Bird hills

A map from "Tičnice iz naravoverja: zanesljivi kažipoti v slovensko prazgodovino" [Bird-hills from Natural Religion: Reliable Waymarks of Slovene Prehistory] self published book by Leopold Sever in 2013. 

It is showing "gradišča" [hill-forts] (blue circles) and "tičnice" [bird-hills] (red circles) in the historical  Slovene regions in Slovenia and southern Austria...

In Slovenia, there are currently more than 200 hill-forts known as (gradišče) and more than 200 bird-hills known under various names (Tičnica, Tičn’ca, Tičistan,  Tičerca, Tičnik, Tičevo, Na tičnici, Tičjak, Tičjek, Križ na tičnici, Ptičjek, Za tičnico, etc).

According to local lore, these were the hills where people once performed religious ceremonies (???), fed birds (???) and "exposed their dead to the birds so that the birds could carry the soul of the  deceased into the sky" (???) before burials...Oh and they believed that these hills were haunted and should be avoided after dark...

Thanks to @another_barbara for alerting me to this.  The book is mentioned in this paper:

Staroverstvo - the Old Religion - the Slovene Pre-Christian Religion

In several parts of Eastern Bosnia and Hercegovina, at the end of the wheat harvest, a patch of wheat is left unharvested "for God's birds". 

In pre-Christian times, Slavs believed that souls of their dead entered birds and through birds entered heaven, Iriy. So feeding birds with grain was basically a form of feeding the ancestors, sacrificing to the ancestors...

Scandinavians did the same, although they don't seem to remember why...

I talked about this in several of my posts: Nav, Bird wedding, Julenek...

Slavs also believed that the bountiful grain harvest was direct result of the good will of the dead ancestors...

And that good will was the result of their descendants remembering them and providing them with food (grain, bread) and drink (water, milk, red wine).

So...

I talked about the importantce of feeding the dead with bread in several of my posts like "Soul breads" "Dead man loaf"... 

According to the Serbian folklore, it is important that the food served to the dead contains "a bit of everything that land gives birth to". It was believed that the dead are the source of life and that they give back manyfold what we give to them...

It is important that the food for the dead contain especially "a bit of all the grains" again because the dead will give us back manyfold of what we give them... 

This is the root of "Koljivo" the meal made from boiled grains, nuts, raisins and sugar used in the Eastern Orthodox Church for commemorations of the dead...

The origins of koliva predate Christianity. In the Ancient Greece, panspermia, a mixture of cooked seeds and nuts, was offered during the pagan festival of the Anthesteria, which was primarily concerned with placating ancestral spirits...  

So when a priest tells you that you should not bring food to the grave for your dead, because that is a pagan custom, and that instead you should make koljivo, which is Orthodox Christians custom...

Serbian ethnographer Veselin Čajkanović believed that originally the sacrifice offered to the dead included blood sacrifice as well. The meal contained not just plant food, but also one of each type of farmed animal, ritually slaughtered, drained of blood, and roasted...

Blood was given to the dead, as it was their favourite drink...I talked about blood sacrifices in many of my posts...

 And the meat was eaten by the living...

Again all of this was done because people believed that their dead are the ones who "make the crops (and especially grain) grow"...

Depiction of Diduch (grandfather), symbolic representation of the ancestral spirit which governs the lives of the living (and most importantly determines how good grain harvest will be). From Central European Slavic mythology / folklore. 

I talk about Diduch and it's symbolic representation in my post "Diduch"...