May 27, 2021
Over the past month or so I’ve watched five songbird nests fail. Three were cardinal nests, one American robin, the other belonged to gray catbirds. Two were confirmed rat snake predations (direct observation), there was at least one suspected rat snake predation, and one unknown failure, but most definitely predatory in nature.
Rat snakes are well known nest predators and take many nests each spring. It seems their first act of spring is to seek out birds’ nests. They are adept at their job as rat snakes are considered top predators of nesting birds.
Other predators seen lurking in the woods and actively, yet quietly, searching for nests recently have been bluejays and crows, both notorious corvid raiders of nest robbing repute.
I don’t suspect raccoons or other mammal predators in the recent incidents as they tend to leave a mess at the scene. The predations at the two suspect nests sites, the cardinal sites, were clean and neat extractions. In one case eggs were left in the nest. I suspect the incubating adult bird was the victim there.
One of our cardinal nests was quickly taken over by mourning doves after being vacant for no more than a day or two.
There are probably many dozens of active nests which have been and will be successful this season here at the museum, and the birds, if not direct victims themselves, seem to bounce back quickly and start new nests when earlier attempts fail for whatever reason, not just predation.
There is a new cardinal nest in a holly tree in Explore the Wild. As I look at the female sitting on the nest incubating eggs, I wonder if she and her eggs will be there in the morning. Mortality in passerine nests is apparently very high. But there are too many variables in the equation which can steer the percentages either way, so I won’t even try to speak of numbers. So far, all of the passerine nests, wild nests, that I’ve observed have failed and did not fledge birds.
Of course, I’ve seen many fledgling chickadees, titmice, thrashers, towhees, and other songbirds, so many are surviving to the fledging stage. A high percentage of these birds, though, won’t make it either. The first three weeks off the nest being the most perilous.
On the bright side, here’s a few shots of our Canada goose family.