This comes from the official Canada website that Bonaparte's Gull has "large
increases" and they come to this conclusion with CBC data! Based on your
accounts they are completely wrong, but I thought it was a credible site since
it was from the Canadian Government. My bad.
see
https://wildlife-species.canada.ca/bird-status/oiseau-bird-eng.aspx?sY=2019&sL=e&sM=c&sB=BOGU
On Sunday, October 18, 2020, 10:04:07 AM EDT, Richard Veit
<[email protected]> wrote:
I dont think this is correct. the "increase" in Maine is up from a few
hundred birds in the entire state to a couple of thousand (on all counts), and
that was only in one year. Similarly, most of the "increase" in North Carolina
is due to a single data point. Counts of many tens of thousands have been
recorded on the Great Lakes, on the USA/Canadian border in the Campobello
Island, in Massachusetts and in North Carolina, mostly in the 1970s and 1980s,
but with a few counts of this magnitude into the 1990s. There have been no
records of any concentrations othis magnitude (tens of thousands) anywhere as
far as we can tell, and I do not see how relatively small increases in Maine
and North Carolina can account for these birds. i dont know what the basis of
a "big increase" in Canada is, but that seems to conflict with the opinions of
everyone in the USA who was followed these Bonapartes flocks for 20-40 years.
On Sat, Oct 17, 2020 at 4:56 PM David Nicosia <[email protected]> wrote:
In Canada, they list Bonaparte's Gulls as having a "large increase".
In Shai's graph of CBC you can see a definite decline of wintering BOGUs from
the 70s, 80s and 90s to the 2010s in the RI and LI areas.
https://www.flickr.com/photos/96951581@N02/50482248298/
I ran sea surface temperature departures from normal for the last 10 years and
you can see that the area centered around Nova Scotia/Maine has warmed 1-2C in
this time period. To see if maybe the BOGUs are wintering farther north on the
east coast, I looked at CBC data from Maine and indeed there is a significant
increase in BOGUs for their CBCs which matches the declines that Shai showed. I
couldn't get the Nova Scotia data to work for some reason. I also looked
farther south and in NC, for instance, there also has been significant
increases in CBC data for BOGUs too. So the decline at least around LI and
maybe even around Niagara Fall's probably is related to the warming climate.
Birds are shifting their wintering ranges farther north. In the Great Lakes
area, if the waters remain open farther north some birds just don't make it
down. The same is for the northeast coast. In NC, I don't have much of an
answer other than the sea surface temperatures haven't warmed as much there.
On Wed, Oct 14, 2020 at 10:14 AM <[email protected]> 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
P.S. Hope the attached graph comes through - if now (and you're interested) I
can send on the side.
-----Original Message-----
From: [email protected]
<[email protected]> On Behalf Of Willie D'Anna
Sent: Wednesday, October 14, 2020 9:34 AM
To: '& [NYSBIRDS]' <[email protected]>
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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