Evidence for direct interspecific competition in wildfowl and between hybrids and their parent species is scarce. This study examined threat displays and agonistic encounters (n = 324) in a goose flock of 140 Swan Geese and 13 hybrids with Greylag Goose living in Heidelberg, SW Germany. In general, agonistic behaviour made up less than 1% of the time budget throughout the year as measured by focal animal sampling. Most encounters (84%) were won by the initiator, both in Swan Geese and in hybrids. No difference was found between Swan Geese and hybrids in the outcome of an encounter, suggesting equal competitive quality. There were differences with respect to threat postures with hybrids performing diagonal neck threats more often and intentional movements less often. This seems to be related to their hybrid origin, since Greylag Geese most often show diagonal neck and forward threat displays. There was no direct evidence for hybrid superiority or inferiority.
REFERENCES
M. L. Arnold
,
S. A. Hodges
1995. Are hybrids fit or unfit relative to their parent species? Trends Ecol. Evol. 10: 67–71. Google Scholar
G. A. Baldassarre
,
E. G. Bolen
1994. Waterfowl ecology and management. Wiley & Sons, New York. Google Scholar
G. A. Baldassarre
,
S. L. Paulus
,
A. Tamisier
,
R. D. Titman
1988. Workshop summary: techniques for timing activity of wintering waterfowl. In:
M. W. Weiler
(ed.).
Waterfowl in winter. Univ. of Minnesota Press, pp. 181–188. Google Scholar
G. G. Barnes
,
T. D. Nudds
1991. Salt tolerance in American black ducks, mallards, and their F-1 hybrids. Auk 108: 89–98. Google Scholar
K. M. Bauer
,
U. N. Glutz von Blotzheim
1968. Handbuch der Vögel Mitteleuropas. Bd. 2, Anseriformes 1. Teil. Akademische Verlagsgesellschaft, Frankfurt/Main. Google Scholar
International Birdlife
2001. Threatened Birds of Asia: the International Red Data Book. BirdLife International, Cambridge. Google Scholar
J. M. Black
,
M. Owen
1988. Variations in pair bond and agonistic behaviors in barnacle geese on the wintering grounds. In:
M. W. Weiler
(ed.).
Waterfowl in winter. Univ. Minnesota Press, pp. 39–57. Google Scholar
H. Boyd
1953. On encounters between wild white-fronted geese in winter flocks. Behaviour 5: 85–129. Google Scholar
C. Braillet
,
A. Charmantier
,
F. Archaux
,
A. dos Santos
,
P. Perret
,
M. M. Lambrechts
2002. Two blue tit Parus caeruleus populations from Corsica differ in social dominance. J. Avian Biol. 33: 446–450. Google Scholar
L. M. Brodsky
,
P. J. Weatherhead
1996. Behavioral and ecological factors contributing to American Black Duck-Mallard hybridization. J. Wild. Manage. 48: 846–852. Google Scholar
A. Bühl
,
P. Zöfel
2002. SPSS Version 10. Einführung in die moderne Datenanalyse unter Windows. Addison-Wesley, München. Google Scholar
N. H. K Burton
,
P. R. Evans
2001. Aggressive behaviours and correlates of dominance in purple sandpipers Calidris maritima at a communal winter roost. Ibis 143: 248–254. Google Scholar
C. Darwin
1859. On the Origin of Species by the Mean of Natural Selection. John Murray, London. Google Scholar
J. del Hoyo
,
A. Elliott
,
J. Sargatal
1992. Handbook of the birds of the world. Vol. I. Ostrich to Ducks. Lynx eds, Barcelona. Google Scholar
J. Delacour
1954–1964. The Waterfowl of the World. Vol. I–IV. Country Life Ltd., London. Google Scholar
S. Delany
1993. Introduced and escaped Geese in Britain in summer 1991. Brit. Birds 86: 591–599. Google Scholar
D. A. Frazer
,
C. M. Kirkpatrick
1979. Parental and brood behaviour of Emperor geese in Alaska. Wildfowl 30: 75–85. Google Scholar
J. T. Garcia
,
B. E. Arroyo
2002. Intra- and interspecific agonistic behaviour in sympatric harriers during the breeding season. Anim. Behav. 64: 77–84. Google Scholar
