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December 2013

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From:
Casey Tucker <[log in to unmask]>
Reply To:
Casey Tucker <[log in to unmask]>
Date:
Sat, 21 Dec 2013 01:30:27 -0500
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Hi Folks,

 

The annual (or is that
bi-annual?) discussion on the merits of feeding Snowy Owls has been very
interesting, and this year’s discussion has remained impressively civil for the
most part.  I have a great deal of
respect for everyone who has shared their views on this subject, and thank them
for doing so.

 

That being said, I’d like
to suggest that we table this discussion.

 

Arguments can be made for
and against feeding of Snowy Owls in winter; however none of these arguments is
supported by any scientific evidence.

 

Most of our understanding
on supplemental feeding of over-wintering birds comes from granivorous feeder
birds, and at least one European study suggests that birds visiting feeders in
winter are more successful breeders the following spring (Robb et al. 2008). This
would suggest that supplemental feeding can have a positive effect.  However that doesn’t mean it’s true for all
species, especially since it’s thought that Snowy Owls that come south
typically do not breed when, and if, they return to the northern breeding
grounds after winter.

 

I am aware of no such supplemental
feeding studies on wintering Snowy Owls, and until such a study is done we really
can’t be certain of anything including whether it’s beneficial or not, whether
they will associate people with food or not (especially since they don’t
encounter many people in their breeding grounds in the Arctic), or
any other arguments that have been made one way or the other.

 

Snowy Owls in winter
divide into two major groups, which are primarily divided by the boreal forest
zone.  The few studies that have looked
at over-wintering diet in Snowy Owls has primarily focused on owls north of the
boreal zone, where they primarily feed on grouse.  A single grouse can sustain an owl for
several days, and owls have been known to sit on un-finished grouse carcasses to
keep them from freezing so that they can feed on them at a later time.

 

“From studies on owls
trapped during the winter to the south of the boreal forest, no general
comments can be made, studies indicating that while some birds are both very
fat and in good condition, others are extremely exhausted and sometimes
desiccated.  At Logan International
Airport in years where the population was chiefly adult birds rather than
juveniles, many of the adults were underweight (Smith 1997)” (Potapov and Sale
2012).

 

I think the best rules/guidelines
that we can follow regarding supplemental feeding of Snowy Owls in winter are like
the first and second rules of the movie “Fight Club” (the first and second rules
are that you don’t talk about it).

 

If you’re interested in
reading a current synthesis of our scientific knowledge of Snowy Owl biology I
would highly recommend checking out the book “The Snowy Owl” by Eugene Potapov
and Richard Sale (details below).

 

Until we have tested
evidence that supports or disproves that supplemental feeding is either
beneficial or harmful, I’d like to suggest tabling the discussion in favor of
sharing actual reports of the whereabouts of owls throughout the state. Happy Birding & Happy Holidays! Casey Tucker 

****************************************************************************************************************** 

 

Cited

 

Potapov, E. and R. Sale.
2012. The Snowy Owl. T & AD Poyser. London.

 

Robb, G.N., R. A.
McDonald, D.E. Chamberlain, S.J. Reynolds, T. J.E. Harrison and S. Bearhop.  2008.  Winter
feeding of birds increases productivity in the subsequent breeding season.
Biology Letters. 4:220-223.

 

Smith, N. 1997.
Observations of wintering Snowy Owls (Nyctea scandiaca) at Logan Airport, East
Boston, Massachusetts from 1981-1997. In: Duncan, J.R., D.H. Johnson, and T.H.
Nicholls (eds.). Biology and Conservation of Owls of the Northern
Hemisphere:591-597.  Second Int. Symp.,
Feb. 5-9, 1997.  Winnipeg, Manitoba,
Canada: United States Dep. Agric.

                                          
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