Surplus killing

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A stoat surplus killing chipmunks (Ernest Thompson Seton, 1909)
Multiple sheep killed by a cougar

Surplus killing, also known as excessive killing, henhouse syndrome,[1][2] or overkill,[3] is a common behavior exhibited by predators, in which they kill more prey than they can immediately eat and then they either cache or abandon the remainder. The term was invented by Dutch biologist Hans Kruuk after studying spotted hyenas in Africa[4] and red foxes in England.[5][6] Some of the other animals which have been observed engaging in surplus killing include orcas,[7] zooplankton,[8] humans,[9] damselfly naiads,[10] predaceous mites [citation needed], martens,[11] weasels,[12] honey badgers,[13] jaguar [citation needed], leopards,[13] lions,[14][13] wolves,[15] spiders,[13] brown bears,[16][17] American black bears,[18] polar bears,[14] coyotes,[14][19] lynxes,[20] minks,[21] raccoons[22] and dogs.[citation needed]


In Tasmania, in a single dog attack, 58 little penguins were killed.[23] In mainland Australia, a single fox once killed around 74 penguins over several days, eating almost nothing.[24] One leopard in Cape Province, South Africa killed 51 sheep and lambs in a single incident.[25] Similarly, two caracal in Cape Province killed 22 sheep in one night, eating only part of the buttock of one carcass.[26] Up to 19 spotted hyenas once killed 82 Thomson's gazelle and badly injured 27, eating just 16%.[1]

In late autumn, least weasels often surplus-kill vole and then dig them up and eat them on winter days when it is too cold to hunt. In March 2016, a pack of 9 grey wolves in Wyoming was found to have killed 19 elk. John Lund, of the Wyoming Game and Fish Department, said that he had never documented surplus killings that extreme from grey wolves.[27] In Florida, laboratory experiments documented cases of surplus killing in larvae of the predatory midge Corethrella appendiculata against specific larval stages of different species of mosquitoes of the genus Toxorhynchites.[28]

Possible causes[edit]

In surplus killing, predators eat only the most-preferred animals and animal parts. Bears engaging in surplus killing of salmon are more likely to eat unspawned fish because of higher muscle quality, and high-energy parts such as brains and eggs.[1] Surplus killing can deplete the overall food supply, waste predator energy and risk them being injured. Nonetheless, researchers say animals surplus-kill whenever they can, in order to procure food for offspring and others, to gain valuable killing experience, and to create the opportunity to eat the carcass later when they are hungry again.[1][29]

See also[edit]


