Habitat loss and raptor predation: Disentangling long- and short-term causes of red grouse declines

Simon J. Thirgood, Steve M. Redpath, Daniel T. Haydon, Peter Rothery, Ian Newton, Peter John Hudson

Research output: Contribution to journalArticle

75 Citations (Scopus)

Abstract

The number of red grouse (Lagopus lagopus scoticus) shot in the UK has declined by 50% during the 20th century. This decline has coincided with reductions in the area of suitable habitat and recoveries in the populations of some avian predators. Here we use long-term records of shooting bags and a large-scale manipulation of raptor density to disentangle the effects of habitat loss and raptor predation on grouse populations. The numbers of grouse harvested on the Eskdale half of Langholm Moor in southern Scotland declined significantly during 1913-1990 and grouse bags from the whole moor from 1950 to 1990 exhibited an almost identical but non-significant trend. Hen harriers (Circus cyaneus) and peregrine falcons (Falco peregrinus) were absent or bred at low densities on this moor throughout this period but heather-dominant vegetation declined by 48% between 1948 and 1988. Harrier and peregrine breeding numbers on Langholm Moor increased to high levels following protection in 1990 whilst grouse density and grouse bags declined year after year until shooting was abandoned in 1998. The prediction of a peak in grouse bags on Langholm Moor in 1996 based on the patterns of bags during 1950-1990 was supported by the observed peaks in 1997 on two nearby moors with few raptors which formerly cycled in synchrony with Langholm Moor. This study demonstrates that, whilst long-term declines in grouse bags were most probably due to habitat loss, high levels of raptor predation subsequently limited the grouse population and suppressed a cycle. This study thus offers support to theoretical models which predict that generalist predators may suppress cycles in prey populations.

Original languageEnglish (US)
Pages (from-to)651-656
Number of pages6
JournalProceedings of the Royal Society B: Biological Sciences
Volume267
Issue number1444
DOIs
StatePublished - Apr 7 2000

Fingerprint

Lagopus lagopus scoticus
Raptors
grouse
raptor
habitat loss
birds of prey
habitat destruction
heathlands
Ecosystem
predation
bags
Population
Recovery
Scotland
Breeding
predator
Theoretical Models
Falco peregrinus
predators
Circus

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)

Cite this

Thirgood, Simon J. ; Redpath, Steve M. ; Haydon, Daniel T. ; Rothery, Peter ; Newton, Ian ; Hudson, Peter John. / Habitat loss and raptor predation : Disentangling long- and short-term causes of red grouse declines. In: Proceedings of the Royal Society B: Biological Sciences. 2000 ; Vol. 267, No. 1444. pp. 651-656.
@article{c5a8493ff4ae4a2b8d19cdb9df4c7894,
title = "Habitat loss and raptor predation: Disentangling long- and short-term causes of red grouse declines",
abstract = "The number of red grouse (Lagopus lagopus scoticus) shot in the UK has declined by 50{\%} during the 20th century. This decline has coincided with reductions in the area of suitable habitat and recoveries in the populations of some avian predators. Here we use long-term records of shooting bags and a large-scale manipulation of raptor density to disentangle the effects of habitat loss and raptor predation on grouse populations. The numbers of grouse harvested on the Eskdale half of Langholm Moor in southern Scotland declined significantly during 1913-1990 and grouse bags from the whole moor from 1950 to 1990 exhibited an almost identical but non-significant trend. Hen harriers (Circus cyaneus) and peregrine falcons (Falco peregrinus) were absent or bred at low densities on this moor throughout this period but heather-dominant vegetation declined by 48{\%} between 1948 and 1988. Harrier and peregrine breeding numbers on Langholm Moor increased to high levels following protection in 1990 whilst grouse density and grouse bags declined year after year until shooting was abandoned in 1998. The prediction of a peak in grouse bags on Langholm Moor in 1996 based on the patterns of bags during 1950-1990 was supported by the observed peaks in 1997 on two nearby moors with few raptors which formerly cycled in synchrony with Langholm Moor. This study demonstrates that, whilst long-term declines in grouse bags were most probably due to habitat loss, high levels of raptor predation subsequently limited the grouse population and suppressed a cycle. This study thus offers support to theoretical models which predict that generalist predators may suppress cycles in prey populations.",
author = "Thirgood, {Simon J.} and Redpath, {Steve M.} and Haydon, {Daniel T.} and Peter Rothery and Ian Newton and Hudson, {Peter John}",
year = "2000",
month = "4",
day = "7",
doi = "10.1098/rspb.2000.1051",
language = "English (US)",
volume = "267",
pages = "651--656",
journal = "Proceedings of the Royal Society B: Biological Sciences",
issn = "0962-8452",
publisher = "Royal Society of London",
number = "1444",

}

Habitat loss and raptor predation : Disentangling long- and short-term causes of red grouse declines. / Thirgood, Simon J.; Redpath, Steve M.; Haydon, Daniel T.; Rothery, Peter; Newton, Ian; Hudson, Peter John.

