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--Boundary_(ID_KdhPhOpTTU+M0UHr6w+ReQ)
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As many of you know, Red-breasted Nuthatches are an irruptive migrant species, as are a number of the finch species that breed in the Boreal Forest. That is, from time to time, large numbers move south from their breeding areas in the Boreal Forest. Currently it is thought that large numbers move south in response to a lack of food available for the upcoming winter.
For Nova Scotia, this translates into large numbers of Red-breasted Nuthatches being seen every 2-3 years in the fall at places like Brier Island. Two years ago was a peak year with hundreds of nuthatches moving southwest through the island. Last year was a low year with very few migrant birds observed.
What's a bit confusing is that the observations on NatureNS often do not reflect what happens on Brier Island in the coming fall. For example, given the reports that Bob and others have sent in today I would expect to see very few Red-breasted Nuthatches moving this fall. However, given where we should be in the irruptive cycle I expect this to be a better movement year than last year, though perhaps not a peak year.
One possible explanation is that much of Nova Scotia's Red-breasted Nuthatch population may be augmented by fall irruptions from New Brunswick and points north. Many of these birds may stick around through the following summer. If that's the case then one might expect to see more birds in the woods and at feeders in the year following an eruption and less around in a year following a low point in the cycle. 2010 was a high year and last year a low one. This seems to support what I expect and what Bob and others are seeing.
I had a look at the Christmas Bird Count data and it is not a bad match for the fall migration observations I have but, it's not perfect (CBC peaks for the last ten years were in 2005, 2008 and 2010 while lows were in 2003, 2007 and 2009. The missing years reflect intermediate years where numbers were on their way down or up).
Looking back at the Red-breasted Nuthatch reports that are recorded in NS Birds over this same time period showed me that there aren't a lot reported in any year unfortunately so there is no clear indication of whether there were more around than usual in a given season.
So, there is some evidence suggesting that my possible explanation might be correct but not a large amount. It will have to remain simply a possible explanation.
All the best,
Lance
Lance Laviolette
Glen Robertson, Ontario
lance.laviolette@lmco.com
From: naturens-owner@chebucto.ns.ca [mailto:naturens-owner@chebucto.ns.ca] On Behalf Of Bob McDonald
Sent: Thursday, June 28, 2012 1:20 PM
To: naturens@chebucto.ns.ca
Subject: EXTERNAL: Re: [NatureNS] Nuthatches
My feeling is the same - none at our feeders (we had a regular pair of RBNU's until last year) and hearing or seeing few or none in the field. I believe this topic has been previously discussed but I cannot recall any good reasons for the decline(s) put forward.
Bob McDonald
Halifax
--Boundary_(ID_KdhPhOpTTU+M0UHr6w+ReQ)
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s=3DMsoNormal><span style=3D'font-size:11.0pt;font-family:"Calibri","=
sans-serif";color:#1F497D'>As many of you know, Red-breasted Nuthatch=
es are an irruptive migrant species, as are a number of the finch spe=
cies that breed in the Boreal Forest. That is, from time to time, lar=
ge numbers move south from their breeding areas in the Boreal Forest.=
Currently it is thought that large numbers move south in respo=
nse to a lack of food available for the upcoming winter.<o:p></o:p></=
span></p><p class=3DMsoNormal><span style=3D'font-size:11.0pt;font-fa=
mily:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></=
p><p class=3DMsoNormal><span style=3D'font-size:11.0pt;font-family:"C=
alibri","sans-serif";color:#1F497D'>For Nova Scotia, this translates =
into large numbers of Red-breasted Nuthatches being seen every 2-3 ye=
ars in the fall at places like Brier Island. Two years ago was a peak=
year