In the following clip we can see a Lesser Black-backed Gull waiting for the Puffins to come back in to their burrows. A Gull will sometimes do this in an attempt to get an easy meal - by waiting for the Puffins to return with their catch the Gull can chase the Puffins to steal some fish without having to go fishing for itself. This process is called kleptoparasitism.
Whilst Gulls will use kleptoparasitism to get a bit of extra food the Puffins are still able to adequately feed their chick. This is because Puffins typically carry up to 30 Sandeels at a time (sometimes over 60!), so dropping a few to distract a Gull so that it can get to its burrow safely is not a huge loss of food.