Spot the Difference
Photographs, words and digital art Nick Sidle
Photograph – Monarch Butterfly, Danaus chrysippus
Monarch Butterflies make an incredible journey every year, they are truly migratory spending the winters in Mexico and California and the summers in Northern America, a round trip of thousands of miles. For a butterfly this is a very big deal, if you think that watching one flutter across a garden in the summer can look like hard work, annually commuting the length of a continent is a staggering achievement. It is also an achievement of a cultural heritage for the species. The trip is made at speeds of around 6 mph which means the journey is longer than the lifespan of a single butterfly, the migration is multi-generational.
Photograph – Monarch Butterfly caterpillar, Danaus chrysippus
Monarch butterflies breed en route, and it takes four generations to complete the movement from Mexico to Canada in the spring. There are also smaller populations outside the Americas, including Australia, which tend to stay in one place but which may have arrived after an even more extended journey. These new populations have particularly become established since 1800, possibly a connection to increased human movement around the world after the industrial revolution, these ‘pioneer’ butterflies may just have hitched a ride.
The migratory groups in the Americas however do not, meaning they must be as efficient at flying as they possibly can be, they need all the help they can get, which brings us to the subject of spots. The Monarch Butterfly is notable in its appearance by the prominent large white spots on the wings. It was observed that close butterfly relatives, which do not migrate, did not have them leading researchers at The University of Georgia to wonder if there might be an advantage from the spots for the Monarch’s exceptional journeys.
Photograph – Monarch Butterfly, Danaus chrysippus
What they found was that the butterflies with larger white wing spots were more successful in migrating long distances but this was, on the face of it, surprising. It might be expected that the more black there was on the wings, the more heat from the sun would be absorbed and butterflies need that heat to get moving. The researchers have suggested that possibly the difference in temperature arising from the difference in heat absorption between the white and black areas on the wings changes air flow and reduces drag making flying more efficient.
Digital art – Monarch Butterflies, Danaus chrysippus
The differences are small, the most successful migrants had 3% less black and 3% more white on their wing markings, so the balance probably has to be ‘just right’.
Whilst that question, like the butterflies themselves, hangs in the air there is also the challenge of navigation. Just like aerodynamics, this must be as efficient as possible, there is no room for expending excess effort and energy by getting lost or taking a long way round. The Monarch Butterfly makes the longest migration of any insect and one of the longest of any animal, they have to have got finding their way right. Put simply, they set off in Canada and end up two months later at specific sanctuary locations in Mexico.
Digital Art – Monarch Butterflies, Danaus chrysippus
What guides their flight? Recordings of signals from neurons in the butterflies’ antennae and eyes were made at The University of Massachusetts and showed that the cues the butterflies would be following were almost entirely from the position of the sun. The system was shown to be based on clock neurons in the antennae and direction (azimuth) neurons in the eyes. These two inputs would have to be integrated to deliver navigation. The team has even suggested that it could be possible to build a robotic butterfly powered by the sun and navigating by its position integrated with an awareness of time, which could follow the Monarch’s migration.
Digital Art – Monarch Butterflies, Danaus chrysippus
So, we have advanced science giving us insights into aerodynamics and the workings of a butterfly’s nervous system and letting us begin to understand how they make one of the great journeys of the natural world. Does this make our technological civilisation the first that can really touch and appreciate what is happening? Not really. Butterflies have an important place in Central and South American cultures, they have been used as symbols on temples in ceremonies and on warriors’ armour as well as decoration on everyday household items. There are gods with butterfly forms, including the Aztec deity Xochiquetzal who was shown as having a human face and arms but the body and wings of a butterfly.
Digital art – Xochiquetzal
The Monarch Butterfly was known as Quetzalpapalotl by the Masahuas people, which translates as ‘daughter of the sun’.
Many Native American beliefs about butterflies link them to spirits and death. Aztec stories have butterflies taking warriors’ souls to their final resting place.
Digital art – Monarch Butterfly, Danaus chrysippus
Specifically, in some communities, Monarch Butterflies were also said to be the souls of children who had died but who have returned to this earth. There is a story related to migration as well. It was told that a group of indigenous American people were on a march to relocate from the Rocky Mountains to central Mexico. It was bitterly cold and the elderly, infirm and young children could not keep up and were left behind. To help try and relieve the cold temperatures, they covered themselves with resin and pollen but it was only a partial reprieve. It was at this point that their God appeared to them and, in an act of compassion, turned them into butterflies so that they could continue their journey and find their families.
Digital art – Monarch Butterflies, Danaus chrysippus, in forest sanctuary
Fir tree forests in the Mexican states of Mexico and Michoacán are said to be the descendants of their parents and kin who waited and welcomed them with open arms, as the trees do for the migrating Monarchs today.
So, can cultural stories ever co-exist with hard science and data, can they ever also have a foundation in what is seen as rigorously tested ‘fact’ based on records and observation? Perhaps the two worlds do come together or perhaps it might be more accurate to say that sometimes the two worlds collide.
Digital art – Monarch Butterfly, Danaus chrysippus
The arrival of the Monarch butterflies in Mexico is very consistent and at their specific Mexican sanctuaries for the winter begins on, or very close to, the 2nd of November each year.
Digital art – Monarch Butterfly, Danaus chrysippus
The 2nd of November is also the generally accepted date of the culturally hugely significant celebration of ‘The Day of the Dead’, the ‘Dia de los Muertos’ in that country.
Digita art – Dia de los Muertos
In that connection, some say that the Monarchs carry the souls of all the ancestors returning for their annual visit to the still living.
Digital art – Monarch Butterflies, Danaus chrysippus, in forest sanctuary
Photographs, test and digital art ©Nick Sidle all rights reserved