Cockerel standing on (or above) a lion. Painting on wood. Kirovsky Regional Museum, from ethnographic material collected in Vologda region.
Middle of Leo, 2nd of August, is when Slavs used to celebrate the day of Perun, the the end of summer and the beginning of autumn. The sacred bird of Perun, the storm god, was the fire cockerel. When Christianity replaced the old Slavic pagan religion, in Serbia Perun was replaced with Sveti Ilija Gromovnik (St Ilios the Thunderer, the Thundering Sun) and the cockerel became associated with this "Thundering" saint. The cockerel, the sacred bird of the thunder god is slaughtered, cooked and eaten on the day of St Ilios the Thunderer "so that the sun would not burn the grain". This is a clear sacrifice to the Storm god for rain...Interestingly it has to be "the oldest" cockerel. Remember Perun is the the old sky god, old sun, the old head of Triglav, two other heads being Jarilo (young sky god, young sun) and Svetovid (adult sky god, adult sun)...This again confirms the link between the cockerel and Perun.
I believe that the fact that cockerel is the sacred bird of Perun, the Storm god, is why the weather-vanes placed on top of churches are in the shape of a cockerel. Weather-vanes like this one from 19th century Russia:
However the official theory is that cockerel shaped weather-vanes or weathercocks are placed on top of church steeples because of St Peter.
In "Encyclopedia of Religions" by John G. R. Forlong we read that "Pope Gregory I in the 6th century said that 'the cock (rooster) was the most suitable emblem of Christianity, being the emblem of St Peter'" Some say that it was as a result of this that the cock began gradually to be used as a weather vane on church steeples. In the 9th century, Pope Leo IV had a figure of a cockerel placed on the Old St. Peter's Basilica. Also in the 9th century Pope Nicholas I ordered the figure of a cockerel to be placed on every church steeple, as a symbol of Jesus' prophecy of Peter's betrayal (Luke 22:34), that Peter would deny him three times before the rooster crowed on the morning following the Last Supper.
This is the oldest surviving cock weathervane. The early ninth-century Gallo di [Bishop] Ramperto, Brescia, Italy.
So it seems that the placing of the cockerel weather-vanes on Christian church steeples has nothing to do with Perun and everything to do with St Peter. However in Slavic folk tradition St Peter seems to have acquired a lot of characteristics of Perun. He is the Saint who Eastern Slavs pray to for rain, as we can read in the "Songs of the Russian People" by W. R. S. Ralston.
In "Slovenska mitologija - enciklopedijski recnik" by Svetlana M. Tolstoj, Ljubinko Radenkovic we can read that Bulgarians and Russians considered 29th of Jun, Petrovdan, the day of St Peter, to be the end of summer and the beginning of autumn. Just like Serbs considered 2nd of August, Ilindan, the day of St Ilija the Thunderer, the Thundering Sun, old Perundan, the day of Perun, to be the end of summer and the beginning of Autumn. In "Перуника – цвет небеског или хтонског света?" by Ljubinko Radenkovic we read that in Dubrovnik region people used to celebrate St Petar Bogišar (St Peter of the Iris flower). Iris is in the Balkans known as Perunika, Perun's flower. I wrote about the link between Iris and Perun in my post about Ognjena Marija.
So it seems that both St Ilija (mainly) and St Petar became replacement for Perun.
If so, is the cockerel standing on top of church steeples symbol of St Peter, there to remind people of St Peter' betrayal of Jesus? Or is the cockerel standing on top of church steeples symbol of Perun, there to protect the church from the wrath of the storm god???
And did cockerel jump onto church steeples directly out of Slavic mythology, or did Goths, who before their migration westward lived for centuries mixed with eastern Slavs, act as intermediaries?
This is very interesting indeed, don't you think?