eBangor

The effects of saltmarsh conservation grazing on breeding Common Redshank Tringa totanus

Sharps, Elwyn Andrew (2015) The effects of saltmarsh conservation grazing on breeding Common Redshank Tringa totanus. PhD thesis, Prifysgol Bangor University.

[img] Text
Signed Declaration Elwyn Sharps.pdf
Restricted to Repository staff only

Download (50kB)
[img]
Preview
Text
Elwyn Sharps PhD thesis final version.pdf

Download (12MB) | Preview

Abstract

The Common Redshank Tringa totanus breeding population on British saltmarshes has reduced by > 50% since 1985, with declines linked to changes in grazing management. Conservation initiatives have encouraged low-intensity grazing of < 1 cattle ha-1 but Redshank have continued to decline. This study investigated effects of grazing intensity on Redshank nest survival, and how conservation management can reduce nest mortality. This was studied by: (a) recording nest survival though monitoring of individual nests on saltmarshes subject to different livestock densities, (b) characterising vegetation at these nests, (c) quantifying spatial and temporal variation in nest trampling probability by GPS logging cattle, and (d) comparing nest survival on saltmarshes with alternative conservation management. Both nest trampling and predation risk increased with cattle density to almost 100% at 1 cattle ha-1. Predation risk may be higher on grazed marshes because vegetation height at nests decreased to only 11cm at the highest grazing intensities. GPS logging showed that livestock concentrate their grazing, and therefore trampling, in the areas of most importance for breeding Redshank during the breeding season. A large scale comparison showed that grazing with adult cattle resulted in higher nest survival than mowing or no management, but that grazing with young cattle resulted in a 99% risk of trampling. These results therefore show that even < 1 cattle ha-1 grazing can reduce Redshank nest survival to near zero, directly by trampling and indirectly by increasing predation through reducing vegetation height. The conservation benefits of grazing may be increased by reducing livestock densities, grazing with adult cattle, or by increasing the number of drinking troughs spread across the saltmarsh as this could move livestock away from Redshank breeding areas. Further research is needed into the potential role of rotational grazing systems that limit livestock access to Redshank habitat during the nesting season.

Item Type: Thesis (PhD)
Subjects: Degree Thesis
Departments: College of Natural Sciences > School of Ocean Sciences
Degree Thesis
Date Deposited: 14 Aug 2015 15:41
Last Modified: 19 Dec 2016 11:27
URI: http://e.bangor.ac.uk/id/eprint/5254
Administer Item Administer Item

eBangor is powered by EPrints 3 which is developed by the School of Electronics and Computer Science at the University of Southampton. More information and software credits.