Tag Archives: floral oils

The week the Swifts departed

It’s become something of a ritual.  Each year in the first week of August, we scan the sky nervously.  We’re looking for birds but anticipating an absence.  It’s not that we want the swifts to go but we know they must.  The next part of their life is lived in Africa where they spend the months of September to April after their long migration.   When they leave us, it’s a sign that the year has moved on and summer is gradually giving way to autumn.

This year the swifts arrived at the beginning of May.  We had been watching out for them for several days and then finally we noticed a few birds swooping around in the sky above our house.  With that dark crossbow silhouette and those rapid bursts of wing beats interspersed with smooth glides, we were relieved and pleased to see that the swifts had returned.  Messages circulated on our local WhatsApp group celebrating their arrival and it was clear that our neighbours were just as interested as us.  Gradually their numbers built up as more birds arrived from Africa.  Numbers varied and, on some days, we saw none but at their peak this year up to 30 swifts were swooping and screaming across the valley below our house.  The valley contains a community garden with flowers and trees and most likely the swifts come to feed on the insects that breed there. 

Throughout late spring and summer we watched them flying backwards and forwards at high speed, changing direction as they banked and turned, sometimes going into steep dives pulling out at what seemed like the last minute, screaming as they went.  Sometimes a group flew about together, individual birds adjusting their relative positions before splitting into smaller groups like rockets at a firework display.  Sometimes the birds flew towards our terrace of houses, turning finally to avoid the brickwork or deftly navigating the gap between this and the next terrace.

Swifts near our house

The position of our house gave us a very privileged view of the birds.  It is one of a terrace of five houses built on a ridge on the southern edge of Totnes overlooking the valley and community garden so that our kitchen window is level with the tops of the trees below.  Sometimes, when the birds were flying about near the houses, they passed at speed very close to our kitchen window giving us views worthy of a nature documentary programme.  Sometimes, when we sat outside on the patio, the birds passed directly overhead screaming as they went, a joyous and very visceral experience.   

Swifts over Totnes seen from our kitchen window in 2020

Sitting outside, we could also see some of the birds swooping up to the eaves of two houses in adjacent terraces where they made nests.  They also nested in the roof space of one of the houses in this terrace and, for the first time, they occupied a wooden bird box fixed near the eaves on another house.  The box was put up several years ago by a neighbour.   It was occupied by sparrows one year and tree bumblebees in another but this year the swifts used it.  Swifts tend to return to the same places to nest each year so we have high hopes of seeing them in this box in the future. 

The second week of August arrived and the birds were still about.  Although we expected them to go any day, they still had the ability to surprise.   On the 10th just before 9 o’clock with the sun setting, I was standing outside looking across the valley, watching the light fade and the colours changing.  I hadn’t seen swifts that day and wondered if they had left.  The western sky was still bright, a luminous pale blue, and light cloud in the northern sky gathered pinkish-orange tinges from the setting sun.  Suddenly, above the general hum of human activity I heard the familiar screaming sound announcing the arrival of a volley of swifts.  About ten birds in groups of two or three were heading straight towards me just above head height.  At the last minute, though, they changed course to fly through the gap between the terraces. 

If all this wasn’t exciting enough, I had a second fascinating close encounter with the non-human world in the same week, this time with a very different species and some distance away from Totnes.

The second story began when, in the first week of August, Tim Worfolk, a local bird illustrator and naturalist, reported on social media that he had seen some rare and unusual bees on a nature reserve south of Exeter.  This was the first report of this species in Devon and I couldn’t resist the opportunity to go to have a look.  So, on August 9th I made the 40-minute drive to the Exminster Marshes, part of the river Exe floodplain and a wetland nature reserve managed by the RSPB.   I had driven through a shower on my way over and rain threatened later but it was my only free day that week.    I parked in the reserve car park and made my way down a lane towards the Exeter Canal and the river Exe.  Signs of water were never far away.  Although the lane was enclosed by hawthorn bushes and other scrub, reeds grew through the vegetation and a ditch half full of water ran alongside the lane.  Late summer flowers grew in the hedges including bright yellow fleabane, the lemon-yellow snap dragon-like flowers of common toadflax and the pink cushions of hemp agrimony. 

