[mou] questions on Great Gray Owls

[Jim Williams]

We might at this point be suffering from owl-information overload. 
Risking that, however, I offer the following comments from Dr. James 
Duncan, owl expert from Winnipeg. Several days ago, I asked him some 
questions about Great Gray Owls, which he kindly answered.
Jim Williams
Wayzata, Minnesota

Begin forwarded message:

From: "Duncan, James (CON)" <JDuncan@gov.mb.ca>
Date: January 12, 2005 4:05:11 PM CST
To: "'Jim Williams'" <two-jays@att.net>
Cc: "Duncan, James (CON)" <JDuncan@gov.mb.ca>
Subject: RE: questions on Great Gray Owls

Hi Jim,

Thanks for the opportunity to help. I will do my best to answer your
questions below.

I will use CAPS TO ANSWER, which I hope are not too annoying, but will 
serve
to help id my responses.

Cheers, Jim
_________________________________________
Dr. James R. Duncan, Manager
Biodiversity Conservation Section
Wildlife and Ecosystem Protection Branch
Manitoba Conservation
Box 24, 200 Saulteaux Crescent
Winnipeg, MB R3J 3W3
204-945-7465 work
204-945-3077 fax
jduncan@gov.mb.ca

Subject: questions on Great Gray Owls

1. Is it reasonable to believe that the Great Gray Owls we are seeing
here right now are stressed to any degree simply by their displacement?

MIGRATION IS A DANGEROUS TIME FOR ANY ORGANISM, INCLUDING HUMANS.

Is the need to find food, which has brought them here, by itself at
this point stressful?

YES, BUT ONE AUTHOR OF ANIMAL BEHAVIOUR NOTED BEAUTIFULLY ... STRESS AND
EMOTION ACT AS POWER UNITS, PUSHING AN ORGANISM FROM FROM ONE SITUATION 
TO ANOTHER.  THE POINT IS THAT SOME STRESS IS BENEFITIAL (ENABLING 
SURVIVAL),
TOO MUCH IS HARMFUL.

2. Is there reason to believe that owls encountering objects with which
they are not familiar or might not be familiar (vehicles, trains, power
lines, multiple and frequent observers) are stressed by those
experiences?

WISONSIN BIOLOGIST DON FOLLEN WROTE AN ARTICLE IN PASSENGER PIGEON
DESCRIBING THE PHENOMENON OF FOCAL CONCENTRATION IN OWLS.  WHEN AN OWL 
IS CONCENTRATING ON A VOLE IT MAY FLY INTO THE PATH OF AN ONCOMING CAR
SEEMINGLY UNAWARE THAT THE CAR IS THERE.  IT SEEMS THAT MANY OWLS, AND 
MANY OTHER FORMS OF WILDLIFE, ARE SIMPLY NOT ADAPTED TO AVOID FAST 
MOVING VEHICLES, A RELATIVELY RECENT PHENOMENON FROM AN EVOLUTIONARY 
PERSPECTIVE.

IN MY OPINION, MANY OBSERVERS AT A RESPECTFUL DISTANCE, WOULD NOT 
STRESS A FREE-LIVING HUNTING BIRD.  REPEATEDLY APPROACHING A BIRD TOO 
CLOSE CAUSING IT TO CHANGE PERCHES FREQUENTLY IS NOT APPROPRIATE 
BEHAVIOUR AND LIKELY STRESSFUL TO THE ANIMAL.

FOLLOWING RADIO-MARKED GREAT GRAY OWLS FOR MANY YEARS TAUGHT ME HOW 
CLOSE I COULD APPROACH -  IT VARIES BETWEEN BIRDS, AND YOU HAVE TO TAKE 
THE CUES FROM THE OWL.  I ALSO LEARNED THAT IN THE WILD GREAT GRAY OWLS 
HAVE
ACCIDENTS, DAMAGING THEMSELVES ON SHRUBS AND WILLOWS.  YES, SOME 
COLLIDE WITH WIRES, FENCES, ETC. BUT MOST SEEM ADEPT AT AVOIDING THEM.  
I THINK THEY BENEFIT FROM POLES USED FOR HUNTING PERCHES.  RELATIVELY 
FEW GET ELECTROCUTED BY POWER LINES.

3. Can this stress, if it exists, be a factor in the birds' ability to
successfully hunt?

LIKE PEOPLE, A STARVING OR TIRED BIRD IS MORE ACCIDENT PRONE AND MORE
VULNERABLE (LESS WARY) TO PREDATORS SUCH AS GOSHAWKS, GREAT HORNED 
OWLS, LYNX, MARTEN, ETC.

4. What is the usual success ratio for a hunting owl? How many strikes
might it make before successfully capturing prey?

ADULT BIRDS ARE MORE EFFICIENT HUNTERS THAN LESS EXPERIENCED BIRDS.  IN 
1992 I ESTIMATED SUCCESS RATES FOR WINTER HUNTING GREAT GRAYS, BUT THIS 
WAS BASED ON A RELATIVELY SMALL SAMPLE -- 30 TO 50 % OF SNOW PLUNGES 
WERE SUCCESSFUL. I WOULD CAUTION AGAINST USING THIS ESTIMATE TO JUDGE 
IF A HUMAN ACTIVITY IS IMPACTING OR STRESSING GREAT GRAY OWLS.  MORE 
RESEARCH IS NEEDED ON HUNTING SUCCESS RATES.

