As explained, the effort goes best with using two ducks. I usually buy gutted and dressed down ducks. To be clear, the most meat of these ducks you can use for different meals: two ducks provide 4 breasts (duck breast with oriental sauce) and 4 legs (e.g. Duck legs from the oven or Duck confit).
Then all that is left are the heads, necks, feet, the wings and the carcass. I always discard the heads, but my Chinese neighbors remind me that the tongues are delicious too. From the skin of the neck, back and tail end, you can make duck fat.
Then from the feet,neck, wings and carcass, I make a duck broth. For that we submerge these in a large enough pot, adding water, salt and some laurel leaves and simmer for 2 hours. The resulting broth is rich in flavor. Upon cooling overnight in the fridge, you will see some whitish fat on top and a jelly broth. The feet also are a delicacy in China, but I use them for the broth as they are a great supply of duck gelatin.
Now for this terrine, we use the duck meat that comes off the carcass, neck and wings after a 2 hr simmer. That amounts to about 17 oz or 500 g from two ducks. We will also use some 5 oz (150 g) of the duck broth, especially the top part, that is more fatty. All the rest is chicken livers, pork collar meat and some pork (back) fat. Some brandy and port wine or red wine, salt and spices. We refer to the recipe of the pate de campagne for the details of filling and cooking the terrine.
pan to hold water to cook
parchment paper and aluminum foil
If you cannot get your hands on a duck, you can substitute by using duck legs and use the skin also for the broth to provide for fat and gelatin.
Or use another bird: a goose or even a chicken. The taste will be slightly different, but still very good
You may also substitute part of the chicken livers by livers from responsibly and ethically fattened ducks and geese (foie gras). This will create an impressive rich taste of the pate.