Ground-nesting seabirds are vulnerable to human intrusion which can potentially impair their breeding success. We examined whether tourist traffic on a boardwalk through a Silver Gull Larus novaehollandiae breeding colony affected the birds' behaviour sufficiently to potentially decrease reproductive success. Nest density was positively correlated with distance from the boardwalk. Gulls nesting ≤5 m from the boardwalk were more vigilant towards a stationary investigator than those further away. Tourists walking past breeding gulls stimulated a large increase in intra-specific aggression; stopping alongside parents with mobile chicks increased their intra-specific aggression even more. Larger tourist groups (≥3) stimulated more intra-specific aggression than smaller ones. An investigator walking past breeding gulls similarly stimulated an increase in intra-specific aggression, but the investigator's clothing colour, noise emission level and walking speed had no effect on the birds. An ambulatory investigator in another colony infrequently visited by people had a similar effect on gulls' intra-specific aggression, but these birds generally reacted more strongly to human intrusion. Silver Gulls' behavioural responses to tourist traffic could potentially decrease their reproductive success. These responses could be reduced by regulating traffic volume and flow and tourists' group size and behaviour, but the species' public image currently probably mitigates against such regulation occurring.

Silver Gull, tourist, boardwalk, group size, vigilance, intra-specific aggression, disturbance
Anderson, D.W. 1988. Dose-response relationship between human disturbance and brown pelican breeding success. Wildlife Society Bulletin 16: 339-345.
,
Dose-response relationship between human disturbance and brown pelican breeding success
,
Wildlife Society Bulletin
, vol.
16
(pg.
339
-
345
)
Anderson, D.W. and Keith, J.O. 1980. The human influence on seabird nesting success: Conservation implications. Biological Conservation 18: 65-80.
,
The human influence on seabird nesting success: Conservation implications
,
Biological Conservation
, vol.
18
(pg.
65
-
80
)
Anderson, M.J. 2001. A new method for non-parametric multivariate analysis of variance. Austral Ecology 26: 32-46.
,
A new method for non-parametric multivariate analysis of variance
,
Austral Ecology
, vol.
26
(pg.
32
-
46
)
Anderson, M.J. 2003. XMATRIX: a FORTRAN computer program for calculating design matrices for terms in ANOVA designs in a linear model. Department of Statistics, University of Auckland: New Zealand.
,
XMATRIX: a FORTRAN computer program for calculating design matrices for terms in ANOVA designs in a linear model
Anderson, M. J. 2004. DISTLM v.5: a FORTRAN computer program to calculate a distance-based multivariate analysis for a linear model. Department of Statistics, University of Auckland: New Zealand.
,
DISTLM v.5: a FORTRAN computer program to calculate a distance-based multivariate analysis for a linear model
Anderson, M. J. 2005. PERMANOVA: a FORTRAN computer program for permutational multivariate analysis of variance. Department of Statistics, University of Auckland: New Zealand.
,
PERMANOVA: a FORTRAN computer program for permutational multivariate analysis of variance
Beale, C.M. and Monaghan, P. 2004. Human disturbance: people as predation-free predators? Journal of Applied Ecology 41: 335-343.
,
Human disturbance: people as predation-free predators?
,
Journal of Applied Ecology
, vol.
41
(pg.
335
-
343
)
Blumstein, D.T., Anthony, L.L., Harcourt, R. and Ross, G. 2003. Testing a key assumption of wildlife buffer zones: is flight initiation distance a species-specific trait? Biological Conservation 110: 97-100.
,
Testing a key assumption of wildlife buffer zones: is flight initiation distance a species-specific trait?
,
Biological Conservation
, vol.
110
(pg.
97
-
100
)
Brown, K.M. and Morris, R.D. 1995. Investigator disturbance, chick movement, and aggressive behavior in Ring-billed Gulls. Wilson Bulletin 107: 140-152.
,
Investigator disturbance, chick movement, and aggressive behavior in Ring-billed Gulls
,
Wilson Bulletin
, vol.
107
(pg.
140
-
152
)
Burger, J. 1981. Effects of human disturbance on colonial species, particularly gulls. Colonial Waterbirds 4: 28-36.
,
Effects of human disturbance on colonial species, particularly gulls
,
Colonial Waterbirds
, vol.
