This year's annual survey of corncrake numbers in Scotland show that numbers are at their lowest level since 2003. In this blog Paul Walton, our head of habitats and species, takes a closer look at these birds, the work done to help them so far and what now must happen to ensure corncrakes remain a breeding species in Scotland.
Scottish corncrakes in decline
To hear corncrakes calling from Hebridean meadows is a special experience – the poet Kathleen Jamie calls them ‘the little gods of the fields’ - and the story of corncrake conservation in Scotland really is an extraordinary one. It combines huge challenges, the application of science, partnership across NGOs, government, crofters and farmers - and renowned success in terms of conservation outcomes. But in the past three years numbers have fallen, not yet close to levels of 30 years ago, but enough to trouble anyone with a care for Scottish wildlife.
Having occurred in every single Scottish county in the late 1800s, this secretive, migratory farmland-dweller went into national decline and disappeared from most areas in their native range through the 20th century, accelerating post-second world war as agriculture intensified. Similar declines occurred across the bird’s European range. By the late 1980s, only around 430 calling males were left in Scotland, confined almost entirely to the Hebrides and Orkney - with none at all in the rest of Britain.
At that time, RSPB Scotland undertook ecological research to find out what the species requires to thrive, and in turn how those requirements might practically be delivered in our agricultural systems. The results showed that corncrakes need tall (20 cm +), herb-rich grasslands to be available from when they arrive back from African wintering grounds in April, through to September, when breeding is completed. The grass sward must be maintained by annual mowing or grazing, critically, timed between late summer and winter.
Earlier mowing kills corncrake chicks and reduces breeding productivity. This is a short-lived bird, with few surviving beyond two years and, therefore, it is essential that high levels of breeding productivity are achieved, or in other words, that enough chicks are hatched– the research showed that to maintain the population an average of about 4.5 fledged chicks (those surviving to adulthood) per adult female per year is needed1. In Scottish farmland, this can only be achieved if areas of early and late vegetation cover are provided next to meadows and if the mowing of those meadows – the main nesting and chick-rearing habitat during summer – is delayed at least until early August or, preferably, later. Late mowing is a trade-off, however, with farmers and crofters risking weather damage and reduced grass crop quality when they delay the harvest.
In the 1990s scientists, conservationists, government agriculture officials, advisers, farmers and crofters came together to design and implement corncrake schemes that hit the right balance in helping dwindling corncrake populations, and supporting agricultural communities while working practically. RSPB Scotland nature reserves on the islands were test sites for management trials. The schemes were adjusted to reflect the evidence from research, and were brought in as part of mainstream agri-environment support for land managers.
The results were impressive: the national decline halted soon after the conservation programme began, and breeding numbers started to rise for the first time in over a century. The increase continued until the population had roughly trebled to 1,241 calling males (fig.1) by 2011. Scientific analysis indicated that these targeted measures put in place by land managers on the ground were sufficient to generate the observed increase in numbers2.
Figure 1: Calling Male Corncrakes in GB and IoM, 1978–2017. Grey bars = totals in annually monitored Core Areas of Scotland (holding >90% of total); Black bars = totals beyond core areas.
The Scottish corncrake morphed from ‘little god’ to ‘poster boy’ for publicly funded agri-environment schemes delivering real and measurable positive impacts on wildlife. Corncrake management payments became important elements of income for agricultural communities in key areas for wildlife. This was a tangible manifestation of farmers and crofters being supported to provide society with more than just food, of ‘public money supporting public goods’ - the public good being the natural heritage in our fields.
The programme did not succeed, however, in increasing the breeding range of corncrakes. It proved problematic to provide corncrake agri-environment management payments in areas where there were not yet actually any corncrakes. So, the species remains highly localised, and therefore still vulnerable and highly dependent on ongoing conservation in Scotland.
Now, RSPB Scotland monitoring has revealed that over the last three years, there have been successive declines in the Scottish corncrake population. The 2017 UK annual survey recorded 866 calling males in Scotland, a drop of 33% since 2014 (1,289 calling males), and the lowest numbers since 2003.
Over the same period, Scottish Government data shows that there has been a substantial decrease in the extent of corncrake management under agri-environment schemes (fig.2). A large part of that decrease is the result of the gap between the end of Scottish Rural Development Programme Rural Priorities Scheme (SRDP RP) and the start of the new Agri-environment and Climate Scheme (AECS) in 2014 and 2015.
SNH did provide gap year payments, but this may not have been sufficient to address the issues. Moreover, there are indications, in some areas, that uptake by land managers may be lower under AECS than under previous schemes (though it is entirely possible that we may see an increase in uptake in the remaining years of the scheme). It is evident, though, that following a reduction in the payment rate for late cutting, there is likely to be a decrease in the number of land managers opting for the latest cutting date (1st September), instead choosing to have the flexibility to cut earlier in August (fig 3).
Agricultural management is not the only possible driver of corncrake population trends: in 2013, for example, the population dip was apparently partly due to the very cold, late spring, and slow growth of meadow plants that the species requires. The influence of issues in the wintering grounds in Africa, or on migration, cannot be ruled out. But we know that corncrake populations are highly sensitive and responsive to how grassland in meadows is managed, and we know that - regardless of other potential factors - if it is to be retained as a part of our natural heritage, the species will need the right management to be in place, making the right habitat available. Given corncrake conservation is a priority under Scotland’s Biodiversity Route Map to 2020, securing that end is a shared ambition.
Figure 2: Agri-environment deployment for corncrake in Scotland between 2013 and 2017.
Figure 3: The percentage of delayed mowing area in agri-environment plans under SRDP and AECS in Scotland between 2009 and 2021
Therefore, RSPB Scotland will be seeking discussions with the Scottish Government and other partners to ensure that:
Some will doubtless ask, in these deeply uncertain and financially challenged times - in particular with regard to the future of agricultural subsidy - whether we should not simply be content to let this secretive brown bird dwindle away as a casualty of inevitable change. What would we be really be losing? Not only would we lose a bird that is interwoven into both the natural and cultural heritage of Scotland, we would be losing the most successful and tangible example we have of agricultural communities being supported to deliver for a threatened species. More than this, those Scottish communities maintain extensive livestock systems that deliver huge additional cultural and environmental benefits – and the corncrake payments in some instances have become significant in terms of the viability of these high nature value systems. Scientists have found that grassland management for corncrakes benefits a host of other species, including bumblebees, spiders, beetles, and it significantly increases the species richness of wild plants3. Surely this partnership progress benefits all of Scotland and reflects the best in cross-sectoral working and cooperation - and that is simply too precious to lose.