The decline of Common Kestrels Falco tinnunculus in a forested area of northern England: the role of predation by Northern Goshawks Accipiter gentilis

S. J. Petty, D. I. K. Anderson, M. Davison, B. Little, T. N. Sherratt, C. J. Tomas, Xavier Lambin

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

We have previously documented the decline of the Common Kestrel Falco tinnunculus over a 23-year period in a large coniferous forest in northern England. Kestrels fed predominantly on Field Voles Microtus agrestis, which were most abundant in young plantations (1-11 years old). Over the 23 years, voles remained abundant in the study area, but their numbers fluctuated cyclically. Here we consider whether the decline of Kestrels was linked to predation by Northern Goshawk Accipiter gentilis. Goshawks first bred in the study area in 1973 and increased until 1989, after which numbers stabilized. We use a number of approaches to explore the role of Goshawk predation, all of which are correlative, but independent. First, there was a significant negative relationship between Kestrel and Goshawk numbers after controlling for a decline in vole habitat. Short-eared Owls Asio flammeus , which also hunt by day, declined over the same period as Kestrels. Second, numbers of Tawny Owl Strix aluco and Long-eared Owl Asio otus did not decline as Goshawk numbers increased. These two species are also vole-dependent, but active by night, and less vulnerable to Goshawk attack. Third, six species of raptor comprised 4.5% of 5445 Goshawk prey items during the breeding season, but more Kestrels were killed than the combined total of all other raptors. Goshawks not only killed many adult Kestrels in early spring, prior to breeding, when it would have most impact on population levels, but there was also a temporal trend for predation on Kestrels to be inversely density-dependent. Finally, we estimated that Goshawks removed more Kestrels than were recorded each spring in the study area. We interpreted this as indicating that immigrant Kestrels were being removed continually, mostly before they could breed. We conclude that the decline of Kestrels (and possibly Short-eared Owls) was mainly due to predation by Goshawks. This study provides some of the strongest evidence yet of the role of predation in the hierarchical structuring of raptor communities.

Original languageEnglish
Pages (from-to)472-483
Number of pages11
JournalIbis
Volume145
Issue number3
DOIs
Publication statusPublished - 2003

Keywords

  • VOLE MICROTUS-AGRESTIS
  • OWLS STRIX-ALUCO
  • INTRAGUILD PREDATION
  • TRAVELING-WAVES
  • CONIFER FOREST
  • KIELDER-FOREST
  • POPULATION
  • DENSITY
  • DYNAMICS
  • RAPTORS

Cite this

The decline of Common Kestrels Falco tinnunculus in a forested area of northern England: the role of predation by Northern Goshawks Accipiter gentilis. / Petty, S. J.; Anderson, D. I. K.; Davison, M.; Little, B.; Sherratt, T. N.; Tomas, C. J.; Lambin, Xavier.

In: Ibis, Vol. 145, No. 3, 2003, p. 472-483.

Research output: Contribution to journalArticle

Petty, S. J. ; Anderson, D. I. K. ; Davison, M. ; Little, B. ; Sherratt, T. N. ; Tomas, C. J. ; Lambin, Xavier. / The decline of Common Kestrels Falco tinnunculus in a forested area of northern England: the role of predation by Northern Goshawks Accipiter gentilis. In: Ibis. 2003 ; Vol. 145, No. 3. pp. 472-483.
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AU - Davison, M.

AU - Little, B.

AU - Sherratt, T. N.

AU - Tomas, C. J.

AU - Lambin, Xavier

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N2 - We have previously documented the decline of the Common Kestrel Falco tinnunculus over a 23-year period in a large coniferous forest in northern England. Kestrels fed predominantly on Field Voles Microtus agrestis, which were most abundant in young plantations (1-11 years old). Over the 23 years, voles remained abundant in the study area, but their numbers fluctuated cyclically. Here we consider whether the decline of Kestrels was linked to predation by Northern Goshawk Accipiter gentilis. Goshawks first bred in the study area in 1973 and increased until 1989, after which numbers stabilized. We use a number of approaches to explore the role of Goshawk predation, all of which are correlative, but independent. First, there was a significant negative relationship between Kestrel and Goshawk numbers after controlling for a decline in vole habitat. Short-eared Owls Asio flammeus , which also hunt by day, declined over the same period as Kestrels. Second, numbers of Tawny Owl Strix aluco and Long-eared Owl Asio otus did not decline as Goshawk numbers increased. These two species are also vole-dependent, but active by night, and less vulnerable to Goshawk attack. Third, six species of raptor comprised 4.5% of 5445 Goshawk prey items during the breeding season, but more Kestrels were killed than the combined total of all other raptors. Goshawks not only killed many adult Kestrels in early spring, prior to breeding, when it would have most impact on population levels, but there was also a temporal trend for predation on Kestrels to be inversely density-dependent. Finally, we estimated that Goshawks removed more Kestrels than were recorded each spring in the study area. We interpreted this as indicating that immigrant Kestrels were being removed continually, mostly before they could breed. We conclude that the decline of Kestrels (and possibly Short-eared Owls) was mainly due to predation by Goshawks. This study provides some of the strongest evidence yet of the role of predation in the hierarchical structuring of raptor communities.

AB - We have previously documented the decline of the Common Kestrel Falco tinnunculus over a 23-year period in a large coniferous forest in northern England. Kestrels fed predominantly on Field Voles Microtus agrestis, which were most abundant in young plantations (1-11 years old). Over the 23 years, voles remained abundant in the study area, but their numbers fluctuated cyclically. Here we consider whether the decline of Kestrels was linked to predation by Northern Goshawk Accipiter gentilis. Goshawks first bred in the study area in 1973 and increased until 1989, after which numbers stabilized. We use a number of approaches to explore the role of Goshawk predation, all of which are correlative, but independent. First, there was a significant negative relationship between Kestrel and Goshawk numbers after controlling for a decline in vole habitat. Short-eared Owls Asio flammeus , which also hunt by day, declined over the same period as Kestrels. Second, numbers of Tawny Owl Strix aluco and Long-eared Owl Asio otus did not decline as Goshawk numbers increased. These two species are also vole-dependent, but active by night, and less vulnerable to Goshawk attack. Third, six species of raptor comprised 4.5% of 5445 Goshawk prey items during the breeding season, but more Kestrels were killed than the combined total of all other raptors. Goshawks not only killed many adult Kestrels in early spring, prior to breeding, when it would have most impact on population levels, but there was also a temporal trend for predation on Kestrels to be inversely density-dependent. Finally, we estimated that Goshawks removed more Kestrels than were recorded each spring in the study area. We interpreted this as indicating that immigrant Kestrels were being removed continually, mostly before they could breed. We conclude that the decline of Kestrels (and possibly Short-eared Owls) was mainly due to predation by Goshawks. This study provides some of the strongest evidence yet of the role of predation in the hierarchical structuring of raptor communities.

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KW - OWLS STRIX-ALUCO

KW - INTRAGUILD PREDATION

KW - TRAVELING-WAVES

KW - CONIFER FOREST

KW - KIELDER-FOREST

KW - POPULATION

KW - DENSITY

KW - DYNAMICS

KW - RAPTORS

U2 - 10.1046/j.1474-919X.2003.00191.x

DO - 10.1046/j.1474-919X.2003.00191.x

M3 - Article

VL - 145

SP - 472

EP - 483

JO - Ibis

JF - Ibis

SN - 0019-1019

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ER -