Marsh Harrier Returns to the Wetlands

Word spread quickly last week that a rare visitor was spending a day at Cabragh Wetlands. The Eurasian marsh harrier was once a very familiar sight in Ireland and Britain, with the Victorian folk lore writer Charles Swainson reporting an old story that considerable numbers of harriers would land on the Wiltshire downs before heavy rain. Victorian hunters, egg and skin collectors raided nests and shot them out of the sky. Agro-chemicals and drainage of fenland habitat caused more problems, with organochloride pesticides wrecking attempts to re-establish numbers in the 1950’s and 60’s. By the 1970’s there was just one breeding pair in the west of Britain and one at the great Suffolk nature reserve at Minsmere, which is perfect harrier reedbed habitat. Many books published before the end of the millennium did not even record the marsh harrier as a resident of or visitor to Ireland.



Reduction in chemical use allowed numbers to grow at about 20% per year, and by 2000 there were 206 breeeding females spread from Kent to the Orkneys, with individuals crossing the Irish Sea. With luck a success story is developing.



Marsh harriers are the biggest and heaviest of the harriers, with the male about 50cm long and the female larger. She has a brown body and wings with a pale yellowish head, throat and forewing. It was a male that visited Cabragh, magnificently photographed by Eamonn Brennan, who captured its pale body, head and wings as it spent some time investigating our owl box atop a telephone pole. Most impressive were the great reddish-brown shadings on his wings. Old Irish names include Duck Hawk and Snipe Hawk, which reflect the lifestyle of the marsh harrier as he glides over reedbeds and wetlands searching for prey.



The marsh harrier is not a fast-flying hunter. In fact he is master of slow flight, gliding silently over reedbeds at barely 10mph, giving himself every chance to spot mice, frogs, reptiles, eggs, nestlings and rodents that make up its varied diet. Like the owl, marsh harriers have keen hearing, with facial feathers hiding large ear openings which help it to funnel sound and improve ability to detect prey in thick reedbeds. Nests are a mass of reeds and willow twigs, lined with grass and containing four or five eggs, which the female incubates for 36 days, with the male feeding them for another 40 before the young fly. Resident harriers spend winters in communal roosts on wetland sites.



It was a real pleasure to have a migratory marsh harrier at Cabragh for a day. Perhaps they will nest here in the future, though our ducks, snipe, frogs and mice will have to be on their guard.