I quick check of ebird in Januaries indeed shows many more BOGUs wintering
into Lower Michigan, Lake Huron and vicinity in milder winters. The colder
winters they do not stay up there at all. There are all south. That could
explain some of the lower numbers recents years.
On Thursday, October 15, 2020, 03:12:51 PM EDT, David Nicosia
<daven102...@gmail.com> wrote:
To clarify, I wonder if they are sticking around the upper Great Lakes more in
the winter since the ice has been much less recently up there. That would
affect our numbers in NY
On Thu, Oct 15, 2020 at 3:10 PM David Nicosia <daven102...@gmail.com> wrote:
I wonder if BOGUs are wintering farther north due to recent milder winters?
On Wed, Oct 14, 2020 at 7:12 PM <rc...@nyc.rr.com> wrote:
I’m most pleased at the developing discussion on small gulls and other bird
population fluctuations (mainly declines ☹).
One quick thought – on choice of statistics (which several raised): when
dealing with crowd sourced data (yeah, that includes CBC, well-tended though it
is), it’s always apples and oranges to some degree. If the effect is strong
enough, it will carry through across a number of approaches (as seems to be the
case here, not insignificantly!).
The best evidence for this discussion would be either (1) a Zeusian, universal,
longitudinal population census worldwide, or (if Zeus isn’t around), a really
accurate sampling census, based on sightings by a giant number of random field
groups, to determine likelihood. Neither such precise dataset is readily at
hand. So we have to squint at what we have, augmented by rich, expertized field
observations, which fortunately are in at least adequate supply.
As I said at the start of my post, I didn’t have much time this morning and
grabbed what I could find quickly. Very pleased to see additional info others
have posted (e.g., from CBCs where the data parameters are known personally,
and thus trustable, as w/Dick’s), or longitudinal counts from Niagara (a world
concentration point, with systematic censuses), or even careful notes from
Gravesend Bay (though movements here can be ephemeral – but hey, it’s still
information, and I like the place!).
Hope folks keep grappling with how to best sort all of this stuff out. Citizen
science at its best should actively embrace these issues – even though I
actually kind of hate the term “citizen science” as it’s sort of condescending
and ambiguous, but probably that’s just me.
Best to the list,
Rick
From: Richard Veit <rrvei...@gmail.com>
Sent: Wednesday, October 14, 2020 5:07 PM
To: rc...@nyc.rr.com
Cc: Willie D'Anna <dannapot...@roadrunner.com>; & [NYSBIRDS]
<nysbird...@list.cornell.edu>; Emily Peyton <epey...@nyc.rr.com>
Subject: Re: [nysbirds-l] Bonaparte's Gulls
here is a plot of bonaparte's gulls on massachusetts cbcs 1979-2018. All the
major coastal aggregation spots i know of (Campobello Is, maine, Newburyport,
MA, Provincetown and Nantucket, MA, Jones Inlet, NY, Staten Island, NY) have
dropped from thousands to tens of thousands of birds to handfuls. We missed it
on the Staten Island CBC this year and saw hardly any at Nantucket. I used
just total birds rather than birds per party hour in the graph because the
birds are all in one place and are either seen or not seen, regardless of how
many people or groups on the cbc (more or less)........
On Wed, Oct 14, 2020 at 10:08 AM <rc...@nyc.rr.com> wrote:
Willie, that is very interesting. I had a quick look at CBC results - for NJ
rather than NY, so as to avoid including any "Niagara Falls concentration
effect," and the recent trend does appear to be a decline (with a few
‘exception’ years mixed in). In this graph "120" is 2019, and numbers extend
back to turn of century. I know "birds per party hour" is a rough measure (I
was a CBC compiler for > 25 years, potential party-hour reporting vagaries
acknowledged), but the numbers do suggest either a decline in population or
a shift in wintering behavior.
Sorry, this was a quick take, now back to the ol’ day job…
Rick
-----Original Message-----
From: bounce-125036389-3714...@list.cornell.edu
<bounce-125036389-3714...@list.cornell.edu> On Behalf Of Willie D'Anna
Sent: Wednesday, October 14, 2020 9:34 AM
To: '& [NYSBIRDS]' <nysbird...@list.cornell.edu>
Subject: RE:[nysbirds-l] Bonaparte's Gulls
I have enjoyed the recent posts about Bonaparte's Gulls. Some of the
highest concentrations of Bonaparte's Gulls in the world occur along the
Niagara River, with estimates of 50,000 to 100,000 on some days. It is a
spectacle to witness this blizzard of gulls on the Niagara but it seems that
numbers have declined, particularly in the last ten to 20 years. It is
unfortunate that the only evidence that I can offer for this are my own
subjective observations. Counts of gulls on the Niagara have been done
sporadically and it is only in recent years that organized counts have been
conducted on a yearly basis, with three counts per season (late
fall/winter), by the Canadian Wildlife Service.
Numbers of Bonies, as they are affectionately called here, month to month
along the Niagara, are highly interesting. Twenty to fifty years ago,
numbers would begin to build on the Niagara in late July with most of these
birds consisting of one-year-olds. By mid August, there would be a
significant influx of adults, only just finished with their breeding
activities in Canada. Hundreds of individuals could be seen at the source of
the river (Buffalo/Fort Erie) and below the falls or in the
Lewiston/Queenston area. At times there would be well over a thousand,
particularly when there was a good southwesterly blow that would push more
of them to the eastern end of Lake Erie. These numbers more or less
continued, perhaps with a slight decrease, into October, although whenever
there was a southwesterly blow numbers would spike considerably. The big
numbers would arrive in late October/early November and reach their highest
levels later in November. Numbers would then slowly decrease into January
when at some point, ice formation would cause most of them to depart. During
some milder winters, several hundred would remain through the season. In a
typical winter, only a handful would remain. Starting in February, numbers
would slowly start to increase and by late March they would be abundant
again. Numbers would dwindle during April and they would be completely gone
by about the third week of May, save for a variable number of non-breeding
birds. June and July have been the nadir of the Bonies occurrence on the
Niagara, although there were usually some immatures around, particularly on
Lake Erie.
To me, the most dramatic change with the Bonies here has been the numbers
during spring. Whereas their spring numbers used to be very comparable to
those during late fall, there have been some springs recently where peak
numbers were barely into the hundreds, as opposed to the multi-thousands we
were accustomed to. August through October numbers are also much lower these
days, with counts of over 100 usually only occurring now when there is a bog
blow off of Lake Erie. Peak numbers now seem to occur later than in the
past, in December rather than November.
One change that birders have enjoyed is that numbers of wintering birds are
seen more consistently now, likely due to our warming climate.
The Bonies are one reason that the Niagara River has been designated an
important bird area (IBA). It is obvious that the Niagara River has played
an important part in the life cycle of a significant proportion of the
species numbers since the 1960s. Whether or not that will continue remains
to be seen.
Good birding!
Willie
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Professor, Biology
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