Favorite thing: Lokrum has some places to sit down and buy a drink. However, prices are comparable to those on Dubrovnik's city walls. It is therefore recommended to buy most drinks in Dubrovnik and only buy those drinks at Lokrum which you want to consume in a café or bar. There is one close to the ferry jetty which makes good sandwiches, while Café / Bar „Lake“ a the dead sea offers drinks only (26,00 kuna for a small beer). The restaurant in the ruins of the monastery is a very scenic place but too posh and far too expensive for my taste.
These birds are mentioned as an attraction in Lokrum. They have been introduced during the Habsburg years (19th century) and have settled in pretty well. You can see them quite everywhere and some tourists look for a lost feather of a peacock. You can hear their sound all over the island.
Peacocks usually do not make trouble, but can someties be annoying when you try to take a sunbath. They do not really care about people and may just walk along between tourists, touching their faces with the big feathers. Peacocks are not that easy to scare away. They are not agressive but can become so when you tease them too much. Hens are usually a little shyer.
P.S.: Though the term peacock is used to describe this animal, a peacock is only the male form of peafowl. The female one is called a peahen.