T. P. Good
,
J. C. Ellis
,
C. A. Annett
,
R. Pierotti
2000. Bounded hybrid superiority in an avian hybrid zone: effects of mate choice, diet, and habitat choice. Evolution 54: 1774–1783. Google Scholar
B. R. Grant
,
P. R. Grant
1996. High survival of Darwin's Finch hybrids: effect of beak morphology and diets. Ecology 77: 500–509. Google Scholar
A. P. Gray
1958. Bird hybrids. A Check-List with Bibliography. Technical Communication No. 13 of the Commonwealth Bureau of Animal Breeding and Genetics. Farnham Royal, Edinburgh. Google Scholar
E. J. M. Hagemeijer
,
M. J. Blair
1997. The EBCC Atlas of European breeding birds: Their distribution and abundance. T & AD Poyser, London. Google Scholar
R. A. Hinde
1973. Behavior. In:
D. S. Farner
,
J. R. King
,
K. C. Parkes
(eds).
Avian Biology. Vol. III. pp. 480–535. Google Scholar
S. H. Hurlbert
1984. Pseudo-replication and the design of ecological field experiments. Ecol. Monogr. 54: 187–211. Google Scholar
I. R. Inglis
,
J. Lazarus
,
R. L. L. F. Torrance
2000. Breeding status and aggressive communication in the harlequin duck Histrionicus histrionicus.
Wildfowl 51: 139–153. Google Scholar
J. B. Kjaer
,
P. Sorenson
,
G. Su
2001. Divergent selection on feather pecking behaviour in laying hens Gallus gallus domesticus.
Appl. Anim. Behav. Sci. 71: 229–239. Google Scholar
J. R. Krebs
,
N. B. Davies
1996. Einführung in die Verhaltensökologie. Blackwell, Hamburg. Google Scholar
J. N. Kristiansen
,
N. S. Jarrett
2002. Interspecific competition between Greenland White-fronted Geese Anser albifrons flavirostris and Canada Geese Branta canadensis interior moulting in west Greenland: mechanisms and consequences. Ardea 90: 1–13. Google Scholar
J. Lazarus
,
I. R. Inglis
1978. Breeding behaviour of the Pinkfooted goose: parental care and vigilant behaviour during the fledging period. Behaviour 65: 62–88. Google Scholar
H. Lind
,
H. Poulsen
1963. On the morphology and behaviour of a hybrid between Goosander and Shelduck Mergus merganser L. × Tadorna tadorna L. Z. Tierpsych. 20: 558–569. Google Scholar
M. Lühmann
1953. Über die geschlechtsgebundene Vererbung der Färbung bei der Kreuzung von weißen und grauen Gänsen und ihre Bedeutung für die Züchtung von Kennrassen. Archiv Geflügelkunde 17: 163–179. Google Scholar
L. Machlis
,
P. W. D. Dodd
,
J. C. Fentress
1985. The pooling fallacy: problems arising when individuals contribute more than one observation to the data set. Z. Tierpsych. 68: 201–214. Google Scholar
J. Madsen
,
C. E. Mortensen
1987. Habitat exploitation and inter-specific competition of moulting geese in east Greenland. Ibis 129: 25–44. Google Scholar
P. Martin
,
P. Bateson
1993. Measuring Behaviour. An introductory guide. Cambridge Univ. Press. Google Scholar
J. R. Mason
,
L. Clark
1990. Sarcosporidiosis observed more frequently in hybrids of mallards and American black ducks. Wilson Bull. 102: 160–162. Google Scholar
R. G. Mathers
,
W. I. Montgomery
1996. Behaviour of brent geese Branta bernicla and wigeon Anas penelope feeding on intertidal Zostera ssp. Proc. Royal Irish Acad. 96: 159–167. Google Scholar
J. Meyer
1995. Bastardierung von Gänsen in den Rheinauen. Ornithol. Mitt. 47: 31–35. Google Scholar
C. Moulia
,
N. Le Brun
,
C. Loubes
,
R. Marin
,
F. Renaud
1995. Hybrid vigour against parasites in interspecific crosses between two mice species. Heredity 74: 48–52. Google Scholar
T. Nyegaard
,
J. N. Kristiansen
,
A. D. Fox
2001. Activity budget of Greenland White-fronted Geese Anser albifrons flavirostris spring staging on Icelandic hayfields. Wildfowl 52:41–53. Google Scholar
S. L. Paulus
1988. Time-activity budgets of non-breeding Anatidae: a review. In:
M. W. Weiler
(ed.).
