Actually just found a paper relating old Black Woodpecker (largest woodpecker in Europe) holes to wild honey colonies.

"A cavity for honey bees needs a volume of at least 20 l in order to allow them to hoard enough honey to overwinter (Seeley, 1985). The black woodpecker (D. martius L.) is the largest woodpecker in the Palearctic and excavates spacious nest cavities (Johnsson, Nilsson & Tjernberg, 1993; Blume, 1996), making it a key candidate for creating nest sites that are suitable for honey bee colonies in managed forests. In the forest clusters of the Biosphere Reserve Swabian Alb, there is a long record of trees worked by black woodpeckers (Sikora, Schnitt & Kinser, 2016). Because of the high ecological value of microhabitat structures in managed beech forests, such trees get permanently marked and are protected as a measure of biodiversity promotion (Bütler et al., 2013). In September 2017, we inspected 98 trees from a list of 282 trees in a forest area of 180 km2 that are known to contain woodpecker cavities older than 10 years (Sikora, Schnitt & Kinser, 2016)."

They found that about 7% of the 98 holes were occupied.

https://peerj.com/articles/4602/

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html