Spatio-temporal trends in the predation of large gulls by peregrine falcons (Falco peregrinus) in an insular breeding population

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Individual diet specialization occurs in many populations of generalist predators, with specific individuals developing specialist strategies in their feeding behaviour. Intraspecific resource partitioning is hypothesised to be common amongst species in higher trophic levels where competition for resources is intense, and a key driver in breeding success and community structure. Though well-studied in other predators, there is sparse data on ecological specialization in raptors, which are important drivers of community and trophic structure. In this study, the breeding season diet of an insular population of peregrine falcons (Falco peregrinus) was determined from indirect analysis of prey remains collected over three years. An unexpected result was the high proportion of large gulls (Laridae), of the genus Larus, in the diet of two breeding pairs of peregrines. Large gulls made up 18.44% by frequency of total prey recorded and 30.81% by biomass. Herring gulls (Larus argentatus) were the most common large gull prey, with immatures most frequent (67.95%) compared to adults (19.23%). Overall, most gulls predated were immatures (80.77%). Frequency of predation varied between breeding pairs and months, but was consistent over the three years. Most gulls were taken in April (37.17%), followed by May (19.23%), with a smaller peak of immature herring gulls taken in August and September. The pattern of regular predation by peregrines on large gulls is a new observation with important implications for understanding individual diet specialization in raptors, and its effect on bird populations and community structure.

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  • Araujo MS Bolnick DI & Layman CA 2011: The ecological causes of individual specialization. Ecology Letters 14: 948–958.

  • Bang P & Dahlstrom P 2011: Animal tracks and signs. OUP Oxford 264.

  • Bolnick DI Svanback R Fordyce JA Yang LH Davis JM Hulsey CD & Forister ML 2003: The ecology of individuals: Incidence and implications of individual specialization. The American Naturalist 161: 1–28.

  • Beebe FL 1960: The marine peregrines of the northwest Pacific coast. The Condor 62: 145–189.

  • Booker H & Price D 2014: Manx Shearwater recovery on Lundy: Population and distribution change from 2001 to 2013. Journal of the Lundy Field Society 4: 105–116.

  • Brown A Price D Slader P Booker H Lock L & Deveney D 2011: Seabirds on Lundy: their current status recent history and prospects for the restoration of a once-important bird area. British Birds 104: 139–158.

  • Brown R Ferguson J Lawrence M & Lees D 2003: Tracks and signs of the birds of Britain and Europe 2nd ed. Christopher Helm London 333.

  • BTO 2016: Retreived August 25 2016 from

  • Castellanos A Arguelles C Salinas F Rodriguez A & Ortega-Rubio A 2006: Diet of breeding peregrine falcons at a coastal lagoon Baja California Sur Mexico. Journal of Raptor Research 40(3): 241–244.

  • Constantini D Casagrande S Di Lieto G Fanfani A & DelľOmo G 2005: Consistent differences in feeding habits between neighbouring breeding kestrels. Behaviour 142: 1409–1421. DOI: 10.1163/156853905774539409.

  • Davis TJ & Jones TA 2007: The birds of Lundy. Devon bird watching and preservation society and Lundy field society Berrynarbor Devon 319.

  • Dawson RD Mossop DH & Boukall B 2011: Prey use and selection in relation to reproduction by peregrine falcons breeding along the Yukon River Canada. Journal of Raptor Research 45(1): 27–37. DOI: 10.3356/JRR-09-84.1.

  • Dehnhard N Eens M Sturaro N Lepoint G Demongin L Quillfeldt P & Poisbleau M 2016: Is individual consistency in body mass and reproductive decisions linked to individual specialization in foraging behaviour in a long-lived seabird? Ecology and Evolution 6(13): 4488—4501. DOI: 10.1002/ece3.2213.

  • Dixon A 2005: The prey of peregrines Falco peregrinus at breeding territories in Northumberland. Transactions of the Natural History Society of Northumbria 64: 111–120.

  • Drewitt E & Dixon N 2008: Diet and prey selection of urban-dwelling peregrine falcons in southwest England. British Birds 101: 58–67.

  • Garcia GO Susana BoM & Yorio P 2014: Prey composition of peregrine falcons (Falco peregrinus) preying upon a mixed-species seabird colony in Argentine Patagonia. Ornitologia Neotropical 25: 1–5.

  • Horswill C Matthiopoulos J Ratcliffe N Green JA Trathan PN McGill RAR Phillips RA & O’Connell TC 2016: Drivers of intrapopulation variation in resource use in a generalist predator the macaroni penguin. Marine Ecology Progress Series 548: 233–247. DOI: 10.3354/meps11626.

