-0.025918

4803+S3168.410.68411109.594801-0.2127935

4813+S3196.530.9653198.84811-0.3632355

4883+S3142.480.4248196.754881-0.074068

4933+S3154.360.5436168.164931-0.137626

Deadbirds

0.083543-0.229432-0.2668136238

0.0587725-0.0443755-0.2052213001

-0.0158065-0.1766275-0.1230982019

-0.019819-0.20080950.0411479945

-0.057269-0.00532050.1232710927

0.0754645-0.1507335

0.1486525-0.255647

0.072308-0.119115

0.1185855-0.0908135

0.151916-0.226436

0.1016795-0.170047

0.1483850.0201455

0.1390225-0.3221475

0.024158-0.3430125

-0.031803-0.096003

0.0234625-0.2537745

-0.023136-0.298768

0.112433-0.023136

0.0915145-0.1927845

-0.078669-0.365536

-0.08129050.1256475

-0.0893155-0.214666

-0.048495-0.2458565

0.1048360.0237835

0.132442-0.3390535

0.034216-0.351733

0.1308905-0.36682

0.109544-0.085624

0.083008-0.143832

-0.050742-0.153355

-0.081772-0.2603015

0.123454-0.1918215

0.137043-0.358153

0.1030705-0.266454

-0.003876-0.233498

-0.13035-0.1830475

0.071131-0.08648

0.0776045-0.0976615

0.0456115-0.3144435

0.133833-0.347453

-0.069039-0.2665075

0.0774975-0.059516

-0.0082095-0.038437

-0.09402350.0155445

0.1437840.025442

-0.0616025-0.156993

0.102482-0.2079785

0.0404755-0.314711

0.0337345-0.211777

0.07402-0.37645

0.145817-0.0513305

0.046628-0.034692

0.081617-0.2611575

0.0230345-0.0819325

-0.0056415-0.170582

-0.041647-0.262067

0.09542-0.1786605

0.0694725-0.2641

0.023302-0.016609

0.121849-0.290743

0.0774975-0.2504575

0.0920495-0.381479

-0.016823-0.034264

0.0955805-0.0862125

-0.0771710.030043

-0.0082095-0.3154065

-0.036618-0.1897885

0.09221-0.2051965

0.046414-0.28764

0.1325490.018594

0.117141-0.2575195

-0.003448-0.3518935

0.1109885-0.333971

-0.0132385-0.362861

-0.0475855-0.356655

0.036998-0.125321

-0.147042-0.261853

0.0146885-0.1224855

0.0227135-0.076101

0.041492-0.2683265

0.0962225-0.3124105

-0.059516-0.205785

0.1038195-0.223547

-0.2855535

-0.032766

-0.124037

-0.2659725

-0.3189375

-0.11751

-0.3272835

-0.229004

-0.0292885

-0.248478

-0.2971095

-0.20418

-0.35505

-0.2695035

0.1130215

-0.1501985

-0.124144

-0.156779

-0.204929

-0.207604

-0.1515895

0.045986

-0.3069535

-0.1282635

-0.0855705

-0.0954145

-0.1458115

-0.34542

-0.0393465

-0.1217365

-0.2448935

0.086753

-0.020354

-0.043145

-0.1356465

-0.310752

-0.1275145

-0.3359505

-0.026132

-0.311608

-0.3725445

-0.1861505

0.0282775

-0.1813355

-0.298982

-0.1932125

-0.159454

-0.210814

-0.2136495

-0.070965

-0.0255435

-0.3301725

-0.3462225

-0.244091

-0.025918

-0.2127935

-0.3632355

-0.074068

-0.137626

Dead

Alive

Discriminant

Feeding Efficiency (%)

