Nest intrusion and infanticidal attack on nestlings in great cormorants Phalacrocorax carbo: why do adults attack conspecific chicks?


Infanticide, the killing of young animals by conspecifics, has been observed in diverse taxa. The function of infanticide has been classified as exploitation, sexual selection, parental manipulation or resource competition. We observed infanticidal behavior and its reproductive results at five breeding colonies of great cormorants from January to August 2008. Eighteen cases of nest intrusions and/or attacks toward a chick by conspecific non-nest-owners were observed, and two of them were filmed. In both attacks, perpetrators pecked the necks of chicks several times with display. The chicks bent their necks down onto the nest and remained stationary. Our data did not support the exploitation hypothesis because adult cormorants did not use chicks as food. In addition, the perpetrators were not true parents and did not mate with the female nest owner, indicating that parental manipulation and sexual selection hypotheses were unlikely explanations. On the other hand, concurrent presence of adults during prelaying and chick-rearing periods at a particular colony affected the occurrence of nest takeovers and intrusions and/or attacks, suggesting that some conflicts over nests arise between individuals that are at different stages of the breeding cycle. Digital videos relating to this article are available at and

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 99

This is the net price. Taxes to be calculated in checkout.

Fig. 1
Fig. 2


  1. Aguilera E (1990) Parental infanticide by white spoonbills Platalea leucorodia. Ibis 132:124–129

  2. Ashbrook A, Wanless S, Harris MP, Hamer KC (2008) Hitting the buffers: conspecific aggression undermines benefits of colonial breeding under adverse conditions. Biol Lett 4:630–633. doi:10.1098/rsbl.2008.0417

  3. Bartlett TQ, Sussman RW, Cheverub JM (1993) Infant killing in primates––a review of observed cases with specific reference to the sexual selection hypothesis. Am Anthropol 95:958–990

  4. Chek AA, Robertson RJ (1991) Infanticide in female tree swallows: a role for sexual selection. Condor 93:454–457

  5. Childress RB, Bennun LA, Harper DM (2002) Population changes in sympatric Great and Long-tailed Cormorants (Phalacrocorax carbo and P. africanus): the effects of niche overlap or environmental change? Hydrobiologia 488:163–170

  6. Claessen D, deRoos AM, Persson L (2004) Population dynamic theory of size-dependent cannibalism. Proc R Soc Lond B Biol Sci 271:222–240. doi:10.1098/rspb.2003.2555

  7. Cramp S, Simons KEL (1977) Handbook of the birds of Europe the Middle East and North Africa: the birds of the Western Palearctic, vol 1: Orstrich-Ducks. Oxford University press, UK

  8. Crook JR, Shields WM (1985) Sexually selected infanticide by adult male barn swallows. Anim Behav 33:754–761

  9. Daunt F, Wanless S, Harris MP, Monaghan P (1999) Experimental evidence that age-specific reproductive success is independent of environmental effects. Proc R Soc Lond B Biol Sci 266:1489–1493

  10. Daunt F, Wanless S, Harris MP, Money L, Monaghan P (2007) Older and wiser: improvements in breeding success are linked to better foraging performance in European shags. Funct Ecol 21:561–567

  11. Ebensperger LA (1998) Strategies and counterstrategies to infanticide in mammals. Biol Rev 73:321–346

  12. Emlen S, Demong NJ, Emlen DJ (1989) Experimental induction of infanticide in female wattled jacanas. Auk 106:1–7

  13. Freed LA (1986) Territory takeover and sexually selected infanticide in tropical house wrens. Behav Ecol Sociobiol 19:197–206

  14. Fujioka M (1986) Infanticide by a male parent and by a new female mate in colonial Egrets. Auk 103:619–621

  15. Gilchrist HG, Gaston AJ (1997) Factors affecting the success of colony departure by thick-billed murre chicks. Condor 99:345–352

  16. Honma A, Oku S, Nishida T (2006) Adaptive significance of death feigning posture as a specialized inducible defense against gape-limited predators. Proc R Soc Lond B Biol Sci 273:1631–1636. doi:10.1098/rspb.2006.3501

  17. Hotta M (1994) Infantiide in little swifts taking over costly nests. Anim Behav 47:491–493

  18. Hrdy SB (1979) Infanticide among animals: a review, classification, and examination of the implications for the reproductive strategies of females. Ethol Sociobiol 1:13–40

  19. Hunt JD, Evans RM (1997) Brood reduction and the insurance-egg hypothesis in double-crested cormorants. Colonial Waterbirds 20:485–491

  20. Kempenaers B, Peters A, Foerster K (2008) Sources of individual variation in plasma testosterone levels. Philos Trans R Soc Lond B Biol Sci 363:1711–1723

  21. Kermott LH, Johnson LS, Merkle MS (1991) Experimental evidence for the function of mate replacement and infanticide by males in a north-temperate population of house wrens. Condor 93:630–636

  22. Lynn SE (2008) Behavioral insensitivity to testosterone: why and how does testosterone alter paternal and aggressive behavior in some avian species but not others? Gen Comp Endocrinol 157:233–240

  23. Meek SB, Robertson RJ (1991) Adoption of young by replacement male birds and experimental study of eastern bluebirds and a review. Anim Behav 42:813–820

  24. Miyatake T, Katayama K, Takeda Y, Nakashima A, Sugita A, Mizumoto M (2004) Is death-feigning adaptive? Heritable variation in fitness difference of death-feigning behaviour. Proc R Soc Lond B Biol Sci 271:2293–2296. doi:10.1098/rspb.2004.2858

