Last
night the ranger team went out with artist and member of the Scottish Raptor
Study Group Keith Brockie to help tag osprey chicks near Lochan Oisinneach
Mor.
This beautiful
area provides perfect habitat for ospreys, which breed successfully in wooded
landscapes with access to freshwater lochs and rivers. Typically ospreys will
build a large, dense nest of sticks high in the tops of Scots Pine or other
coniferous trees (although some use artificial platforms and even electricity
pylons). They typically lay a clutch of three eggs from mid-April to mid-May,
with young birds fledging between mid-July and August.
In the
past, ospreys bred throughout the British Isles, but were persecuted to
extinction by the early 20th century. Following successful
reintroduction at Loch Garten, Scotland has become a stronghold for a new
osprey population and there are around 40 pairs of osprey in Perthshire. A
possible sighting of new chicks at the nest near Lochan Oisinneach Mor brought
us out to assist with the challenging task of ringing the birds, to help with
ongoing monitoring of the osprey population and its breeding success. This monitoring
is vital in order to secure their well-being in the longer term and results of surveys
carried out by the Scottish Raptor Study Group inform conservation planning and
policy at a local, regional and national level.
Reaching
the nest, or eeyrie, in order to ring chicks involves some spectacular
rope-work and is only permissible with a Schedule 1 licence. Thin string is
thrown high into the tree, with the aid of a stone to carry it up and over a
suitably sturdy branch and back to the ground. The string is then used to winch
up a climbing rope. This secured, the climber ascends using mechanical jumars
to reach the top of the rope, then free climbs up to the nest, arranging the
rope for the return abseil down. Keith performed these tricky manoeuvres with
the swiftness of an acrobat, avoiding rusty old nails stuck into the tree trunk
by collectors aiming to illegally take eggs from the nest site and the razor
wire set up to deter the collectors.
However,
on reaching the nest site there had been no sign of an adult bird. Ospreys are
typically monogamous and highly faithful to their partners and their nest.
Usually the female would be guarding the chicks, so her absence and the lack of
sounds or signs of droppings indicated that there were no chicks after all.
Having checked, Keith confirmed the nest was empty. Nearby, we found several
osprey feathers and a broken osprey eggshell, but there was no sign of the egg
having been fertilised. It was not certain what had happened and why the nest
had been abandoned. Nests may fail because of adverse weather or inexperienced
birds breeding for the first time as well as through disturbance. Perhaps the
ospreys would try again here or close by.
We
decided to visit another nearby nest. Here we found a female circling as we
approached, calling and alarming to the chicks, who would have been lying flat
in the nest. It wasn’t possible to climb the very old and rotten tree to reach
the eeyrie, so we watched for a while, and then retreated some distance to let
the ospreys settle down in peace, whilst we surveyed the nest with a telescope.
We were delighted to see two, large, very healthy-looking chicks in the nest,
stretching their wings and being fed by the female bird. They will soon fledge
and eventually become independent enough to soar high above lochs and rivers, perfecting
the art of fishing through plummeting dives underwater.
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