My first article
on polar bears !
There has been
20 years with no trend
in ice breakup dates
for Western Hudson Bay
polar bears.
All polar bear females
tagged by researchers
around Churchill in
Western Hudson Bay
last year, were still
on the ice as of
June 25, 2019.
Contrary to predictions
of ever-declining ice cover,
the lack of a trend in sea ice
breakup dates for Western
Hudson Bay is now twenty
years long.
The polar bears
are repeatedly claimed
to have been
seriously harmed
in recent years
by a loss of sea ice.
The claims are made
by leftist liars.
Sea ice breakup
has never come
before June 15.
The earliest recent
spring ice breakup
date did not come in 2012,
when sea ice hit a summer
record low – but in 1999,
when Hudson Bay sea ice
suddenly began to melt
by late June
rather than mid-July
(Cherry et al. 2013;
Castro de la Guardia et al. 2017;
Lunn et al. 2016).
There has been no
obvious trend
in breakup dates for
Western Hudson Bay
polar bears since 1999
(and no trend in fall freeze-up dates either).
Cherry and colleagues (2013)
studied WHB bears between
1991 and 2009 and stated:
“Throughout the study,
bears arrived ashore
a mean of 28.3 days
(S.E. = 1.8)
after 30% ice cover …”
No matter when
that arbitrary 30%
sea ice coverage
has been reached,
the bears leave the ice
when they feel like it.
On average, the bears
stay on the floating ice
until about four weeks
after the official
sea ice ‘breakup’
point is reached.
The overall trend in time
polar bears spend onshore
since 1979 has declined,
but there has been
no trend since 2001.
That's NOT what was expected
or predicted, especially given
the marked decline in global
sea ice levels from 2007-2015.
(Crockford 2017)
Last year, virtually all bears
that came off the ice around
Churchill had arrived
by the third week of July
last year (16th - 22nd).
REFERENCES:
Castro de la Guardia, L., Myers, P.G.,
Derocher, A.E., Lunn, N.J.,
Terwisscha van Scheltinga, A.D.
2017
"Sea ice cycle in western Hudson Bay,
Canada, from a polar bear perspective."
Marine Ecology Progress Series 564: 225–233.
Cherry, S.G., Derocher, A.E.,
Thiemann, G.W., Lunn, N.J.
2013
"Migration phenology
and seasonal fidelity
of an Arctic marine predator
in relation to sea ice dynamics."
Journal of Animal Ecology 82:912-921.
Crockford, S.J.
2017
"Testing the hypothesis
that routine sea ice coverage
of 3-5 mkm2 results in
a greater than 30% decline
in population size
of polar bears
(Ursus maritimus)."
PeerJ Preprints 19 January 2017.
Lunn, N.J., Servanty, S.,
Regehr, E.V., Converse, S.J.,
Richardson, E. and Stirling, I.
2016
"Demography of an apex predator
at the edge of its range – impacts
of changing sea ice on polar bears
in Hudson Bay. "
Ecological Applications, in press.