Now I would like to know if behavioural responses are correlated (for example, do birds that sing back quickly also approach the speaker quickly). Normally I would use a simple Pearson correlation for this, but as I have two measures for each bird I don't know if I can do that here.

So, my questions are can I use Pearson correllations given that my data is balanced (every bird has two measures for every behaviour)?

If not, is there a repeated measures alternative to the Pearson correlation?

Thanks!