Pesticides, paving and higher temperatures have put huge strain on butterflies in cities over past two decades, finds study
Thursday 16 February 2017 06.01 GMT
Butterflies have vanished from towns and cities more rapidly than from the countryside over the past two decades, according to a new study.
Industrial agriculture has long been viewed as the scourge of butterflies and other insects but city life is worse – urban butterfly abundance fell by 69% compared to a 45% decline in rural areas over 20 years from 1995.
Butterfly species such as the small copper and small heath have suffered particularly disastrous urban declines, according to the study published in the journal Ecological Indicators.
Scientists at Butterfly Conservation, the University of Kent and the Centre for Ecology and Hydrology found that numbers of small heath fell by 78% in urban areas compared to just 17% in the countryside, while small copper abundance fell by 75% in urban areas compared to 23% in the countryside.
Prof Tom Brereton, head of monitoring at Butterfly Conservation and one of the study’s co-authors, said causes included heightened effects of climate change in cities, building on urban green space, the loss of surprisingly wildlife-rich brownfield sites, council cuts and the neglect of parks and pesticide-wielding gardeners who have also turned lawns and flower beds into driveways and patios.
He said: “Urban areas are under massive pressure. People are paving over gardens for drives or patios and putting more pesticides on their gardens per area than are put on farmland. Bigger gardens are being sold off for development and councils have less resources for managing green spaces.”
The study, which compares trends for 28 species in urban and countryside environments, found that most urban butterflies are emerging earlier and are longer-lived than the same species living in rural areas.
On average, city butterflies emerge two days earlier than their country cousins. Urban brimstones are on the wing five days earlier than those found in rural locations.