Recent research about butterflies losing colours due to global warming and biodiversity loss has caused entomologists and greens to sit up and take notice of the startling revelation. While some experts concur with the studies, others see no link between temperature, biodiversity and insect colours. TreeTake takes a look …
“Butterflies go fluttering by
On coloured wings that catch the eye.
On wings of orange and silvery blue,
On wings of golden yellow, too.”
Unfortunately, the very colours that inspired many to pen poems on butterflies, the fairies of the insect world, appear to be fading, going by recent studies that warn of an adverse impact of rising temperatures and deforestation on the vibrant hues.
The Centre for Wildlife Studies (CWS) India Facebook page shared an article linking deforestation to butterflies losing their vibrant colours, indicating that as forests were cut down, the remaining butterflies were often duller, showing a decline in the diversity of colourful species. This happened because the loss of tropical forest habitats led to a loss of the specific environmental conditions needed for bright colours to function and evolve.
Deforestation removes the specific habitats where colourful butterflies thrive. Scientists have also observed a pattern where deforested areas have a lower proportion of bright-coloured butterflies compared to well-preserved forests. They say that a decrease in colour diversity in butterfly populations can signal a decline in overall ecological health. Experts link this trend to human activities like cutting down forests and agricultural exploitation, which replace habitats with less diverse ecosystems.
A study on the Amazon rainforests said that due to deforestation, butterflies were forced to adapt rapidly which affected their appearance and the ability to survive According to Ricardo Spaniol from the Federal University of Rio Grande do Sul, after deforestation, the most colourful species were often found to be the ones that disappeared first, as the native vegetation cover was lost and they were exposed to predators. He said this represented an accelerated process of discolouration in Amazonian butterfly communities. Another study found that rising temperatures affected the behaviour and life cycle of butterflies, too, apart from their colours. It said some species had shown changes in their patterns of reproduction.
The loss of colour diversity could also be an indicator of the health of other organisms in the ecosystem, he said. It was a cause of concern for the researchers that these changes might be signalling more negative, cascading effects for different species and ecosystems.
As per experts, butterflies can lose their colours due to ageing, damage to their wings, or environmental factors like light exposure, habitat loss, and climate change. Ageing butterflies lose scales, while pigments in some scales can fade over time, and damage from extreme weather can also cause a loss of pigmentation.
Causes of colour loss
Ageing is one of the reasons. As butterflies age, they naturally lose the tiny scales on their wings, which causes their colours to fade and their wings to look more transparent or tattered. Pigment breakdown is another reason. The chemicals that create pigmented colours can break down over time. Extreme weather can have an adverse impact. Events like droughts and floods can damage a butterfly's wings, leading to a loss of pigmentation.
Habitat loss is a key reason. Deforestation and the simplification of ecosystems can also impact colour. Scientists have observed butterflies in degraded habitats becoming duller, which is a symptom of environmental stress. Cutting down trees drastically affects the environment. Brightly coloured butterflies, which evolved to blend in with vibrant natural foliage, are more easily spotted by predators in simplified, degraded landscapes.
Studies have shown that the most colourful species are often the first to disappear locally after deforestation, replaced by duller, earth-toned species that are better suited to the new environment. Light exposure also has a drastic effect. Butterflies in collections can lose their colour because light causes the pigment chemicals to break down over time.
The phenomenon of butterfly populations losing colour is known as ecological discolouration, which occurs due to habitat loss, which forces colourful, adapted species to become duller or disappear, making them more vulnerable to predators. However, it is a signal of ecological degradation. This loss of colour isn't just a loss of beauty; it's a measurable signal that an ecosystem is becoming degraded and less complex.
But as long as there is hope for restoration, all is not lost. Fortunately, research shows that as forests regenerate, the brighter species can begin to return, indicating that restoration efforts can help bring back colour and diversity.
Colour is important
The colourful wings of butterflies have evolved over millions of years. In shady forests, they function with the help of colours. So, in places where forests have been cleared or where monoculture has been adopted, a decline has been seen in brightly coloured butterflies, say experts. It is worrisome, as it is an indicator of habitat degradation.
Survival: Colour is important for a butterfly’s survival. It provides the pretty insect camouflage and alerts it against predators.
Reproduction: Fading colours can make a butterfly less successful at attracting a mate and reproducing.
