Squirrels don't wait for Hazel nuts to ripen
Albeit a time of falling leaves and falling temperatures, hazel nuts are ripening rapidly in their leafy cups in this season of nature's bounty with woodlands abounding with blackberries, sloes, haws, hips, chestnuts, acorns, mushrooms and other autumn fruits.
Our native Hazel is one of those in-between plants, on the one hand not big enough to be called a proper tree but on the other hand a bit too big to be regarded as a shrub. To qualify for the title 'tree', a plant should have a single woody stem and stand more than five metres tall. While Hazel often grows more than five metres tall, it is always multi-stemmed, so it is a big shrub rather than a small tree.
Hazel thrives in limey soils. It can form pure shrubby woodlands, most notably on the Burren plateaus of north Clare and in the Glens of Antrim, but it occurs widely throughout Ireland as a understorey in woodlands and hedgerows its soft, floppy, hairy leaves always tipped with a sudden sharp point.
Hazel is unusual in that it flowers in winter. Both male and female flowers are borne on the one plant and they appear long before the leaves. The male flower is the well-known 'lamb's tail', that long, dangling, bright yellow catkin that is so obvious on the shrub's bare branches.
In contrast, the female flower is so tiny that it would be inconspicuous were it not for its bright red colour as it sits like a tiny red sea anemone on a bare branch. Wind-borne pollen from the male catkins fertilises the female flowers and the fruit, the hazel nut, follows at this time of year.
Wood Mice and Red Squirrels feast on the nuts. Red Squirrels leave the nuts to ripen and crack them open so a broken shell on the ground is evidence that a Red Squirrel has been at work. Mice gain entry by gnawing a round hole in the side of the nut. Fallen nuts that escape being eaten go on to produce Hazel seedlings.
Grey Squirrels don't wait for the nuts to ripen; they eat them when they are green. As a consequence, intensive grazing by several Grey Squirrels can result in a shrub never getting to produce ripe fruit thereby failing to reproduce. The future survival of our native Hazel in areas that support large populations of Grey Squirrels is therefore being compromised by these alien rodents from North America.