  • Krebs CJ 1999: Ecological methodology 2nd ed. Benjamin-Cummings Menlo Park California 654.

  • Marti CD Bechard M & Jaksic FM 2007: Food habits 129–151. In: Bird DM Bildstein KL Barber DR & Zimmerman A (eds.) Raptor research and management techniques. Raptor Research Foundation Hancock House Canada 463.

  • Navarro-Lopez J Vergara P & Fargallo JA 2014: Trophic niche width offspring condition and immunity in a raptor species. Oecologia 174: 1215–1224. DOI: 10.1007/s00442-013-2855-9.

  • Nelson RW 1990: Status of the peregrine falcon Falco peregrinus pealei on Langara Island Queen Charlotte Islands British Columbia 1968–1989. The Canadian Field-Naturalist 104: 193–199.

  • Nelson RW 2004: The 1995 Peregrine falcon survey on Langara Island 35–37. In: Banasch U & Holroyd G (eds.) The 1995 Peregrine falcon survey in Canada. Canadian Wildlife Service Occ. Paper No. 110.

  • Pagani-Nunez E Barnett CA Gu H & Goodale E 2016: The need for new categorizations of dietary specialism incorporating spatio-temporal availability of individual diet specialization. Journal of Zoology 300 (1): 1–7. DOI: 10.1111/jzo.12364.

  • Paine RT Wootton JT & Boersma PD 1990: Direct and indirect effects of peregrine falcon predation on seabird abundance. The Auk 107: 1–9.

  • Price D Slader P & Booker H 2014: Breeding cliff-nesting seabirds. Lundy Field Society Annual Report 2013 63: 85–92.

  • Ratcliffe DA 1993: The peregrine falcon. 2nd ed. T & AD Poyser London 454.

  • R Core Team 2016: R: A language and environment for statistical computing. R Foundation for Statistical Computing Vienna Austria

  • Sargeant BL 2007: Individual foraging specialization: niche width versus niche overlap. Oikos 116: 1431–1437. DOI: 10.111l/j.0030-1299.2007.15833.x.

  • Schoener TW 1974: Resource partitioning in ecological communities. Science 185: 27–39.

  • Sutton LJ 2015a: Prey spectrum and foraging behaviour of coastal peregrine falcons Falco peregrinus in South Devon. Devon Birds 68(2): 3–12.

  • Sutton LJ 2015b: Population status of the peregrine falcon Falco peregrinus on Lundy. Lundy Field Society Annual Report 2014 64: 98–102.

  • Sutton LJ 2016: Status of the peregrine falcon Falco peregrinus on Lundy: Breeding ecology and prey spectrum. Journal of the Lundy Field Society 5: 75–88.

  • Terraube J Guixe D & Arroyo B 2014: Diet composition and foraging success in generalist predators: Are specialist individual’s better foragers? Basic and Applied Ecology 15: 616–624. DOI: 10.1016/j.baae.2014.08.008.

  • Velarde E 1993: Predation of nesting larids by peregrine falcons at Rasa Island Gulf of California Mexico. The Condor 95: 706–708.

  • White CM Cade TJ & Enderson JH 2013: Peregrine falcons of the world. Lynx Edicions Barcelona 379.

  • Whitfield DP Reid R Haworth PF Madders M Marquiss M Tingay R & Fielding AH 2009: Diet specificity is not associated with increased reproductive performance of golden eagles Aquila chrysaetos in Western Scotland. Ibis 151: 255–264. DOI: 10.1111/j.1474-919X.2009.00924.x.

  • Wiens JA 1984: Resource systems populations and communities 397–436. In: Price PW Slobodchikoff CN & Gaud WS (eds.) A new ecology: Novel approaches to interactive systems. John Wiley & Sons New York 515.

  • Wright SJ 1980: Density compensation in island avifaunas. Oecologia 45: 385–389.

  • Zabala J & Zuberogoitia I 2014: Individual quality explains variation in reproductive success better than territory quality in a long-lived territorial raptor. PLoS ONE 9(3): e90254. DOI: 10.1371/joumal.pone.0090254.

  • Zuberogoitia I Martínez JE González-Oreja JA Calvo JF & Zabala J 2013: The relationship between brood size and prey selection in a peregrine falcon population located in a strategic region on the Western European flyway. Journal of Ornithology 154(1): 73–82. DOI: 10.1007/s10336-012-0872-9.

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