Well, take us through the methods because it's not an easy task, is it, gathering this data?

Phenomenally difficult.

Hugely rewarding now that we're there.

But yeah, really, really difficult.

So in essence, what we needed to do to show in this species whether or not plastic was having an impact was to mark thousands, thousands of individual animals.

and then follow them through time to figure out what their fate was.

And that can be somewhat difficult to do because how do you individually mark thousands of animals and make sure that those marks are not lost, that they're retained over many years, sometimes decades? What we relied on was actually something that's kind of cool, a little bit of an old school technology that there's been a few criticisms lately that applying metal leg bands to birds is...

ancient.