Question: How can you tell if the bird vomit/droppings are old or new?

Renata Medeiros answered on 18 Jun 2013:

When the animal vomits or poos on top of you, then you know they’re very new! 🙂 And those are the best ones!
Some seabirds (and also other birds) instead of vomit, throw away what we call pellets (little balls with bits from the animals they ate – bones, feathers, fur, depending on what they’ve been eating). The birds I study produce proper liquid vomit which they use to feed their chicks but also to scare away predators (that is why sometimes they vomit when they are caught). You can easily find pellets and study them even if they are old but you wouldn’t be able to find vomit unless you see the animal vomiting, it would just dry out very quickly. You can find old droppings though and, if you didn’t see the animal doing it, the only way to know if it’s fresh or old is whether it’s dried or wet. It is very hard to get DNA from old droppings (more than 1-2 days), except in the case of penguins because the ice preserves the DNA very well.