A Field Notebook: Bridge of Grudie, Loch Maree

Sunday, 14 July 2024

Bridge of Grudie, Loch Maree

Photo: Azure hawker.

Bridge of Grudie is an iconic dragonfly site on the edge of Loch Maree near Gairloch in the north west highlands. In particular it's a special place for the Holy Grail of dragonflies, the azure hawker, and there are spectacular views across the loch to Slioch which rises to a height of 981m, 3218ft. Occasionally golden eagles fly over and you can be serenaded by the calls of breeding black-throated divers. There are few places like Bridge of Grudie.

Today we did well and managed to find at least two spectacular male azure hawkers and an ovipositing female, plus common hawkers and four-spot chasers. In the past I've also seen northern emerald here, but these were my first azures.

Looking towards Slioch.

Common hawker drying its wings having just emerged from its exuvia which you can see is still attached to the grass.

Dragonflies spend most of their lives in ponds as larvae. They can live for two or three years underwater before they eventually climb up onto a stem of vegetation and the larvae "skin" hardens and splits open to allow the adult dragonfly to emerge. The now empty larvae shell is known as the exuvia.

When the adults first emerge their wings are soft and they have to sit in the sun for a while to allow their wings to harden. Until this process of "drying out" is complete they can't really fly properly, just short distances and they are susceptible to predators. During this period their colours also become brighter. Presumably they are less colourful when they first emerge in order to be better camouflaged whilst vulnerable.

Looking again at the photo, you can really see why the wings are soft at first, it's because they have to fold up into the shell of the exuvia. The adult lives just a few weeks, probably less than 10% of it's total life span.