Why does an Oak sometimes hold on to it's dead leaves?

Holly Leaf Miner: The perilous existence behind a leaf blemish...

European Nuthatch
(Sitta europaea)

Bonnet Fungi
(Mycena species)

King Alfred's Cake (Daldinia concentrica)

Brimstone Butterfly (Gonepteryx rhamni)

Snakeflies
(Raphidioptera family)

Black-spotted Longhorn Beetle
(Rhagium mordax)

Turkey Tail
(Trametes versicolour)

Oak Gall Wasps...and other galls

Cuckoo-spit, Spittlebugs and Froghoppers
(Philaenus, Neophilaenus, Aphrophora spp.)

Common Dog-violet
(Viola riviniana)

Bulfinch
(Pyrhula pyrrhula)

Ichneumon wasps

False Ladybird
(Endomychus coccineus)