Guest blog by Dr Matthew Carroll, Conservation Scientist at RSPB Centre for Conservation Science
Craneflies as a food source for upland breeding birds
The British uplands are home to internationally-important breeding bird populations. And for some of these species, a key part of their diet during the breeding season is something you might not have expected – craneflies, or daddy longlegs as they’re often better known. For birds that breed on blanket bogs – deep peat soils that occur on rolling hills in the wettest areas of the uplands – craneflies can make up a big part of the diet during this critical period.
Photo of a cranefly by Matthew Carroll
Both chicks and adults can rely on cranefly larvae and adults for food during the breeding season. For species like golden plover and red grouse, it’s been shown that chick growth and survival rates are higher when there are more craneflies available. So these unassuming flies are a very important part of the food chain. But research we’ve just published in Nature Communications suggests that climate change might threaten the whole food web.
Craneflies need wet peat to survive and thrive
The key link in the chain is soil moisture. Cranefly larvae live in the top few centimetres of peat, and they die when the peat becomes too dry. Some of our previous research published in Global Change Biology, Maintaining northern peatland ecosystems in a changing climate: effects of soil moisture, drainage and drain blocking on craneflies has shown that higher cranefly abundances are associated with wetter peat, so things like inappropriate drainage can cause their populations to fall.
Climate warming could make peat too dry
But it’s not just drainage that could make the peat become drier. Climate change could lead to warmer, drier summers, and this could threaten cranefly populations even on bogs that have never been drained. So our work examines this system, to see what the impacts of climate change might be.
We used a model that predicts how wet peat bogs are, based on weather (temperature and rainfall) and landscape characteristics (altitude, steepness of slopes). We then combined these predicted water-table depths with observations of cranefly abundance so that, for a given set of weather and landscape conditions, we could estimate cranefly abundances. And then we used our cranefly predictions to see how bird populations responded to varying food supplies, and how things might change in the future.
First, we looked at the Peak District, where big bird surveys were carried out in 1990 by English Nature and 2004 by Moors for the Future Partnership. We found that where our model predicted the highest cranefly abundances to be, the largest breeding bird populations had been seen. This pattern was found for three iconic upland species that eat craneflies during the breeding season – golden plover, dunlin and red grouse. So, where there was more food, there were more birds!
Cranefly declines = golden plover and dunlin declines
Then, we used climate change projections to see what might happen in the future. We found that as summer temperatures rise and rainfall decreases, blanket bogs are indeed predicted to become drier. This would mean that cranefly populations could fall by up to 80% by the late 21st Century. In some places, high cranefly abundances would be restricted to the wettest bits of the landscape. Relatively dry areas like the North York Moors may end up with very few craneflies left at all.
Photo of golden plover by Andy Hay (rspb-images.com)
And what would these declines in cranefly abundance mean for the birds? Well in the Peak District, we could see big abundance declines. Dunlin abundance was projected to decline by about 50%, whilst golden plover abundance was projected to decline by nearly 30% - these are clearly big losses. By the late 21st Century, both dunlin and golden plover might only be found in the wettest areas that still retain enough food for them.
Conservation action for craneflies
So, it might seem a bit bleak – our model suggests that climate change could threaten some of our important upland bird populations. But there is hope. Our previous research has shown that blocking drainage ditches, which increases soil moisture levels, can increase cranefly populations. Drain blocking, along with re-vegetating bare peat, are key parts of blanket bog restoration and conservation strategies that the RSPB are involved with, in places such as Dove Stone in the Peak District and Lake Vyrnwy in mid Wales. These actions should help to keep bogs wet and provide a better future for the whole ecosystem as the climate changes. Knowing how climate affects hydrology, how hydrology affects invertebrates, and how prey availability affects birds, we can start to identify conservation actions. To maintain our upland bird populations in the face of a changing climate, we need to ensure that blanket bogs stay wet and craneflies remain abundant.
