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| A Bittern showing off it's camouflage in Clifton Pond Reedbed - © Harry McMahon |
Harsh winters can often spell
trouble for many of our resident and over-wintering birds. One of the greatest
challenges for wild birds during cold periods is to find food and ensure that they
eat enough to be able to build up adequate fat supplies to store on their bodies
and burn for energy.
As 2010 drew to an end, we
witnessed the coldest December on the Nature Reserve since local records began
(1960). From late November, snow and ice began to spread across the lakes
covering all but the smallest areas of open water. Concern grew for our
over-wintering bittern population, an incredibly rare species of heron which
has traditionally suffered during such cold winters.
As the bittern’s usual
feeding areas, hidden deep within the reedbeds, became locked in ice, they were
forced into the open to search for food. Through much of December and January visitors
to the Reserve were treated to unprecedented views of up to four of these normally
shy and secretive birds as they fed, rather exposed, in the outflow between
Coneries Pond and the River Trent.
The bittern’s gold and brown
striped plumage would otherwise make the perfect camouflage in their marshy
habitat with extensive stands of common reed – making them very difficult to
spot. When alarmed, they stop and stretch their neck and beak upwards. Markings
along the neck imitate dry reed stems perfectly and the bittern has even
mastered the art of swaying in the wind to really blend in with its
surroundings.
Over the last week as the
remaining ice covering the lakes receded, the bitterns returned to their usual
feeding and roosting grounds of Clifton Pond and the Delta reedbeds. Despite
almost two months of frozen water on the Reserve, it would seem as though the bitterns
were unaffected. A total of five birds were counted returning to roost on
Clifton Pond on the 15th!
Causing a Stir!
The excitement surrounding
the arrival of the bitterns each year at Attenborough is wholly justified when
you consider the rarity of this species and their unsettled past. Drainage of
wetlands and persecution led to the extinction of the bittern in the UK by the late
19th century. They returned to breed in 1911 yet despite a steady
increase through the 1950’s the population never reached more than 80
individuals. In 1997 the population crashed to its lowest number since the
1920’s, with just 11 males recorded! – Counting the number of booming males is
the only way to accurately establish the population size.
Fortunately things are now looking
up for the bittern. A combination of careful reedbed management and biodiversity
action plans, which encourage the creation of wetland habitats, has meant that
the population is now showing a positive recovery. A total of 87 males were recorded
in the UK
last spring!
Each year there is a
programme of management work here at the Nature Reserve which includes
maintaining the reedbeds for bittern and other wildlife. Staff and volunteers
work tirelessly to remove willow saplings and dead vegetation that would otherwise
cause this wetland habitat to dry out. As part of the recent floodwall
mitigation, reedbeds have also been created on Coneries Pond, Church Pond and
Tween Pond that are sure to attract species like the bittern to Attenborough for
many years to come.
