[obol] Re: Coos Gyr, lotsa Cacklers 10/18/2014
- From: David Irons <llsdirons@xxxxxxx>
- To: "whoffman@xxxxxxxx" <whoffman@xxxxxxxx>
- Date: Tue, 21 Oct 2014 14:14:14 -0700
I went online looking for sources documenting both over water and non-stop
overnight/long-distance migrations of falcons. I found one reference to a
Peregrine making non-stop 4200 mile flight from Europe to Africa. On Sunday
Phil Pickering and I had an adult Peregrine come in off the ocean first thing
in the morning at Boiler Bay. Hard to know if it was on a hunting run or a
migrant.
I agree with Wayne. Adaptation to new food sources is often a factor in new
patterns of occurrence in raptors. If it works it will be repeated.
Dave Irons
Sent from my iPhone
On Oct 21, 2014, at 11:43 AM, "Wayne Hoffman" <whoffman@xxxxxxxx> wrote:
> Hi -
>
> Dave is correct that most raptors follow migratory routes mostly over land.
> Many have great unwillingness to cross water, and some seem to suffer
> mortality on even modest crossings. From my years in the Florida Keys, I
> have a lot of experience with raptors travelling down the Keys in fall, and
> then certain species retracing their course back to the mainland. Turkey
> Vultures, Swainson's Hawks, Broad-winged Hawks, and Short-tailed Hawks in
> particular were often seen making these return trips. At that time
> Swainson's and Short-tails were unknown in Cuba, just 90 miles to the south,
> even though both species were regular moving up and down the Keys. I also
> heard several accounts from boaters of finding multiple "hawks" floating dead
> on the water off the keys during the period of fall migration. We were never
> able to find out which species, or determine causes of death, but evidently
> for some species, ocean crossings were very difficult or risky.
>
> This does not apply to Peregrine Falcons, however, as they are well-known to
> regularly make long over-water flights. Merlins also seemed very willing to
> head out over the ocean. Ospreys and Swallow-tailed Kites also regularly
> migrate south out of Florida toward Cuba and the Yucatan Peninsula. I don't
> think we know enough about Gyrfalcon movements to be able to say how willing
> they are to make long ocean crossings. I suspect they are physiologically
> capable of flying directly from SW Alaska to Oregon or northern California.
> I doubt they regularly try to kill geese over the ocean, as I imagine they
> would have difficulty feeding on them at sea, particularly if the surface was
> at all rough.
>
> So, the possibility of following geese south remains speculative. The most
> likely alternative explanation for the regular occurrence of Gyrfalcons with
> geese in SW Oregon/NW California is that individuals that made it into that
> area over land encountered the geese, and made a habit of returning in
> subsequent years. I do not know whether we know ages on many of the fall
> birds down here, but if many are adults, return migration would be supported.
> The fall concentrations of Cackling Geese in those areas is a recent
> development, so however the Gyrs are getting there, it probably is recent as
> well.
>
> Wayne
>
>
>
>
> On Tue, Oct 21, 2014 at 4:57 AM, Tim Rodenkirk <timrodenkirk@xxxxxxxxx> wrote:
> The migration route difference makes sense Dave, I wonder how the Gyr(s) find
> the cacklers? There has been a Gyr or several Gyrs that show up where the
> Aleutian cacklers are for the past decade or so. The Gyr reports have
> followed the cacklers south into CA some years also if I remember correctly.
>
> Tim R
> Coos Bay
>
> On Mon, Oct 20, 2014 at 11:40 PM, David Irons <llsdirons@xxxxxxx> wrote:
> Alan et al.,
>
> I suspect that the apparent connection between the arrival of Aleutian
> Cackling Geese and the earliest Gyrfalcons of the season in Coos County is
> temporal only and that it has little to do with the route each species took
> to get here. As a general rule, raptors are diurnal migrants whose migratory
> routes are mostly over land, which allows them to take advantage of thermal
> uplift that occurs during daylight hours. Aleutian Cackling Geese take a more
> direct route from their Arctic breeding grounds, which takes them across well
> over a thousand miles of open ocean. When migrating, geese to continue flying
> all day and all night, making a mostly non-stop flight. When hunting
> waterfowl, falcons essentially blast their prey to the ground with a
> high-speed stoop from above. I can't imagine a falcon, even a Gyr grabbing a
> goose out of midair or carrying one very far after knocking it down into the
> water. With no terra firma on which to dine, what point would there be to the
> falcons following their prey base out over the open ocean?
>
> Dave Irons
> Portland, OR
>
> Subject: [obol] Re: Coos Gyr, lotsa Cacklers 10/18/2014
> From: acontrer56@xxxxxxxxx
> Date: Mon, 20 Oct 2014 15:06:26 -0700
> CC: obol@xxxxxxxxxxxxx
> To: timrodenkirk@xxxxxxxxx
>
>
> There has been a pattern of occasional October Gyrs on the south coast. I
> wonder if they simply fly down with the geese. Why not?
> .
> .
> Alan Contreras
> acontrer56@xxxxxxxxx
>
> Eugene, Oregon
>
>
>
>
> On Oct 20, 2014, at 3:01 PM, Tim Rodenkirk wrote:
>
> Jim Heaney observed a GYRFALCON at New River, Coos this past weekend (on
> Saturday). I remember when Dave Pitkin was still alive, that he observed a
> Gyrhanging with the ALEUTIAN CACKLING GEESE in that same area for a few falls
> and perhaps followed the flocks down from Alaska. I was with Terry Wahl on
> Sunday (the 19th) and he got a call from Rick McKenzie who has a large ranch
> near New Lake in the same area where the Gyr was seen. Rick said he had
> 20,000 Aleutians on his ranch, a pretty huge number for fall (perhaps the
> most he has had on his place this time of year?).
>
> Jim mentioned seeing the Gyr carrying a gull but also saw evidence of cackler
> kills along the beach there...
>
> Merry migration!
> Tim R
> Coos Bay
>
>
>
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