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Two young satellite-tagged hen harriers have vanished
in Lancashire in unexplained circumstances.
The female birds, named Sky and Hope, both fledged
this year from nests on the United Utilities Bowland Estate in Lancashire where
they had been protected around the clock by RSPB staff and volunteers.
Hen harriers are England’s most threatened bird of
prey and this season there were only four successful nests in the whole
country. Sky and Hope were among the first chicks to fledge in England since
2012.
Sky was officially named and adopted by pupils from Brennand’s Endowed Primary School in Slaidburn in Bowland. Hope was given her name by
members of the RSPB’s youth groups from Macclesfield and Leighton Moss,
Lancashire.
The birds were both fitted with lightweight solar-powered satellite tags, designed to be
operational for around three years. Satellite tags are frequently used by
conservation organisations to find out more about the movements of species. For
example, The British Trust for Ornithology has been following the migration of
tagged cuckoos since 2011.
Scientists tracking the movements of the young hen
harriers became concerned when their tags stopped transmitting. Sky’s satellite
signal stopped suddenly on the evening of Wednesday 10 September with the data
suggesting she was roosting at her last known location, while Hope’s last’s
known location was sent on the morning of Saturday 13 September.
Both of the birds had left their nest sites on the
United Utilities Estate several weeks earlier but had remained in the Bowland
area since fledging. Searches were made but neither Sky nor Hope have been
recovered.
Experts think it is improbable that the loss of
satellite transmission is due to technical failure. Only a tiny percentage of
hen harriers fitted with satellite tags since 2007 have stopped transmitting
when it was known the tracked bird was alive.
Bob Elliot, RSPB Head of Investigations, said: “In our
experience, this satellite technology is normally very reliable and it is rare
for them to fail for technological reasons. Losing two birds in such a
short time frame and in the same geographical area is strange.
“Based on the last known data and our understanding of
the technology, Sky appears to have suffered a catastrophic tag failure at
roost suggesting either natural predation or human intervention as the likely
causes for her sudden failure to transmit. However, we would not expect natural
predation to stop the tag transmitting data so suddenly. Hope’s tag was
transmitting reliably, with no evidence of any technical problems.”
TV presenter and
hen harrier campaigner Chris Packham said: “It’s incredibly disheartening to
discover that two of this year’s chicks have already apparently failed to survive.
It shows how vulnerable hen harriers are and that four nests are nowhere near
enough. Without satellite tagging, these disappearances might never have come
to our attention but technology is on our side and we will keep watching.”
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The disappearance of the birds has been reported to
Lancashire Police and the RSPB is offering a £1,000 reward. Anyone with
information about either of the birds should contact
Crimestoppers on
0800 555 111 or, alternatively, call the
RSPB’s confidential hotline on 0845 466 3636.
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