​Modern ecological research increasingly relies on DNA to discover what animals eat.

Two broad classes of DNA-based strategies—called DNA metabarcoding and metagenomics—can provide complementary data that provide insight into what animals eat and why it matters.

When should we select one versus the other (or try combining both)?

Direct observation is the oldest method in ecology.

Before sequencers and statistical ecology matured into their modern forms — there were notebooks, binoculars, and patient observers recording what animals ate, one bite at a time.

So how does dietary DNA metabarcoding compare to actually watching animals eat?

Well, it’s different, and sometimes it can be transformative. Both can be essential if your goal is to understand ecology or protect endangered species.

​Understanding animal diets is fundamental to ecology, evolution, and conservation—but different methods reveal different aspects of feeding behavior. Two widely used approaches, DNA metabarcoding and stable isotope analysis, answer overlapping questions in very different ways.

At First Bite: Why Do Animal Diets Matter? 

Understanding what animals eat is central to ecology, evolution, and conservation. Diets shape species interaction networks, how energy flows through food webs, and what animals can do when environments change. For decades, ecologists have inspected animal scats using microscopes to identify what they have been eating. Today, DNA-based approaches offer a powerful alternative.

So how do these two methods stack up—and when should you use each?