[NatureNS] high eagle numbers -unintended consequences

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From: Donna Crossland <dcrossland@eastlink.ca>
Date: Sun, 5 Apr 2020 10:16:54 -0300
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&amp;nbsp;&amp;nbsp;&amp;nbsp; The common Gull became t
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I can't resist supporting Burkard's statement regarding the 
intended/unintended consequences of humans on wild populations.

Food-supplemented eagle populations created from industrial poultry 
operations in Kings County are having a far-reaching negative effect on 
other species in other counties, and possibly other provinces.  
Hopefully we are starting to recognize this and will work together to 
curb the trend, starting by no longer feeding eagles.  (It's a mystery 
how the tossing out of poultry, dead of questionable causes, is not 
considered a biofood security issue...(?))

Many who spend time in the wilder places of NS, and those who live near 
lakes, know of the detrimental effects of increasing eagle numbers, but 
we have only anecdotal evidence to support concerns.  Hopefully we won't 
actually need a formal study to realize that feeding and augmenting 
eagle populations is a bad idea, now that they have recovered from DDT.  
Holding special eagle events with ~ 40 eagles rather than 400 eagles, 
should still provide an impressive show, while being mindful of the 
needs and struggles of other bird species such as loons and osprey. 
'Balance' should be the goal.  But I am afraid that no one seems to be 
in charge of setting this goal, or looking at critical thresholds.  One 
department says the issue of feeding eagles falls under the auspices of 
the other.  Such high numbers of eagles in a small area should ring 
alarm bells by anyone's standards.  This as an unnaturally high 
population that can and does have unintended consequences.

A few years ago, I had opportunity to chat with Dr Malcolm Hunter, well 
known wildlife biologist, about our unnaturally high eagle populations.  
He fully agreed that inflated eagle numbers are problematic, and stated 
that there are similar consequences from increasing eagle populations in 
the US, making particular reference to eagle impacts on nesting heron 
colonies.  A quick internet search reveals lots of concerns stated over 
declines of heron colonies.  As well, some folks on PEI have noted 
rising eagle numbers (likely Kings Co eagles?) and predation on nesting 
osprey.

Numerous nature-loving people in Queens-Annapolis Counties have 
recounted tormented stories of watching nesting eagles relentlessly 
harass and kill loon chicks.   A loon chick, flightless until autumn, 
cannot change lakes and spends the whole season trying to avoid being 
eaten by eagles.  The large numbers of eagles in the Annapolis Valley 
disperse to nest on numerous Nova Scotia lakes where food sources are 
much more limited than 'down on the chicken farm'.   The common loon has 
a load of stressors placed on it already, with acidic lakes, altered 
fish populations, high methyl mercury levels in many lakes, and remote 
lakes on which they have nested on for centuries now lined with 
cottages- all add up to placing our loon populations in jeopardy.

Over the past week or so, I have been searching for a suitable location 
to place an artificial, floating  loon nest platform on the Annapolis 
River.  Prior to the shut down of the turbines the high fluctuations in 
water levels made it impossible for loons to nest, and the floating 
platform offered some potential help to offset this human-caused 
impact.  Banks are undergoing a remarkable stabilization since the 
turbines have ceased operations, but again this year, I struggle to find 
a suitable location.  One of the best sites closest to my house had a 
report of 5 eagles sitting in the tree above a little cove where I 
thought the loons might nest, and the same observer saw one of the 
eagles flying with nesting material to a site behind the cove. It's 
unlikely this site will work for loons, despite the Annapolis River 
offering ideal habitat with a bountiful fish population.

It is delightful to hear the call of the loon from this river at night, 
so I'll give it a try but chances of success are likely slim.

What's the solution?  Rendering plants for our chicken carcasses, fewer 
eagles (this will take a while to take effect, since they are 
long-lived), and striving for better balance.

Regarding historical populations of gulls:

John G. T. Anderson 
<https://bioone.org/search?author=John_G._T._Anderson>,Katherine R. 
Shlepr <https://bioone.org/search?author=Katherine_R._Shlepr>,Alexander 
L. Bond <https://bioone.org/search?author=Alexander_L._Bond>,Robert A. 
Ronconi   2016.A Historical Perspective on Trends in Some Gulls in 
Eastern North America, with Reference to Other Regions 
<https://bioone.org/search?author=Robert_A._Ronconi>

Donna Crossland

Tupperville, NS


On 2020-04-05 12:27 a.m., Burkhard Plache wrote:
> To your claim that gulls increased in numbers:
> My understanding is that they took advantage of open landfills
> and also discard of fishing fleets.  At least that is the common
> understanding of the situation in Europe.
> With the closure of open landfills, gull numbers declined.
>
> My remark should not distract from the fact that human
> interventions (intentional or unintentional) tend to have
> unexpected and/or unintended consequences.
>
> Burkhard
>
> --------------
> Re: David Webster
>
> [...] This reminds my of the Sea Gull cycle.
>
>      The common Gull became threatened in the early 1900's due to
> harvesting of eggs for food so egg gathering was  forbidden. They
> responded gradually and eventually became so abundant that they were
> threatening Terns.
>
>      A sensible solution would have been to allow Sea Gull egg
> harvesting but instead people were hired (or rounded up) to make
> distracting noises whenever a male gull was about to get lucky in
> areas where Terns also nested.
>
>      So one by one, and I would not care to predict what will take the
> hit, but logically waterfowl which frequent fresh water/coastal water
> will be vulnerable. Perhaps even Sea gulls or Terns.


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    <p>I can't resist supporting Burkard's statement regarding the
      intended/unintended consequences of humans on wild populations.<br>
    </p>
    <p>Food-supplemented eagle populations created from industrial
      poultry operations in Kings County are having a far-reaching
      negative effect on other species in other counties, and possibly