I spent half-term with the family in the sun in the Cairngorms National Park. As we have two of our most iconic reserves there, Abernethy and Insh Marshes, I was keen to pay a visit. It was great to hear that the number of lekking male capercaillie at Abernethy has increased this year but alas, we failed to see any on our (very) early morning drive. We wait with trepidation to see how the June weather turns out as our research shows a strong correlation between poor productivity and wet Junes. At least Scotland seems to have had the better of the weather this month.
The visit to Insh Marshes was my first. Lying on the floodplain of the River Spey, the site is special for its breeding waders (snipe, curlew, lapwing, redshank), rare plants (eg string sedge) and invertebrates. It's a magical place. The floodplain still has many characteristics of a naturally-functioning system and, as I saw on site, in the wet winter of 2015 one of the tributaries has cut a new path, creating dynamic wet features alive with wildlife.
It’s an interesting year for Insh as we are undertaking a study of lapwing productivity. In recent years we have noted a decline in their productivity but previous research has not been able to identify the main cause. This year we have a dedicated researcher monitoring the nests and the chicks to find out what happens. The initial results show that many early nests were lost during the night with significant fox activity identified on the trail cameras and badgers also present. We are now actively considering whether we need to start fox control there next year as the flood regime means it isn’t practical to install an anti-predator fence.
As always, our approach to the issue of predation is based on evidence and guided by our Council agreed policy.
Our 2007 review of the evidence of the impacts of predation on wild birds concluded that generalist predators, such as foxes and corvids, can sometimes reduce the population levels of ground-nesting birds (such as waders, seabirds and gamebirds), and a more recent (soon to be published) review confirms these findings. By contrast, the evidence that breeding songbird numbers are limited by predation is weak. Rather, there is compelling evidence – some of it experimental – that changes in farming practices have led to the declines of many farmland songbirds, and emerging evidence that numbers of some woodland songbirds have declined due to long-term changes in woodland structure.
Deciding to use lethal predator control is something we never take lightly.
Our approach means that we seek evidence of a problem, check whether there is a non-lethal solution, make sure that the killing of predators would be legal, effective and not harm their own conservation status. If we can satisfy ourselves of all these things then we can make a decision. As in previous years (see here and here), I have included tables below which show the lethal vertebrate control undertaken on reserves (which now number 210 sites covering more than 150,000 hectares across the UK). Some of the numbers are higher than in previous years as the dataset covers a longer period (17 months) due to a change in the annual reporting schedule.
Finally, it is worth remembering that non-lethal approaches, although not realistic in some circumstances, can be very effective. To illustrate this point, I have included a graph to show how well anti-predator fences are performing. 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 (Fig. 1).
This is a fantastic result and a great return for the effort invested by our ecologists and reserve teams.
Vertebrates controlled on RSPB reserves in 2014-15
Below are tables summarising the vertebrate control undertaken by RSPB and our contractors on reserves during the period 1 April 2014 to 31 August 2015. The recording period is longer than in previous years as we altered our annual reporting timetable. The extended period means that larger numbers of vertebrates were killed than in the previous 12 month reported period. 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
NB Feral means released birds outside their normal range.
b) For other reasons
Fig. 1. 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 has been regularly monitored.
And to close, here's another gratuitous picture of the stunning Insh Marshes (credit Andy Hay, rspb-images.com)
Great work Martin. Would it be true to say that predation is really a compounding problem where the population of a given species has been driven to very low levels by other factors, such as habitat change (e.g. lapwing), or where breeding populations are naturally clustered (e.g. little terns)? So lethal predator control may be an option in the early days of species recovery, but will be less relevant as (or if) those populations begin to increase in density and range? Many of our breeding waders are now confined to so few places, in such low numbers, that any level of predation can prevent recovery. You don't really say above that predator control might be a short-term necessity before populations become resilient to such losses.
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