4
(pg.
28
-
36
)
Burger, J. and Gochfeld, M. 1981. Discrimination of the threat of direct versus tangential approach to the nest by incubating herring and great black-backed gulls. Journal of Comparative Physiology and Psychology 95: 676-684.
,
Discrimination of the threat of direct versus tangential approach to the nest by incubating herring and great black-backed gulls
,
Journal of Comparative Physiology and Psychology
, vol.
95
(pg.
676
-
684
)
Burger, J. and Gochfeld, M. 1983. Behavioural responses to human intruders of herring gulls (Larus argentatus) and great black-backed gulls (L. marinus) with varying exposure to human disturbance. Behavioural Processes 8: 327-344.
,
Behavioural responses to human intruders of herring gulls (Larus argentatus) and great black-backed gulls (L. marinus) with varying exposure to human disturbance
,
Behavioural Processes
, vol.
8
(pg.
327
-
344
)
Burger, J. and Gochfeld, M. 1993. The importance of the human face in risk perception by black iguanas, Ctenosaura similis. Journal of Herpetology 27: 426-430.
,
The importance of the human face in risk perception by black iguanas, Ctenosaura similis
,
Journal of Herpetology
, vol.
27
(pg.
426
-
430
)
Burger, J. and Gochfeld, M. 1998. Effects of ecotourists on bird behaviour at Loxahatchee National Wildlife Refuge, Florida. Environmental Conservation 25: 13-21.
,
Effects of ecotourists on bird behaviour at Loxahatchee National Wildlife Refuge, Florida
,
Environmental Conservation
, vol.
25
(pg.
13
-
21
)
Carrick, R. and Murray, M.D. 1964. Social factors in population regulation of the silver gull, Larus novaehollandiae Stephens. Australian Wildlife Research 9: 189-199.
,
Social factors in population regulation of the silver gull, Larus novaehollandiae Stephens
,
Australian Wildlife Research
, vol.
9
(pg.
189
-
199
)
Carrick, R., Wheeler, W.R. and Murray, M.D. 1957. Seasonal dispersal and mortality in the silver gull, Larus novae-hollandiae Stephens, and crested tern, Sterna bergii Lichtenstein, in Australia. Australian Wildlife Research 2: 116-144.
,
Seasonal dispersal and mortality in the silver gull, Larus novae-hollandiae Stephens, and crested tern, Sterna bergii Lichtenstein, in Australia
,
Australian Wildlife Research
, vol.
2
(pg.
116
-
144
)
Davis, A.K., Maney, D.L. and Maerz, J. C. 2008. The use of leukocyte profiles to measure stress in vertebrates: a review for ecologists. Functional Ecology 22: 760-772.
,
The use of leukocyte profiles to measure stress in vertebrates: a review for ecologists
,
Functional Ecology
, vol.
22
(pg.
760
-
772
)
DesGranges, J. and Reed, A. 1981. Disturbance and control of selected colonies of double-crested cormorants in Quebec. Colonial Waterbirds 4: 12-19.
,
Disturbance and control of selected colonies of double-crested cormorants in Quebec
,
Colonial Waterbirds
, vol.
4
(pg.
12
-
19
)
Fetterolf, P.M. 1983. Effects of investigator activity on ring-billed gull behavior and reproductive performance. Wilson Bulletin 95: 23-41.
,
Effects of investigator activity on ring-billed gull behavior and reproductive performance
,
Wilson Bulletin
, vol.
95
(pg.
23
-
41
)
Flemming, S.P., Chiasson, R.D., Smith, P.C., Austin-Smith, P. and Bancroft, R.P. 1988. Piping plover status in Nova Scotia related to its reproductive and behavioral responses to human disturbance. Journal of Field Ornithology 59: 321-330.
,
Piping plover status in Nova Scotia related to its reproductive and behavioral responses to human disturbance
,
Journal of Field Ornithology
, vol.
59
(pg.
321
-
330
)
Frid, A. and Dill, L. 2002. Human-caused disturbance stimuli as a form of predation risk. Conservation Ecology 6: 11-26.
,
Human-caused disturbance stimuli as a form of predation risk
,
Conservation Ecology
, vol.
6
(pg.
