The Decline of Urban Butterflies
[photographic credit: Edward Badley, Flickr]
In 2014 the United Nations stated that by 2050, 66% of the world’s population is projected to be Urbanised. Cities are considered vital for development, and poverty reduction by concentrating economic activity and creating transportation links to rural areas. This link to urban society is associated with better education, health, and opportunity. But what are the impacts on our native wildlife?
One surprising impact of cities is the effects on butterfly phenology, a study by Diamond et al. (2014) found that the urban environment had similar phenology delaying effects to climate change. Similarly, a study by Dennis et al. (2017) showed that urban populations of UK butterflies have shown to be facing greater declines compared to rural populations. This is thought to be due to many environmental pressures that are heavily associated with the urban environment, including fragmentation of habitat, small often concreted gardens and pollution.
The study (Dennis et al. 2017) also found that certain species of British butterflies are more likely to suffer in the urban environment, such as the Brown Argus Butterfly Aricia agestis, which favors calcareous grasslands, where the food plant Rock-rose Helianthemum nummularium is found (Butterfly-conservation.org, 2018). In contrast, more generalist species including the whites understandably were more abundant in city landscapes.
Monitoring urban butterfly species is increasingly important due to current trends in populations. We can all help protect British Butterflies by taking part in citizen science projects such as the ‘Big Butterfly Count’, ‘Migrant Watch’ and many more!
Click the links below to find out more.
United Nations Department of Economic and Social Affairs, Population Division
World Urbanization Prospects: The 2014 Revision, Highlights (ST/ESA/SER.A/352)
S.E. Diamond, H. Cayton, T. Wepprich, C.N. Jenkins, R.R. Dunn, N.M. Haddad, L. Ries
Unexpected phenological responses of butterflies to the interaction of urbanization and geographic temperature
Ecology, 95 (2014), pp. 2613-2621
Emily, B. Dennis, Byron, J.T., David, B. and Tom, M., 2017. Urban indicators for UK butterflies. Ecological indicators.
Butterfly-conservation.org. (2018). Butterfly Conservation – Brown Argus. [online] Available at: https://butterfly-conservation.org/50-1301/brown-argus.html [Accessed 14 Feb. 2018].
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