Somehow, the bulk of text composed for my post about cuckoo ID did not appear 
in what got send out.


Basically what I meant to send out with the four photos was that ID of cuckoos 
at this time of year can be compounded by the presence of young "black-billed" 
yellow-billed cuckoos.


I also wanted to say I am NOT questioning here the ID of black-billed cuckoos 
recently reported by both John Drummond and Steve Mlodinow.  Their 
reports/photos are solid.


Fall Webworms (Hyphantria cunea) are present at Tempel's Grove and are known to 
be prominent in the late summer diet of cuckoos.  They live within webs 
enlarged to include the leaves on which they feed.  At this time of year the 
webs can be multiple feet across.  They leave the webs, however, after feeding 
for a period of several weeks to pupate and overwinter in the leaf litter on 
the ground.  This is when they are most vulnerable to bird predation.  The true 
tent caterpillars often mentioned in the diet of cuckoos are in the genus 
Malacosoma (we have five species in CO) are late spring-early summer 
caterpillars which build smaller, whiter webs they use as home bases at night, 
venturing out to feed "unprotected" during the day.


Grasshoppers, such as the two-striped shown on the other email, were being fed 
to the young dependent cuckoo by an adult yellow-billed.  They are also 
mentioned in the BNA account of cuckoos as being prominent in cuckoo diets.


Dave Leatherman

Fort Collins

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