Wednesday, 16 November 2005

Master of the reedbeds

Sunday morning found me settled in Dawkes hide, looking north across the Norfolk Wildlife Trust’s Cley Marshes reserve. It was early enough for the hide to be relatively still and the only other birdwatchers present were a handful of regulars. Judging by the conversation, these ‘old boys’ had been coming here for many years, enjoying the wide range of birds attracted by the reserve’s position on the North Norfolk coast. As I scanned the reed-fringed pools and wet grassland, passing over teal, shoveler, gadwall and resting waders, my gaze settled on the familiar shape of a harrier working the edge of the reeds in search of prey. As the bird turned, the sun caught on the golden cap – a marsh harrier and a real master of East Anglia’s reedbeds.

With a little patience, good views of this wonderful raptor are virtually guaranteed at a number of sites across Norfolk and Suffolk. Yet, the fortunes of this species have undergone dramatic change over the last 200 years. In the early 1800s, the marsh harrier was common across much of Britain and Ireland but widespread persecution led to a rapid and well-documented decline. By the late 1870s the species was restricted to the Norfolk Broads. Over the next thirty years there were a number of failed nesting attempts, the birds falling foul of persecution and the unwelcome attentions of egg collectors, and the ‘last’ recorded nesting attempt was in 1899. It was not until 1921 that a successful attempt was again documented and a recovery of sorts began. With the exception of 1937 and 1940, nesting attempts have been recorded every year since 1928, although there was another decline in breeding numbers in the 1960s. This was attributed to the use of organochlorine pesticides, which hit predatory birds hard because of their position at the top of a contaminated food chain.

Most of the recovery has happened since the mid-1970s and there are now thought to be at least 200 breeding females nationally. Male marsh harriers can form bigamous relationships, so the number of breeding females is the most appropriate unit by which to measure the population. Two important changes in the behaviour of this species may have contributed to the population increase. First is the tendency for some individuals to overwinter here, rather than make a migratory journey south to wintering grounds in southern Europe and Africa. The second change has been for birds to nest away from reedbeds, moving into arable crops, a habit that was first documented in west Norfolk in 1982. The skill of these birds when hunting and the way in which they use the wind to work their way across the ground make them a delight to watch, especially from a comfortable hide in good company.

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