At this time last year it was already obvious that the annual crop of rowan berries in the north had failed and over very large areas there were no berries at all. This had serious consequences for the tens of thousands of immigrant birds that invade the Highlands every Autumn, mainly from Scandinavia. Instead of being able to linger and gorge themselves for the start of the winter months, the bird were forced to move south and west, many even to Ireland to find enough food. So it was with bated breath that we awaited this coming Autumn as far as the crop of rowan berries were concerned. Judging by what I have seen around Inverness and elsewhere in the north, plus many readers’ comments, there is once more a bumper crop of rowan berries. In the countryside in general the berries are just ripening. Nearer towns and villages where the climate, including the temperatures, is slightly better, the berries are already the rich red that is so welcome to all.
The rich red clusters of berries are already so heavy they are weighing the branches down and even the smaller, younger trees have their rich crop. The rowan is sometimes called the mountain ash partly because it will sometimes grow on the upper tree line limit on hillsides. Birds often leave the seeds in their droppings and this is why you can sometimes find isolated rowans well away from any others. Already this year small parties of mistle thrushes, often family parties, will be eating them. These small flocks will often defend a rowan tree against all comers that may include blackbirds. When the redwings and fieldfares come for Scandinavia, including redwings from their breeding grounds in Iceland, the mistle thrushes are waiting for them. In the end the mistle thrushes have no chance as they are just overwhelmed by the sheer numbers of their thrush family cousins from abroad.
It is not only birds that will take the rowan berries as they are a favourite food of the pine marten. If you look under rowan trees at this time of the year and for the next few weeks you may find the droppings of pine martens. They will be heavy and red in the unmistakable colour of the rowan berries as the undigested parts of the berries are passed through. Pine martens have even been seen leaping up at the clusters of the berries where they are out of the animals’ reach. Despite that we may think of the so called carnivorous diet of the pine marten, studies in the Highlands have shown that no less than 11% of their diet is fruits and nuts that include rowan berries. Badgers will also take the berries and have even been known to climb up the trunks of a tree to get at the lower branches. Wood mice will also freely take the berries and will often store them in old birds’ nests for later consumption. They are also classed as one of the “primary” foods of the red squirrels. The caterpillars of several different moths feed on rowan leaves including the brimstone moth and the orange underwing. However, no butterfly caterpillars have been recorded on them. Interestingly when the importance of trees to insects is considered the first five are, in order, oak, willow, birch, hawthorn and blackthorn. Rowan is, surprisingly, much lower down the list at 17th despite its attraction to birds and mammals.