Home / Butterflies & Moths / Main Causes of Butterfly Decline
The direct loss of natural and semi-natural habitats such as unimproved grassland, woodland and forest, scrub, heathland, moorland, and wetland due to intensification of farming, forestry and development.
Wetland drainage, France
Changes in the management regimes of semi-natural habitat such as over and under grazing, agricultural abandonment and cessation of woodland management, leading to habitat structures which no longer provide the right conditions for species to breed.
Overgrown grazing pasture
Increasing fragmentation is caused by direct habitat loss and land use change (particularly over-simplification of the surrounding unsuitable habitat â?? the matrix) and may reduce population viability for some species even when habitat quality within remaining patches is high.
Intensively managed farmland leaves remaining semi-natural habitats isolated
A warming climate has caused both upward altitudinal and northwards latitudinal shifts in butterfly distributions. However, many declining species are less likely to expand their distribution northwards because of habitat loss and fragmentation. Climate change can have severe negative impacts on butterflies and their habitats through extreme climatic events such as wildfires, summer drought and very mild winters. In northern Europe, a warmer and wetter climate may reduce habitat quality, by for example longer growing seasons leading to increased grass growth. In tundra habitats climate warming is threatening several endemic species due to more rapid scrub and tree regrowth which threaten open habitats. In southern Europe, climate warming is causing local extinctions and range contractions at the trailing margins of many species.
The increase in nitrogen deposition from agriculture and vehicle emissions is thought to have an indirect effect on butterflies by altering plant communities. For example, nutrient enrichment is encouraging coarse grasses in grasslands and open woodland, and loss of warm microclimates that many species need to breed successfully (e.g. areas of bare ground or sparse vegetation). Nitrogen deposition can also lead to acidification, loss of essential minerals, and imbalance in N/P ratios in caterpillarsâ?? diet.
Manure spreading increases production but can lead to nitrogen deposition in surrounding areas
The use of pesticides, herbicides, and artificial fertilisers has had significant direct effects on butterfly survival and indirect effects by allowing the agricultural intensification of habitats. Neonicotinoid pesticides are used on a wide range of arable crops to control insect pests and there is growing evidence that they are harming bee populations and other pollinators. The decline of widespread butterflies has been correlated with neonicotinoid use.
Spreading fertilizers and pesticides can lead to loss of biodiversity both within fields and surrounding field margins and semi-natural habitats