Date: 10/17/20 1:56 pm
From: David Nicosia <daven102468...>
Subject: Re: [nysbirds-l] Bonaparte's Gulls
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 <rcech...> 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: <bounce-125036389-3714678...> <
> <bounce-125036389-3714678...> On Behalf Of Willie D'Anna
> Sent: Wednesday, October 14, 2020 9:34 AM
> To: '& [NYSBIRDS]' <nysbirds-l...>
> 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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