Mice and butterflies

[Paul Cherubini]

Stan Gorodenski wrote:

> My question is:  Are these observations made on large and small roosts
> that are separated from one another to such a degree that the same bird
> population would not likely feed on more than one roost? The cited part
> of Monarch watch does not make it clear if they are or not.

Stan, the roosts are about 15 - 50 miles apart so the same bird
population would not likely feed on more than one roost.

> If roosts are separated from one another to such a degree that the same
> bird population would not likely feed on more than one roost, then these
> observations could be viewed as a valid argument against thinning.  

Maybe, maybe not. Thinned and dense forests offer both survival 
advantages and disadvantages. Insects have a hierarchal 
behavioral system and given a choice between dense and thin 
forests, monarchs typically choose forests of intermediate density.  
In other words, the butterflies do not usually choose really dense 
forests even though such forests should provide better protection 
against overnight freezing temperatures and predators.  

Here is a real life example of how the hierarchal behavioral 
system functions:  During the autumn when the monarchs
are en route to Mexico they sometimes encounter a large field of 
nectar plants.  As evening approaches, the butterflies normally seek 
shelter in nearby groves of trees.  But sometimes many of the 
butterflies stay out in the open fields for the night even though this 
causes them to be more exposed to storms that might come up 
and to ground dwelling predators.  Here are a couple photos
I took in northeastern Kansas in mid-September this year
of monarchs that stayed out in the open fields at night:

Sunset photo:
http://i5.photobucket.com/albums/y189/mastertech/evena.jpg 

Sunrise photo:
http://i5.photobucket.com/albums/y189/mastertech/evenb.jpg

Paul Cherubini
El Dorado, Calif.

 
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