STI at the start of the winter

MusselsLost

Exclosures12.1

Estuary-wide12.1

Model prediction11.4

MusselsLost

0

0

0

Percent

Percent of mussels lost over the winter

DisturbanceCosts

NoDist%dead

500499.33333333330.1333333333

1000995.66666666670.4333333333

15001459.66666666672.6888888889

20001882.66666666675.8666666667

3500301014

5000385023

75004693.333333333337.4222222222

100005153.333333333348.4666666667

&R&14&D

DisturbanceCosts

00.13333333330.41.066666666711.0666666667

01.22.33333333337.320.6666666667

04.46.9113.8230.5333333333

07.911.320.8554.3766666667

015.236666666723.6240.096666666763.6666666667

027.733333333337.653.066666666775.3766666667

041.4753.066666666765.1180.0333333333

053.163.566666666772.80

No Disturbance

10% without costs

10% with costs

50% without costs

50% with costs

Initial number of birds

Percent mortality

Costs of disturbance

NoDepletion

0.13333333330.13333333330.13333333330.20.06666666670.40.41

1.13333333330.43333333331.03333333330.93333333331.43333333332.33333333333.97

4.62.68888888894.37666666673.97666666673.75666666676.9112.58

7.98333333335.86666666677.48333333337.257.516666666711.318.8266666667

17.33333333331415.813333333317.523333333315.8123.6240.0566666667

29.33333333332326.266666666725.266666666724.837.660.05

45.333333333337.422222222242.356666666741.641.823333333353.066666666786.8

55.848.466666666753.352.566666666751.033333333363.566666666798.9766666667

Big

NoDist

BigNC

Best10

Worst10

Small

SmallNC

Initial number of birds

Percent mortality

10% of area disturbed or lost

0.66666666670.13333333330.80.66666666670.83.26666666671.0666666667

5.63333333330.43333333333.75.93333333335.611.06666666677.3

12.66666666672.68888888899.513333333312.5810.846666666720.666666666713.82

18.93333333335.866666666714.7518.883333333316.083333333330.533333333320.85

36.28333333331429.6238.7633.426666666754.376666666740.0966666667

49.62340.450.733333333343.463.666666666753.0666666667

62.843333333337.422222222257.3866.933333333360.6275.376666666765.11

69.733333333348.466666666766.375.066666666775.433333333380.033333333372.8

Big

NoDist

BigNC

Best50

Worst50

Small

SmallNC

Initial number of birds

Percent mortality

50% of area disturbed or lost

FileExtAgeFM% in fieldsProportion of time feedingMean mass loss% MortalityInitial NFinal NULDepULNoDep

00a001AllAll4.410.5410.010.250049900.0666666667

00b001AllAll15.230.6420.860.310009970.83333333330.8333333333

00c001AllAll23.20.7223.021.07150014842.88888888892.2444444444

00d001AllAll32.160.7847.442.4200019526.16666666675.3833333333

0.00E+00AllAll58.150.8815.186.573500327015.714285714313.9047619048

00f001AllAll69.090.90817.0911.65000442026.733333333322.8666666667

00g001AllAll78.460.95823.217.077500622046.088888888939.6888888889

00h001AllAll82.240.97243.0623.510000765061.066666666750.8333333333

00i001AllAll82.890.97657.7130.72125008660

00j001AllAll84.550.98173.8237.93150009310

00k001AllAll85.640.982108.0260.35200007930

00l001AllAll88.550.992140.5486.43300004070

500499.6666666667

991.6666666667991.6666666667

1456.66666666671466.3333333333

1876.66666666671892.3333333333

29503013.3333333333

3663.33333333333856.6666666667

4043.33333333334523.3333333333

3893.33333333334916.6666666667

000

000

000

000

000

000

000

000

0

0

0

0

No decline

Depletion

No Depletion

Number of oystercatchers in September

Percent starving by March

500

991.6666666667

1456.6666666667

1876.6666666667

2950

3663.3333333333

4043.3333333333

3893.3333333333

Initial N

3. HOURS FEEDING: oystercatcher (open symbols), little stint, sanderling, dunlin, curlew. Exe estuary, Burry Inlet, Bangor flats, Seine estuary; Cadiz bay.

4. MORTALITY (from autumn to spring) % (se) % (se) N* Predicted ObservedWash*: shellfish abundant 4 0 1.4 (0.3) Wash*: shellfish scarce 3 15.9(4.9) 16.8 (6.4)Exe: low bird density 3 2.3(0.4) 1.7 (0.3)Exe: high bird density 3 3.8(0.1) 3.5 (1.0)Burry Inlet: cockles and mussels: 1 0 ?Bangor mussel beds: 1 0 ?

* Number of years* Assuming upshore intake rates same as on Exe

Basic principles upon which the models are built

1 Well-established behavioural decision rules so that animals in the model are likely to respond to environmental changes as real ones would

2 Include some natural history details because these adaptations can be critical to bird survival

3Calibration may be needed - because we don't know every parameter value precisely

4 Validation of mortality predictions otherwise predictions should not be believed

http://www.dorset.ceh.ac.uk/shorebirds/FIND OUT MORE ON:Co-workers:Richard Stillman Richard Caldow Sarah Durell Andy West

EVEN A SMALL DECREASE IN MORTALITY COULD BE VERY IMPORTANT!!

Equilibrium population size..population size is very sensitive to mortality rate, irrespective of the density-dependence on the breeding groundsWeak density dependence in summer Oystercatcher rangeStrong density dependence in summer

Chart1

161.96473.868

56.34295.504

29.5128.314

18.2360.596

0.5960.102

0.1020.07

0.07

bT = 0.3

bT = 0.7

Adult annual mortality (%)

Sheet1

Adult mortality (%)Stable Population Size

bT = 0.3bT = 0.7

214338641619601433.864161.96

447386856342473.86856.342

6955042951095.50429.51

8283141823628.31418.236

105965960.5960.596

121021020.1020.102

1470700.070.07

1624240.0240.024

Sheet1

00

00

00

00

00

00

0

bT = 0.3

bT = 0.7

Adult mortality (%)

Equilibrium Population Size (000s)

Sheet2

Sheet3

The model had to be able to predict FITNESSMortality rate over the winterBUT ALSO2Fat reserves in springPRINCIPLE: If the FITNESS of the birds in the non-breeding season is maintained, the quality of the estuary for the birds is being maintained