Recently, I had the pleasure of paying my first visit to our Loch of Strathbeg reserve in Aberdeenshire. The office window has one of the best views in the whole of the RSPB as it looks directly onto a tern island which, thanks to the installation of a predator fence, creates a cacophony.
Loch of Stratbeg (Andy Hay, rspb-images.com)
Built over the winter of 2013-14 to exclude otters which were feasting on eggs, the fence has helped the reserve go from 10 pairs of common terns and 30 pairs of black headed gulls raising no chicks at all in 2012 or 2013 to 178 pairs of terns and 36 black headed gulls in 2017 raising almost 300 chicks. This year looks to be equally successful.
This is another reminder of the impact that fences erected to exclude predators can have on breeding productivity of ground nesting birds.
As I have written in previous years (for example see here), deciding to introduce any form of predator control (lethal or non-lethal) is something we never take lightly. It’s always based on evidence* and guided by our Council-agreed policy.
The RSPB’s approach to any type of predator control means that we first seek evidence of a problem, check whether there is a non-lethal solution and if so implement that. In many cases (as for the terns at Loch of Strathbeg) this does the job needed.
We now have fences at 28 reserves protecting breeding waders over 874 ha. At sites with anti-predator fences, lapwing productivity has been consistently above that necessary for population maintenance (0.6 chicks fledged per pair), even though at most sites only a proportion of the suitable habitat is protected by the fence. The graph below shows mean Lapwing productivity at RSPB reserves with anti-predator fencing, at which productivity has been regularly monitored. Bars show + one standard error. The figures above the bars show the number of reserves with anti-predator fencing, at which productivity was monitored.
But non-lethal methods, whilst always our preferred way of doing things, are not always practical. Lethal vertebrate control on RSPB reserves is only considered where the following four criteria are met:
If we can satisfy ourselves of all these things, then we can be sure to make the right decision.
Below are tables summarising the vertebrate control undertaken by RSPB and our contractors on reserves during the period 1 September 2016 to 31 August 2017, and during the period 1 September 2015 to 31 August 2016 for comparison. Only reserves where control was undertaken during the year have been included. Vertebrate control commissioned by third parties as part of existing rights is not included here.
a) For conservation reasons
No. of reserves
Feral Barnacle Goose (eggs)
To protect ground-nesting birds
UK eradication project to benefit White-headed Ducks
To protect Red Squirrels
Deer - Fallow
To restore woodland
Deer - Muntjac
Deer - Red
To restore woodland & heathland
Deer - Roe
Deer - Sika
To restore heathland & woodland
Gull - Large (adults)
To protect terns
Gull - Large (eggs)
To protect Water Voles
To protect ground-nesting birds & Orkney Voles on Orkney, where recently introduced
* Plus 133 killed (by shooting and Larsen trap) through the Curlew Trial Management Project, although this includes individuals killed in the wider area, not just on the reserve itself
** Plus 20 killed (by shooting) through the Curlew Trial Management Project, although this includes individuals killed in the wider area, not just on the reserve itself
b) For other reasons
Brown Rat & mice
Hygiene around buildings
To protect hydrological infrastructure (2015/16)/for welfare of animals suffering from myxomatosis (2016/17)
Feral Canada Goose (eggs)
Air safety (& damage to adjacent farmland in 2015/16)
Feral Greylag Goose (eggs)
*As I reported in an earlier blog, we have recently published a review of the impact of predation on wild birds based on 81 relevant scientific papers and reports covering 908 cases where the effect of a predator on changes in the numbers of a prey species had been measured. The headlines from our review are that…
…Predator numbers have increased in the UK over the last decades.
…The UK has very high densities of red fox and crows compared to other European countries.
…Seabirds, waders and gamebirds are limited by predation whereas pigeons, raptors & owls, woodpeckers and songbirds are not limited by predation. A few exceptions to these general statements exist.
…There is a real need for research to understand how landscape-scale management could be used to provide longer-term sustainable solutions to reduce the numbers of generalist predators and their impacts on species of conservation concern.
Vanellus - in a recent blog about the paper that our scientists published reviewing the impact on predation on wild birds, we say "The very high densities of foxes and crows in the UK suggests that our countryside is capable of supporting large numbers of these predators, and we currently spend a lot of time and money managing these predators through fencing and lethal control. An alternative approach would be to try to understand why we have such high densities compared with other parts of Europe and then to manage aspects of the landscape to limit opportunities for these predators. We discuss possible landscape-wide approaches in our paper. For example, patches of woodlands and forestry can provide breeding areas for generalist predators, and can therefore increase the predation pressure on birds nesting in the surrounding landscape and there is some good evidence from studies to show that waders avoid nesting close to woodlands. In addition, the near-absence of top predators in many parts of the UK (e.g. golden eagle, goshawk, lynx and wolf, just to mention some very charismatic species that are widespread in continental Europe) means that the natural "top-down" control of intermediate-sized predators (i.e. intra-guild predation) is just not happening at the same scale as in mainland Europe. Similarly, the release of around 50 million gamebirds into the UK countryside every year for shooting purposes provide lots of food for predators like foxes, thereby increasing the numbers of these predators that can survive and thrive in our landscape. In spring, when gamebird numbers are at their lowest, it is likely that foxes and other generalist predators have to turn to native species to feed themselves and their young, which add pressure on ground nesting birds of conservation concern. In our paper, we argue that better landscape planning and regulation of non-native gamebird releases, as well as encouragement of natural intra-guild predation processes might be a more effective, cheaper and sustainable solution to reduce the populations of generalist predators. However, this is not a "quick fix", and the traditional techniques of lethal control and predator fencing to minimise predation on key bird populations might be the only remedy in order to protect what we have in the short-term."
You can read more at ww2.rspb.org.uk/.../can-predation-limit-bird-populations-in-the-uk.aspx
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