Red Admiral at windfall fruit

Any sunny spell of weather these days and you are likely to come across a Red Admiral, basking or  nectaring on flowering Ivy. Red Admirals are generalist butterflies and late flowering Buddleia, Asters or other late blooming bushes will be used too. Red Admirals are also partial to fruit, and rotting, windfall pears or apples attract many individuals. Last week, a pear and an apple tree at a car park provided a glut of food for Red Admirals and wasps alike. About a dozen Red Admirals were around, either feeding on the fruit under the trees, wings closed, or basking on leaves with their wings fully open. Wasps were also feeding on the fruit, but the butterflies were not keen on sharing their table, so every time a wasp got too close the Red Admiral flicked its wings open (top shot) and flushed it out.

A basking fresh individual.

Red Admiral's admirable camouflage

A Red Admiral flew into the cherry tree as I was in the garden. I had seen where it had landed and how it positioned itself head down and as I looked for it I realised how wonderfully camouflaged, matching the colours and patterning of a branch. Can you spot it? If you can't I have cropped a photo at as slightly different angle, showing the antennae. I then made a sudden movement and the butterfly slightly opened its wings, exposing the red marks on its forewings (bottom photo). It had started to rain, and it was much cooler so the butterfly will probably spend the night roosting like that in the tree, well concealed from visual predators.

The patrolling Red Admiral

Since the beginning of June, Red Admirals have been well established, having returned from the Mediterranean in their one way spring migration. Females should be mating and looking for sunny nettle patches in which to lay their eggs. Males should be looking for receptive females to mate with. They will produce one or more broods in the summer. As temperatures drop in the autumn, butterflies will prepared themselves for the autumn migration and then they become very apparent in gardens, where they feed on buddleia and other nectar rich flowers. Male and female have the same wing colour pattern. If you have a good view of the abdomen when the butterfly is resting with its wings open, a swollen abdomen will allow you to identify a female, but otherwise it might be easier to tell them apart by their behaviour in early summer.
 Last week, in the afternoon, I have flushed a Red Admiral from the same sunny spot on a grassy area amongst trees, where they were sitting day after day, exactly where I often found them last year. This afternoon was unusually warm and, as I left work, a Red Admiral sat on a low hedge on a wooded glade teeming with nettles in our university campus (above). It would sit and then fly up patrolling around the trees and chasing passing bumblebees in a similar way a Speckled Wood male would do, and then return to the same perch. I had never noticed this behaviour in the Red Admiral, but it appears that I had observed a male, and that red Admiral males actually defend territories. It might seem hard to believe that beautiful, fluttery butterflies actually engage in any kind of aggressive interaction. Indeed, butterflies have no offensive weapons other than their wings, and, butterfly contests, even when they are defending a territory are often perceived as chases instead of aggressive interactions. However, there is now abundant research showing territorial behaviour in a number of butterfly species. The important point is not the presence of an actual fight but the outcome: as a result of the behaviour the owner remains in the territory and the intruder flies away. Royce Bitzer and Kenneth Shaw studied the territorial behaviour of the Red Admiral on the Iowa University campus. They captured and marked individual Red Admirals with different spots of paint and observed their behaviour once released. They found that Red Admirals spend the morning feeding, but each evening males establish temporary territories for a couple of hours before roosting. Males spent most of their time perched, but occasionally patrolled their territory boundaries. They were not seen feeding. Birds or other butterfly species were chased in a linear way, but male intruders are chased upwards in a spiral. In Red Admiral chases, the owner often retains ownership and the intruder flies away. Good territories are likely to be an area containing resting spots from where passing females can be easily detected, usually with linear features (e.g. a pavement or a few trees in a line). The maintenance of these temporary territories could allow better access to receptive females moving into their roost, as mating is thought to happen in the roosting sites in trees.

A particularly bright red and intact individual, maybe the result of a first local brood?

Two days later a much more faded individual with tattered wings, on the same favoured spot on the grass.

More information
Red Admiral and Painted Lady Research Site. Here.

Bitzer, R. J., & Shaw, K. C. (1979). Territorial Behavior of the Red Admiral, Vanessa atalanta (L.)(Lepidoptera: Nymphalidae). Journal of Research on the Lepidoptera, 18(1), 36-49. here.

Three bright characters for the end of August

Some invertebrates appear as heralds of autumn, and today three striking ones were present in the garden. Migrant Hawkers have been around for a while, forming loose swarms that hunt between 2 and 8 m high, often well away from water. In the cooler, shorter days of late summer it becomes easier to come across sunbathing ones, perched on a branch, often more than one near each other. I flushed this male a few times as I went about in the garden, until I finally spotted him hanging from its perch. I got so close taking the macro above that I could have kissed him.

A single Red Admiral was also about, alternating between feeding in the buddleia and basking on a brick wall. During sunny spells she closed its wings, while during passing clouds she revealed its fresh, amazingly marked wings to their full splendor. This was a beautifully marked individual, the small, delicate blue markings on the edge of its wings very apparent.

