waders and their estuarine food supplies - Vlaams Instituut voor de ...

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No Spet us 214 Nereis 215 Nereis 716 Nereis 217 Nereis 218 Patella 219 Scmbiailiuiti 770 V. ..'/.,. iiluriii 771 -. roMcularia IM „/„r;„ ',l>i, ul,ir in 227 Senihiiuhmu :,iiuliirui 229 Semhieulurru 7 ii i v, „ ihicnluriii 231 Scrobicularia 232 Scrvbiiulunu 233 Si nihil llliinu 234 Scrobicularia 215 (Tpiua 2.17 77r.«/a 238 Tinu/a 239 77/)u/a 240 77/iu/a 241 ///'„/„ :42 71/.,./,, 241 /);.„;„ 244 /,,.„/„ 245 7if.u/„ 246 7i>u/a 247 /y.,,/a 248 7i/««a 749 lipulu :5(i /i/.i,/,, 251 7!/>i
Notes lo appendix: PREY PROFITABILITY AND INTAKE RATE 1: \H)\\ ol Anuiliir.i taken was 3.1IK) me. bill 56'. of the prey could not he eaten completely, due to klepiopamsjtism hv oilier hird species. Since Swennen estimated thai 74: in these case-, .ui overage. 10% of the flesh was eaten, the weighl of the average prey laken was estimated to be 1637 76-77: mg. 2-3: Since the birds also look Maennia and Wren, a selection was mode of 5 nun periods during which AjWTtiCoUi was the dominant prey. 4: Cockle height ha- been convened lo lengih using Table 5 81: m /wails i 19911. ash assumed to he 20 r ' (being ihe average winter level: Zwarts 1991). 5: The intake rale varied between 1.4 and 2.2. mg s ' during 82: six different winter months. The dala were pooled since the observation nine- were limned. 8-15: Since the birds also took Msiilus. a selection was made ,if 5 min periods with Cerastoderma as dominant prey. 83: 25: Feeding area was exposed 5 h during daylight in January: iiii-1- equivalent to 6.5 h per low water period. Goss-Custard (1977) noted lhat the avarage prey weight was overestimated since small prey were probably missed and flesh 85-87: also remained in ihe shell. 26-29: Ash assumed to be I3"3f in summer (being the average summer value; /.warts 19911 31: The flesh remaining in the -hell has been measured 94-112: (14.8% relative to lotal AFDW). 117-126 33-38: The same dala are given separately for individuals by Swennen etal. (1989). 127-132 52-54: Since the birds also took Tt/iula. a selection was made of 5 min period- .luring which eanhworms were Ihc dominant 134-161: prev. 55: It l- assumed lhat the bird- took ihe average prey present. 56: It i- assumed lhat the ash content i- 40 'he same area in later years; Blomert & Zwarts unpubl.). 57-64: Ash of Littorina in winter is assumed lo be 10% (Chambers & Milne 1979). 164-165 65-69: Since the birds also took Nereis, a selection was made of 5 min periods during which Macoma was ihe dominant prey- 70: Since the birds also took Cerastoderma. a selection was made of 5 min periods during which Macoma was the dominant prey. 167: 71-72: The estimation of the consumption per low water feeding period is based upon measuremenLs of the feeding rate in 182: colour-marked non-breeding birds (study 71) and breeding birds (study 72). but Ihc feeding activity and mean 184-191; prey weight were based on counls and prey collection, respectively, in which breeding and non-breeding birds could not be distinguished. That is why a calculation of the 209 low tide consumption |41 g AFDWi would be too high for ihe non-breeding, even if ihey remained 6 h on ihe feeding area, since presumably iheir feeding activity would be lower than for ihe breeding birds. Intake rate of captive birds averaged for two experimental conditions lera-ed and " A pair of individually marked Oystercatchers visited tidal mudflats adjacent lo their nesl during short feeding bouts: Studies 76 and 77 give ihe averages for Ihe week before and after eggs were laid, respectively: feeding role already given hy Hulscher (1982: Kig. 2" I Since the birds also took Macoma, a selection was made of 5 min periods during which Nereis was ihe dominant prey. The birds usually only look the siphon. This partial consumption did not cause an overcsliiiiation of the consumption, since the llc-li taken was estimated from Ihe si/e of the pieces of flesh extracted from the shell. The birds look small Mya in one jerk, taking Ihe siphon bul leaving o pan ol the body behind in the shell. When this was imitated in the laboratory 22', of Ihe llesh remained behind. Tin- was laken as a correction factor. Study 85 and 86 give same data as Body 87-93 averaged lor all months and split up for slabbers, dorsal and ventral hammerers. Iniake rales are given hv Boatea 11988). Exposure nine according li. Goss-Cusuud (unpubl.). details in Cayford (1988) Summary of Ihe data are published by Kns 11982). Ens & (ios-Cusiard 11984), Suiherland & Ens < 1987). Since the birds also took Cerastoderma. a selection was made of 5 min periods with Msiilus as dominant prey. The majority of the data arc given in Goss-Custard er al. 1984. Goss-Custard & Durell 1987 & 1988. The intake rate- were recalculated, however, from the actual AFDW/mussel length relationships measured mi the mussel bed. month and year in question, whereas ihe original paper gave siandardi/cd intakes rales Ash assumed io be 20'. in winter. Observations were restricted to 5 h around low water, and give according to Hepple-lon (1971) an overesiimation when exlrapolated to the extreme long exposure limes in October (stud) I64i. when the birds were less active al Ihe end of the feeding period. Hungry, captive Oystercatchers were offered shelled Mytilus. The llesh remaining in the shell has been measured (7.6% relative to lotal AFDW). The intake rates deviates Irom those orginally published (Zwarts & Dreni 19811. due to recalculation. Exposure lime of ihe musselbed in May was. as in the other months. 6-6.5 h. but the watched adults were breeding birds and
