Every July I swear I won’t do it again. I’m tired after squeezing fieldwork into every possible hour for the last four months. I’m covered in itchy insect bites. And I’ve worn a hole in yet another pair of boots. I’m definitely not doing this again.
And every following spring I do.
Because as the frosts and morning mists of winter give way to spring sunshine, and green shoots start appearing in the fields, I need to go and see if the curlew have returned again. And when I hear that first ‘cu-lee, cu-lee’ call, I instantly feel more alive.
I’ve been helping with the annual wader survey in the Upper Thames for four years now – just one of team of birdwatchers who together have been making this happen since 2005. But the wader project isn’t just about counting birds – it’s about actively helping them. Together with my colleague, Charlotte, part of my day-job is supporting the farmers in the area who are keen to keep lapwings and curlew part of their worked environment. It’s another example of farmers working at landscape scale for the wildlife they cherish.
The Upper Thames river valleys cover 35,298 hectares – a mosaic of farmed pasture, meadows, and arable fields. It also includes a small handful of nature reserves, including the RSPB’s Otmoor reserve.
The wader project currently works with over 130 farmers and land managers spanning this landscape. Whilst practices that could be potentially challenging to ground-nesting waders, such as spring rolling of grass, are unusual in this area, this year hay cutting over the damp summer proved particularly difficult for birds and farmers alike. By contrast, the early spring was very dry, and many sites had little surface water available.
So how did waders do in 2017?
This year the standardised lowland wader survey recorded 328 pairs of breeding waders across the whole landscape. Of these, 97% of the redshank and snipe were recorded on the Otmoor reserve, but 30% of lapwing and 98% of curlew were recorded on predominantly farmland sites.
Compared to previous years, the biggest changes have been the increases in redshank, snipe and lapwing on the Otmoor reserve. Keeping parts of the reserve wetter into July and August appears to have helped snipe, whilst fencing a key field against mammalian predators some years ago significantly improved lapwing breeding success.
Note: this graph reflects records across the whole landscape, although for practical reasons the number and distribution of sites sampled isn’t always exactly the same each year.
Home-grown curlews?
The question of whether a species’ population is changing because of changes to birth or death rate, or to movement in or out of the area might seem a bit of a technicality, but it’s quite important. Curlew in particular can live for over thirty years and are very site-faithful. On average they need to fledge around 0.5 chicks per territorial pair each year in order for their local population to be stable.
This spring, for the second year running, the wader project was complemented by a study of the productivity of curlew in the Upper Thames. As curlew here mainly nest in meadows, finding their nests can be very difficult. Success seems to be due a combination of elevation, luck and an enormous amount of patience! Due to the height of the vegetation by June, monitoring chicks to see if they fledge successfully is, unfortunately, impossible.
However, this year the project found eleven nests, of which four hatched successfully. Combined with the outcomes from the eight nests monitored in 2016, this means 37% are known to have hatched successfully.
To avoid the risk of overestimating hatching success (nests that fail quickly are less likely to be found), we use the daily survival probability instead. In 2016 this probability of a curlew nest surviving from one day to the next was 96.2% and in 2017 it was 95.1%. Over the whole nesting period, this equates to a hatching probability of 33% in 2016 and 24% in 2017.
We try to determine the nest outcomes based on the state of the egg remains and nest, temperature logs and the behaviour of adult curlews. However, without suitable trail cameras, it is rarely possible to be totally certain of the primary reason for nest failure.
The curlew study also includes analysis of the habitats curlew choose to nest in, compared to nearby areas that they don’t use. This year we were assisted by MSc student Matt Purkis, whose number crunching has highlighted some interesting points.
For example, curlew appear to nest in fields with the greatest variety in vegetation height and the densest vegetation. Also, the early indications are that curlews are more likely to use areas that have a greater abundance of large-sized insects on both the vegetation itself, and in the air near ground level.
This year we also supported one farmer in temporarily fencing a curlew nest to protect it, and a few sites undertake some control of foxes and crows. These interventions are often difficult, expensive and not without risks of their own. Studies such as this one are essential to making sure that interventions to help breeding curlew are addressing the key issues and are as effective as possible. All being well, we hope to repeat the curlew project next year to increase our sample size.
A future for curlew in the Upper Thames
The quiet, unassuming river valleys threading their way through Oxfordshire and surrounding counties are still regionally important for breeding waders in the lowlands. And with curlew arguably one of the highest conservation priorities of the UK, many local people are aware that if we lose them from this area, it could be many decades before they come back.
To date, agri-environment schemes have been crucial to supporting the wet pasture and meadows that waders here rely on. We understand that some options, such as Management of species-rich grassland and Management of wet grassland for breeding waders, which so far have only been available through Higher Tier Countryside Stewardship, will be available through Mid Tier from 2018. We very much hope this will make it easier for farmers to access this support.
Meanwhile, if you’re local to the area, have good bird identification skills and would like to help monitor and protect farmland waders, get in touch. I can’t promise that your boots will stay waterproof, but I can guarantee you’ll be making a real difference for wildlife. And you just might to do it again.