Canvasback and parasitic redhead egg identity data

Validating the accuracy of protocols and field observations is important
to maintain consistency amidst changing observers or study sites. To aid
inferences on interspecific brood parasitism, we validated 200 field
observations of egg identification to the species level against
mitochondrial DNA sequencing for nests where interspecific brood
parasitism was suspected. Of the samples submitted for sequencing, 29
failed to sequence resulting in 171 DNA verified samples of canvasback
(Aythya valisineria) and redhead (Aythya americana) eggshell
membranes. We found observers were highly accurate at differentiating eggs
between the two species despite experience level, and hatched eggshell
membranes contained the best quality tissue samples for sequencing success
when compared with eggshell tissue samples from earlier in incubation. Our
investigation showcases the utility of non-invasive molecular techniques
to validate field protocols and rejects egg identification as a major
source of uncertainty when trying to account for interspecific brood
parasitism in parasitized canvasback nests.