Dr Geetanjali Mishra of the zoology department, Lucknow University, said: “Butterflies are losing their vivid wing colours primarily because of deforestation and the replacement of rich, colourful tropical forests with monochrome human infrastructure like buildings and plantations. These vibrant hues are not just aesthetic. They play a crucial role in survival. Bright colours help butterflies attract mates and evade predators through camouflage or warning signals. As natural habitats are replaced with dull, uniform environments, butterflies adapt by becoming less colourful, which may reduce their chances of reproduction and survival. This phenomenon is a stark reminder of how human activity can subtly but significantly alter the natural world. Similarly, flowers are losing their colour and attractiveness due to the decline in insect populations, especially pollinators like bees and butterflies. As insect numbers drop by as much as 40% globally over the last 150 years, plants are evolving to become less visually appealing because there's less incentive to attract pollinators. Some flowers are even shifting their blooming phases, leading to mismatches with insect life cycles. This breakdown in the ancient flower-insect relationship threatens pollination, plant reproduction, and food security. To combat this, ordinary people can take meaningful steps. Supporting reforestation initiatives, planting native flowering plants, and creating butterfly-friendly gardens can help restore vibrant habitats. Reducing the use of pesticides and advocating for green urban planning also contributes to healthier ecosystems. The loss of butterfly colouration isn't just a cosmetic change; it signals a deeper ecological imbalance. Diminished butterfly populations can disrupt pollination networks, affecting plant reproduction and food chains. Moreover, the fading colours symbolise a broader loss of biodiversity and natural beauty, reminding us of the urgent need to preserve the richness of our environment.”
Elaborating further, she said: “One major factor is temperature. It also affects colouration. It changes the vibrancy of colours, which is one factor. Secondly, one must understand that the colours of most insects evolved through coevolution between flowers and insects. So, the greater the plant diversity, the more brilliantly coloured the insects become. So, plants developed their colour and scent to attract insects, and the pigmentation they take from them develops the colours of insects. So, both of these factors have an impact not only on butterflies but also on plant diversity overall. Some studies suggest that when insect populations decline, plants begin to reduce the size and colour of their flowers. The same reversal is also true here: if plant diversity is declining or deforestation is occurring, insects will lose their source of nutrition, which is very important in colour development. Hence, on the one hand, there is a direct effect of temperature, plus the deforestation that is causing the loss of flowers and consequently a lack of nutrition, which is also affecting colour. And the reverse effect is that as insects decrease, plant diversity will decrease. Fragrance and flower colour will also decrease. So, it's a loop.”
“Butterfly colours are also physical, not just pigmentary. Butterflies belong to the Lepidoptera group, and Lepidoptera means scaled wings. So, butterflies have scales, and those scales would stick to our hands if we catch a butterfly. Each individual scale is covered with different types of three-dimensional structures, nanostructures that act like multiple reflective layers. Each structure reflects reflections. Those reflections are responsible for the colours. We need to save the Earth. Reforestation is essential. Controlling global warming is important. The scale at which these changes are occurring is massive. If we don't reduce pollution, global warming, deforestation, and fundamentally limit the spread of humanisation, it will be very, very difficult. This is the start of a downward spiral,” she added.
Naturalist Ankush Dave said: “The colour of butterflies reflects their ability to maintain their body temperature. Darker butterflies absorb more heat from the sun, increasing their body temperature. Therefore, butterflies living in colder regions are typically darker in colour. Butterflies in areas with already high temperatures are typically lighter in colour to help reduce the increase in body temperature. Global warming is causing temperatures to rise everywhere, and butterflies living in hotter regions are becoming lighter in colour to adjust to the heat. Similarly, some darker butterflies migrate from warmer regions to cooler regions, or sometimes to higher altitudes in the mountains, to maintain their body temperature.”
However, Dr N Srinivasa and Dr Kamal Jaiswal of BHU did not concur with the view, saying they saw no direct connection between global warming or deforestation on insect colours. But it did mean that they were not getting a good environment, they said. Prof V Elangovan of the department of zoology, Baba Saheb Bhimrao Ambedkar University, Lucknow, said: “Habitat destruction definitely causes the loss of biodiversity, which includes butterflies also. But we need to study more to determine if it is impacting the characteristics or characteristic features of any organism. It may be that they are adapting to changes in their surroundings. If an organism wants to survive, it needs to change according to the changing climatic conditions. Only then can it sustain; otherwise, it will perish. But overall, we cannot say that all butterflies are changing colours. The butterflies need to merge with the host plant colouration to escape from predation. These are all possibilities. But I cannot say that due to habitat destruction, butterflies are changing colour. Habitat destruction is different. Colour change is different. Light change is possible because of pollution or due to industrialisation, and the animals may adapt to certain conditions. It is also very well proved.”
