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Thanks for taking the time to do this analytic and sharing.  What a remarkable tool e-bird is.


Ruth Stewart
E. Dorset, VT


________________________________
From: Vermont Birds <[log in to unmask]> on behalf of Ian Worley <[log in to unmask]>
Sent: Wednesday, October 3, 2018 11:07 PM
To: [log in to unmask]
Subject: [VTBIRD] Lake Champlain Great Egret abundance Aug/Sept. 2018. A few numbers

For all the birders viewing Great Egrets on Lake Champlain this August
and September, it was a bumper year.  Here are some comparisons with
previous years.

When looking at the numbers, keep in mind that the farther back in time
the fewer the number of birders.  The years since 2012, or so, are
reasonably comparable with this year.

The following table looks at the number of Lake Champlain basin reports
in eBird with more than 9 Great Egrets per checklist for August and
September.  There are four numbers for each year:
     (a) The number of checklists having more than 9 Great Egrets for
Aug/Sept  (for this year 44 in August and 114 in September)
     (b) The highest number of Great Egrets reported for Aug/Sept (for
this year 29 in August and 56 in September)
     (c) The number observations of with 25 or more Great Egrets for
Aug/Sept (for this year 3 in August and 7 in September)
     (d) The average water height above sea level for Aug+Sept.
Highlighted are three exceptionally low water years.

2018    44/114---29/56---3/7       [94.2]
2017      1/3---22/28--0/1              95.9
2016   10/41---39/123---2/7        [94.2]
2015      2/6---14/52---0/2             96.0
2014      0/6----8/24---0/0              95.2
2013      1/1---10/12---0/0             96.2
2012    20/6---30/21---2/0           [94.5]
2011      4/0---14/8---0/0               96.9
2010      2/5---16/17---0/0             95.3
2009      0/0
2008      0/0
2007      0/0
2006      0/0
2005      2/0---15/6---0/0
2004      2/0---17/7---0/0
2003      4/5---21/31---0/2

The three years with clearly the highest Great Egret counts and the most
submissions to eBird in August and September (2018, 2016, 2012) are also
the years with the lowest water levels (average = 94.3 feet above sea
level).  The average height for the other years is 96.0, approaching two
whole feet higher. The differences in Great Egret numbers comparing 2016
and 2018 with 2015 and 2017 is very striking.

  The lowest ever recorded level for the lake was in 1908 at 92.4 feet,
which must have been astounding.  The lowest level this year was on
October 1st at 93.96 feet above sea level .... only a foot and a half
above the all time record low.

Being waders, the egrets are obviously enjoying all the added feeding
grounds, while giving us the joy of their presence as well!

Best to all .....

Ian