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Occurrence and variability of tactile interactions between wild American crows and dead conspecifics.

Abstract

Observations of some mammals and birds touching their dead provoke questions about the motivation and adaptive value of this potentially risky behaviour. Here, we use controlled experiments to determine if tactile interactions are characteristic of wild American crow responses to dead crows, and what the prevalence and nature of tactile interactions suggests about their motivations. In Experiment 1, we test if food or information acquisition motivates contact by presenting crows with taxidermy-prepared dead crows, and two species crows are known to scavenge: dead pigeons and dead squirrels. In Experiment 2, we test if territoriality motivates tactile interactions by presenting crows with taxidermy crows prepared to look either dead or upright and life-like. In Experiment 1, we find that crows are significantly less likely to make contact but more likely to alarm call and recruit other birds in response to dead crows than to dead pigeons and squirrels. In addition, we find that aggressive and sexual encounters with dead crows are seasonally biased. These findings are inconsistent with feeding or information acquisition-based motivation. In Experiment 2, we find that crows rarely dive-bomb and more often alarm call and recruit other crows to dead than to life-like crows, behaviours inconsistent with responses given to live intruders. Consistent with a danger response hypothesis, our results show that alarm calling and neighbour recruitment occur more frequently in response to dead crows than other stimuli, and that touching dead crows is atypical. Occasional contacts, which take a variety of aggressive and sexual forms, may result from an inability to mediate conflicting stimuli.This article is part of the theme issue 'Evolutionary thanatology: impacts of the dead on the living in humans and other animals'.

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  • Authors+Show Affiliations

    ,

    School of Environmental and Forest Sciences, University of Washington College of the Environment, Seattle, WA 98195-5350, USA kaelis@uw.edu.

    School of Environmental and Forest Sciences, University of Washington College of the Environment, Seattle, WA 98195-5350, USA.

    Source

    Pub Type(s)

    Journal Article
    Research Support, U.S. Gov't, Non-P.H.S.

    Language

    eng

    PubMed ID

    30012745

    Citation

    Swift, Kaeli, and John M. Marzluff. "Occurrence and Variability of Tactile Interactions Between Wild American Crows and Dead Conspecifics." Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, vol. 373, no. 1754, 2018.
    Swift K, Marzluff JM. Occurrence and variability of tactile interactions between wild American crows and dead conspecifics. Philos Trans R Soc Lond, B, Biol Sci. 2018;373(1754).
    Swift, K., & Marzluff, J. M. (2018). Occurrence and variability of tactile interactions between wild American crows and dead conspecifics. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 373(1754), doi:10.1098/rstb.2017.0259.
    Swift K, Marzluff JM. Occurrence and Variability of Tactile Interactions Between Wild American Crows and Dead Conspecifics. Philos Trans R Soc Lond, B, Biol Sci. 2018 09 5;373(1754) PubMed PMID: 30012745.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Occurrence and variability of tactile interactions between wild American crows and dead conspecifics. AU - Swift,Kaeli, AU - Marzluff,John M, PY - 2018/02/25/accepted PY - 2019/09/05/pmc-release PY - 2018/7/18/entrez PY - 2018/7/18/pubmed PY - 2018/7/18/medline KW - American crow KW - comparative thanatology KW - dead conspecific KW - dead heterospecific KW - necrophilia KW - tactile interactions JF - Philosophical transactions of the Royal Society of London. Series B, Biological sciences JO - Philos. Trans. R. Soc. Lond., B, Biol. Sci. VL - 373 IS - 1754 N2 - Observations of some mammals and birds touching their dead provoke questions about the motivation and adaptive value of this potentially risky behaviour. Here, we use controlled experiments to determine if tactile interactions are characteristic of wild American crow responses to dead crows, and what the prevalence and nature of tactile interactions suggests about their motivations. In Experiment 1, we test if food or information acquisition motivates contact by presenting crows with taxidermy-prepared dead crows, and two species crows are known to scavenge: dead pigeons and dead squirrels. In Experiment 2, we test if territoriality motivates tactile interactions by presenting crows with taxidermy crows prepared to look either dead or upright and life-like. In Experiment 1, we find that crows are significantly less likely to make contact but more likely to alarm call and recruit other birds in response to dead crows than to dead pigeons and squirrels. In addition, we find that aggressive and sexual encounters with dead crows are seasonally biased. These findings are inconsistent with feeding or information acquisition-based motivation. In Experiment 2, we find that crows rarely dive-bomb and more often alarm call and recruit other crows to dead than to life-like crows, behaviours inconsistent with responses given to live intruders. Consistent with a danger response hypothesis, our results show that alarm calling and neighbour recruitment occur more frequently in response to dead crows than other stimuli, and that touching dead crows is atypical. Occasional contacts, which take a variety of aggressive and sexual forms, may result from an inability to mediate conflicting stimuli.This article is part of the theme issue 'Evolutionary thanatology: impacts of the dead on the living in humans and other animals'. SN - 1471-2970 UR - https://www.unboundmedicine.com/medline/citation/30012745/Occurrence_and_variability_of_tactile_interactions_between_wild_American_crows_and_dead_conspecifics L2 - https://royalsocietypublishing.org/doi/full/10.1098/rstb.2017.0259?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -