Animal Cognition

, Volume 1, Issue 2, pp 77–82 | Cite as

Sexual differences in memory in shiny cowbirds

  • Andrea Alejandra Astié
  • Alejandro Kacelnik
  • Juan Carlos Reboreda
Original article


Avian brood parasites depend on other species, the hosts, to raise their offspring. During the breeding season, parasitic cowbirds (Molothrus sp.) search for potential host nests to which they return for laying a few days after first locating them. Parasitic cowbirds have a larger hippocampus/telencephalon volume than non-parasitic species; this volume is larger in the sex involved in nest searching (females) and it is also larger in the breeding than in the non-breeding season. In nature, female shiny cowbirds Molothrus bonariensis search for nests without the male’s assistance. Here we test whether, in association with these neuroanatomical and behavioural differences, shiny cowbirds display sexual differences in a memory task in the laboratory. We used a task consisting of finding food whose location was indicated either by the appearance or the location of a covering disk. Females learnt to retrieve food faster than males when food was associated with appearance cues, but we found no sexual differences when food was associated with a specific location. Our results are consistent with the view that parasitism and its neuroanatomical correlates affect performance in memory tasks, but the effects we found were not in the expected direction, emphasising that the nature of avian hippocampal function and its sexual differences are not yet understood.

Key words Spatial memory Hippocampus Molothrus bonariensis Sexual differences Memory task 


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  1. Briskie JV, Sealy SG (1990) Evolution of short incubation periods in the parasitic cowbirds, Molothrus spp. Auk 107:363–365CrossRefGoogle Scholar
  2. Clayton NS, Krebs JR (1994) Hippocampal growth and attrition in birds affected by experience. Proc Natl Acad Sci USA 91:7410–7414PubMedCrossRefGoogle Scholar
  3. Clayton NS, Krebs JR (1995) Memory in food-storing birds: from behaviour to brain. Curr Opin Neurobiol 5:149–154PubMedCrossRefGoogle Scholar
  4. Clayton NS, Reboreda JC, Kacelnik A (1997) Seasonal changes in hippocampus volume in parasitic cowbirds. Behav Proc 41:237–243CrossRefGoogle Scholar
  5. Cosmides L, Tooby J (1997) Dissecting the computational architecture of social inference mechanisms. In: Bock G, Cardew G (eds) Characterizing human psychological adaptations (Ciba Foundation Symposium 208). Wiley, Chichester, pp 132–158Google Scholar
  6. Eichenbaum H (1996) Is the rodent hippocampus just for “place”? Curr Opin Neurobiol 6:187–195PubMedCrossRefGoogle Scholar
  7. Friedmann H, Kiff LF (1985) The parasitic cowbirds and their hosts}. Proc West Found Vertebr Zool 2:226–302Google Scholar
  8. Gaulin SJC, Fitzgerald RW (1989) Sexual selection for spatial learning ability. Anim Behav 37:322–331CrossRefGoogle Scholar
  9. Hampton RR, Shettleworth SJ (1996) Hippocampal lesions impair memory for location but not color in passerine birds. Behav Neurosci 110:831–835PubMedCrossRefGoogle Scholar
  10. Jacobs LF, Gaulin SJC, Sherry DF, Hoffman GE (1990) Evolution of spatial cognition: sex-specific patterns of spatial behavior predict hippocampal size. Proc Natl Acad Sci USA 87:6349–6352PubMedCrossRefGoogle Scholar
  11. Kattan GH (1993) Extraordinary annual fecundity of shiny cowbirds at a tropical locality and its energetic trade-off. Abstracts of the North American research workshop on the ecology and management of cowbirds, Austin, Texas, p 20Google Scholar
  12. Krebs JR, Sherry DF, Healy SD, Perry VH, Vaccarino AL (1989) Hippocampal specializations of food storing birds. Proc Natl Acad Sci USA 86:1388–1392PubMedCrossRefGoogle Scholar
  13. Mason P (1987) Pair formation in cowbirds. Evidence found for screaming but not shiny cowbirds. Condor 89:349–356CrossRefGoogle Scholar
  14. Massoni V, Reboreda JC (1998) Costs of parasitism and the lack of defenses on the yellow-winged blackbird-shiny cowbird system. Behav Ecol Sociobiol 42:273–280CrossRefGoogle Scholar
  15. O'Keefe J, Nadel L (1978) The hippocampus as a cognitive map. Clarendon, OxfordGoogle Scholar
  16. Patel SN, Clayton NS, Krebs JR (1997) Hippocampal tissue transplants reverse spatial memory deficits produced by ibotenic acid lessions of the hippocampus in zebra finches (Taeniopygia guttata). J Neurosci 17:3861–3869PubMedGoogle Scholar
  17. Reboreda JC, Clayton NS, Kacelnik A (1996) Species and sex differences in hippocampus size between parasitic and non-parasitic cowbirds. NeuroReport 7:505–508PubMedCrossRefGoogle Scholar
  18. Rothstein SI (1990) A model system for coevolution:avian brood parasitism. Annu Rev Ecol Syst 21:481–508CrossRefGoogle Scholar
  19. Scott TW (1991) The time of the day of egg laying by brown-headed cowbird and other icterines. Can J Zool 69:2093–2099CrossRefGoogle Scholar
  20. Scott DM, Ankney CD (1983) The laying cycle of brown-headed cowbirds: passerine chickens? Auk 100:583–592Google Scholar
  21. Sherry DF, Vaccarino AL (1989) Hippocampus and memory for food caches in black-capped chickadees. Behav Neurosci 103: 308–318CrossRefGoogle Scholar
  22. Sherry DF, Vaccarino AL, Buckenham K, Herz RS (1989) The hippocampal complex of food-storing birds. Brain Behav Evol 34:308–317PubMedCrossRefGoogle Scholar
  23. Sherry DF, Forbes MRL, Khurgel M, Ivy GO (1993) Females have a larger hippocampus than males in the brood-parasitic brown-headed cowbird. Proc Natl Acad Sci USA 90:7839–7843PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Andrea Alejandra Astié
    • 1
  • Alejandro Kacelnik
    • 2
  • Juan Carlos Reboreda
    • 1
  1. 1.Instituto de Biologí y Medicina Experimental-CONICETBuenos AiresArgentina
  2. 2.Department of ZoologyUniversity of OxfordOxfordUK

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