More Red Admirals seen later in year by Garden BirdWatchers 

The British Trust for Ornithology,  (BTO) have a team of people working to monitor, not only birds but other wildlife in people’s gardens, known as  Garden Birdwatch.  In their latest newsletter “Red Admiral resurgence in gardens” Garden BirdWatchers have reported the Red Admiral (Vanessa atalanta) appeared in the highest numbers this year, with unprecedented numbers still being reported in October. I filmed one in my garden 15 Oct, but also saw one on 24th October, during a brief sunny spell. Such a beautiful butterfly, the Red Admiral, is a migrant from Northern Africa and continental Europe. It is not regarded as a resident species, although the immigrant females lay eggs here and it is their offspring that we see in the summer months. The caterpillars use common and small nettles as a food plant, with pellitory-of-the-wall and even hop may also be used. So whether your garden is in England, Ireland, Scotland or Wales, is along the sea shore, in the town centre or even the top of some mountains you may be lucky to see a Red Admiral!

 

Nurturing Nature Red Admiral butterfly

 

As many people will know, here in Britain mammals such a bats, hedgehogs and dormice truly hibernate. Insects do not hibernate in the strict scientific meaning of the word, they go into a dormant state, though for this article I will use the word most people associate with winter inactivity, hibernation! In fact some insects are most active during the winter months, such as the Winter moth, December moth and Spring usher moth. In my garden I saw one 24th October, the latest ever. What do you do if you find hibernating butterflies in your house?

 

 Hibernating  butterflies

It is known insects enter a dormant stage during winter, either as an egg, larva, pupa or adult. A few adult butterflies, namely the Brimstone, Large Tortoiseshell, Comma, Small Tortoiseshell and the noisy Peacock, do hibernate. However, sadly, the Large Tortoiseshell does n’t anymore in the UK as it is officially extinct! A few specimens have been found on the Isle of Wight and photographed by Mathew Oates.,  a National Trust naturalists. Some people find the Peacock and Small Torstoishell in their homes, garages and sheds. I have found Large Cabbage Whites on the inside of my garage roof, during the winter months. They were amongst some Large Cabbage White chrysalises and may have for all I know, emerged from them early during a warm spell and decided to stay there.

Hibernating Red Admirals- A myth?

For much of the twentieth century, although at one time they may well have been a resident, (Fox and Dennis), Red Admirals were considered to be incapable of regularly overwintering in Britain and Ireland and were regarded as immigrants, i.e. visitors that bred in warm weather as opposed to residents.  Indeed according to Thomas (2010) and again in his latest reprint (2014), “Although a few Red Admirals may seem to hibernate in the British Isles during mild winters, these generally settle in exposed places, such as on tree trunks or under branches and usually perish. It is likely that these are late emerging adults that become trapped after the onset of conditions too cold for flight. The few adults that are seen on sunny days from December to February are believed to result from late caterpillars that were able to develop in warm spots”. It is quite possible that this may once have been the case. New and more detailed research has now come up with more up to date information.

Increasing Red Admiral numbers

The recording of increasingly numerous Red Admirals from Citizen Scientist recorders from the long term United Kingdom Butterfly Monitoring Scheme  re-enforces the fact that their numbers are increasing, but this work does not tell researchers much about their phenology over winter period. (UKBMS operates Apr-Sept). 

Fortunately, the national recording scheme (Butterflies for the New Millennium) run by Butterfly Conservation, generates a huge amount of data, recorded by thousands of citizen scientists and professional recorders/researchers, throughout the year.

 

 

Red Admirals winter sightings 2006-07

Fig. 3 The distribution of V. atalanta records in Britain and Ireland during the period Dec 2006-Feb 2007. Dots represent the presence of at least one individual V. atalanta in each 10km x 10 km grid square of the British or Irish Ordnance Survey. (Fox and Dennis)

A new resident butterfly to Britain?

Using this data, Fox and Dennis (2010) studied Red Admiral occurrence in Britain in the winter.

There are several factors that have been considered in this study:

A huge amount of data recorded by of thousands of citizen scientists and professional recorders/researchers;

Significant increase of winter numbers over time;

Significant increase in winter distribution;

Increased winter survival;

Observations of larval activity, survival and development during the winter;

Winter observations of male territorial behaviour, courtship, mating and egg laying;

Observations;

Climate change;

Substantial shift in the phenology of the butterfly.

The records of many thousands of Citizen Science recorders, with observed Red Admiral winter behaviour and recent climatic change,  Fox and Dennis state that under the right conditions, the Red Admiral can successfully reproduce here in the UK all year round and are now once again resident in Britain and Ireland.

Do Red Admirals hibernate?

As far as can be ascertained Red Admirals, do not hibernate. i.e. they don’t enter a long dormant stage as Peacock, Small Tortoiseshell and others do. They seem to simply roost on inclement days and fly around and get on with life on winter days when the weather is better.

Interested in a simple, non complicated Butterfly Conservation app for smartphones?   iRecord Butterflies App

Refs. Besides my own and experiences:

Fox, F. & Dennis, L. H. (2010) ” Winter survival of Vanessa atalanta: a new resident butterfly for Britain and Ireland?  Entomologist’s Gazette 61: 94-103

Thomas J & Lewington R, (2010) & (2014), “The Butterflies of Britain and Ireland” British Wildlife Publishing, Milton on Stour, Gillingham, Dorset.

Thanks to Richard Fox of Butterfly Conservation for his helpful input.