Date: 6/26/26 4:54 am From: Nick Bolgiano <nickbolgiano...> Subject: Third Breeding Bird Atlas update: continued low numbers of cuckoos
After year one of this breeding bird atlas, I sent out an email on this topic, but now we are into the third season and not much has changed. Both Yellow-billed Cuckoo and Black-billed Cuckoo continue to be reported in low numbers.
During the second Breeding Bird Atlas, in 2004-2009, Yellow-billed Cuckoo was reported in 66% of blocks while Black-billed Cuckoo was reported in 34% of blocks. In my two Breeding Bird Surveys, regular cycles have occurred, with periodic higher numbers coinciding with caterpillar outbreaks, such as spongy (formerly gypsy) moths and webworms. But, no cuckoos in my two routes during the three years of this atlas, which is unprecedented. During the atlas, I have recorded 9 Yellow-billeds and 1 Black-billeds, where I would normally have expected to record many more. (Around here, Yellow-billeds usually outnumber Black-billeds by roughly 10:1.)
Not having many cuckoos means that PA has not experienced widespread caterpillar outbreaks, which is probably a good thing for the trees. However, the low cuckoo numbers are very atypical of what we usually find.
