Mike asked -

> I have long assumed that it was important to clean out my chickadee and
> swallow nestboxes once a year. Does this mean that I should stop? Or
> is that reading too much into these findings, applying them too broadly?
> Perhaps their study was conducted in a much colder climate, where all
> the mites were killed off in the winter. Are mites the impetus for
> cleaning out nestboxes? Or is it something else? Thoughts???

Recent studies of bluebird and swallow boxes have found that certain
parasitic wasps look for the mite and louse eggs/larvae in the old nesting
material and lay their eggs in them. The young parasitic wasps hatch
and consume the eggs/larvae from within thus killing the mite/louse. The
current recommendation is, if one does clean out a box, to leave the nesting
material on the ground at the base of the fencepost, etc. That way you do
not disrupt the natural predator/prey relationship. This fits with the
findings that some birds prefer to re-nest using old material. I suppose
you could say that the bird is "trusting" that the wasps have cleansed the
old stuff already.

- Jack


Jack Bowling
Prince George, BC
jcbowling at mindlink.bc.ca