Date: 8/2/17 12:40 pm
From: Karen Saxton <kcsaxton...>
Subject: [obol] Re: butterflies
walked out with my dogs and saw one flittering about my lawn. I'm between
Coquille and the coast!

On Mon, Jul 31, 2017 at 9:15 AM, Wayne Hoffman <whoffman...> wrote:

> It is my understanding that California Tortoiseshells and several
> relatives are in fact migratory, but the current movements are probably not
> migration. These swarms are presumably local production from the abundant
> Ceanothus in these areas of the Cascades. Later in fall survivors will be
> moving south into
> California (and elsewhere?) for winter, and in spring a much smaller
> migration of survivors will come back north. Just as with birds, during
> the migration periods, these butterflies will be seen scattered more widely
> across the state. Civen the numbers currently in the Cascades, I expect
> them to be common on the coast this year, where few if any breed, on the
> fall east wind days that bring us big dragonfly migrations.
>
> The occasional boom year like this are likely the result of the
> co-occurrence of several things - weather conditions that favor lush growth
> of Ceanothus foliage, a substantial initial population (good overwinter
> survival south of us) and perhaps most importantly, lower than usual
> populations of their parasitic wasps. I think we do not generally realize
> how important these wasps are in butterfly and moth population dynamics.
>
> Wayne
>
> On 7/30/2017 9:23:45 PM, Jim Anderson <jimnaturalist...> wrote:
> Howdy OBLrs
>
> The movement of the California Tortoiseshell butterflies is not (in my
> opinion) a "migration" as such, but an "outbreak." I believe it's linked to
> population dynamics of some kind, but not thoroughly understood. It
> happened in Bend about 30-years ago, and unless research is carried
> out annually within the tortoiseshell populations, it's probably difficult
> to really put your finger on this or that cause.
>
> Saying that, I also believe it's tied to nature's way of insuring survival
> of a species. When weather and food plants are in balance, the butterfly's
> larvae get what they need to develop the necessary chemicals
> to metamorphose into adults successfully and then lay uncountable millions
> of eggs; which in turn hatch and defoliate their food plants--which I
> have a hunch is even good for the plants in some way. ,
>
> In addition, while this is going on, the butterfly parasites also go into
> supercharge mode and somehow have the ability to lay eggs on the jillions
> of caterpillars. During the similar event some 30-years ago west of Bend,
> we could actually hear the larvae munching on ceanothus leaves as they
> defoliated all the bushes.
>
> What was also unbelievable were the millions of chrysalis hanging on the
> bare branches of the ceanothus. If you got close to them and stomped
> your foot they would all begin to shake and clang like tiny bells. What a
> show!
>
> We took 20 chrysalides home with us to photograph emerging butterflies.
> However, if my memory serves me correctly, of the 20 chrysalides, 8 or 9
> developed butterflies, but bright green adult wasps emerged from all
> the others.
>
> Another facet of an outbreak provides the species enough adults insects in
> summer to go far from the "breeding territory" and pioneer new habitat,
> further increasing the chances of the species to succeed even further.
>
> During the outbreak some 30-years back I can recall the CA highway
> department installing special truck washing equipment near Redding that
> was used to wash smashed butterflies out of the radiators to keep
> the trucks from overheating.
>
> But now as I ponder on this magnificent phenomenon, on second thought,
> perhaps the butterflies are just attempting to beat the hundreds
> of thousands of humans predicted to be in Madras for the eclipse of the
> Sun...
>
> Jim Anderson
> Sisters
> ------------------------------------------------------------
> -----------------------------------------------------------
>
> On Sun, Jul 30, 2017 at 7:56 PM, Nicholas Mrvelj <nickmrvelj...>
> wrote:
>
>> I spent some time in the greater Sunriver area myself this weekend. I
>> can confirm seeing extraordinary numbers of California Tortoiseshells.
>> During a hike around the Todd Lake area, we counted about 5-8 per second on
>> average. All were heading in the same direction, often seeming to be at
>> the mercy of the wind. Many perished on the roadways.
>>
>> Just south of Sunriver proper I saw 4-5 Common Nighthawks in flight each
>> evening.
>>
>> Good birding,
>> -Nick Mrvelj
>>
>> On Sun, Jul 30, 2017 at 6:09 PM Larry McQueen <larmcqueen...> wrote:
>>
>>> Ok, this is not about birds, but something to behold in the Cascades
>>> right now. *Nymphalis* *californica*, the California Tortoiseshell, is
>>> now doing a mass movement. I have been on a family trip this past week,
>>> staying at Sunriver. We encountered thousands of these butterflies, first
>>> near the top of the McKenzie Pass and again on the Cascades Lakes Highway,
>>> south of the 3 Sisters. We found them in great numbers everywhere, all
>>> seemingly flying in the same direction, maybe down slope. This had to be a
>>> movement of the entire population (at least local), not millions, but
>>> billions of this species. Pyle describes this phenomenon in “The
>>> Butterflies of Cascadia”, as a release caused by a build-up of numbers over
>>> years, and then followed by scarcity for years. I don’t know how well
>>> studied this migration is, or where the butterflies end up.
>>>
>>> This was not a birding trip, but I always love watching the Pygmy
>>> Nuthatches. Crossbills were common around Sunriver. There was a single
>>> Nighthawk on the entire trip, where there ought to have been many.
>>>
>>> Larry
>>>
>>>
>
>
> --
> Jim
> Please note my new email address: <jimnaturalist...>
>
>

 
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