The Bird Observatory on the Calf was established in 1959 and became an
official British Bird Observatory in 1962. From March to November each
year wardens live on the Calf, keeping detailed records of migration
and of the breeding birds which visit the Island. To record the birds,
the wardens must first catch them.
The Heligoland trap is a large tunnel of fine wire mesh with a catching
box at one end. The "driver" lightly tapping the nearby vegetation
drives the birds into the trap, calling and arm waving. The door flap
on the collecting box is closed when the last bird enters, allowing
each bird to be carefully removed and placed in soft bags for
transporting back to the Observatory. There the wardens record details
about the birds, such as species, weight, age, sex and condition. Those
which are not already ringed, have a ring placed on their leg. Then
they are all released again.
A mist net is a very fine net suspended between two poles. Birds, and
other wildlife such as bats, fly into the net which is virtually
invisible. The nets are patrolled regularly and the birds are carefully
removed when caught and taken to the Observatory for recording.
The ringing of the birds is one of the main duties of the wardens of
the Calf Observatory. Ringing involves placing a light metal ring on
one of the bird’s legs for recording and identification purposes and is
painless to the bird. Ringing helps to monitor migratory routes and
destinations, lifespan, causes of death, changes in population numbers
and breeding success. The rings feature an identity number for each
bird and are applied to the bird’s leg using special pliers ensuring
that the ring closes perfectly to the required size.
By the end of the year 2001 99,042 birds of 134 species had been ringed
since the Observatory opened of which 11,280 have been traced along
their migration routes by other bird observatories.
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Bird Directory 
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