Is it possible that your correspondent has come across a colony of mining bees of a species hitherto foreign to our shores? Unlikely!
I embark on a tale of amateur research and conjecture; perhaps my readers will be recognise the creatures and inform me.
I have spent many hours poring over the evidence in books and on the internet. I cannot help but feel a certain frisson of excitement. The winged creatures I recently photographed on an offshore Kerry island would seem, by appearance, location, seasonal activity and behaviour to be one of two species listed as absent from Ireland. One of these species is so rare as to be on the endangered species list throughout its range.
If a bee expert says I’m wrong and denounces my presumption, I will be a tad disappointed, but I will present the evidence on which it is based.
On a sunny afternoon in early September, while negotiating a cliff path on the Great Blasket island, I came upon a buzz of activity as a hundred or more bees came and went from small burrows dug in the sparsely vegetated hard sand. Slightly smaller than honey bees, they seemed to have no malevolent intent and did not attack me as I photographed them.
They clearly had more important matters on their mind: procreation. At one stage I came upon a ball of bees, which rolled about the path until one flew off with another attached. I concluded that one of the bunch was a queen, and the others were pheromone-fired males seeking to mate with her.
Back at home, I checked my photos against native bees of similar appearance, but could find none. However, a bee not recorded in Ireland, the yellow-legged mining bee, Andrena flavipes looked similar and internet photos illustrated similar mating behaviour. Experts noted that while it is one of “the commonest and most obvious of the spring-flying solitary bee species over much of southern England.”, there are no records from Scotland or Ireland. In Wales it is confined to the south coast.
Andrena flavipes has two flight periods, March to May, and June to early August. Other details matched their behaviour: nests constructed in the ground, often found in dense groups in exposed banks and cliffs and in sparsely vegetated field margins.
However, the fact that they did not fly in September made me wonder if my Blasket bees might be another mining bee species, the sea aster bee, Colletes halophilus, not recorded in Ireland and a globally endangered rarity. If this was correct, they should of course, be protected.
The sea aster bee is uniquely associated with sea asters (Aster tripolium) which grow on coastal saltmarshes, stabilised sand dune areas, sea walls and low sea cliffs. It has a very restricted range globally, and its association with salt marshes makes it especially vulnerable to rising sea levels or destruction of salt mashes during the building of defences against rising seas.
Sea aster bees are on the wing in late August and in September, foraging on sea asters (Aster tripolium) which are then are in bloom; there are acres of them on my local bay, tall, mauve daisy-like flower, with yellow centres. I have not seen these bees here; not surprising as they are listed as absent from Ireland.
Like the yellow-legged bees, their nest burrows are dug in stabilised sandy material with sparse vegetation cover, this ensuring maximum ground surface temperatures.
Sometimes, they nest in colonies of thousands of individual burrows. I saw perhaps a hundred burrows. They were indeed excavated in stabilised sand with sparse plant cover.
My conclusion that they might be the rare Colletes halophilus rather than the relatively common Andrena flavipes rests, in part, because they were flying at the right time of year. Also, internet photographs of Colletes halophilus shows red hairs on the thorax (as in my photos) while the thoraxes of yellow-legged bees are bald or black. However, I saw no sea aster flowers on the Great Blasket. I walked only upland paths and they might exists on stabilised dunes near where I saw the bees.
Have I found a colony of rare bees? Probably not, but it’s just possible. Watch this space for further news.
Meanwhile, the entertaining memoir of Eric Dempsey, one of the doyens of Irish birdwatching has been published by Gill & Macmillan. It might be subtitled “How I became a Birder as soon as I was Fledged”. Author of The Complete Guide to Ireland’s Birds, it tells some great birding stories — and others.
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