Tag Archives: swifts

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)

Watering cans, wild flowers and swifts – looking back at the Garden in July

At this time of year, only a small corner of the Leechwell Garden is visible from our kitchen window; the rest is obscured by the thick green wall erected by the trees. I can still see the three silver birches, also two of the benches and the lower part of the water course, popular with young children who like to paddle, especially during the hot weather we experienced this July.

July 14 5
red valerian in seed

There had been storms about and we did hear distant rumbles of thunder on more than one occasion but in Totnes this month there was little or no rain for more than three weeks. With the sultry temperatures everything began to look rather parched. Many of the flowers on the red valerian lining the paths near the Garden turned to seed; this felt earlier than previous years. The plants acquired a downy covering of numerous seeds equipped with small parachutes to aid windborne dispersal; no wonder it grows everywhere. I was also surprised to see ripe blackberries – in my mind blackberries are a feature of autumn.

July 14 6
blackberries

The swifts were an almost constant feature this month, shrieking over the Leechwell Garden morning and evening. Typically there were ten or so probing the air above the Garden looking for insects. On the 21st, the swift spectacular stepped up a notch and we counted more than 40 that evening. I had noticed flying ants in our garden so I wondered if the extra food had attracted the birds.

swifts over Totnes
swifts over the Garden

What is it about the swifts that captures our attention? We have to look, we have to try to count. They speed past our house, they manoeuvre, change course quickly and regroup like miniature spitfires in an old Battle of Britain film. But suddenly, on the 28th we noticed their absence. They had gone, making their way back to Africa for the winter. We miss them.

Down in the Leechwell Garden, one problem this July has been the lack of easily accessible water. There was no actual shortage; water flows freely through the garden but it has to be carried some distance as there are no taps. This was the first prolonged dry spell for some years and I sensed that plant growth was being affected. The Garden volunteers came up with the clever idea of providing watering cans for visitors so that, as they looked around, they could also water the plants. Some of the watering cans are child-sized so watering can become a game.

July 14 4
The pergola with clematis Perle d’Azur and lavender. The notice urges visitors to help with watering.

On the pergola, purple seemed to be the colour of the month. The later flowering clematis showed well and the path was lined with burgeoning banks of lavender.

July 14 1
wild flower bank

At the far end of the pergola there is a long wild flower bank. This has been carefully planted and showed a fine mixture of native plants in July – I saw proud yellow-flowered stems of mullein, floppy flowers of evening primrose, peering ox eye daisies, wild marjoram, musk mallow, knapweed, and, towering above them all, spindly purple-flowered verbena bonariensis (native to South America).

July 14 9
marjoram

It’s very good to see the wild flower bank as it’s one way to provide extra habitat for pollinators. I saw plenty of insects there in the morning but later they seemed to desert this part of the Garden for the attractions of other flowers. One of the competitors was a large patch of golden marjoram covered with white flowers; on sunny afternoons this positively pulsated with honeybees and hoverflies. The beautiful borage also continued to flower well and its starry blooms were well used by bumble bees.

July 14 3
borage

July 14 7
borage with bumblebee

 

I want to finish with more pictures of bees and flowers.

 

July 14 8
scabious with honeybee

July 14 2
I found this marigold with a bee turning in circles rubbing its abdomen around the flower centre. I think this might have been a leaf-cutter bee. I hope so.

The picture of the swifts was taken by Hazel Strange.

Disturbing the natural order – the case of neonicotinoid insecticides and farmland birds

Apus apus 01.jpg
A swift

 

One of my favourite nature writers is Mark Cocker who has the ability to capture a scene or an idea in a few hundred words. Despite his immense knowledge he never loses his sense of awe and with clever use of metaphor, his descriptions of nature leap in to life.

Here is Cocker writing about the interdependence of birds and insects:
“…… that vast efflorescence of insect life is integral to spring. After all, those swifts newly screaming over our village and the chorus that greets us at first light are little more than arthropods processed by avian digestive systems”.

