Interesting to read a new study carried out at the RSPB’s Lake Vyrnwy reserve on the subject of curlew habitat. Quite apart from the enormous elephant in the room surrounding the issue of predation and ground-nesting waders, this study comes at an interesting moment for me. I’ve just started to think about breeding habitat for curlews on the Chayne after a disastrous few breeding seasons during which not a single chick has fledged off the hill.
As discussed in some detail before on this blog, I am convinced that the main reason behind this failure is predation, particularly of nests and eggs, but I have also noticed that any eggs which do survive to hatch tend to produce moderate chicks which seldom thrive and soon wither away within a week or two. A dodgy chick squeals and mumbles almost incessantly, so the final cause of death may simply read “predation” when in reality the stoat or badger might never have found a fit, silent chick. Equally, overgrazed breeding habitat leads to inordinately high predation levels – after all, a fox is not to blame for short nesting cover, but you won’t hear him complaining about it.
As part of my agriculture course, I am required to write a short study on soils from a field of my choice. A few weeks ago, I took a clutch of samples from one of the in-bye fields on the Chayne where curlews frequently feed and nest and submitted them to a series of tests in the classroom. As expected, the pH was somewhere between 5 and 5.5 – not a surprise for waterlogged hill ground, but interesting to make the connection that earthworm densities drop off dramatically in acid soils.
This ties in to the findings of the RSPB’s report, and raises interesting ideas about the possibility of liming and fertilising some areas of the low ground in order to improve the invertebrate numbers (as a proxy for “curlew food”). If the chicks which do hatch on my ground end up malnourished, it’s important that I take steps to remedy that.
Further than the practical implications of these findings, taken as a whole, they essentially suggest that a curlew’s ideal habitat depends upon small scale mixed farming in the uplands – a business-type that has flatlined in the past fifty years. With one exception, I can’t think of any of my neighbours who have bought in lime for their in-bye in the past ten years, and the overall pH and soil structure of the glen must be declining year on year. In this light, it’s an interesting thought to consider that even the “good old days” for curlews were just an industrial bi-product, much in the same way as the waders that breed on grouse moors are now derided by some as “unnatural”, as if “natural” was ever anything more than a mobile, crazily subjective baseline.
I do baulk slightly at the idea that further investigations should include the exclusion of livestock from fields where curlew are breeding on account of the risk that sheep pose to curlew chicks. I am quite convinced that sheep eat curlew chicks, and I saw a sheep eating a grouse chick earlier this summer – I’m told it’s to do with nutrient deficiencies and is simply a means of getting vitamins or minerals where otherwise they might be in short supply. Where I struggle with the suggestion is the idea that exclusion might be an answer. There would be no faster way of alienating the farmer from his curlews than by telling him that he couldn’t have his lambing ewes down on the in-bye in springtime – the idea may well reduce the risk of harm caused by livestock, but it is so impractical as to be meaningless. Conservation measures have to consider existing land uses and integrate with them, not present a fresh maze of uncompromising roadblocks.
I’ve been working on a black grouse conservation project near Blairgowrie where the landowner has been told not to put his cows on the hill until July for fear that they might trample greyhens on the nest. Ok, it’s a reasonable (if marginal) concern, but the slight risk of damage to a nest or two is nothing when balanced with the many benefits of cows on the hill to the population of black grouse as a whole. Rather than explore the benefits of excluding sheep from curlew nests, why not explore why sheep appear to be “hunting” curlew chicks? From what I have seen and heard, it is a habit favoured by individual animals rather than the species as a whole, and if the flock simply required additional supplements or concentrates, everyone might be satisfied. After all, sheep and curlews have lived side by side for centuries, and it would be a mistake to rush into new and confusing edicts.
These new findings are important, but they represent part of a wider picture of habitat, land use change and the relationships between predators and prey. Some might argue that the curlew’s retreat from the hills is just a process of rebalancing; the gentle ejection of a coastal bird that was never suited to live in the heather. This is a logical (if not sensible or compassionate) notion, but it depends upon the birds having somewhere else to go.