Naturalist Dr Mukul Pandya said it was quite possible that this was happening and that there was an urgent need for corrective steps like checking biodiversity loss and planting more such shrubs that acted as host plants for butterflies. “All this deforestation, climate change and biodiversity loss is happening because of our greed. Butterflies’ colours may be diminishing. I fully agree with this. I wish there were similar studies done here. However, this is absolutely possible. It happens that many butterflies mimic plants to protect themselves from predators. Some butterflies carry poisonous substances inside their bodies, extracting them from plants so that birds won't feed on them. And some butterflies are such that they mimic them because their predators know that this is a very brightly coloured butterfly, and it might contain some poisonous substance. So, if biodiversity decreases, then this poisonous substance is likely to reduce the colours of these butterflies and their populations. And this is already happening. We remember when we went anywhere as children, we used to see a lot of butterflies. Now, we do not find so many butterflies either in our gardens or in places where there is good biodiversity. There are butterflies, damselflies, and dragonflies, but not as numerous as they should be. It is great that in some places, like Lucknow, they have built huge parks. But I think that in the parks that have been built, a lot of trees of the same kind have been planted. Instead of having a monoculture, they should have used at least five to six different kinds of plants. And whenever any park or any such thing is developed, they should talk to an expert there and get those shrubs planted that are host plants for butterflies. This will increase biodiversity. But unfortunately, development authorities have the least idea about biodiversity.”
What can be done
To prevent live butterflies from losing colour, their habitats should be protected by avoiding chemicals and maintaining suitable environments with shady spots. Habitat loss should be checked by protecting ecosystems, as monoculture and deforestation lead to a loss of biodiversity and can affect the vibrant colours of butterflies. One should minimise chemical use in the garden, such as pesticides, which can be lethal to butterflies and their caterpillars.
To protect them from climate change, it should be ensured that there are shady spots available, especially in warmer climates, to help them regulate their body temperature, which can affect their colour and overall health. One should avoid touching butterfly wings, as it can remove the coloured scales, causing them to fade over time. Dr Andrew Bladon of Cambridge University was reported as saying: “We need to make landscapes more diverse to help conserve many of our butterfly species. Even within a garden lawn, patches of grass can be left to grow longer – these areas will provide cooler, shady places for many species of butterfly. In nature reserves, some areas could be grazed or cut, and others left standing. We also need to protect features that break up the monotony of farm landscapes, like hedgerows, ditches, and patches of woodland.”
To sum up, there are two main solutions to the discolouration of butterflies and ecosystems at large. The first is protecting habitats, preventing further degradation and the development of more monoculture forests. Indigenous communities can, and do, play a critical role in the protection of these forests and ecosystems worldwide. The second key solution is in restoration. Research has shown that forests that were left to restore for 30 years showed key increases in butterfly biodiversity. So even where natural habitats have diminished, there is still hope to bring back the true colours of these delicate, pretty insects, which show a flash of colour whenever they fly by.
Making a butterfly garden
Butterflies need both host plants, where they lay their eggs, as well as nectar plants, which provide them with nutrition. Good host plants in India for butterflies include curry leaf and citrus plants (for swallowtails), milkweed (for Monarchs), Bael (for the Common Mormon), castor, passion fruit, and Aristolochia indica. These plants serve as food for caterpillars, helping to sustain the lifecycle of butterflies in the garden. Flowering plants like dahlia, zinnia and marigold, etc., would provide nectar. To make a butterfly garden, one should plant native species to provide the most beneficial environment for local butterflies. There should be both host and nectar plants. While host plants are crucial for caterpillars, adult butterflies also need nectar. The plantation should be in clumps to make them more visible to butterflies. Most importantly, no pesticides should be used to keep butterflies and caterpillars safe.
Butterflies have an important role as bio-indicators. They are pollinators, part of the food chain and act as climate change barometers too. It is time everyone did their bit for the winged jewels who add that extra dash of colour to a garden, for would anyone want to live in a less colourful world? ([email protected])
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