11
-
26
)
Geist, C., Liao, J., Libby, S. and Blumstein, D.T. 2005. Does intruder group size and orientation affect flight initiation distance in birds? Animal Biodiversity and Conservation 28: 69-73.
,
Does intruder group size and orientation affect flight initiation distance in birds?
,
Animal Biodiversity and Conservation
, vol.
28
(pg.
69
-
73
)
Gillet, W. H., Hayward, J. L. and Stout, J. F. 1975. Effects of human activity on egg and chick mortality in a glaucous-winged gull colony. Condor 77: 492-495.
,
Effects of human activity on egg and chick mortality in a glaucous-winged gull colony
,
Condor
, vol.
77
(pg.
492
-
495
)
Gochfeld, M. 1981. Differences in behavioral responses of young common terns and black skimmers to intrusion and handling. Colonial Waterbirds 4: 47-53.
,
Differences in behavioral responses of young common terns and black skimmers to intrusion and handling
,
Colonial Waterbirds
, vol.
4
(pg.
47
-
53
)
Gutzwiller, K.J. and Anderson, S.H. 1999. Spatial extent of human-intrusion effects on subalpine bird distributions. Condor 101: 378-389.
,
Spatial extent of human-intrusion effects on subalpine bird distributions
,
Condor
, vol.
101
(pg.
378
-
389
)
Gutzwiller, K.J. and Marcum, H.A. 1997. Bird reactions to observer clothing color: Implications for distance-sampling techniques. Journal of Wildlife Management 61: 935-947.
,
Bird reactions to observer clothing color: Implications for distance-sampling techniques
,
Journal of Wildlife Management
, vol.
61
(pg.
935
-
947
)
Harris, M.P. and Bode, K.G. 1981. Populations of little penguins Eudyptula minor, short-tailed shearwaters Puffinus tenuirostris and other sea birds on Phillip Island Victoria Australia 1978. Emu 81: 20-28.
,
Populations of little penguins Eudyptula minor, short-tailed shearwaters Puffinus tenuirostris and other sea birds on Phillip Island Victoria Australia 1978
,
Emu
, vol.
81
(pg.
20
-
28
)
Hart, N. S. 2001. Variations in cone photoreceptor abundance and the visual ecology of birds. Journal of Comparative Physiology A 187: 685-698.
,
Variations in cone photoreceptor abundance and the visual ecology of birds
,
Journal of Comparative Physiology A
, vol.
187
(pg.
685
-
698
)
Hayward, L.S. and Wingfield, J.C. 2004. Maternal corticosterone is transferred to avian yolk and may alter offspring growth and adult phenotype. General and Comparative Endocrinology 135: 365-371.
,
Maternal corticosterone is transferred to avian yolk and may alter offspring growth and adult phenotype
,
General and Comparative Endocrinology
, vol.
135
(pg.
365
-
371
)
Higgins, P.J. and Davies, S.J.J.F. (eds). 1996. Handbook of Australian, New Zealand and Antarctic Birds, Volume 3: Snipe to Pigeons. Oxford University Press, Melbourne.
,
Handbook of Australian, New Zealand and Antarctic Birds, Volume 3: Snipe to Pigeons
Holmes, N., Giese, M. and Kriwoken, L.K. 2005. Testing the minimum approach distance guidelines for incubating royal penguins Eudyptes schlegeli. Biological Conservation 126: 339-350.
,
Testing the minimum approach distance guidelines for incubating royal penguin
,
Eudyptes schlegeli. Biological Conservation
, vol.
126
(pg.
339
-
350
)
Hunt, G.L.J. 1972. Influence of food distribution and human disturbance on the reproductive success of herring gulls. Ecology 53: 1051-1061.
,
Influence of food distribution and human disturbance on the reproductive success of herring gulls
,
Ecology
, vol.
53
(pg.
1051
-
1061
)
Hunt, G.L.J. and Hunt, M.W. 1975. Reproductive ecology of the western gull: the importance of nest spacing. Auk 92: 270-279.
,
Reproductive ecology of the western gull: the importance of nest spacing
,
Auk
, vol.
92
(pg.
270
-
279
)
Kitaysky, A.S., Kitaiskaia, E.V., Piatt, J.F. and Wingfield, J.C. 2003. Benefits and costs of increased levels of corticosterone in seabird chicks. Hormones and Behavior 43, 140-149.
