Please use this identifier to cite or link to this item: http://hdl.handle.net/1893/29839
Appears in Collections:Biological and Environmental Sciences Journal Articles
Peer Review Status: Refereed
Title: How important are different non-native conifers in Britain to Common Crossbills Loxia curvirostra curvirostra?
Author(s): McNab, Eilidh
Summers, Ron
Harrison, Gavin
Park, Kirsty J
Contact Email: k.j.park@stir.ac.uk
Issue Date: 2019
Citation: McNab E, Summers R, Harrison G & Park KJ (2019) How important are different non-native conifers in Britain to Common Crossbills Loxia curvirostra curvirostra?. Bird Study, 66 (1), pp. 64-72. https://doi.org/10.1080/00063657.2019.1614143
Abstract: Capsule Pines physically defend their seeds against seed-eating birds and mammals more than spruces or larches. Cone characteristics reflect the rate at which Common Crossbills Loxia curvirostra curvirostra extract seeds from different non-native conifers in Britain. Aims To assess the profitability of different non-native conifers in Britain for Common Crossbills in winter. Methods We measured cone and seed parameters of conifers (Norway Spruce Picea abies, Sitka Spruce Picea sitchensis, Lodgepole Pine Pinus contorta and Japanese Larch Larix kaempferi) introduced into Britain and compared these with the native Scots Pine Pinus sylvestris. Feeding trials with captive Common Crossbills assessed intake rates. Results The pines had thick and long scales, Japanese Larch had thin, short scales but thick seed coats and Sitka Spruce had thin, papery and short scales, and the thinnest seed coat. The two spruce species had more seeds per cone and the kernels had a higher energy content than the pines and larch. Feeding trials, simulating cones in winter, found that Common Crossbills failed to access seeds in closed Scots Pine cones. They also had difficulty in prising the scales of closed Lodgepole Pine cones but were able to forage on partially open cones. They took longer to extract seeds from large, open Lodgepole Pine cones than small ones, reflecting the effect of increasing scale thickness in larger pine cones. They also took longer to extract Lodgepole Pine seeds than Sitka Spruce and larch seeds. Although Common Crossbills could extract seeds quickly from open Sitka Spruce cones, the small seed size made the energy intake rate similar to Japanese Larch, if all seeds contained a kernel. However, after accounting for the proportion of seeds with a kernel, Sitka Spruce was the more profitable. Conclusion The conifer food resource for crossbills in Britain has changed through the planting of non-native conifers. The physical properties of the cones and seeding phenology influence the rate at which Common Crossbills can extract seeds.
DOI Link: 10.1080/00063657.2019.1614143
Rights: This item has been embargoed for a period. During the embargo please use the Request a Copy feature at the foot of the Repository record to request a copy directly from the author. You can only request a copy if you wish to use this work for your own research or private study. This is an Accepted Manuscript of an article published by Taylor & Francis Group in Bird Study on 31 May 2019, available online: http://www.tandfonline.com/10.1080/00063657.2019.1614143.

Files in This Item:
File Description SizeFormat 
FINAL_crossbill_paper_submission.pdfFulltext - Accepted Version624.77 kBAdobe PDFUnder Embargo until 2021-01-01    Request a copy

Note: If any of the files in this item are currently embargoed, you can request a copy directly from the author by clicking the padlock icon above. However, this facility is dependent on the depositor still being contactable at their original email address.



This item is protected by original copyright



Items in the Repository are protected by copyright, with all rights reserved, unless otherwise indicated.

If you believe that any material held in STORRE infringes copyright, please contact library@stir.ac.uk providing details and we will remove the Work from public display in STORRE and investigate your claim.