The conservationist's dilemma: an update on the science, policy and practice of the impact of predators on wild birds (5)

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I’ve been the RSPB’s Conservation Director since May 2011. As I settle into the job, I’ll be blogging on all the big conservation topics and providing an inside view of our conservation projects. I hope you enjoy reading it and feel inspired to join in t

The conservationist's dilemma: an update on the science, policy and practice of the impact of predators on wild birds (5)

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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:

  • That the seriousness of the problem has been established;
  • That non-lethal measures have been assessed and found not to be practicable;
  • That killing is an effective way of addressing the problem;
  • That killing will not have an adverse impact on the conservation status of the target or other non-target species.

If we can satisfy ourselves of all these things, then we can be sure to make the right decision.

Vertebrates controlled on RSPB reserves in 2016/17

 

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

Species

2015/16

2016/17

Reason

No. of reserves

Total killed

No. of reserves

Total killed

Feral Barnacle Goose (eggs)

1

101

0

0

To protect ground-nesting birds

Ruddy duck

1

1

0

0

UK eradication project to benefit White-headed Ducks

Grey squirrel

2

14

2

11

To protect Red Squirrels

Carrion/Hooded Crow

14

475

15

528*

To protect ground-nesting birds

Deer - Fallow

6

78

5

59

To restore woodland

Deer - Muntjac

3

33

4

55

To restore woodland

Deer - Red

9

299

9

432

To restore woodland & heathland

Deer - Roe

9

334

7

375

To restore woodland

Deer - Sika

2

176

3

105

To restore heathland & woodland

Fox

33

390

37

414**

To protect ground-nesting birds

Gull - Large (adults)

2

8

1

11

To protect terns

Gull - Large (eggs)

3

Not recorded

4

>33

To protect terns

Mink

15

81

16

103

To protect Water Voles

Stoat

1

1

0

0

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 

Species

2015/16

2016/17

Reason

No. of reserves

Total killed

No. of reserves

Total killed

Brown Rat & mice

4

Not recorded

7

Not recorded

Hygiene around buildings

Rabbit

1

150

1

Not recorded

To protect hydrological infrastructure (2015/16)/for welfare of animals suffering from myxomatosis (2016/17)

Feral Canada Goose (eggs)

2

102

1

120

Air safety (& damage to adjacent farmland in 2015/16)

Feral Greylag Goose (eggs)

1

84

1

79

Air safety

*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.

Comments
  • Thanks for a very clear and well explained explanation of what RSPB is doing. I'm confident this is the right approach - removing the opportunity for smear and innuendo that would go with anything other than honesty.

    Predation is, inevitably,  a painfully headline issue but it is perhaps a cover for the far more serious issue of what decades of intensification and, with it, simplification of habitats has done to the landscape. Yes, it's still green but farming has been hugely effective at wiping the detail and variety from most of our landscape - the reduction of the rough patches, the inconvenient corners and the less intensively managed bits has left forgotten urban 'wasteland' as often more important than the countryside.

    Changes to farming support give a vital opportunity to reverse this trend not on a reserve but on a landscape scale - and before anyone thinks this is just an attack on farmers, its worth pointing out that even before Brexit farming incomes are under intense pressure. We need to be ready to continue paying for our landscapes - but the landscape we want, not one driven by farmers pushed to ever fiercer intensification.

  • 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

  • What, if any, is the link between the high density of foxes and crows and the millions of pheasants released in the countryside that end up as road kill?

  • Great to see this all set out so clearly, and the RSPB applying common sense backed up by sound science - long may that continue.