Date: 12/30/18 4:40 pm
From: Roger Freeman <freemanbecard...>
Subject: [obol] Re: Winter Barn Swallow in Central Oregon
At the risk of piling on about winter BASW ..... Barb Dolan/John Thomas had
2 BARN SWALLOWS on the Silverton CBC in 2016 (Dec 30). Not sure if those
made it to eBird or not.
Roger Freeman

On Sun, Dec 30, 2018 at 9:19 AM <clearwater...> wrote:

> In addition to the Barn Swallows recorded on the Antone CBC near Dayville
> (4 birds on Dec 21, 2004), one was found on the Madras CBC last year.
>
> Certainly there may be any number of factors, not directly linked to
> anthropogenic climate change, that could cause a Barn Swallow or other
> swallow species to wander north in winter. Dave and Lars mentioned a few
> such causes.
>
> But once a swallow ends up in central Oregon in winter, it needs to be
> finding food, or the chances of it staying alive and non-torpid long enough
> to be observed are scant.
>
> Availability of flying insects is linked to local temperatures. When there
> are more winter days with temperatures well above freezing, that has to be
> helpful to swallows that have wound up -- for whatever reason -- far north
> of their normal winter range.
>
> If a swallow manages to find a spot with thermal input (such as sewage
> treatment ponds), that might help also it to find enough food to survive
> through minor cold spells. The idea of "urban heat islands" that was often
> trotted out by climate-change skeptics a couple of decades ago (including
> here on OBOL) might have some relevance for winter swallows, even if it was
> a red herring when applied to the issue of mean global temperatures.
>
> But swallows still need to move between those "islands" with better food
> availability. It stands to reason that they can do this successfully, more
> frequently, as average winter temperatures tend to become milder.
>
> --
> Joel Geier
> Camp Adair area north of Corvallis
>
>

 
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