Pocket-Sized Paradises Welcome Butterflies to Cities

Andrea Reiman

Pocket-Sized Paradises Welcome Butterflies to Cities

Urban gardens can attract some of nature’s most beautiful pollinators. A new study brings us on an exciting journey to understand the nuances of complex networks of butterflies and flowers. Scientists use this new information to recommend the best flowers to sustain urban populations of both common and rare butterflies.

Mukherjee, Swarnali et al. “Butterfly-plant network in urban landscape: Implication for conservation and urban greening.” Acta Oecologica 92 (2018) 16-25 DOI: 101016/2018.08.003 

Butterflies are best known for their beauty. Yet, people may not know that they’re hard-working community members. Butterflies spend most of their time pollinating- a process required for successful plant regeneration. Their work benefits both natural ecosystems as well as man-made farms and gardens.

Recently, pollinator populations have been crashing. Urban expansion and farming are taking their toll. While metropolitan hubs may be the land of opportunity for humans, they don’t tend to offer much to pollinators.

How can cities become more welcoming to pollinators?

These are the questions that Dr. Swarnali Mukherjee and her team of researchers at India’s University of Calcutta have been attempting to address. In a recent study published in the journal Acta Oecologica, they study how small gardens of flowering plants sustain butterflies in cities. The researchers observed experimental gardens to find out which butterflies fed from the flowers of which plants. The team planted 30 varieties of wildflowers in small gardens throughout Kolkata, hoping to lure a variety of butterflies. The butterflies did not disappoint. Hundreds of butterflies from nearly 50 different species visited the gardens.

The authors designed a “flower power” ranking system, using their observations of butterfly feeding activity in the gardens. Plants that attracted many butterfly species were called generalists. Plants that attracted only one, or a small number, of butterfly species were labeled specialists. Each butterfly species was also classified as either generalist or specialist. This classification system helped the team to understand the complex butterfly-plant ecological network.

Building upon previous research about butterfly feeding habits, the authors discuss how small gardens can be used to attract a great variety of butterfly species. Butterflies sense the color, shape and nectar production of a flower – the flower’s functional characteristics - before settling down to drink. These characteristics influence whether a flower will attract a variety of generalist butterflies or a smaller number of specialist butterfly species. Knowing these traits can help scientists select flowers for gardens to conserve butterfly populations.

This study shows that by growing flowers in even the smallest of spaces, people in cities can play an important role in protecting butterfly populations. At a time in which human activity is driving many species to extinction, it is encouraging to see that we can help the planet’s ecosystems stay healthy and keep people fed by creating something beautiful.

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