April 26, 2014 - EARTH - The following stories constitutes some of the latest incidents of mass animal die-offs across the globe.
Half A Million Carp Dead In Cumberland River, Kentucky
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The silver carp is known for its explosive and high jumping that can be a danger to boaters.
USGS |
Several sources in Kentucky - including our colleagues at
WKMS in Murray
- are reporting on a massive and sudden die-off of silver carp in the
Cumberland River below the Lake Barkley dam, downriver from Nashville
and Clarksville. Estimates of "tens of thousands", maybe as many as
500,000 of the invasive Asian carp species, are believed to have
perished in a 24-hour period.
The cause of the die-off is unknown and being investigated, but Kentucky
Department of Fish and Wildlife's Paul Rister has this to say to online
newspaper
KyForward:
"Whenever there is one species of fish, you are definitely thinking
viral or bacterial. It's not anything water quality wise. If it was
oxygen-related or chemical related you would see other species"
The silver carp - known for its high jumping skills that can be a
danger to boaters - is one of four invasive carp that are illegal to
"possess or transport" in Tennessee, according to the Tennessee Wildlife
Resources agency.
The spread of silver carp is so worrisome that wildlife officials are researching special chemicals to poison them.
Here is some detailed information about Asian carp distribution in the U.S. as of last year.
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NPR.
UK Barn Owls Suffer Worst Year On Record Due To Bitterly Cold Spring
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A barn owl in flight.
Marlene Finlayson / Alamy |
Barn owls suffered their worst year on record in 2013 as they struggled in the bitterly cold spring, conservationists have said.
Results from barn owl monitoring schemes around the UK revealed the
number of sites where nesting took place last year was significantly
down in every area compared to previous years, and some surveys found no
nests with eggs in at all.
Overall the number of occupied nests was
down 71% on
the average across all previous years, according to the Barn Owl Trust,
which collated the information from 21 independent groups stretching
from Jersey in the Channel Islands to south-west Scotland.
A survey in Berkshire which normally finds 14 nests in use and a
surveyor in Yorkshire who normally finds 25-30 occupied nests both
found none at all, while surveys in Buckinghamshire and Sussex were both
down more than 90% on normal levels.
Conservationists described the situation as the "worst year ever recorded" for the flagship farmland species.
The dramatic drop in nesting was largely down to the
freezing spring in 2013, with the coldest March since 1962 which left
many barn owls dead, a report by the Barn Owl Trust said.
Almost four times as many dead barn owls were reported to the British
Trust for Ornithology in March 2013 than normal and by mid-April it was
possible that there were fewer barn owls alive in the UK than at any
time since records began, the report said.
David Ramsden, senior conservation officer for the Barn Owl Trust said:
"It's a lot to do with the fact that March was like January. Just when
it should be getting warmer and mortality should have been dropping, it
continued."
The icy weather, which reduced the availability of the bird's small
mammal prey, was the latest in a series of extreme weather events going
back to 2009 which had hit barn owl populations, he said.
"If we stop having frequent extreme weather events the population could
recover in a couple of years to what it was before the extreme weather
events began in December 2009."
But even those population levels were not terribly high, as the barn owl
had suffered a historical decline from the mid 1800s through to the
late 1980s, as a result of increasingly intensive agriculture which
affected barn owls' habitat and prey.
A survey in the late 1990s revealed there were around 4,000 pairs.
Ramsden said the population had probably increased from that level in
the face of early springs and mild winters over the past decade or so,
before being hit by a string of extremes starting with the very cold
winter of 2009-10.
Whether the barn owl could recover from the record lows seen in 2013
would depend on whether climate change would mean more extreme weather
conditions, with cold winters affecting barn owls more than wet weather
or drought, he said.
Land management also played a role, he said, adding that creating
habitat for flagship species such as barn owls would also boost other
wildlife such as birds and butterflies.
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The Guardian.
Too Much Spring Ice Threatens Alaskan Polar Bears
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| Female polar bear with cubs. |
Five meters of ice - about 16 feet thick - is threatening the survival
of polar bears in the Southern Beaufort Sea region along Alaska's Arctic
coast, according to Dr. Susan J. Crockford, an evolutionary biologist
in British Columbia who has studied polar bears for most of her 35-year
career.