The Exminster Marshes showing the flat watery landscape

I left the lane to cross open grassland criss-crossed by ditches with rough stony bridges.  Clumps of tussocky grass grew across the marshy land along with stands of creeping thistle that attracted small copper and small tortoiseshell butterflies and some chunky hoverflies.  Cows grazed nearby and this would have been a peaceful spot had it not been for the M5 motorway bridge crossing the marshes towards the north creating a continuous background hum of traffic noise.

At the end of the field path, I crossed the cycle track and scrambled up to the towpath at the edge of the Exeter Canal.  The pleasant town of Topsham with its Dutch-gabled buildings lay across the river Exe on the far side of the canal.  The towpath was quiet, most likely because of the weather, but a few walkers passed and two stand-up paddleboarders drifted lazily past on the canal. A little drizzle was now falling and I began to wonder if any bees would be about but I decided to press on.  Banks of reeds lined the towpath and flowers grew up through the vegetation.   I noticed the pink flowers of marsh woundwort with their intricately decorated lip and a few tall spikes of purple loosestrife.  Then, as I walked southward, thick clumps of yellow flowers appeared in the canal-side greenery.  This was yellow loosestrife, a plant that grows in wet places and, with its copious sprays of bright yellow cup-shaped flowers produced in late summer, it shone like a beacon of light on this gloomy day.   Each flower contained large amounts of grainy yellow pollen and the plant grew in many places along the canal up to the lock where the canal and river merge. (The picture at the top of this post shows some the yellow loosestrife flowers)

Vegetation by the side of the Exeter Canal showing yellow loosestrife and marsh woundwort. Topsham is in the background.

Light drizzle continued to fall and I had almost given up on finding bees when I spotted a medium-sized dark insect in one of the yellow loosestrife flowers.  Visually, I couldn’t see much to distinguish this insect except some white hairs on the hind legs. Photographs also showed the prominent white hairs on the back legs along with some black as well.  These characteristics together with the association of the insect with the yellow loosestrife flowers showed that this was a female Macropis europaea, the yellow loosestrife bee, one of the bees I had come to find.  The photographs also showed a few small drops of rain on the insect which was sheltering on this damp day and essentially immobile, making it easier for me to take pictures.  Further along the canal, I came across another dark insect also resting in a yellow flower and in this case, photos revealed its swollen hind legs and its prominent yellow face, characteristic of a male of the same species. 

Female Macropis europaea showing the white and black hairs on her hind legs. Look out for the raindrops.
Male Macropis europaea showing his swollen back legs
Male Macropis europaea showing his yellow face and swollen back legs

These are the bees reported by Tim Worfolk but why was I so interested in seeing them?  They are rare which is of course one reason. They also have some very unusual characteristics being the only UK species of bee that collects floral oils and they find these oils in the flowers of yellow loosestrife.   

Within the flowers there are tiny glands that secrete floral oils.  The glands, termed trichome elaiosomes, are found towards the lower part of the inside surface of the petals and along the stamen tubes and the oils collect near the glands.  The female Macropis bees have specialised brushes of hair on their front and middle legs that they use to collect these oils which are then transferred to the hairs on their back legs, sometimes mixed with pollen also collected from the flowers.  The female bees use the oils for two purposes, to waterproof the inside of the nest chambers they construct in wet places and, mixed with pollen, to provide food for their larvae. 

When I visited, the damp conditions prevented the females from flying so I was unable to observe them collecting pollen or oils.  Local naturalist John Walters has a nice video of the female bees collecting pollen where the bees look like they are wearing bright yellow pollen pantaloons.

I was glad to have made the trip to Exminster Marshes, despite my doubts about the weather.  Seeing these oil-collecting bees and understanding the close and reciprocal relationship they have with the yellow loosestrife flowers was an unexpected gift.   

But what about the swifts?  August 13th was the last day we saw the birds near our house so we assume they are now on their long migratory journey.  Their presence has not only entertained us but has enriched our lives this year, bringing us closer to the non-human world.  It has been an excellent year for the birds in terms of numbers and it was good to see them reproducing so well, especially in this time of environmental crisis. 

Marsh woundwort with common carder bumblebee (Bombus pascuorum)
Small copper butterfly (Lycaena phlaeas)
Hoverfly (Helophilus trivittatus)