Waterfowl in winter. Univ. Minnesota Press, Minneapolis, pp. 135–152. Google Scholar
S. F. Pearson
,
S. Rohwer
2000. Asymmetries in male aggression across an avian hybrid zone. Behav. Ecol. 11: 95–101. Google Scholar
P. J. Pietz
,
D. A. Buhl
1999. Behaviour patterns of mallard Anas platyrhynchos pairs and broods in Minnesota and North Dakota. Wildfowl 50: 101–122. Google Scholar
C. Randler
2001. Field identification of hybrid wildfowl — Geese. Alula 7: 42–48. Google Scholar
C. Randler
2002. Behaviour of mallard x red-crested pochard Anas platyrhynchos x Netta rufina hybrids in late winter/ early spring. Vogelwarte 41: 287–291. Google Scholar
C. Randler
2003a. Verhalten eines Hybriden zwischen Kolbenente Netta rufina und Moorente Aythya nyroca.
Ornithol. Beob. 100: 59–66. Google Scholar
C. Randler
2003b. Reactions to human disturbances in an urban population of the Swan Goose Anser cygnoides in Heidelberg SW Germany. Acta Ornithol. 38: 47–52. Google Scholar
L. V. Short
1975. The contribution of the mule to scientific thought. J. Reprod. Fertil. Suppl. 23: 359–364. Google Scholar
J. Stahl
,
R. H. Drent
,
H. van der Jeugd
2001a. Opportunistic underlings try their fortune elsewhere: inter-flock exchange in wintering barnacle geese. In:
J. Stahl
Limits to the co-occurrence of avian herbivores. How geese share scarce resources. Diss. Univ. Groningen. Google Scholar
J. Stahl
,
P. H. Tolsma
,
M. J. J. E. Loonen
,
R. H. Drent
2001b. Subordinates explore but dominants profit: resource competition in high arctic barnacle goose flocks. Anim. Behav. 61: 257–264. Google Scholar
J. Stahl
,
R. M. Veeneklaas
,
S. J. van der Graaf
,
M. J. J. E Loonen
,
R. H. Drent
2001c. Conversion factors for energetic expenditure of actively foraging brent and barnacle geese obtained by non-invasive heart rate telemetry. In:
J. Stahl
Limits to the co-occurrence of avian herbivores. How geese share scarce resources. Diss. Univ. Groningen. Google Scholar
R. N. Wiedenmann
,
K. N. Rabenold
1987. The effects of social dominance between two subspecies of dark-eyed juncos, Junco hyemalis.
Anim. Behav. 35: 856–864. Google Scholar
I. Würdinger
1978. Jahres- und tageszeitliche Verteilung von Schlaf, Komfortverhalten, Lokomotion, Nahrungsaufnahme und aggressivem Verhalten bei juvenilen und adulten Streifengänsen Anser indicus vorm.
Eulabeia indica. Z. Tierpsych. 46: 306–323. Google Scholar
