I posted a note to my butterfly list to ask if anyone knew if there was
evidence whether increased lights at night may have affected populations of
insects that Nighthawks prey on. This response below from one of our area's
entomolgy professors cites a British study that indicates that lights appear
not to have caused a decline in the larger moth species, but that there
still has been a severe decline in the populations of the larger moths
something like Dennis Paulson reported for the SE US insect populations and
I expect has also occurred in the Pacific Nothrwest. While increased crow,
possibly gull and maybe increased cat predation may be enough alone to
account for the great decline in "Common" Nighthawks, it could be expected
that a much lower population of large insects prey species would by itself
also lead to a much lower population of Nighthawk predators.
Stewart Wechsler
Ecological Consulting
West Seattle
206 932-7225
ecostewart at quidnunc.net

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-----Original Message-----
From: NorWestLeps at yahoogroups.com [mailto:NorWestLeps at yahoogroups.com]On
Behalf Of David James
Sent: Tuesday, July 11, 2006 7:49 AM
To: NorWestLeps at yahoogroups.com
Subject: Re: [NorWestLeps] FW: [Tweeters] nighthawks and insect abundance


In a paper just published (Biological Conservation Vol 132 (2006) pages
279-291), Kelvin Conrad and co-authors from Rothamsted and Lulworth in the
UK, show (using light trapping indices) that two thirds of 337 British
'macro-moths' have declined during the past 35 years. Seventy one of these
are declining so fast that they would be considered 'endangered' under world
conservation guidelines.

The issue of 'astronomical light pollution' from increased urbanization was
addressed as being a possible reason for moth species declines. However,
contrary to expectations moth declines at 'dark' (ie rural) sites were
actually slighter greater than at 'light (metropolitan) sites.

The authors conclude that common and widespread macro-moth species in
Britain are undergoing severe population declines, unaffected by light
competition. Instead, they point the finger at widespread deterioation of
suitable environmental conditions. A similar decline has already been
described for British butterflies and the authors suggest that these data on
the lepidopteran fauna of the UK signal a 'biodiveristy crisis' for Britain
and are a strong indicator that insects may be undergoing great losses in
other temperate zone industrialized countries.

It is very likely that a similar degradation of our lepidopteran fauna is
occurring in the PNW.

Dr David G. James
Associate Professor
Department of Entomology,
Washington State University,
Irrigated Agriculture Research and
Extension Center, 24106 North Bunn
Road, Prosser, Washington 99350
.

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