Determining the cause of the hen harrier decline on the Orkney Islands: an experimental test of two hypotheses

A Amar, S M Redpath

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

A supplementary feeding and predator removal experiment was conducted on the hen harrier population on West Mainland, Orkney, to test whether increased predation pressure or shortage of food was responsible for the poor breeding success and potentially the decline of this population. Although numbers of crows appeared to have increased since 1983, the removal of hooded crows from breeding territories of male harriers had no detectable effect on any of the breeding parameters measured. The provision of supplementary food to male harriers significantly increased their numbers of breeding females, but had no detectable effect on either lay date, clutch size or hatching success. Results suggest that the current low levels of polygyny are a consequence of a shortage of fund during the pre-lay period. Conservation management for this species should therefore be directed towards increasing the harriers' food supply, especially during the pre-lay period.

Original languageEnglish
Pages (from-to)21-28
Number of pages8
JournalAnimal Conservation
Volume5
DOIs
Publication statusPublished - 2002

Keywords

  • CIRCUS-C-CYANEUS
  • POPULATION
  • PREDATION
  • POLYGYNY
  • NESTS
  • VOLES

Cite this

@article{bce69a3b7090493a9bda4ce6e387b293,
title = "Determining the cause of the hen harrier decline on the Orkney Islands: an experimental test of two hypotheses",
abstract = "A supplementary feeding and predator removal experiment was conducted on the hen harrier population on West Mainland, Orkney, to test whether increased predation pressure or shortage of food was responsible for the poor breeding success and potentially the decline of this population. Although numbers of crows appeared to have increased since 1983, the removal of hooded crows from breeding territories of male harriers had no detectable effect on any of the breeding parameters measured. The provision of supplementary food to male harriers significantly increased their numbers of breeding females, but had no detectable effect on either lay date, clutch size or hatching success. Results suggest that the current low levels of polygyny are a consequence of a shortage of fund during the pre-lay period. Conservation management for this species should therefore be directed towards increasing the harriers' food supply, especially during the pre-lay period.",
keywords = "CIRCUS-C-CYANEUS, POPULATION, PREDATION, POLYGYNY, NESTS, VOLES",
author = "A Amar and Redpath, {S M}",
year = "2002",
doi = "10.1017/S1367943002001038",
language = "English",
volume = "5",
pages = "21--28",
journal = "Animal Conservation",
issn = "1367-9430",
publisher = "Wiley-Blackwell",

}

TY - JOUR

T1 - Determining the cause of the hen harrier decline on the Orkney Islands: an experimental test of two hypotheses

AU - Amar, A

AU - Redpath, S M

PY - 2002

Y1 - 2002

N2 - A supplementary feeding and predator removal experiment was conducted on the hen harrier population on West Mainland, Orkney, to test whether increased predation pressure or shortage of food was responsible for the poor breeding success and potentially the decline of this population. Although numbers of crows appeared to have increased since 1983, the removal of hooded crows from breeding territories of male harriers had no detectable effect on any of the breeding parameters measured. The provision of supplementary food to male harriers significantly increased their numbers of breeding females, but had no detectable effect on either lay date, clutch size or hatching success. Results suggest that the current low levels of polygyny are a consequence of a shortage of fund during the pre-lay period. Conservation management for this species should therefore be directed towards increasing the harriers' food supply, especially during the pre-lay period.

AB - A supplementary feeding and predator removal experiment was conducted on the hen harrier population on West Mainland, Orkney, to test whether increased predation pressure or shortage of food was responsible for the poor breeding success and potentially the decline of this population. Although numbers of crows appeared to have increased since 1983, the removal of hooded crows from breeding territories of male harriers had no detectable effect on any of the breeding parameters measured. The provision of supplementary food to male harriers significantly increased their numbers of breeding females, but had no detectable effect on either lay date, clutch size or hatching success. Results suggest that the current low levels of polygyny are a consequence of a shortage of fund during the pre-lay period. Conservation management for this species should therefore be directed towards increasing the harriers' food supply, especially during the pre-lay period.

KW - CIRCUS-C-CYANEUS

KW - POPULATION

KW - PREDATION

KW - POLYGYNY

KW - NESTS

KW - VOLES

U2 - 10.1017/S1367943002001038

DO - 10.1017/S1367943002001038

M3 - Article

VL - 5

SP - 21

EP - 28

JO - Animal Conservation

JF - Animal Conservation

SN - 1367-9430

ER -