I used the flash to counteract the sunshine and reveal the intricate patterning of the underwings, which can make the butterfly well camouflaged.

This garden spider, Araneus diadematus, is one of the largest in the garden, she hangs her web on the side of the rubbish bin, and has her retreat under the rim. Given the size of this species, detailed inspection of the epigyne is possible without even disturbing the spider (click on the photo to see it).

Red Admiral showing and hiding

 A fresh female Red Admiral basked on a sycamore trunk, probably with a full stomach after feeding on an early flowering buddleja nearby. It sat there wings outstretched, showing its bright, contrasting colours for a while, but then it decided it had enough and folded them, revealing its remarkably cryptic underside.

Little riders on the wind

The mass influx events of Painted Ladies - such as during the summer of 2009 - and wildlife documentaries on the Monarch Butterfly have made butterfly migration familiar to everybody. Many butterfly species are now known to carry out bidirectional migrations, for those of the northern hemisphere, towards the north in the spring and towards the south in the autumn. Surprisingly, the extent of fascinating behaviour was only recognised relatively recently. Up to the 1930s, the only butterfly that was acknowledged to migrate was the American Monarch, Danaus plexippus, with evidence for migration in other species dismissed even from experienced entomologists and lepideropterists as "overflow": one way dispersal movements from successful, very dense populations. One early researcher was set to change matters: Carrington Bonsor Williams (widely known as C.B.), from Rothamsted Experimental Station in the U.K. He was passionate about insect migration and amassed large amounts of data on the subject, in Britain and abroad. In his 1930 book Migration of Butterflies and later work, he presented evidence for migration for over 200 species of butterflies worldwide, including support for return migration. He also helped organise the collation of data collected by naturalists across the U.K. on insect migration. His analyses of these data gave strong evidence for migration for six species of British butterflies: the Painted Lady, Small Tortoiseshell- which also hibernates in the U.K. - , Red Admiral, Large White, Clouded Yellow and Pale Clouded Yellow. For the Red Admiral, the records  showed clearly a dominant proportion of individuals flying in a northerly direction up to the end of July, and a southerly direction during September and October:

(Figure from Williams 1951)

In the case of the Painted Lady and the Large White, the lack of evidence for a return migration puzzled Williams:

I have already (Williams et al. I942, p. 250) pointed out the difficulty of accounting for the persistence of a habit of movement in one direction only on any theory of evolution. If we accept that directional movement in butterflies is simply an overflow from an over-populated area, and that none of the emigrants ever return; then the species must be perpetuated by the offspring of those individuals which do not emigrate. Thus a habit must persist for countless generations, in spite of the fact that all  individuals which develop it die without contributing to the continuity of the species.

He was optimistic though, and correctly predicted that return flights would be found in all species once enough research effort was put into it, making butterfly migration as important a phenomenon as that in birds. Indeed, recent research - some of it carried out in Rothamsted - including meteorological analysis of prevailing winds when influxes of Painted Ladies occur, and entomological radar research has shown that the Painted Lady taked advantage of tailwinds as a migratory aid and that the reason that these flights were not detected is that they fly at high altitude.
 Migrating butterflies are tracking suitable breeding grounds, areas where larval food plants are abundant. Red Admiral caterpillars feed on fresh, rapidly growing nettles. At the end of spring, nettles start to wither in the Mediterranean winter grounds, so the spring Red Admiral adult generation flies to Northern Europe - and also up mountains - where nettles are luscious. They mate and lay eggs in the north and the resulting autumn generation of adults migrates due south in the autumn.

(Figure from Mikkola 2003)
Unlike birds, butterflies breed both in the winter and summer grounds, and also unlike birds, each generation makes a one way trip, leaving the return journey to their offspring.
(Photo above, a fresh, autumn generation Red Admiral feeding on Cherry Laurel, 19 Aug 2011)

References
Williams, C. (1951). Seasonal Changes in Flight Direction of Migrant Butterflies in the British Isles The Journal of Animal Ecology, 20 (2) DOI: 10.2307/1537

Kauri Mikkola (2003). The red admiral butterfly (Vanessa atalanta) is a true seasonal migrant: an evolutionary puzzle resolved? European Journal of Entomology, 100, 625-626


Stefanescu, C., Alarcon, M., & Àvila, A. (2007). Migration of the painted lady butterfly, Vanessa cardui, to north-eastern Spain is aided by African wind currents Journal of Animal Ecology, 76 (5), 888-898 DOI: 10.1111/j.1365-2656.2007.01262.x

Chapman, J., Nesbit, R., Burgin, L., Reynolds, D., Smith, A., Middleton, D., & Hill, J. (2010). Flight Orientation Behaviors Promote Optimal Migration Trajectories in High-Flying Insects Science, 327 (5966), 682-685 DOI: 10.1126/science.1182990

A november gift

Each passing day is shorter and with a weaker sun than the previous one, and each Red Admiral sighting feels like a lovely gift. This afternoon, a battered individual sat basking on the fence, cleaning its head, with its body and wide open wings angled, casting a long shadow, capturing the maximum warmth of the sun. After a few minutes, it fluttered to the Erysimum and fed on it. For a while, it alternated feeding - later on the flowers already in the shade - and warming.

