Taken from Wikapedia:
The largest recorded nested bird roast is 17 birds, attributed to a royal feast in France in the early 19th century (originally called a
Rôti Sans Pareil, or "Roast without equal") - a
bustard stuffed with a
turkey, a
goose, a
pheasant, a
chicken, a
duck, a
guinea fowl, a
teal, a
woodcock, a
partridge, a
plover, a
lapwing, a
quail, a
thrush, a
lark, an
Ortolan Bunting and a
Garden Warbler. The final bird is small enough that it can be stuffed with a single olive; it also suggests that, unlike modern multi-bird roasts, there was no stuffing or other packing placed in between the birds. This dish probably could not be legally recreated in the modern era as many of the listed birds are now protected species.
[1] [2].
In the United Kingdom, a turducken is a type of
ballotine called a "multi-bird roast."