5. How many voles must an adult Great Gray Owl eat during an average
winter day to  survive?

4-6, DEPENDING ON HOW BIG THE VOLES ARE.

6. How long can a Great Gray Owl go without food before it becomes to
weak to hunt?

I DON'T KNOW, BUT I WOULD GUESS ABOUT A WEEK IN WINTER.  THE PROBLEM IS 
THAT AS A BIRD GETS HUNGRY, IT GETS ACCIDENT PRONE AND MORE VULNERABLE 
TO
PREDATION.

7. We are approaching a period of several days of predicted below-zero
(F) temperatures. What impact will this colder weather have on the
birds' need for nourishment?

CLEARLY COLD WEATHER INCREASED THEIR NEED FOR FOOD, BUT THE PLUMAGE OF 
A GREAT GRAY KEEPS IT QUITE WARM IF IT IS SHELTERED FROM THE WIND.  IF 
THEY
ARE EATING WELL THEY CAN SURVIVE EXTREMELY COLD WEATHER.

8. How best can observers meet the needs of the birds during periods of
observation? Should observation be limited overall? Should there be
limits to approach? Should there be limits to duration of observation?
Are there clues an observer can use to determine if the owl is becoming
stressed or agitated, to determine that an observation should be
terminated?

PEOPLE SHOULD USE COMMON SENSE - SEE MY EARLIER COMMENTS.  WATCHING 
THEM FROM A CAR OR THE ROAD WITH BINOCULARS AND SCOPES SHOULD NOT 
STRESS THE BIRDS.  WALKING OUT ACROSS A FIELD RIGHT UP TO THE TREE IT 
IS PERCHED IN TO SEE IT CLOSER IS NOT SOMETHING I WOULD DO.  ALONG 
ROADS, I TYPICALLY KEEP AT LEAST ONE TELEPHONE POLE AWAY FROM A BIRD ON 
A HYDRO POLE.

9. What advice might you offer birders as they seek to balance their
continuing desire (repeated trips by some individuals) to see as many
of the birds are possible with their desire to do no harm to these
creatures that, to some degree, have placed themselves in our care?

I THINK MY COMMENTS ABOVE ADDRESS THIS.

HERE IS ANOTHER POINT I'D LIKE TO MAKE.

I USE AN ARTIFICIAL MOUSE OR VOLE-LIKE LURE TECHNIQUE TO CATCH AND BAND
GREAT GRAY AND NORTHERN HAWK OWLS.  I PERSONALLY THINK FOR THIS PURPOSE 
IT IS AN ACCEPTIBLE TECHNIQUE -- IT IS USED ONCE, AND THE BIRD IS 
RELEASED
WITHIN MINUTES OF CAPTURE.  I KNOW SOME PEOPLE IN MANITOBA WHO HAVE 
USED ARTIFICIAL LURES TO BRING OWLS CLOSER TO PHOTOGRAPH THEM, AND SOME 
DID SO REPEATEDLY.  I AM OPPOSED TO THIS PRACTISE SINCE IT CAUSES THE 
BIRDS TO EXPEND ENERGY REPEATEDLY.

I SOMETIMES GET ASKED IF FEEDING OWLS LIVE OR FROZEN-THAWED LAB MICE IS 
OK, FOR PHOTOGRAPHY OR SIMPLY BECAUSE WELL-INTENTIONED PEOPLE WANT TO 
HELP HUNGRY OWLS.  I THINK THIS PRACTISE HAS PROS AND CONS.

PROS - THE OWLS GET SOME FOOD ENERGY FOR THEIR EFFORT, AND THIS WOULD
COMPENSATE THE OWLS FOR THE ENERGY THEY EXPEND (RE PHOTOGRAPHERS).

CONS - THIS PRACTISE HAS BEEN SHOWN TO CONDITION SOME OWLS TO APPROACH
PEOPLE AND CARS IN ANTICIPATION OF BEING FED.  ONE OWL NEAR WINNIPEG WAS
NICKNAMED "LUNCHBOX" BY THOSE FEEDING IT.  SUCH CONDITIONED BEHAVIOUR 
MAY
LURE SOME OWLS TO THEIR DEATH IF THEY APPRAOCH HIGH TRAFFIC AREAS, OR 
PEOPLE NOT FAMILIAR WITH THE CONTEXT (THEY ASSUME THE OWL IS ATTACKING 
THEM AND MAY HARM THE OWL IN SELF DEFENSE.

AS A GENERAL POLICY, IT IS ILLEGAL TO FEED WILD ANIMALS IN MANITOBA 
UNLESS
IT IS FOR DEPARTMENT APPROVED CONSERVATION PURPOSES OR PERMITTED 
RESEARCH. MN MAY HAVE ITS OWN POLICY ON THESE MATTERS.

HOPE THIS HELPS!