Another favourite nature writer, Kenneth Allsop wrote, nearly fifty years ago, also about bird/insect interdependence. He took the example of a pair of dunnocks in the breeding season who consume more than 1000 insects each day just to maintain their chicks. Many of those insects, he pointed out, will be garden pests, “worth bearing in mind when irritated by bird damage to the green peas and apple buds”.

Despite this obvious dependence of bird life on insects, we still dump insecticides on to our gardens, parks and farmland with little real thought about the long term consequences.

One class of insecticide that has recently attracted scrutiny is the neonicotinoids. The neonicotinoids were introduced in the 1990s and are now very widely used to kill insect pests on a broad range of crops. In the UK, for example, a large proportion of the oil seed rape is grown using seed treated with neonicotinoids. One of the advantages of the neonicotinoids is their selectivity for invertebrates; in principle they have low toxicity towards vertebrates. There has, however, been increasing concern about effects of the neonicotinoids on non-target insects such as bees and the accumulation of the chemicals in soil and water courses with more general effects on invertebrates.

New worries about the neonicotinoids surfaced last week in a paper published in Nature by Hallmann and colleagues from Radboud University in the Netherlands. The Dutch group investigated whether these chemicals might be affecting the numbers of farmland birds indirectly by reducing the numbers of insects that these birds depend upon especially in the breeding season.

They took advantage of long-term monitoring schemes in the Netherlands to compare the average concentrations of one neonicotinoid (imidacloprid) in surface water between 2003 and 2009 with bird population trends over the same period. The comparison was made in different regions across the entire country and focussed on 15 species of common farmland bird that depend on invertebrates during the breeding season.

Yellow wagtail.jpg
Yellow wagtail (one of the farmland birds suffering a decline)

 

The comparison showed that in regions where concentrations of imidacloprid in surface water were higher, population growth rates of these insectivorous birds were lower or negative. Although superficially this suggests that imidacloprid has caused the decline in bird numbers, we first need to rule out alternative explanations for the apparent association.

Hallmann and colleagues consider two possible alternatives: first, the apparent effect of imidacloprid might actually reflect an ongoing decline in bird numbers that predated the introduction of this insecticide; second, the apparent imidacloprid effect might actually reflect changes in land use linked to agricultural intensification. They eliminate both of these alternatives.

Another possible confounding factor that the authors seem to have ignored is the effect of other pesticides. The Netherlands is a very intensively farmed country with more than 60% of land under cultivation. Many different chemicals are used to control pests including imidacloprid. It seems likely that areas with high imidacloprid use will be associated with high usage of other chemicals. Another Dutch group has analysed the large numbers of chemicals present in Dutch agriculture and shown that, in some regions, concentrations of imidacloprid are high enough to kill invertebrates but levels of other chemicals also exceed toxic doses. So, it could be imidacloprid that is leading to the decline in farmland birds or it could be a generally toxic environment. Either way, the conclusion is bleak and ought to make us reflect on the way we are producing our food.

Although the effects of imidacloprid described in this paper are open to interpretation, the evidence against the neonicotinoids continues to accumulate and some authors believe they are having widespread deleterious effects on the natural environment. George Monbiot, writing in the Guardian last week, called for a complete ban on the use of these insecticides.

The Center for Food Safety, a US-based non profit organisation, recently took a different approach to the neonicotinoid problem by asking how much the insecticides actually increase crop yield. Analysing 19 published studies, they found either inconsistent or no evidence that neonicotinoids increase yield. So, astonishingly, dumping neonicotinoids on farm crops has little discernable effect on productivity. Have we all been conned by the agrochemical companies?

 

[picture credits:  “Apus apus 01” by Paweł Kuźniar (Jojo_1, Jojo) – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.

Yellow wagtail” by Andreas TrepteOwn work. Licensed under CC BY-SA 2.5 via Wikimedia Commons.]