  1. ^ a b c d Mills, L. Scott (17 December 2012). Conservation of wildlife populations: demography, genetics, and management (2nd ed.). Hoboken, NJ: Wiley-Blackwell. p. 148. ISBN 9780470671504.
  2. ^ Moskowitz, David (4 February 2013). Wolves in the Land of Salmon. Timber Press. p. 144. ISBN 978-1604692273.
  3. ^ Mysterud, Ivar (1980). "Bear Management and Sheep Husbandry in Norway, with a Discussion of Predatory Behavior Significant for Evaluation of Livestock Losses". Bears: Their Biology and Management. 4: 233–241. doi:10.2307/3872873. ISSN 1936-0614. JSTOR 3872873.
  4. ^ Kruuk, Hans (1972). The Spotted Hyena: A study of predation and social behaviour. BBC Books. p. 335. ISBN 0-563-20844-9.
  5. ^ Macdonald, David (1987). Running with the Fox. Unwin Hyman. p. 224. ISBN 0-04-440199-X.
  6. ^ Kruuk, Hans (2009). "Surplus killing by carnivores". Journal of Zoology. 166 (2): 233–244. doi:10.1111/j.1469-7998.1972.tb04087.x.
  7. ^ "Suspected surplus killing of harbor seal pups (Phoca vitulina) by killer whales (Orcinus orca)". Cascadia Research. 2015-12-11. Retrieved 2021-08-09.
  8. ^ Montagnes, David; Fenton, Andy (24 September 2012). "Prey-abundance affects zooplankton assimilation efficiency and the outcome of biogeochemical models". Ecological Modelling. 243: 1–7. doi:10.1016/j.ecolmodel.2012.05.006.
  9. ^ "Four Surplus Killing". Living with Coyotes. University of Texas Press. 2005-12-31. pp. 42–52. doi:10.7560/706323-005. ISBN 978-0-292-79696-6. S2CID 243782280. Retrieved 2022-08-10.
  10. ^ Lounibos, L. P.; Makhni, S.; Alto, B. W.; Kesavaraju, B. (March 2008). "Surplus Killing by Predatory Larvae of Corethrella appendiculata: Prepupal Timing and Site-Specific Attack on Mosquito Prey". Journal of Insect Behavior. 21 (2): 47–54. Bibcode:2008JIBeh..21...47L. doi:10.1007/s10905-007-9103-2. PMC 2600435. PMID 19081802.
  11. ^ Brzeziński, Marcin; Rodak, Łukasz; Zalewski, Andrzej (2014). ""Reversed" intraguild predation: red fox cubs killed by pine marten". Acta Theriologica. 59 (3): 473–477. doi:10.1007/s13364-014-0179-8. PMC 4058055. PMID 24954928.
  12. ^ Oksanen, Tarja; Oksanen, Lauri; Fretwell, Stephen D. (1985). "Surplus Killing in the Hunting Strategy of Small Predators". The American Naturalist. 126 (3): 328–346. doi:10.1086/284420. ISSN 0003-0147. JSTOR 2461358. S2CID 84799770.
  13. ^ a b c d Shen, Zuolin; Wei, Junjie (2018-06-01). "Hopf bifurcation analysis in a diffusive predator-prey system with delay and surplus killing effect". Mathematical Biosciences and Engineering: MBE. 15 (3): 693–715. doi:10.3934/mbe.2018031. PMID 30380326.
  14. ^ a b c Kruuk, Hans (1972). "Surplus killing by carnivores". Journal of Zoology. 166 (2): 233–244. doi:10.1111/j.1469-7998.1972.tb04087.x.
  15. ^ Miller, Frank L.; Gunn, Anne; Broughton, Eric (2011-02-14). "Surplus killing as exemplified by wolf predation on newborn caribou". Canadian Journal of Zoology. 63 (2): 295–300. doi:10.1139/z85-045.
  16. ^ Lincoln, Alexandra E; Quinn, Thomas P (2019-03-04). "Optimal foraging or surplus killing: selective consumption and discarding of salmon by brown bears". Behavioral Ecology. 30 (1): 202–212. doi:10.1093/beheco/ary139.
  17. ^ "Far North Grizzlies Develop Taste for Muskoxen, Alaska Science Forum". June 21, 2011. Archived from the original on August 7, 2011.
  18. ^ Horstman, Louise P.; Gunson, John R. (1982). "Black Bear Predation on Livestock in Alberta". Wildlife Society Bulletin. 10 (1): 34–39. JSTOR 3781799.
  19. ^ Ewer, R. F. (1968). Ethology ofmammals. London: Logos Press Ltd.
  20. ^ Odden, John; Linnell, John D. C.; Moa, Pål Fossland; Herfindal, Ivar; Kvam, Tor; Andersen, Reidar (2002). "Lynx Depredation on Domestic Sheep in Norway". The Journal of Wildlife Management. 66 (1): 98–105. doi:10.2307/3802876. JSTOR 3802876.
  21. ^ Short, Jeff; Kinnear, J.E.; Robley, Alan (2002-03-01). "Surplus killing by introduced predators in Australia—evidence for ineffective anti-predator adaptations in native prey species?". Biological Conservation. 103 (3): 283–301. Bibcode:2002BCons.103..283S. doi:10.1016/S0006-3207(01)00139-2.
  22. ^ Hartman, Lisa H.; Gaston, Anthony J.; Eastman, Donald S. (1997). "Raccoon Predation on Ancient Murrelets on East Limestone Island, British Columbia". The Journal of Wildlife Management. 61 (2): 377–388. doi:10.2307/3802594. JSTOR 3802594.
  23. ^ Adamczyk, Ed (2018-10-17). "Dog attack kills 58 penguins in Tasmania". UPI. Retrieved 2020-04-04.
  24. ^ Peacock, Sue (2017-08-10). "Penguins killed in fox attack on Victoria's Middle Island". ABC News. Retrieved 2019-09-26.
  25. ^ Stuart, C. T. (1986). "The incidence of surplus killing by Panthera pardus and Felis caracal in Cape Province, South Africa". Mammalia. 50 (4): 556–558. doi:10.1515/mamm.1986.50.4.553. ISSN 0025-1461.
  26. ^ Skinner, J. D. (1979). "Feeding behaviour in Caracal Felis caracal". Journal of Zoology. 189 (4): 523–525. doi:10.1111/j.1469-7998.1979.tb03979.x.
  27. ^ "Wyoming wolf pack kills 19 elk in rare 'surplus killing'". Archived from the original on 2016-04-04. Retrieved 2016-03-25.
  28. ^ L.P. Lounibos, S. Mahkni, B.W.Alto, B. Kesavaraju (Mar 2008). "Surplus Killing by Predatory Larvae of Corethrella appendiculata: Prepupal Timing and Site-Specific Attack on Mosquito Prey". Journal of Insect Behavior. 21 (2): 47–54. Bibcode:2008JIBeh..21...47L. doi:10.1007/s10905-007-9103-2. PMC 2600435. PMID 19081802.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  29. ^ Hansen, Kevin (2006). Bobcat: master of survival ([Online-Ausg.] ed.). New York: Oxford University Press. pp. 114. ISBN 0195183037.