That's because the thick ice ridges could prevent ringed seals, the
bears' major prey, from creating breathing holes they need to survive in
the frigid waters, Crockford told CNSNews.com.
"Prompted by reports of the heaviest sea ice conditions on the East
Coast 'in decades' and news that ice on the Great Lakes is, for
mid-April, the worst it's been since records began, I took a close look
at the ice thickness charts for the Arctic," Crockford noted in her
Polar Bear Science blog on April 18th.
"Sea ice charts aren't a guarantee that this heavy spring ice phenomenon
is developing in the Beaufort, but they could be a warning," she wrote,
noting that they "don't bode well" for the Beaufort bears.
"What happens is that really thick ice moves in because currents and
winds from Greenland and the Canadian islands push it against the
shore," Crockford told CNSNews.com.
"The male seals arrive in the area in early spring
to set up breeding territories. They drill a hole through the ice to
maintain breathing holes close to the shore. But there's a limit. They
can drill through two meters (about seven feet) of ice. But too much
beyond that and they're in trouble."
"The reason that's important is that seals mate right after the pups,
who are born in April, are weaned. So the male seal wants to be there,
but he has to have breathing holes. If the ice is too thick, he has to
move off someplace else," she explained.
But this is the same time that female polar bears are just emerging with
their newborn cubs from maternity dens either on or near the shore.
"When those bears come out of their dens in the spring, they need to
find seals right away because they will have gone six months without
eating," Crockford said. "If there are no seals, they have to go further
out, where there's thinner ice."
"Spring and early summer are really a critical time for polar bears.
That's when they need to eat as many seals as they can because that's
when they put on fat for the rest of the year. If they have trouble
doing that in the spring, they're in big trouble."
There were comparably high levels of spring ice in the Beaufort Sea in
2004 and 2006, when bear counts were "one of the pieces of evidence used
to have the bears listed as 'threatened' in the U.S.," Crockford
pointed out.
"Polar bear biologists were finding some bears quite thin and found a
population decline," she said, which they attributed to melting summer
ice caused by global warming.
"But the biologists were not there to see the thick [spring] ice. All
they saw was thin bears," she pointed out. "They blamed the poor
condition of the bears on summer ice, instead of acknowledging that it
was likely the condition of the ice in the spring that was the cause of
the problem."
"Female [polar bears] with cubs having trouble feeding are one aspect of
the repercussions of thick ice," Crockford added. "The other
repercussion is that other bears, instead of hanging around and
starving, probably left the area. They could have gone to the Chukchi
Sea, which is located between the U.S. and Russia near the Bering
Strait."
The international IUCN Polar Bear Specialist Group (PBSG) conducted a
polar bear population survey for the area in 2006. It reported a decline
in the adult polar bear population and reduced cub survival rates,
which was used to list the bears as a "threatened species" in the U.S.
in 2008.
But the PBSG did not take into account the fact that polar bears "can
just move" to other areas if their food supply is limited, Crockford
told CNSNews.com. "If some of those bears were part of that count, it
would look like they died," she pointed out.
In its 2013 status update, released on February 14th, the PBSG repeated
its 2006 "reduced" population estimate, putting the Southern Beaufort
Sea at 1,526 bears and "declining due to a negative trend in sea ice
conditions, particularly over the continental shelf, resulting from the
continuing effects of climate warming."
However, in what Crockford characterizes as an "astonishing admission,"
the update also stated that "it is important to note that there is the
potential for un-modeled spatial heterogeneity in mark-recapture
sampling that could bias survival and abundance estimates. A thorough
re-assessment of survival and abundance is underway and a final result
is anticipated in 2014."
"What's shocking is that the PBSG have now admitted that the 'movement
of bears' issue essentially invalidates the 2006 population estimate and
the much-touted 'reduced survival of cubs'," Crockford said in a March
24th blog post.
"This is a cyclical pattern that is quite specific to that part of
Alaska, which has been known about since the 1970s," when wildife
biologists noticed "ten times as many seals as usual in the Chukchi Sea.
There were more bears, too," Crockford told CNSNews.com.
"It seems to happen every 10 years, so it should be expected by people
who work in the area. And not just by people who study polar bears, but
also people who study seals."
"It looks like similar conditions are setting up now, and we know the timing is right," she added. "We're keeping an eye on it."
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CNS News.
