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Hi Everyone,
The Bird Studies Canada (BSC) information that was being discussed a week o=
r so ago about Common Loon populations seemed to me to be focused on easter=
n Canada and the Maritimes as a whole rather than specifically Nova Scotia.=
Several BSC scientists have been looking at the Canadian Lake Loon Survey =
(CLLS) data from across Canada to determine factors affecting Common Loon r=
eproductive success. They have published a number of papers showing that Me=
rcury concentrations and the acidity of lakes negatively affect this. Summa=
ries of a number of these papers were in the BSC publication that Ally and =
Kathy sent links for.
One of those scientists, Dr. Doug Tozier, was kind enough to provide me wit=
h some more specific information about Nova Scotia's loon population. Dr. T=
ozier analyzed Nova Scotia's CLLS data and came up with the following point=
s:
1. While there was a slight increase in the trend of reproductive succ=
ess in the province between 1991 and 2000, it was likely not statistically =
significant.
2. The longer dataset, from 1991 to 2012 shows a decreasing reproducti=
ve success trend but it is also likely not statistically significant.
Dr. Tozer also provided me with a graph of the reproductive success over th=
e longer period (which I'll be happy to send to anyone who is interested). =
It shows that from 2005 to 2012, the reproductive success has been below th=
e 0.48 mark that BSC indicated was needed to maintain the population. Howev=
er, reproductive success has been increasing over that same time period and=
this year reproductive success is quite a bit above the 0.48 mark. We'll h=
ave to wait a few years to determine whether this level will be maintained =
or if it is simply the high mark of an approximate ten year cycle that Dr. =
Tozier has noted in Common Loon reproductive success.
I also took a look at Environment Canada's Breeding Bird Survey analysis fo=
r Nova Scotia and PEI (they are lumped). It shows a rising trend from 1970 =
to the present (Annual index is 1.7). They categorize this with a high "Ove=
rall Reliability" of a positive population change.
The BSC reproductive success index is defined as the number of six-week-old=
chicks per pair per year. This is used as an index of young loons raised t=
o independence. The Environment Canada index measures the estimated average=
abundance on BBS routes run in a given year by an average observer.
All the best,
Lance
Lance Laviolette
Glen Robertson, Ontario
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<div>Hi Everyone,</div>
<div> </div>
<div>The Bird Studies Canada (BSC) information that was being discussed a w=
eek or so ago about Common Loon populations seemed to me to be focused on e=
astern Canada and the Maritimes as a whole rather than specifically Nova Sc=
otia. Several BSC scientists have
been looking at the Canadian Lake Loon Survey (CLLS) data from across Canad=
a to determine factors affecting Common Loon reproductive success. They hav=
e published a number of papers showing that Mercury concentrations and the =
acidity of lakes negatively affect
this. Summaries of a number of these papers were in the BSC publication tha=
t Ally and Kathy sent links for.</div>
<div> </div>
<div>One of those scientists, Dr. Doug Tozier, was kind enough to provide m=
e with some more specific information about Nova Scotia's loon population. =
Dr. Tozier analyzed Nova Scotia's CLLS data and came up with the following =
points:</div>
<ol style=3D"margin-top: 0pt; margin-bottom: 0pt; margin-left: 36pt; ">
<li>While there was a slight increase in the trend of reproductive success =
in the province between 1991 and 2000, it was likely not statistically sign=
ificant.</li><li>The longer dataset, from 1991 to 2012 shows a decreasing r=
eproductive success trend but it is also likely not statistically significa=
nt.</li></ol>
<div> </div>
<div>Dr. Tozer also provided me with a graph of the reproductive success ov=
er the longer period (which I’ll be happy to send to anyone who is in=
terested). It shows that from 2005 to 2012, the reproductive success has be=
en below the 0.48 mark that BSC indicated
was needed to maintain the population. However, reproductive success has be=
en increasing over that same time period and this year reproductive success=
is quite a bit above the 0.48 mark. We’ll have to wait a few years t=
o determine whether this level will be
maintained or if it is simply the high mark of an approximate ten year cycl=
e that Dr. Tozier has noted in Common Loon reproductive success.</div>
<div> </div>
<div>I also took a look at Environment Canada’s Breeding Bird Survey =
analysis for Nova Scotia and PEI (they are lumped). It shows a rising trend=
from 1970 to the present (Annual index is 1.7). They categorize this with =
a high “Overall Reliability” of a positive
population change.</div>
<div> </div>
<div><font face=3D"Calibri, sans-serif">The BSC reproductive success index =
is defined as the number of six-week-old chicks per pair per year. This is =
used as an index of young loons raised to independence. The Environment Can=
ada index measures the estimated average
abundance on BBS routes run in a given year by an average observer.</font><=
/div>
<div> </div>
<div><font face=3D"Calibri, sans-serif">All the best,</font></div>
<div><font face=3D"Calibri, sans-serif"> </font></div>
<div><font face=3D"Calibri, sans-serif">Lance</font></div>
<div><font face=3D"Calibri, sans-serif"> </font></div>
<div><font face=3D"Batang, serif" size=3D"4"><b>Lance Laviolette</b></font>=
</div>
<div><font face=3D"Batang, serif" size=3D"2">Glen Robertson, Ontario</font>=
</div>
<div><font face=3D"Calibri, sans-serif"> </font></div>
<div><font face=3D"Calibri, sans-serif"> </font></div>
<div> </div>
<div> </div>
<div> </div>
<div> </div>
<div> </div>
</font>
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</html>
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Index of Subjects