,
Benefits and costs of increased levels of corticosterone in seabird chicks
,
Hormones and Behavior
, vol.
43
(pg.
140
-
149
)
Kitaysky, A.S., Wingfield, J.C. and Piatt, J.F. 1999. Dynamics of food availability, body condition and physiological stress response in breeding black-legged kittiwakes. Functional Ecology 13: 577-584.
,
Dynamics of food availability, body condition and physiological stress response in breeding black-legged kittiwakes
,
Functional Ecology
, vol.
13
(pg.
577
-
584
)
Kury, C.R. and Gochfeld, M. 1975. Human interference and gull predation in cormorant colonies. Biological Conservation 8: 23-34.
,
Human interference and gull predation in cormorant colonies
,
Biological Conservation
, vol.
8
(pg.
23
-
34
)
Liu, D., Caldji, C., Sharma, S., Plotsky, P.M. and Meaney, M.J. 2000. Influence of neonatal rearing conditions on stress-induced adrenocorticotropin responses and norepinepherine release in hypothalamic paraventricular nucleus. Journal of Neuroendocrinology 12: 5-12.
,
Influence of neonatal rearing conditions on stress-induced adrenocorticotropin responses and norepinepherine release in hypothalamic paraventricular nucleus
,
Journal of Neuroendocrinology
, vol.
12
(pg.
5
-
12
)
Manly, B.F.J. 1997. Randomization, bootstrap and Monte Carlo methods in biology. Chapman and Hall, London.
,
Randomization, bootstrap and Monte Carlo methods in biology
Martín, J., de Neve, L., Fargallo, J.A., Polo, V. and Soler, M. 2004. Factors affecting the escape behaviour of juvenile chinstrap penguins, Pygoscelis antartica, in response to human disturbance. Polar Biology 27: 775-781.
,
Factors affecting the escape behaviour of juvenile chinstrap penguins, Pygoscelis antartica, in response to human disturbance
,
Polar Biology
, vol.
27
(pg.
775
-
781
)
Martin, P. and Bateson, P. 2007. Measuring Behaviour: an Introductory Guide. Cambridge University Press, Cambridge.
,
Measuring Behaviour: an Introductory Guide
McArdle, B.H. and Anderson, M.J. 2001. Fitting multivariate models to community data: a comment on distance-based redundancy analysis. Ecology 82: 290-297.
,
Fitting multivariate models to community data: a comment on distance-based redundancy analysis
,
Ecology
, vol.
82
(pg.
290
-
297
)
Mills, J.A. 1973. The influence of age and pair-bond on the breeding biology of the red-billed gull Larus novaehollandiae scopulinus. Journal of Animal Ecology 42: 147-162.
,
The influence of age and pair-bond on the breeding biology of the red-billed gul
,
Larus novaehollandiae scopulinus. Journal of Animal Ecology
, vol.
42
(pg.
147
-
162
)
Montgomerie, R.D. and Weatherhead, P.J. 1988. Risks and rewards of nest defence by parent birds. Quarterly Review of Biology 63: 167-187.
,
Risks and rewards of nest defence by parent birds
,
Quarterly Review of Biology
, vol.
63
(pg.
167
-
187
)
Müllner, A., Linsenmair, K.E. and Wikelski, M. 2004. Exposure to ecotourism reduces survival and affects stress response in hoatzin chicks (Opisthocomus hoazin). Biological Conservation 118: 549-558.
,
Exposure to ecotourism reduces survival and affects stress response in hoatzin chicks (Opisthocomus hoazin)
,
Biological Conservation
, vol.
118
(pg.
549
-
558
)
Murray, M.D. and Carrick, R. 1964. Seasonal movements and habitats of the silver gull, Larus novaehollandiae Stephens, in south-eastern Australia. Australian Wildlife Research 9: 160-188.
,
Seasonal movements and habitats of the silver gull, Larus novaehollandiae Stephens, in south-eastern Australia
,
Australian Wildlife Research
, vol.
9
(pg.
160
-
188
)
ödeen, A. and Håstad, O. 2003. Complex distribution of avian color vision systems revealed by sequencing the SWS1 Opsin from total DNA. Molecular Biology and Evolution 20: 855-861.
