Ground nesting birds
Between the 1st March and the 31st July is a particularly vulnerable time for ground nesting birds. Any disturbances can cause them to fly away from their nests neglecting their eggs or chicks. This can result in eggs failing to hatch, chicks dying from cold or lack of food and raids from predators.
Walking on the moors at this time of year it is sometimes unavoidable but, after being closely observed by some curlew tonight, I came across some useful information on the RSPB website. Signs to look out for in a distressed or disturbed bird are: loud repeated alarm calls, approaching you more closely than is usual (including dive bombing), feigning injury to distract you from a nest and circling high above.
Keeping to footpaths (particularly in dense heather), making sure dogs are on a lead, moving away from distressed or disturbed birds quickly and quietly and avoiding steep cloughs all help. In addition, there is also the birdwatcher’s code of conduct.