wasn’t present and the cavity had not been deepened. However, I noticed two older holes in the stub of unknown depth but about the same size. The older holes were surrounded by gray, shadow-like rings that might have been remnants of pitch the species almost invariably spreads around the entrance to its nest. If so, this indicates that red-breasted nuthatches created nest cavities there before.  

results in both adults being soiled with pitch before the young have fledged or taken their first flight, is unknown.”

Pitch spreading calls for an explanation and many observers oblige. One of the most imaginative contends that, The sticky substance applied, serves as protection from predators, for insulation and to lessen the danger of nest breakage at cavity height.”  This assertion, without supporting evidence, seems to endow these little birds with the logical and technical skills of security and engineering professionals. To their credit, other observers admit, “The function of this peculiar habit, which often

Stub with new and old cavities

                          Puzzle: Why do Red-breasted  Nuthatches Spread Pitch Around Their Nest Holes?