[NatureNS] Re:Lack of House Sparrows

Date: Tue, 07 Dec 2010 14:41:44 -0400
From: iamclar@Dal.Ca
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There is no doubt that the House Sparrow has declined in recent  
decades in both Europe and N. America. Yet both Don and Lance could be  
correct. Raw trends in BBS are given as annual % change plus  
reliability of the estimate. For NS, although the trend has been about  
7% decline per year, this has a p value of onlky about 9% of being  
correct, which is not quite the level of probability that is often  
though to be "significant."

The Christmas count data are again certainly convincing on a N. Am. or  
province wide scale, but again the details rather than the trends are  
of interest. In 2009-10, e.g., the Halifax no. per party hour was  
actually up by about 1/3 from the previous year. I, too, sense with  
Don that the HOSP is doing better in recent years in Metro. I also  
note that the addition of counts in recent years has added more  
non-HOSP habitat to the NS CBC totals. Maybe there is a bit of urban  
recovery going on. Also in recent years I have been struck by the  
numbers of House Sparrows living in and around cattle barns. Are they  
often included in CBCs?

As I have noted in my seasonal writeups in "NS Birds" it would be good  
if we had some sort of systematic survey of House Sparrow flocks in  
metro Halifax (and elsewhere?).

Cheers, Ian McLaren

Quoting "Laviolette, Lance (EXP)" <lance.laviolette@lmco.com>:

> Hi Don,
>
> Don MacNeill wrote:
> "We have about 20 visiting our feeders daily in Halifax.  The  
> numbers have been coming back over the last few years."
>  
> The local population around your area may have risen over the last  
> few years but this is not the case province wide. Here are the  
> trends for Nova Scotia from both the Christmas bird counts and the  
> breeding bird surveys.
>
> The trend on Nova Scotia Christmas counts of the last 50 years:
> In the early 1960s House Sparrows were being reported at a rate  
> between 25-28 birds per party hour. During the 1970s and 1980s this  
> number had dropped by about 60% to between 5-10 birds per party  
> hour. In the last ten years the number has never been higher than 2  
> birds per party hour with last year's count producing about 1.2  
> birds per party hour. This represents about a 95% drop in the House  
> Sparrow population in Nova Scotia over the last 50 years.
>
> The breeding bird survey trends of the last 40 years shows a similar  
> decline. The mean annual percent change over this period in the  
> House Sparrow population is almost 5%. In other words, every year  
> for almost 40 years the population has decreased an average of 5%  
> from the previous year. What that means is that this data indicates  
> that the population is only about 13% of what it was 40 years ago.
>
> All the best,
>
> Lance
>
>



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