At my parent's home in New York State, the acorns don't last long. The deer, squirrels, chipmunks and turkeys quickly gobble up, hoard or bury the best nuts, leaving only the small and wormy nuts for the insects and mice. A forest ecologist I once worked for told me that oaks are reproducing poorly in the northeastern US, in part because the unnaturally high deer populations consume so many acorns.
Walking through the woods around Rostock is a stark contrast, despite the similar mix of trees. Here, it is nearly impossible to avoid stepping on piles of big, healthy nuts. Acorns, chestnuts, beechnuts, walnuts. All the trees seem to be dropping fantastic numbers of nuts, and nothing but insects and a few birds seems to be eating them. Here neither deer nor squirrels seem to be common in urban parks as they are in the US. In fact the only wild mammals we have seen around Rostock are Fledermäuse (bats) flying around at dusk and a jackrabbit or two. The ground in the parks is also full of mole tunnels (must be moles, as there are no gophers or other rodent tunnelers here). There are of course some mice and rats, but we haven't seen them and their numbers don't seem up to the task of disposing of all those nuts.
In North America, deer and gray squirrels have increased their numbers and expanded their ranges as humans have removed predators and made food available year-round. In western Europe, where the native animals have a far longer history of being persecuted by humans, where large wilderness areas are rare, and where there seem to be fewer native mammal species anyway (perhaps because of extinctions?) there just doesn't seem to be anyone to fill that urban nut-eater niche. There aren't even any turkeys or other birds big enough to eat nuts whole. Under such circumstances, I wonder if the nut trees do well because their nuts aren't all eaten, or do poorly because their nuts don't get buried, passed though germination-inducing digestive systems and dispersed.