,
Complex distribution of avian color vision systems revealed by sequencing the SWS1 Opsin from total DNA
,
Molecular Biology and Evolution
, vol.
20
(pg.
855
-
861
)
Ottaway, J.R., Carrick, R. and Murray, M.D. 1988. Reproductive ecology of silver gulls, Larus novaehollandiae Stephens, in South Australia. Australian Wildlife Research 15: 541-560.
,
Reproductive ecology of silver gulls, Larus novaehollandiae Stephens, in South Australia
,
Australian Wildlife Research
, vol.
15
(pg.
541
-
560
)
Quinn, G.P. and Keough, M.J. 2002.Experimental Design and Data Analysis for Biologists. Cambridge University Press, New York.
,
Experimental Design and Data Analysis for Biologists
Regel, J. and Pütz, K. 1997. Effect of human disturbance on body temperature and energy expenditure in penguins. Polar Biology 18: 246-253.
,
Effect of human disturbance on body temperature and energy expenditure in penguins
,
Polar Biology
, vol.
18
(pg.
246
-
253
)
Robert, H.C. and Ralph, C.J. 1975. Effects of human disturbance on the breeding success of gulls. Condor 77: 495-499.
,
Effects of human disturbance on the breeding success of gulls
,
Condor
, vol.
77
(pg.
495
-
499
)
Ros, A.F.H., Groothuis, T.G.G. and Apanius, V. 1997. The relation among gonadal steroids, immunocompetence, body mass, and behavior in young black-headed gulls (Larus ridibundus). American Naturalist 150: 201-219.
,
The relation among gonadal steroids, immunocompetence, body mass, and behavior in young black-headed gulls (Larus ridibundus)
,
American Naturalist
, vol.
150
(pg.
201
-
219
)
Royle, N.J., Surai, P. F. and Hartley, I.R. 2001. Maternally derived androgens and antioxidants in bird eggs: Complementary but opposing effects? Behavioral Ecology 12: 381-385.
,
Maternally derived androgens and antioxidants in bird eggs: Complementary but opposing effects
,
Behavioral Ecology
, vol.
12
(pg.
381
-
385
)
Rubolini, D., Romano, M., Boncoraglio, G., Ferrari, R.P., Martinelli, R., Galeotti, P. , Fasola, M. and Saino, N. 2005. Effects of elevated egg corticosterone levels on behavior, growth, and immunity of yellow-legged gull (Larus michahellis) chicks. Hormones and Behavior 47: 592-605.
,
Effects of elevated egg corticosterone levels on behavior, growth, and immunity of yellow-legged gull (Larus michahellis) chicks
,
Hormones and Behavior
, vol.
47
(pg.
592
-
605
)
Sapolsky, R.M., Romero, L.M. and Munck, A.U. 2000. How do glucocorticoids influence stress response? Integrating permissive, suppressive, stimulatory, and preparative actions. Endocrine Reviews 21: 55-89.
,
How do glucocorticoids influence stress response? Integrating permissive, suppressive, stimulatory, and preparative actions
,
Endocrine Reviews
, vol.
21
(pg.
55
-
89
)
Siegel, H.S. 1980. Physiological stress in birds. Bioscience 30: 529-534.
,
Physiological stress in birds
,
Bioscience
, vol.
30
(pg.
529
-
534
)
Smith, G.C. and Carlile, N. 1992. Silver Gull breeding at two colonies in the Sydney-Wollongong region, Australia. Wildlife Research 19: 429-441.
,
Silver Gull breeding at two colonies in the Sydney-Wollongong region, Australia
,
Wildlife Research
, vol.
19
(pg.
429
-
441
)
Smith, G.C., Carlile, N. and Louwerse, I. 1991. The importance of human refuse as a food source for silver gulls Larus novaehollandiae. Australian Bird Watcher 14: 24-27.
,
The importance of human refuse as a food source for silver gull
,
Larus novaehollandiae. Australian Bird Watcher
, vol.
14
(pg.
24
-
27
)
Tinbergen, J.M. and Williams, J.B. 2002. Energetics of incubation. In Avian Incubation, Behaviour, Environment and Evolution. (Ed D. C. Deeming.) pp. 299-313. Oxford University Press, Oxford.
,
Avian Incubation, Behaviour, Environment and Evolution
(pg.
