Hi Nancy,

The "scientific" consensus is that both species of cuckoos are  
excellent dispersers and seem to use the post-breeding season as an  
opportunity to locate high quality breeding sites (i.e., caterpillar  
outbreaks) for the following year.  Their numbers seem to rise and  
fall with caterpillar populations without any lag time.  The  
suggestion from this particular analysis was that cuckoos responded to  
changes in caterpillar populations over scales of hundreds of  

If anyone wants to check out the research, I think you can access it here:


Quoting "Nancy A. Brown" <[log in to unmask]>:

> 2007 was the year of the caterpillars!!! About 3 bad years as the
> invasion proceeded north.  Now that the caterpillar has reached its
> northern limit for winter survival is it possible we are now seeing the
> fallout of the cuckoo's that were following the bug invasion? Will the
> Cuckoo return in numbers next year if they did not find the big
> caterpillar numbers this year and spread out looking for the next
> outbreak of the worms?  Only time will tell.   As for my earlier
> inquiry about the Canada Goose re-nesting after the early spring
> flooding, no indication here in Danby. All the young geese were the
> same size at the same time so no late hatchlings noted.   Nancy
> --------------------------------------------------
> From: "Ian A. Worley" <[log in to unmask]>
> Sent: Friday, July 15, 2011 3:25 PM
> To: <[log in to unmask]>
> Subject: [VTBIRD] Good Yellow-billed Cuckoo year ...
>> There has been a Yellow-billed Cuckoo calling for most of the day   
>> here near the house nearly every day since July 2nd (and once   
>> earlier on June 6th).  It moves around rather continuously.  Every   
>> few days, including today, there is also the call of a Black-billed  
>>  Cuckoo.
>> With the abundance of observations statewide, I thought I'd compare  
>>  the last few years.
>> Using the data in eBird, the last year with as many Yellow-billed   
>> Cuckoos was 2007.  In the list below, the first number following   
>> each year is the number of Vermont locations reporting a   
>> Yellow-billed Cuckoo for all of that year (for 2011 is the number   
>> so far this year). The second number is based on the eBird   
>> statistic "total" which is the number of birds reported per week,   
>> whether from the same location or not .... I created the second   
>> number by totaling the number of birds reported each year through   
>> July 15th so it would directly compare with this year.
>> 2011   18    22
>> 2010     7      4
>> 2009     4      3
>> 2008     8      8
>> 2007    15   18
>> So 2007 and 2011 seem to be banner years for Yellow-billed Cuckoos   
>> in the last five years, with 2009 being the year with the fewest   
>> birds and least widespread sightings.
>> Ian