It is fascinating, and a little heart wrenching, to watch the adult curlew sitting on the nest. The anxiety and tension he or she feels in apparent, especially at night.
Eurasian Curlews are Near Threatened. Many. like those in the video are lowland nesting birds. Whilst all nesting habitats are subject to many pressures it is those in the lowlands which are facing the biggest problems. Traditionally Curlews nested in hay meadows in the lowlands. These provided food and shelter for a growing family and the young were able to fledge before the meadow was harvested.
However these days many, if not most, hay meadows have been replaced by silage fields. These fields contain fast growing grasses that are cut significantly earlier, and often multiple times each year. This prevents the Curlews from breeding successfully and this is what is driving down the populations.
All lowland Curlew nests are under threat and all should be protected like this pair in Wales.