Galls/Nests In Poplar

Are these galls? Nests? From the ground, I cannot see anything living near them. They are located about 30-40 feet up. The bark from that height to the ground looks normal. At first glance the tree, which is in a half-acre stand, looks dead. However there are buds on it, which are very slow in opening. The surrounding trees are leafing out well.
We are in the Ottawa Valley area.

 

High position seems atypical but otherwise it looks like crown gall (Agrobacter).

 

Thanks Ron B. I Googled crown gall and that certainly looks the same.