the cause of the white growths on this robin's legs. among the many robins passing through this morning, a few of them had signs of the leg issue, but this robin seemed to have one of the worst cases. short video: https://youtu.be/bOzc7tqysK0
Found in Pinus sylvestris bark. Weather was nice
They have a large population all over the city and are not hybrids.
Under moss on a pine stump.
Total length about 7 mm.