February 2011 -The Cormorant

 


Cormorant - taken by Lin at the UEA, winter 

During the recent cold weather in November and December, I have noticed significant numbers of cormorants around Bawburgh. Typically I have seen them flying over head, fishing or roosting in tall trees by the river Yare (the river did not freeze where I walked at the UEA in the icy spell we had).

Cormorants are large conspicuous blackish water birds with fairly long necks, often described as reptilian and sinister in appearance. They are typically depicted with wings outspread and it has been assumed that this posture was to aid drying of the wings as they were considered poorly water proofed. A more recent explanation for this habit is to keep a group of the birds spaced out to aid taking off in a hurry. Cormorants are usually associated with the coastline, coastal lagoons and estuaries but increasingly come inland to lakes, reservoirs and gravel pits. They are seen all year round. The RSPB estimate that there are about 9000 breeding pairs in the UK with more than 24,000 birds over wintering here.


 Cormorant - taken by Lin at the UEA, winter

 

Cormorants are expert fishers, floating low in the water, with only head and neck showing. To dive they jump up and plunge in head first or just sink beneath the surface. They can dive down as far as 100 feet, more normally 20 to 30 feet, and can stay under the water for well over a minute if required. In China some fishermen make use of the cormorants fishing expertise and put collars on trained birds. The collars are tight enough to prevent them swallowing fish of a certain size. The birds retrieve their catch back to their owners.  Cormorants are strong fliers, flying with head and neck outstretched and strong wing beats. Cormorants nest in colonies, sometimes numbering thousands of birds. Nest sites are usually rocky cliffs, occasionally in trees. Nesting materials include twigs, grasses, seaweed or reeds, the nests quickly become plastered with bird droppings. Incubation of the 2 to 4 eggs is about a month, involving both parents. Hatchlings have black leathery skin, rapidly developing dark grey down. They are fed regurgitated fish once a day by each parent until they are ready to fly in 5 to 8 weeks.

swimming cormorant - taken by Lin at the UEA, winter

Cormorants in some locations are reported as causing serious economic and ecological damage to fisheries. They consume a wide variety of fish species, usually reflecting availability of stocks. Birds feed individually or in flocks, sometimes working together to increase efficiency. On average an adult cormorant requires 400-500g (about a pound) of food a day. They have protected status under the Wildlife and Countryside Act 1981 which does not allow shooting to cull. If cormorants are causing serious damage to a fishery the owner or manager can apply for a licence to shoot a limited number of birds as an aid to scaring. The Moran Committee (a partnership of fisheries, angling and conservation organisations) has produced a leaflet on ‘Cormorants – The Facts’ which can be found on the internet and the anglers among you may find interesting.  

 

lingibson@bawburghvillage.co.uk 

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