The paper Hydrologically driven ecosystem processes determine the distribution and persistence of ecosystem-specialist predators under climate change was published in the journal Nature Communications 31 July 2015.
Woodland wildlife under threat
The RSPB’s woodland nature reserves are some of the organisation’s most enchanted places up and down the UK. As a young boy a trip to Nagshead in Gloucestershire to search for pied flycatchers and redstarts was always a school holiday treat.
At this time of year woodlands are thrumming with birdsong and butterflies darting about. A few nights ago I went to a woodland in Cambridgeshire and saw silver-washed fritillary butterflies performing courtship flights along the woodland rides. In a few short months woodlands’ beauty will be found by looking down, not up: their floors look like large-scale Jackson Pollock paintings, as the trees spill their multicoloured leaves onto the ground. In fact it’s worth checking out Pollock’s Autumn Rhythm and seeing whether you think it compares to the real thing.
But perhaps not a lot of people know that the picture for our woodland wildlife isn’t looking very rosy. Birds like the willow tit, a woodland specialist, have declined by over 80%, making it our fastest declining resident bird. The State of Nature report showed that of the 1256 woodland species we have data for, 60% have declined over the past 50 years, 35% strongly. Some of our woodland birds migrate, so the problems might lie elsewhere, but equally we know that some of the causes of these declines are right here, in UK woodlands.
Many of our woods have fallen into neglect – the kind of management that keeps them healthy has stopped and they have become less and less suitable for wildlife.
Using wood wisely to help wildlife and the climate
But our woodlands could be wildlife havens again, as well as providing an important natural resource.
We believe that the UK’s woodlands can provide a valuable resource for a range of industries. By being sensitively managed for their useful resources the woodlands could also be made more hospitable to wildlife once more.
Wood from our woodlands could provide an important resource for industries like construction and furniture, where the carbon stored in the wood stays locked up for decades, helping the climate.
Wherever possible, wood should be used in this way, then reused, recycled, and finally, used for energy.
But the UK Government is incentivising the combustion of virgin wood for energy in power stations that produce electricity. Subsidies are available to new dedicated biomass power stations that burn wood, or to coal power stations that convert to burning wood.
This means that virgin wood that could otherwise lock carbon up in furniture or construction could end up being burned. Government predict that by 2017 the UK could be burning six times the UK forest harvest, putting extra pressure on UK forests as well as requiring vast quantities of imported wood.
This could see wood going straight from the forest to the power station. It will also mean that large amounts of wood pellets are going to be imported from North America. Again, Government’s own analysis shows that in many cases burning wood straight from the forest in this way, allowing the carbon to escape into the atmosphere, can, in the short term, be worse for climate change than coal!
Because the Government has not put stringent enough sustainability criteria in place either, this means that North American forests and their wildlife are under severe threat from burgeoning demand for wood for electricity. In fact, only 70% of wood that’s burned has to be sustainable for a company to receive subsidies. This could be a disaster for wildlife overseas.
In addition, large-scale power stations that produce electricity are very inefficient. Drax, a coal power station in the North of England, has already converted one of its units to biomass and plans to convert others. In 2013 Drax imported burned 3.5 million tonnes of biomass and expects to burn 4.5 million tonnes in 2014, with only 150,000 tonnes coming from within the UK. The rest is imported.
Instead, the RSPB would like to see Government designing a policy framework that supports a very different kind of bioenergy industry: one that’s based primarily on efficient combined heat and power technologies and on sustainable feedstocks such as residues, wastes and some woody energy crops.
In some cases a limited supply of wood from local woodfuel markets could support woodland management for wildlife. Although wherever possible the wood burned should be at the end of its life, having been used by other industries first. And where this isn’t possible because the wood isn’t of high enough quality it must at the very least be from woodlands that meet sustainability requirements under the UK Forest Standard and burned in the most efficient way possible.
In this way, many more UK woodlands could be brought back into management, transforming them once more into homes for our rare and wonderful woodland wildlife.
