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Title: A first survey of the global population size and distribution of the Scottish Crossbill Loxia scotica
Authors: Summers, Ron W
Buckland, Stephen Terrence
Keywords: QL Zoology
Issue Date: Jun-2011
Citation: Summers , R W & Buckland , S T 2011 , ' A first survey of the global population size and distribution of the Scottish Crossbill Loxia scotica ' Bird Conservation International , vol 21 , no. 2 , pp. 186-198 . , 10.1017/S0959270909990323
Abstract: A survey of Scottish Crossbills Loxia scotica was carried out in 3,506 km2 of conifer woodland in northern Scotland during January to April 2008 to provide the first estimate of the global population size for this endemic bird. Population estimates were also made for Common Crossbills L. curvirostra and Parrot Crossbills L. pytyopsittacus within this range. Crossbills were lured to systematically selected survey points for counting, sexing and recording their calls for later call-type (species) identification from sonograms. Crossbills were located at 451 of the 852 survey points, and adequate tape-recordings made at 387 of these. The Scottish Crossbill had a disjunct distribution, occurring largely within the eastern part of the study area, but also in the northwest. Common Crossbills had a mainly westerly distribution. The population size of postjuvenile Scottish Crossbills was estimated as 13,600 (95%C.I. 8,130–22,700), which will approximate to 6,800 (4,065–11,350) pairs. Common Crossbills were more abundant within this range (27,100, 95% C.I. 14,700–38,400) and Parrot Crossbills rare (about 100). The sex ratio was not significantly different from parity for Scottish Crossbills. The modal number at survey points was two but numbers were larger in January than later in the survey. The numbers and distribution of all crossbill species are likely to vary between years, depending upon the size of the cone crops of the different conifers: all were coning in 2008. Common Crossbill and Parrot Crossbill numbers will also be affected by irruptions from continental Europe. A monitoring scheme is required to detect any population trend, and further work on their habitat requirement (e.g. conifer selection at different seasons) is needed to inform habitat management of native and planted conifer forests to ensure a secure future for this endemic bird.
Version: Publisher PDF
Description: "The survey was part-financed by Scottish Natural Heritage"
Status: Peer reviewed
ISSN: 0959-2709
Type: Journal article
Rights: Copyright © BirdLife International 2010. Published by Cambridge University Press, available from DOI: 10.1017/S0959270909990323
Appears in Collections:Scottish Oceans Institute Research
University of St Andrews Research
Mathematics & Statistics Research
Centre for Research into Ecological & Environmental Modelling (CREEM) Research
St Andrews Sustainablity Institute Research

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