Queens, harlequins and admirals

The last mild, sunny days of autumn are bringing out scores of insects. Standing under a large flowering ivy today the sound of buzzing bees, bluebottles, droneflies and wasps was extraordinary, especially given that November is only a couple of days away. Yesterday, six red admirals sunnied and gorged themselves on the ivy blossom. They are charging batteries before their migration to South Europe and North Africa.

Red Admiral and passing droneflies on ivy

 A green shieldbug, Palomena prasina, climbing a tree.

 Today, a queen Bombus hypnorum fed on lavender flowers. 

 A female Araneus diadematus spider sat proudly on her silky egg cocoon. 

Honeybees on ivy flowers

Dozens of harlequins and 7 spot ladybirds flew about landing on a sunny wall and leaving again.

September bugs

There is a definite autumnal feel these days. Shorter days, ripening berries and leaves already changing colour. September, however, is a month plentiful on all sorts of bugs. During a walk in our local Millennium Wood, Oppy Wood today, we spotted five butterfly species, Comma, Speckled Wood, Small Tortoiseshell, Red Admiral and Large White. We watched Commas and Speckled Woods sucking the sweet juice of ripe Blackberries.

There were plenty of Daddy Long Legs (tipulidae). Some of them mating.

A couple of Migrant Hawkers patrolled above our heads. A male (top) eventually stopped to rest, hanging from some low branches. He let me get really close to him for some shots.

There also were grasshoppers about - possibly Lesser Marsh Grasshopper, Chorthipphus albomarginatus - 7 spot ladybirds, froghoppers and wolf spiders.

A male Lesser Marsh Grasshopper

Big Butterfly Count

In the last few days, I have been carrying out surveys for the Big Butterfly Count. I did a count in my garden (5 sp.), two in a local wildlife garden (5 and 6 sp.) and two in a local cemetery (3 and 6 sp.). Given the weather, mostly cloudy with some sunny spells, I am quite pleased with the results. Their results website is quite good with an interactive map where you can check the results submitted at a local scale or for a particular species (over 10,000 surveys already submitted) here. The following photos illustrate my results.

 A Common Blue male today, feeding on oregano. The male regularly patrolled his territory in the wildlife garden, stopping occasionally to feed.

Gatekeepers were plentiful today. This female rested on a Knapweed plant.

My local cemetery has a thiving population of Speckled Wood. Lots of territorial disputes were going on yesterday.

This Red Admiral took advantage from a brief sunny spell yesterday near a buddleia growing in the local cemetery.

This is the first year I see Small Coppers in the wildlife garden.

A Holly Blue feeding on lavender

A Common Blue female on Oregano.

Two small whites courting, the females abdomen raised meaning 'not interested'.

Two female Small Whites sunbathing.

Hovering high

Today I read a very interesting paper by David Lack (of fame as an ecologist and evolutionary biologist for his bird studies and his books, of which 'The Life of the Robin' is my favourite). He described his observations on a day of October on top of a high Pyrenean pass. In addition to various flock of migrating birds, he accounts in detail how large numbers of butterflies (mainly Red Admirals and Clouded Yellows) and Common Darter dragonflies (Sympetrum striolatum) steadily crossed the pass towards the Spanish side. That birds migrated had already been well established, but insect migration was then a much more recent, still controversial phenomenon.Lack felt provileged to have witnessed such extraordinary phenomenon, and the feeling was probably enhanced by the beauty of the surrounding mountains, at 2227 m altitude. He wrote "Once in a lifetime perhaps, the ecologist is translated back into a naturalist, through chancing on a spectacle which combines grandeur with novelty. Such was our fortune at the Port de Gavarnie on 13 October 1950."

Cirque du Gavarnie (Photo by Marando-fr, Wikipedia Commons)

Lack's was the first account of hoverflies migrating. In his own words:

Not until we had been at the pass for over an hour did we realize that another insect was migrating, so we do not know whether it was passing from the start. This was a hoverfly, the two collected specimens being males of Episyrphus balteatus. All the other individuals looked the same, and we have no reason to think that any other species was present. The syrphid flies, like the dragonflies, flew steadily forward WSW. against the wind, keeping extremely close to the ground, where the wind was, of course, weaker. Very occasionally one settled for a moment, but otherwise they travelled steadily onward. An estimate of numbers was impossible, but at a guess they were at least twenty times, and perhaps a hundred times, as numerous as the dragonflies. They were the most remarkable migrant of all.

Today there were many E. balteatus in the garden. To think that such tiny, flimsy looking hoverfly, is able of such powerflul climbs and long voyages! It is just plainly amazing.

Episyrphus balteatus on Cat's ear (summer 2006)

A close up. Today, on an ice plant.

Reference
Lack and Lack (1951) Migration of insects and birds through a Pyrenean pass. Journal of Animal Ecology 20:63-67.