Hi Tweets

at Craig Corser: I've seen poisoned Starlings drop out of the sky as you
described.

Here in BC we have no doubt of what's making Barn Owls drop out of the sky.

"Scientists know that at least some owls are dying under gruesome
circumstances, bleeding to death from stomach hemorrhages in an agonizing
and days-long decline. The culprit: An extra-potent class of rat poisons
that has flooded the market in recent decades, designed to more effectively
kill rats, a food source for the owls.

Six of 164 dead barn owls, barred owls and great horned owls in a 2009
Western Canada study had rodenticide levels high enough to kill them
outright, causing the fatal stomach hemorrhages. Pesticide readings in 15
per cent to 30 per cent of the others appeared toxic and seem likely to
handicap owls in a variety of ways, scientists say. Barn owls in particular
could be hurt -- in Western Canada they no longer live anywhere outside the
Lower Mainland (that's Greater Vancouver/Fraser Delta....m), and this month
their protections under the Species At Risk Act were upgraded when they were
reclassified as "threatened," rather than merely being a "species of special
concern." A smaller and more gravely imperiled population, classified as
"endangered," lives in Eastern Canada."
more at:

http://preview.tinyurl.com/27sjtlh

The limiting factor to their range limit seems to be that they lose aural
hunting accuracy in even very slight accumulations of snow, and the Lower
Mainland is the northernmost region in mid-Pacific latitudes where winters
are mostly snow-free and, on average, snow accumulations don't last more
than a few days at most before melting or being washed away by rain.

>From the farmers' POV, it might be a hard sell to ban these anti-coagulants
and to allow rats to flourish just so to maintain the BC Barn Owl
populations, especially given that they're at the extreme northern limit of
their range at the Lower Mainland's latitude. This might seem perverse
public policy.

A compromise might be to establish anti-coagulant-free zones and compensate
farmers for any damages caused by rats. No, not an easy sell, but possible.

Michael Price
Vancouver BC Canada
loblollyboy at gmail.com

Every answer deepens the mystery.
- E.O. Wilson
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