From my summary report to the team:
As for predation by the snakes, I wouldn’t move any of the boxes just on the evidence of this season. Last year it was boxes #1 and #3 where we had a problem; this year it was #7 and #62.
As for nest structures for Mallard and American Black Duck, let us know where you’ve placed them and we will try to work them into our monitoring routine. My references show that the nesting season for these birds extends later into the summer, so we would have the opportunity to extend our work season.
A pattern that I’ve noticed over the years is that the fledge-to-eggs ratio for Hooded Merganser is usually higher than that for Wood Duck. A couple of hypotheses:
(1) Since the mergs start laying eggs a little earlier than the woodies, perhaps they out-compete them and occupy the more favorable boxes for that year. (We don’t see that one species is particularly faithful to a box, and indeed since we see a few mixed clutches, a box may be considered favorable by both species.)
(2) We are more likely to see “dump” and “drop” nests for the woodies: boxes with 20+ eggs. And with these jumbo clutch sizes, it’s more difficult to incubate all the eggs sufficiently.