299
-
313
)
van Tets, G.F. 1969a. Diurnal movement patterns of the Silver gull, Larus novaehollandiae Stephens, at Sydney airport. CSIRO Wildlife Research 14: 111-116.
,
Diurnal movement patterns of the Silver gull, Larus novaehollandiae Stephens, at Sydney airport
,
CSIRO Wildlife Research
, vol.
14
(pg.
111
-
116
)
van Tets, G.F. 1969b. Quantitative and qualitative changes in habitat and avifauna at Sydney airport. CSIRO Wildlife Research 14: 117-128.
,
Quantitative and qualitative changes in habitat and avifauna at Sydney airport
,
CSIRO Wildlife Research
, vol.
14
(pg.
117
-
128
)
Vermeer, K., Morgan, K.H., Smith, G.E.J. and York, B.A. 1991. Effects of egging on the reproductive success of glaucous-winged gulls. Colonial Waterbirds 14: 158-165.
,
Effects of egging on the reproductive success of glaucous-winged gulls
,
Colonial Waterbirds
, vol.
14
(pg.
158
-
165
)
Vleck, C.M., Vertalino, N., Vleck, D. and Bucher, T.L. 2000. Stress, corticosterone, and heterophil to lymphocyte ratios in free-living Adélie Penguins. Condor 102: 392-400.
,
Stress, corticosterone, and heterophil to lymphocyte ratios in free-living Adélie Penguins
,
Condor
, vol.
102
(pg.
392
-
400
)
Vos, D.K., Ryder, R.A. and Graul, W.D. 1985. Response of great blue herons to human disturbance in northcentral Colorado. Colonial Waterbirds 8: 13-22.
,
Response of great blue herons to human disturbance in northcentral Colorado
,
Colonial Waterbirds
, vol.
8
(pg.
13
-
22
)
Weimerskirch, H., Shaffer, S.A., Mabille, G., Martin, J., Boutard, O. and Rouanet, J.L. 2002. Heart rate and energy expenditure of incubating wandering albatrosses: Basal levels, natural variation, and the effects of human disturbance. Journal of Experimental Biology 205: 475-483.
,
Heart rate and energy expenditure of incubating wandering albatrosses: Basal levels, natural variation, and the effects of human disturbance
,
Journal of Experimental Biology
, vol.
205
(pg.
475
-
483
)
Wheeler, W.R. and Watson, I. 1963. The Silver Gull Larus novaehollandiae Stephens. Emu 63: 99-173.
,
The Silver Gull Larus novaehollandiae Stephens
,
Emu
, vol.
63
(pg.
99
-
173
)
Wilkinson, L. 2000. Systat® 10.0. SPSS Inc, Chicago.
,
Systat® 10.0
Wingfield, J.C., Hegner, R.E., Dufty, A.M. and Ball, G.F. 1990. The ‘challenge hypothesis’: theoretical implications for pattens of testosterone secretion, mating systems, and breeding strategies. American Naturalist 136: 829-846.
,
The ‘challenge hypothesis’: theoretical implications for pattens of testosterone secretion, mating systems, and breeding strategies
,
American Naturalist
, vol.
136
(pg.
829
-
846
)
Woehler, E.J., Penney, R.L., Creet, S.M. and Burton, H.R. 1994. Impacts of human visitors on breeding success and long-term population trends in Adélie penguins at Casey, Antarctica Polar Biology 14: 269-274.
,
Impacts of human visitors on breeding success and long-term population trends in Adélie penguins at Casey, Antarctic
,
Polar Biology
, vol.
14
(pg.
269
-
274
)
Wooller, R.D. and Dunlop, J.N. 1979. Multiple laying by the silver gull, Larus novaehollandiae Stephens, on Carnac Island, Western Australia. Australian Wildlife Research 6: 325-335.
,
Multiple laying by the silver gull, Larus novaehollandiae Stephens, on Carnac Island, Western Australia
,
Australian Wildlife Research
, vol.
6
(pg.
325
-
335
)
Ydenberg, R.C. and Dill, L.M. 1986. The economics of fleeing from predators. Advances in the Study of Behavior 16: 229-249.
,
The economics of fleeing from predators
,
Advances in the Study of Behavior
, vol.
16
(pg.
229
-
249
)
This content is only available as a PDF.