Beyond the woods
The RSPB has also been working to explore the possibilities of generating biomass from some of its other kinds of reserves.
Being more resourceful about how we utilise materials from the management of our nature reserves could make a significant contribution to reducing our reliance on fossil fuels and help to provide more sustainable ways through which to provide us with our heat and power.
After the RSPB conducted a few experimental trials turning rush and reed into briquettes that can be burned, the UK Government Department of Energy and Climate Change (DECC) recognised this as an opportunity and seized the initiative by funding the Wetland Biomass to Bioenergy Project. With the potential to utilise existing material, which would enhance areas for biodiversity, and not impact on food production, the idea had huge potential. The project looked to develop the end-to-end processes necessary to remove biomass from an ecological site and turn it into marketable bioenergy products (e.g. briquettes or bio-methane via anaerobic digestion). Set up as a competition, DECC aimed to encourage consortiums of small business, academia and specialists to work together to find a solution.
Starting with 14 applications, seven of which were developed through to feasibility stage, three consortiums of participants made it through to the conclusion, during which time their end-to-end processes were trialled on our own RSPB nature reserves and those or partners.
Each of the three successful consortiums took a different approach to design an end-to-end solution. AB Systems developed specialist tracked harvesters with cut and collection systems, utilised innovative AgBag storage options and a mobile briquetting system. Natural Synergies developed a bespoke medium scale anaerobic digestion unit with specific adaptations for coping with challenging wetland biomass. AMW-IBERS utilised a number of different technologies, including anaerobic digestion, pyrolysis and mobile briquetting, their process separated the biomass into a solid and liquid fraction for conversion. The three projects were conducted across the UK; in Somerset, East of England and Northern Scotland. As a result we know have a portfolio of techniques that can be utilised for the conversion of wetland biomass..
This means that otherwise under utilised material generated during the management of RSPB nature reserves can now be used to generate heat and electricity.
The DECC project enabled the completion of trials and analysis of different biomass types which used different conversion processes. These projects have provided the crucial foundations for future decision making around building sustainable biomass to energy schemes.
 Pers comms, Drax, October 2014
Today, in the nick of time before MPs leave Westminster for the Summer, Government published some new legislation on fracking. But what was announced today was a bitter disappointment for anyone who cares about providing the utmost protection to our most important wildlife sites.
These new rules on fracking were promised back in January this year, at the time of the Infrastructure Act. The Government at the time made a commitment - the Minister's comments to the House are here (26 Jan 2015, Column 586) and the DECC website still shows this commitment here - to an outright ban on fracking in protected areas that would include Sites of Special Scientific Interest, Areas of Outstanding Natural Beauty and National Parks, in other words some of our most precious places for their wildlife and landscapes.
But, the follow up legislation brought out today was a let down in two key ways:
1. Government removed SSSIs from the list. These extremely important wildlife sites will no longer benefit from an outright fracking ban, with Government claiming that existing protections are sufficient.
2. For National Parks and Areas of Outstanding Natural Beauty (as well as The Broads and World Heritage Sites) Government has ruled out hydraulic fracturing (unless it's deeper than 1200m) - the process that happens beneath the surface. But Government included nothing in today's legislation limiting the wells or any of the other surface infrastructure, which could still be located within any protected area.
Government did today reiterate its commitment to ruling out wells and surface infrastructure within protected areas, but gave no detail on how or when this might happen. And if they can renege on protecting SSSIs, this casts doubt on whether they'll stick to that promise.
Even if Government does keep its word, fracking wells could still end up dangerously close to protected areas, with pollution and noise and light disturbance affecting the watercourses and wildlife within them.
What's more, many of the other improvements to regulation for the fracking industry that we and other organisations have been calling for remain unaddressed. And there is growing evidence that it could be tough to make sure fracking doesn't bust the UK's carbon budgets, and that even if this is achieved, it's likely to displace fossil fuels elsewhere and result in a global growth in climate change emissions.
It's safe to say that, in the UK, we don't yet seem to be fit to frack.