In: Proceedings of the Royal Society B: Biological Sciences, Vol. 267, No. 1444, 07.04.2000, p. 651-656.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Habitat loss and raptor predation

T2 - Disentangling long- and short-term causes of red grouse declines

AU - Thirgood, Simon J.

AU - Redpath, Steve M.

AU - Haydon, Daniel T.

AU - Rothery, Peter

AU - Newton, Ian

AU - Hudson, Peter John

PY - 2000/4/7

Y1 - 2000/4/7

N2 - The number of red grouse (Lagopus lagopus scoticus) shot in the UK has declined by 50% during the 20th century. This decline has coincided with reductions in the area of suitable habitat and recoveries in the populations of some avian predators. Here we use long-term records of shooting bags and a large-scale manipulation of raptor density to disentangle the effects of habitat loss and raptor predation on grouse populations. The numbers of grouse harvested on the Eskdale half of Langholm Moor in southern Scotland declined significantly during 1913-1990 and grouse bags from the whole moor from 1950 to 1990 exhibited an almost identical but non-significant trend. Hen harriers (Circus cyaneus) and peregrine falcons (Falco peregrinus) were absent or bred at low densities on this moor throughout this period but heather-dominant vegetation declined by 48% between 1948 and 1988. Harrier and peregrine breeding numbers on Langholm Moor increased to high levels following protection in 1990 whilst grouse density and grouse bags declined year after year until shooting was abandoned in 1998. The prediction of a peak in grouse bags on Langholm Moor in 1996 based on the patterns of bags during 1950-1990 was supported by the observed peaks in 1997 on two nearby moors with few raptors which formerly cycled in synchrony with Langholm Moor. This study demonstrates that, whilst long-term declines in grouse bags were most probably due to habitat loss, high levels of raptor predation subsequently limited the grouse population and suppressed a cycle. This study thus offers support to theoretical models which predict that generalist predators may suppress cycles in prey populations.

AB - The number of red grouse (Lagopus lagopus scoticus) shot in the UK has declined by 50% during the 20th century. This decline has coincided with reductions in the area of suitable habitat and recoveries in the populations of some avian predators. Here we use long-term records of shooting bags and a large-scale manipulation of raptor density to disentangle the effects of habitat loss and raptor predation on grouse populations. The numbers of grouse harvested on the Eskdale half of Langholm Moor in southern Scotland declined significantly during 1913-1990 and grouse bags from the whole moor from 1950 to 1990 exhibited an almost identical but non-significant trend. Hen harriers (Circus cyaneus) and peregrine falcons (Falco peregrinus) were absent or bred at low densities on this moor throughout this period but heather-dominant vegetation declined by 48% between 1948 and 1988. Harrier and peregrine breeding numbers on Langholm Moor increased to high levels following protection in 1990 whilst grouse density and grouse bags declined year after year until shooting was abandoned in 1998. The prediction of a peak in grouse bags on Langholm Moor in 1996 based on the patterns of bags during 1950-1990 was supported by the observed peaks in 1997 on two nearby moors with few raptors which formerly cycled in synchrony with Langholm Moor. This study demonstrates that, whilst long-term declines in grouse bags were most probably due to habitat loss, high levels of raptor predation subsequently limited the grouse population and suppressed a cycle. This study thus offers support to theoretical models which predict that generalist predators may suppress cycles in prey populations.

UR - http://www.scopus.com/inward/record.url?scp=0034615917&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034615917&partnerID=8YFLogxK

U2 - 10.1098/rspb.2000.1051

DO - 10.1098/rspb.2000.1051

M3 - Article

C2 - 10821608

AN - SCOPUS:0034615917

VL - 267

SP - 651

EP - 656

JO - Proceedings of the Royal Society B: Biological Sciences

JF - Proceedings of the Royal Society B: Biological Sciences

SN - 0962-8452

IS - 1444

ER -