Monday, February 04, 2013

Butterfly Conservation.  State of Britain’s Larger Moths 2013

Britain's leading butterfly and moth conservation organisation, Butterfly Conservation, published on the 1st of February a 30-page report on moths.

The report gives us a sad picture: “Across Britain, the total abundance of larger moths declined significantly, by 28%, during the 40-year period from 1968 to 2007.”

Looking beyond the actual state of moth populations, we must search for reasons for the decline.

“Several studies have shown higher abundance and species richness of moths associated with lower intensity farming practices implemented as part of organic conversion, agri-environment schemes or experimental treatments. In particular, moths benefit from the presence of field margins and boundary features, including mature trees. Conversely, we might assume that the general intensification of agricultural management that has taken place since the 1950s, which has included widespread loss of hedgerows, boundary trees and botanically-rich field margins, as well as the intensive use of pesticides, will have impacted negatively on moths.”

Climate change is discussed at length, but this cannot explain the decline, indeed it is likely that warming has allowed the northerly spread of some species.  “Climate Change…seems to have had both positive and negative effects.”

A paragraph is devoted to light pollution but concludes that “…we do not know whether the massive increase in background light levels in Britain has made any contribution to the trends reported here.”

“Habitat changes, especially those related to agricultural intensification, changing woodland management and urbanisation, appear to have had substantial, largely negative impacts on moths.”

Of course habitat must be key, but we need to look closely, beyond that which can be seen with the eye.  In my area, eastern Lincolnshire, I have noticed a dramatic loss of moths in just the last 10 years, as evidenced by splat numbers when driving at night.  My anecdotal impression is that the decline has been much greater than the 28% figure in the report.  However, in my neighbourhood at least, there has not been an apparent habitat loss; instead there has been a lot of tree planting and leaving of arable field margins and conservation minded management of watercourses over the same period. 

The missing piece from the report is any serious consideration of pesticides.  There is just the one mention, part of the longer sentence from  page 19, quoted above, “…as well as the intensive use of pesticides.”  And no mention of neonicotinoids.  This is particularly surprising in the light of the current public debate about neonicotinoids impacting on bee populations.  Accumulating scientific research has now led the EU Commission towards introducing legislative controls.

Why does the Report duck what is likely to be the most significant issue, completely?

Butterfly Conservation News Blog:

Download the Report: State of Britain’s Larger Moths 2013.