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WADERS AND THEIR ESTUARINE FOOD SUP
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plia^ohi. WADERS AND THEIR ESTUARI
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Waders and their estuarine food sup
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WADERS AND THEIR ESTUARINE FOOD SUP
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figuren: Dick Visser omslagfoto: Ja
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15 Versatility of male curlews (Num
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That science is making progress, ma
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INTRODUCTION The remnants of brushw
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When hcnlhic bivalves extend llien
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the burrow depths and on the fracti
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INTRODUCTION Ms,i invest 409 of (he
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able lo sw itch 10 oiher prey which
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Long-term, broadly-based research c
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Chapter 1 SEASONAL VARIATION IN BOD
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SEASONAL VARIATION IN BODY WEIGHT O
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Tahle 1 Weight loss ('•- ± SE) m
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i 60 50 40 30 20 10 0 • INFESTED
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240- SEASONAL VARIATION IN BODY WEI
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20 10 0 -10 -20h 2 3 4 5 6 7 8 9 se
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a E 400 - S. plana 35 mm 320 240 16
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Chapter 2 HOW THE FOOD SUPPLY HARVE
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FOOD SUPPLY HARVESTABLE BY WADERS H
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Methods The study sites were situat
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less than that of bivalves, partly
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I Fig. 3). Peak condition was reach
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total biomass since most of those t
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on the basis of the preceding and t
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However, for obvious reasons, we ma
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prey. A decrease in the prey densit
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Tahle 2. The intake rate ol < lyste
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* ' % -. . ; a X - . - * • ^ •
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(Zwarts & Wanink 1989). In quiet we
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general law relating handling time
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nearly twice as much time (0.79 s).
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4 5 6 7 8 9 size class of Corophium
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and annually. Second, the lower siz
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Prey switching Waders feeding on ti
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autumn and spring, and the contrary
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where they switch to surface-living
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Chapter 3 BURYING DEPTH OF THE BENT
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DEPTH AND SIPHON CROPPING IN SCROBI
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I DEPTH AND SIPHON CROPPING IN SCRO
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DEPTH AND SIPHON CROPPING IN SCROBI
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Table 3. Three-Way analysis Of vari
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Chapter 4 SIPHON SIZE AND BURYING D
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15 20 size (mm) Fig. 3. Cerasioderm
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10 size (mm) SIPHON SIZE AND DEPTH
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o, 7 01 5 | * CL 5- SIPHON SIZE AND
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4 Q) Si •a a. 16- 20- A predator:
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prey risk for an animal al a depth
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Table 6. Size al which there is a m
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* ' 1 /-/ "».-^*«C
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face and so expose themselves to a
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surface in die containers was varie
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50 OOF 310.00 I 5.00 ^ 1.00 3=" 0.5
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Tahle 1. Macoma and Scrobicularia.
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siphon would not have to reach the
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known siphon weight and burying dep
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ACCESSIBLE PREY ARE OFTEN IN POOR C
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1 2 3 4 burying depth (cm) Kin. I.
