According to the BNA (hawk owl account written in 1998), "Early studies suggest that this owl eats primarily small rodents, but recent evidence indicates that grouse, ptarmigan, and hares comprise a greater proportion of their diet than previously thought." Most of the work cited by the BNA authors was done in Scandinavia rather than North America, so it sounds like there are a lot of interesting gaps birders can fill!
Best, Laura On Wed, Nov 18, 2009 at 10:56 AM, Terence Brashear <[email protected]>wrote: > Interesting observation Shawn. > > You might find this paper from "The Condor" interesting since it deals with > prey selection by Northern Hawk-Owl. Of note is the reference to a Northern > Hawk-Owl taking a Spruce Grouse as a prey item. > > http://elibrary.unm.edu/sora/Condor/files/issues/v097n01/p0208-p0220.pdf > > Terry Brashear > > Hennepin County, MN > > http://www.naturepixels.com > > birdnird AT yahoo.com > > --- On Wed, 11/18/09, Laura Erickson <[email protected]> wrote: > > From: Laura Erickson <[email protected]> > Subject: Re: [mou-net] Observations of a Hawk Owl... > To: [email protected] > Date: Wednesday, November 18, 2009, 6:30 AM > > This is a really interesting and insightful post! I suspect the > interactions > noted by Shawn really do have, at heart, to do with the owl and jays' > caches, but we can't know this for sure until we've seen more of these > behaviors. This would be a fascinating thing for birders to keep track of > this winter, and deserves some sort of summary (by Shawn, I'd think) in The > Loon. Last year I got a couple of not-good but interesting photos of a > raven > harassing a hawk owl--this is clearly a different thing, and so it would be > valuable for people who do notice interactions between Hawk Owl and Gray > Jays to send them on, especially when it's known who put food into the > cache > and who is trying to get it. > > There aren't a lot of interspecific interactions reported for the Northern > Hawk Owl. According to The Birds of North America Online: > > >>Nonpredatory Interspecific Interactions > > >>When surrounded by mobbing birds, individual sometimes makes itself thin > and assumes a position of camouflage, with eyes reduced to slits. May > extend > neck forward and give Screeching Call (see Sounds: vocalizations, above; > Cramp > 1985< > http://bna.birds.cornell.edu/bna/species/356/articles/species/356/biblio/bib022 > >). > In Alaska, harassed most often by Gray Jay; also American Robin and Varied > Thrush (*Ixoreus naevius*); robins and thrushes strike perched owls on > occasion. Male hawk owl responded aggressively to an attacking American > Kestrel (*Falco sparverius*) by jumping from its perch and presenting its > talons as the kestrel dove (Kertell > 1986< > http://bna.birds.cornell.edu/bna/species/356/articles/species/356/biblio/bib062 > >). > Generally remains conspicuous and unrestrained (Voous > 1988< > http://bna.birds.cornell.edu/bna/species/356/articles/species/356/biblio/bib128 > >), > however; not easily displaced by smaller birds mobbing it (JRD, PAD). > > >>Observed flying toward and displacing Pileated Woodpecker, in 1 case, > after woodpecker landed in same tree as owl (JRD, PAD); this is a prey > species, and hawk owls use nest cavities of this woodpecker for nesting. > Observed fanning tail and squawking loudly when Common Raven perched 50 m > away (R. W. Nero pers. comm.), but S. Wilson (pers. comm.) reported both > species within 40 m of each other with no interactions observed. In nw. > Ontario, observed chasing Common Raven several times from deer gut pile on > which the owl was feeding; pursued raven for 100 m (S. Walshe pers. comm.). > > Best, Laura > > (If you're interested, my raven-hawk owl photos are here: > > > http://www.flickr.com/photos/48014...@n00/3148423415/in/set-72157611402003364/ > > > http://www.flickr.com/photos/48014...@n00/3149255012/in/set-72157611402003364/ > > Best, > > Laura Erickson > > in Ithaca, NY, dreaming of Peder's Barrow's Goldeneye, Erik's gulls, and > Northern Hawk Owls. > > > On Tue, Nov 17, 2009 at 10:41 PM, <[email protected]> wrote: > > > The Northern Hawk Owl that I happened upon today provided some > interesting > > moments. Most notably was the way in which it interacted with the local > > gray jay family. By interaction, I actually mean complete lack of > > tolerance. The owl was working a recently logged area in the middle of a > > bog. > > Every and anytime the jays were within earshot, the hawk owl was after > > them. > > At one point, I had lost view of the owl and was trying to pish the jays > > in > > and one responded, coming in quite close to investigate. The jay was > > sizing me up, when suddenly it gave a sharp AAAPP!! (That's what it > > sounded > > like), and took off just in time for me to hear a swooosh coming over my > > head. > > The hawk owl was in hot pursuit and appeared falcon like in it's > banking > > and maneuverability. The owl was relentless in driving the jays away. > I > > considered this for a while as I watched and marveled. Was the owl > trying > > to catch and eat the jay? Perhaps. Are there records of hawk owls > > catching > > and eating gray jays? Would love to hear if anyone knows. But then I > > observed something that I really found interesting. The owl, in between > > bouts > > of jay chasing, removed a cached vole from a tree and flew to another > tree > > and re-cached the vole under some peeled bark and lichen in the fork of > > the tree some twenty feet off the ground. I wonder if the jays, clever > as > > they are, have been watching where this owl has been caching voles, and > > might not be stealing from the owl when the opportunity presents itself? > > Like > > squirrels who watch where other squirrels cache their nuts. Would jays > > eat a vole? Interesting to say the least. Towards the end of my > > observing > > the owl, it caught another vole and cached it eight feet off the ground, > > on > > the SIDE of a tree, in a crevice created by peeling bark. The owl had > to > > hang on to the side of the tree like a woodpecker while it worked the > vole > > into the crack, only thing showing when it was done was the tail and > hind > > feet of the vole. During my watching the owl, it cached three voles in > > three > > different trees including the re-cached vole. And there are a lot of > > voles in this area. I counted five that skirted my footsteps during the > > day. > > While in this area (Hedbom Bog) on the St. Louis County side, I also > > observed two male black backed woodpeckers, common redpolls (a few), red > > crossbills (a few), american gold finches, and one pine grosbeak. When > > the > > finches (or the ravens) saw the hawk owl, they would circle around it > and > > chatter in their own ways. All in all, a very enjoyable way to spend a > > very > > seasonable November Day. Good Birding to you. And, if interested, I'll > > post a > > picture of today's owl in the showcase section of MOU. > > Regards, > > Shawn Zierman. > > > > ---- > > Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net > > Archives:http://lists.umn.edu/archives/mou-net.html > > > > > > -- > -- > Laura Erickson > Science Editor > Cornell Lab of Ornithology > 159 Sapsucker Woods Road > Ithaca, NY 14850 > 607-254-1114 > > > If you've found this information useful, I hope you'll consider supporting > our work on behalf of birds and other wildlife. In addition to knowing > that you'll be making a difference for conservation, you'll receive our > award-winning Living Bird magazine and informative BirdScope newsletter > four > times a year. We invite you to join our "force for nature." To sign up or > watch our video about membership, visit > http://www.birds.cornell.edu/NetCommunity/membership or call us at > 1-800-843-2473. > > For the love, understanding, and protection of birds > > There is symbolic as well as actual beauty in the migration of birds. > There > is something infinitely healing in the repeated refrains of nature--the > assurance that dawn comes after night, and spring after the winter. > > --Rachel Carson > > Please consider the environment before printing this e-mail. > > ---- > Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net > Archives:http://lists.umn.edu/archives/mou-net.html > > > > > > ---- > Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net > Archives:http://lists.umn.edu/archives/mou-net.html > -- -- Laura Erickson Science Editor Cornell Lab of Ornithology 159 Sapsucker Woods Road Ithaca, NY 14850 607-254-1114 If you've found this information useful, I hope you'll consider supporting our work on behalf of birds and other wildlife. In addition to knowing that you'll be making a difference for conservation, you'll receive our award-winning Living Bird magazine and informative BirdScope newsletter four times a year. We invite you to join our "force for nature." To sign up or watch our video about membership, visit http://www.birds.cornell.edu/NetCommunity/membership or call us at 1-800-843-2473. For the love, understanding, and protection of birds There is symbolic as well as actual beauty in the migration of birds. There is something infinitely healing in the repeated refrains of nature--the assurance that dawn comes after night, and spring after the winter. --Rachel Carson Please consider the environment before printing this e-mail. ---- Join or Leave mou-net:http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net Archives:http://lists.umn.edu/archives/mou-net.html
