A Snowy Owl Issue

[phaw...@comcast.net]

I was talking with Barbara Volkle, MassBird's moderator, last night and the conversation evolved to Barred and Snowy Owls. In response to a question I briefly explained why so few Snowies are being seen this year, and she asked me to post my understanding of the situation.

    Briefly, I think that an incredible amount has been learned about Snowy Owls in the past decade or two, regarding behavior as well as aging and sexing them. This is due to long-term research by different individuals and organizations that I won't list here, as well as to Project Snowstorm, which developed out of the 2014 explosion of wintering Snowies in much of North America, including Massachusetts.

     Briefly, "we've" learned that there are probably far fewer Snowy Owls than estimated several decades ago, when you roughed out the breeding range, divided it by the average territory each owl theoretically required, and voila, you had an estimated population. However, research indicated that Snowies are heavily dependent on lemmings to feed the female and young. Lemmings have breeding cycles with sharp peaks and deep valleys, and these cycles can vary across the different Arctic regions.

     Snowies are so dependent on lemmings that they have evolved into nomads. As best as I understand it, most hawks (and falcons) are territorial breeders, returning to the same territory to breed every year. If food is in short supply, they might skip breeding for a year. Snowies are so dependent on lemmings that they have evolved to not breed every year in the same location. They search for dense lemming populations and most breed only when and where they have found an adequate prey population to sustain them. Thus, Snowies might wander over hundreds, even thousands of miles searching for adequate prey. They apparently wander individually, though not necessarily "alone." Thus it is possible a new mate is selected every year, the female selecting a male good enough to wow her with lots of lemmings NOW. They are known to move as far west as Asia to find food and mate, and vice versa.

    Research conducted by Denver Holt, originally from Massachusetts, and JF Thierrien from Hawk Mountain, and many others this summer revealed that few breeding pairs were found in the areas where they have recently been relatively abundant. This was seen at other locations as well, so the belief was there was very limited breeding this summer in Arctic North America.

     Project Snowstorm has banded a number of Snowies in recent years, but I don't think many juvenile Snowies have been banded anywhere this year. Most of Snowstorm's fascinating reports are largely of immature birds banded in previous years who have flown far enough south to finally be in range of cell towers so their transmitters can be read. Most of those have stayed fairly far north.

     Thus, there are few juvenile Snowies in North America to migrate south. Second, in the past 15 years we have learned that many Gyrfalcons and Snowy Owls move more latitudinally rather than longitudinally to winter, preferring to feed on large flocks of wintering seabirds from ice floes and frozen shorelines. (Some have even called the Gyr a "pelagic falcon.")

     This is a very quick, off-the-top-of-my-head summary of a fascinating bird and topic. See a presentation by our local Snowy experts, Norman Smith, or by Marcia and Mark Wilson, or look online for a webinar by Denver Holt, J.F. Therrien, or others. (Check out the Owl Institute, which just gave a fascinating presentation on Hawk Owls.) JF just gave a great presentation on Arctic Raptors, including Snowy Owls, for the Hawk Migration Association of North America's free "Lunch and Learn Series." 

https://www.facebook.com/search/posts?q=hawk%20migration%20association%20of%20north%20america%20(hmana)&filters=eyJyZWNlbnRfcG9zdHM6MCI6IntcIm5hbWVcIjpcInJlY2VudF9wb3N0c1wiLFwiYXJnc1wiOlwiXCJ9In0%3D 

      

I'd also encourage those interested to google "Project Snowstorm," and to pick up Scott Weidensaul's superb "Peterson Reference Guide to Owls of North America and the Caribbean" (2015). That is perhaps your best single source of good information on Snowies, even though we've learned a lot in the past seven years.

    I hope this is of help to those who are wondering why we have so few Snowies this winter.      

   

Best,

Paul   

          

Paul M. Roberts
Medford, MA 
phaw...@comcast.net

[markgh...@gmail.com]

Fascinating thanks, if a bit depressing at times

Mark

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[Susan Delaney]

Paul,

This reminds me of the close relationship with Canada Lynx and Snowshoe hares.  When the hares population decreases, the lynx don’t have kittens.  Nature is truly amazing and harmonious 

Sue D 

Sent from my iPhone

On Feb 7, 2023, at 11:49 AM, markgh...@gmail.com wrote:



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