  25. Mock DW (1984) Infanticide, siblicide and avian nestling mortality. In: Hausfater G, Hrdy SB (eds) Infanticide: comparative and evolutionary perspectives. Aldine, New York, pp 3–30

  26. Mumme RL, Koenig WD, Pitelka FA (1983) Mate guarding in the acorn woodpecker: within-group reproductive competition in a cooperative breeder. Anim Behav 31:1094–1106

  27. Newson SE, Hughes B, Hearn R, Bregnballet T (2005) Breeding performance and timing of breeding of inland and coastal breeding Cormorants Phalacrocorax carbo in England and Wales. Bird Study 52:10–17

  28. Ohno T, Miyatake T (2007) Drop or fly? Negative genetic correlation between death-feigning intensity and flying ability as alternative anti-predator strategies. Proc R Soc Lond B Biol Sci 274:555–560. doi:10.1098/rspb.2006.3750

  29. Parsons J (1971) Cannibalism in herring gulls. Br Birds 64:528–537

  30. Picman J (1977) Destruction of eggs by the long-billed marsh wren (Telmatodytes palustris palustris). Can J Zool 55:1914–1920

  31. Pietz PJ (1987) Feeding and nesting ecology of sympatric south polar and brown skuas. Auk 104:617–627

  32. Polis GA (1981) The evolution and dynamics of intraspecific predation. Annu Rev Ecol Syst 12:225–251

  33. R Development Core Team (2008) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. ISBN 3-900051-07-0.

  34. Renton K (2004) Agonistic interactions of nesting and nonbreeding macaws. Condor 106:354–362

  35. Sargeant AB, Eberhardt LE (1975) Death feigning by ducks in response to predation by red foxes (Vulpes fulya). Am Midl Nat 94:108–119

  36. Schjorring S, Gregersen J, Bregnballe T (1999) Prospecting enhances breeding success of first-time breeders in the great cormorant, Phalacrocorax carbo sinensis. Anim Ecol 57:647–654

  37. Schjorring S, Gregersen J, Bregnballe T (2000) Sex difference in criteria determining fidelity towards breeding sites in the great cormorant. J Anim Ecol 69:214–223

  38. Shaw P (1985) Brood reduction in the Blue-eyed shag Phalacrocorax atriceps. Ibis 127:476–494

  39. Sih A, Bell A, Johnson C (2004) Behavioral syndromes: an ecological and evolutionary overview. Trends Ecol Evol 19:372–378. doi:10.1016/jtree.2004.04.009

  40. Smith HG, Wennerberg L, von Schantz T (1996) Adoption or infanticide: options of replacement males in the European starling. Behev Ecol Sciobiol 38:191–197

  41. Spooner A, Pribill S, Picman J (1996) Why do gray catbirds destroy eggs in nests of other birds? Experimental tests of alternative hypotheses. Can J Zool 74:1688–1695

  42. Thorstrom R, Ramos JD, Morales CM (2000) Breeding biology of barred forest-falcons (Micrastur ruficollis) in Northeastern Guatemala. Auk 117:781–786

  43. Trail PW, Strahl SD, Brown JL (1981) Infanticide in relation to individual and flock histories in a communally breeding bird, the Mexican jay (Ahelocoma ultramarina). Am Nat 118:72–82

  44. Urrutia LP, Drummond H (1990) Brood reduction and parental infanticide in Heermann’s gull. Auk 107:772–774

  45. Veiga JP (1990) Infanticide by male and female house sparrows. Anim Behav 39:496–502

  46. Veiga JP (2003) Infanticide by male house sparrows: gaining time or manipulating females? Proc R Soc Lond B Biol Sci 270(Supp 1):S87–S89. doi:10.1098/rsbl.2003.0027

  47. Veiga JP (2004) Replacement female house sparrows regularly commit infanticide: gaining time or signaling status? Behav Ecol 15:219–222. doi:0.1093/beheco/arh003

  48. Verhulst S, Nilsson J (2008) The timing of birds’ breeding seasons: a review of experiments that manipulated timing of breeding. Philos Trans R Soc Lond B Biol Sci 363:399–410. doi:10.1098/rstb.2007.2146

  49. Watanuki Y (1988) Intraspecific predation and chick survival: comparison among colonies of slaty-backed gulls. Oikos 53:194–202

  50. Wilson DS (1998) Adaptive individual differences within single populations. Philos Trans R Soc Lond B Biol Sci 353:199–205

Download references


We would like to thank Yutaka Watanuki for helpful comments during the course of the study, and thanks are also due to Kyle Elliott and two anonymous referees for thoughtful comments that greatly improved the manuscript. We gratefully acknowledge the advice of Narihito Saito and Akira Ishida, and the assistance of Tadashi Tajima and Shinji Hikosaka. The research was funded in part by the Ministry of Agriculture, Forestry, and Fisheries of Japan as Research and development projects for application in promoting new policy of Agriculture, Forestry, and Fisheries.

Author information

Correspondence to Yukiko Inoue.

Electronic supplementary material

Below is the link to the electronic supplementary material.

Supplementary material 1 (M4V 53736 kb)

Supplementary material 2 (M4V 11107 kb)

Supplementary material 1 (M4V 53736 kb)

Supplementary material 2 (M4V 11107 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Inoue, Y., Yoda, K., Fujii, H. et al. Nest intrusion and infanticidal attack on nestlings in great cormorants Phalacrocorax carbo: why do adults attack conspecific chicks?. J Ethol 28, 221–230 (2010).

Download citation


  • Infanticide
  • Phalacrocorax carbo
  • Nest competition
  • Intraspecific aggression
  • Overlapping different breeding motivation