Phoenix rising from the sand

By Athayde Tonhasca

As the waters subside in Germany and the country recovers from July’s catastrophic floods, naturalists may soon be able to evaluate the damage to one species caught in the deluge: the grey-backed mining bee (Andrena vaga). This bee is at home on river flood plains, grasslands, meadows, coastal areas, anywhere with alluvial soils – soil derived from sand and earth deposited by running water – and plenty of willows (Salix spp.) nearby.

A grey-backed mining bee © Ocrdu, Wikipedia Creative Commons

Female grey-backed mining bees dig their nests on spots of firm, sandy soil with sparse vegetation. The species is solitary, although females tend to nest close to each other in aggregations that can be thousands strong. Willows are their only source of pollen, but nectar is taken from a variety of flowers.

A grey-backed mining bee nesting aggregation © Mohra et al. 2004. Solitary Bees: conservation, rearing and management for pollination

Calamitous floods aside, to build a home on flood plains seems like a disaster waiting to happen. Water levels rise and fall, waterways change courses, river banks are washed away: riparian habitats are fragile and ephemeral. But none of this is the end of the world for grey-backed mining bees. Although floods may destroy large numbers of nests or even wipe out whole populations, these bees are well-adapted to disperse and colonise new places. In fact, fragmented populations dispersed over large areas are genetically similar, which suggests free and frequent interconnections between them.

Seven grey-backed mining bee nesting aggregations (red dots) in Germany © Mohra et al. 2004. Solitary Bees: conservation, rearing and management for pollination

Moreover, finding a new neighbourhood has a health benefit. Local populations of grey-backed mining bees grow steadily over the years, with more and more females sharing a nice nesting spot. These agglomerations do not go unnoticed by predators and parasites such as the nomad bee Nomada lathburiana. This parasite invades mining bee nests and lays an egg in the host’s brood cell; the invader’s larva emerges, kills the host’s egg or larva, then eats its provisions. A grey-backed mining bee aggregation targeted by parasites may contract by 50% in four years. But these population crashes are not all caused by natural enemies; some females just up sticks to build new nests on parasite-free sites.

The parasitic bee Nomada lathburiana © James K. Lindsey, Wikipedia Creative Commons

The grey-backed mining bee has been recorded intermittently in Britain since the 1930s, although its identification has not been confirmed until 2014. Currently this bee is confined to a few colonies is southern Britain: its populations may expand or be eliminated if nest aggregations are to be hard hit by rising waters. But even in this doomsday scenario, the grey-backed mining bee is not likely to be gone for long: wandering females in continental Europe should have no problem in crossing the English Channel and making themselves at home in Britain. This ‘here today, gone tomorrow’ lifestyle helps explain the difficulty in tracking the grey-backed mining bee and assessing its conservation status: it was labelled ‘endangered’ in 1987, ‘believed extinct’ in 1991, and ‘data deficient’ in 2020. As a species fine-tuned to transitory and unstable habitats, and highly adept at dispersing and colonising new territories, this unassuming bee takes natural disasters in stride; they are just facts of life.    

Taynish: gold dust!

By Caroline Anderson

This blog covers two visits to Taynish over the course of a week.  The first visit was filled with delight as there was a nice selection of damselflies out, and one or two four-spotted chasers.  I was thrilled, as it had been SO cold this May!

Only a handful of butterflies around but managed to capture this Speckled Wood.   After a holiday weekend of hot weather there should be more butterflies for you to spot – lots of Orange Tips and Small Heaths – these are indeed very small but what they lack in stature they make up for in beauty.  You can get an idea of scale from this dandelion clock. 

One interesting discovery I made as I was rummaging about in the bog at the boardwalk, was this Longhorn Moth – I’ve only ever seen one before and it was during the previous week.   It’s a beautiful gold colour with the most extraordinary antennae.

The bluebells are stunning at the moment, and the air is heavy with their scent.  They are also a great attraction for the pollinator insects – though sometimes you just have to look quite hard for them. This is a scorpion fly making the most of the bluebell cover.

Unfortunately, there was a distinct lack of bees during both visits, I think everything is just a bit later in getting going this year because of the recent low temperatures.   But finally on the pink next to the shore there were one or two getting covered in the gold stuff.  

There was also this wee guy making the most of the pollen – absolutely lathered in it! 

Talking of the gold stuff – check this out!  There’s lots of this type of grass in flower just now – and if you give it a shake you can see the pollen flying out – no wonder my nose is running! 

However, despite the lack of bees during my visits, there is hope, thanks to Heather and Gordon!  

Heather and Gordon, who keep Taynish so special for us all, made some bee houses for our Taynish Trail, and these are now being occupied. If you are considering a bee house, please follow this guidance to assure bees’ health.

The red mason solitary bees pictured below were busily going in and out of the hotel and were an absolute joy to watch.  The holes the bees have been using have been marked to make observation less tricky (that’s what the black dots are next to some of the holes) this also makes photographing them much easier too! 

It’s Garden for Wildlife Week so why not give our pollinators a wee helping hand. Good luck and tag @scotpollinators know how you get on by posting pictures on twitter.