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I—1 • • : : : : ! - ! -|-r 0
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Chapter 7 DOES AN OPTIMALLY FORAGIN
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OPTIMAL FORAGING AND THE FUNCTIONAL
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100 200 300 prey density (n-m-2) Fi
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Table I. Results of five one way an
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Table 2. Results of eight iwo-wav a
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prey density II III Fig. 12. Freque
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PREY SIZE SELECTION AND INTAKE RATE
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Predicted 'passive size selection'
Page 154 and 155: lig. 2. Larger Mussels are less ava
Page 156 and 157: Fig. 5. Scrobicularia plana. Size c
Page 158 and 159: and maiiv are too thick-shelled to
Page 160 and 161: The measurements of handling time i
Page 162 and 163: 1 2 3 4 5 6 7 probing depth (cm PRE
Page 164 and 165: valves may vary by a factor of two
Page 166 and 167: optimal foraging model, the minimum
Page 168 and 169: their gut is full? Do they reduce t
Page 171 and 172: PREY PROFITABILITY AND INTAKE RATE
Page 173 and 174: catchers to take only certain prey
Page 175 and 176: licult error of estimate arose if p
Page 177 and 178: Counts of feeding and non-feeding b
Page 181 and 182: 20 30 40 50 shell length (mm) PREY
Page 185 and 186: Nereis Arenicola tipuia earthwo'm M
Page 187 and 188: take rate. We might therefore expec
Page 189 and 190: prey species, using parallel slopes
Page 191 and 192: 5.0 4.0 1-3.0 a & • % * • * •
Page 193 and 194: time during the feeding period. As
Page 195 and 196: winter. Similarly, handling time in
Page 197 and 198: 5.0 - f-4.0 S 3.0 in I 20 a 2 a | 1
Page 199 and 200: situation arrived in the western pa
Page 203: • ' • 14 PREY PROFITABILITY AND
Page 207: Chapter 10 WHY OYSTERCATCHERS HAEMA
Page 210 and 211: 2 4 6 8 10 time on feeding area (h)
Page 212 and 213: 80- 60- o 80 60- 40- 20- INTAKE RAT
Page 214 and 215: est of bod\ behind: an estimated 22
Page 216 and 217: INTAKE RATE AND PROCESSING RATE IN
Page 218 and 219: Wanink 1993). The energy content of
Page 220 and 221: (7) Age All studies dealt with adul
Page 222 and 223: irds over long periods. As an examp
Page 224 and 225: Discussion There is no difference i
Page 226 and 227: comparison between the weight of ih
Page 228 and 229: . 1', L ! •
Page 230 and 231: Introduction PREDICTING SEASONAL AN
Page 232 and 233: PREDICTING SEASONAL AND ANNUAL FLUC
Page 240 and 241: 1000 r 1 II" 1 - r^Jan'80 PREDICTIN
Page 252 and 253: IOO BO 60 40 20 0 PREDICTING SEASON
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PREDICTING SEASONAL AND ANNUAL FLUC
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WHY KNOT TAKE MEDIUM-SIZED MACOMA W
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in Zwarts & Esselink 1989). The len
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shell length (mm) FIR. 3. Peringia.
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fused, specimens larger than this w
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50 100- s s I — f = S. plana, n=2
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area is twice as large as the touch
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10 15 lower size threshold (mm) Fig
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lime (Hughes 1979). This would furt
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WHY KNOT TAKE MEDIUM-SIZED MACOMA T
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Chapter 13 ANNUAL AND SEASONAL VARI
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VARIATION IN FOOD SUPPLY OF KNOT AN
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Two sites (N and M in Fig. 2) were
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20 30 VARIATION IN FOOD SUPPLY OF K
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20 l i r'l ' i •o j^y^T n ^ ' " ^
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July ' Aug ' Sept Fig. 9. Proportio
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available. There must, however, be
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Chapter 14 SEASONAL TREND IN BURROW
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BURROWING AND FEEDING IN NEREIS SEA
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Table 2. Results of a 2-way analysi
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June 1981 June 1982 is * N.MUD •
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8 10 I 12 JZ 5. -g 1*» •e o i 16
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6 - n=!080 5 • g 4 CP > i 3 CO CD
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1985) and Curlew (/wails ,v, Lsseli
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Chapter 15 VERSATILITY OF MALE CURL
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Smid! 1951. Muus 1967, Wolff 1973,
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0.6 0.8 1.0 1.2 1.4 1.6 jaw lengih
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Na oi both Nrieck Fig. 7. Numenius
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6 8 10 12 14 16 18 worm length (cm)
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too (Fig. 11 A). Indeed, the averag
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VERSATILITY OF CURLEWS FEEDING ON N
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total time spent al the surface. Th
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2 4 . • 2.2 • 30 .-.2.0 to Q. 1
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PREY DEPLETION BY OYSTERCATCHER AND
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the rule: the observed lower limit
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to locate the clams after they had
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Curlew, by bury ing some hundreds o
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PREY DEPLETION BY OYSTERCATCHER AND
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SAMENVATTING 345
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Voorgeschiedenis In 1960 verscheen
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maken. Als gebied A een grotere voe
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omdat ze nog vrijwel niets wegen. l
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kunnen opzuigen. of diep leven en z
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van de uitgerekte sifo over het wad
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het toen niet gemakkelijk hebben ge
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doende nonnetjes van 10 tot 15 mm l
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aangevoerde voedsel en de wulp past
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zijn dan twee jaar en wulpen geen s
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was dan ook dank/ij de inzet van al
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REFERENCES 367
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Allen RL. 1983. Feeding behaviour o
Page 367 and 368:
BreyT. 1989. Der Einfluss physikali
Page 369 and 370:
latie tol chironoiiiiilen en de wai
Page 371 and 372:
huch der Vogel Milteleuropas, Band
Page 373 and 374:
llolmann II. & H. Huerschelmann 196
Page 375 and 376:
l-cndrem D.W. 1984. Flocking, feedi
Page 377 and 378:
Pekkarinen M. 1984. Regeneration of
Page 379 and 380:
lion of Mussels Mytilus edulis hy O
Page 381 and 382:
lulal Dal esiuanes: a comparison of
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