The brambling is a winter finch visitor whose numbers in Britain fluctuate dramatically from year to year according to the beech mast crop across continental Europe, illustrating the welfare impacts of food availability on migratory birds.
Brambling welfare is tightly coupled to beech mast availability across northern Europe. When mast crops fail on the continent, birds must travel further west into Britain, depleting fat reserves. Harsh winters with deep snow covering fallen mast cause starvation mortality. Woodland management that removes mature beech reduces the mast resource on which irruption populations depend.