How do I make this into a bigger study?

The 'bow-hiss' is a courtship behaviour. You might expect to see it more often during the breeding season (February-May).

Suggested longer term study: Why not repreat this observation every week for the next 20 weeks and see whether we get less bow-hissing or more bow hissing over this time? An example graph is shown below. Can you make your own version of the graph?

Do you notice if we get more or less bow-hissing during the breeding season?

Good luck, and have fun!