What is the most likely reason that a long beak could be an adaptation for a bird living in a temperate forest?

A temperate forest is likely to have numerous flowers from flowering plants. Flowers are an evolutionary trend in flowering plants to attracts animals to facilitate pollination. The flowers contain nectar that attracted birds, bees and other nectar-sucking animals. The nectar is produced by nectaries in hollow tube in the flowers. Therefore for birds to access the nectar they require to have long slender beaks as an adaptaition.