Environmental enhancement?

Kenelm Philip fnkwp at aurora.alaska.edu
Thu Jan 17 03:15:45 EST 2002

	A few more examples from Interior Alaska where human disturbance
has benefited butterflies:

1) _Pontia occidentalis_ is a ruderal species. In the wild here it is nor-
mally found on xeric hilltops (where it loves to fly along the edges of
cliffs, luring the collector to over-reach and fall off). It is also found,
however, flying along railroad embankments, and the edges of airstrips.
In 1994 there were a large number of _P. occidentalis_ along the edge of
the Fort Wainwright airstrip in late June. I have also seen this species
flying on airstrips on the North Slope.

2) Dirt roads, and powerline cuts, are excellent collecting sites in
Interior Alaska. Roads are normally considered to be environmental
degradation--and would indeed be such if they covered much of the land
surface. An occasional isolated road through forest or tundra, on the
other hand, provides butterflies with nectar sources (rich carpets of
wildflowers occur along the edges of roads here), and moisture (mud
puddles on the road surface, and moist ditches along the edges). One can
see spectacular assemblages of mud-puddling _Papilio_, _Colias_, _Pieris_,
_Nymphalis_, and _Polygonia_ here--and _Erebia_ are often concentrated on
roadside seeps or in ditches. In the Yukon, there are places along the
Dempster Highway where _Erebia mackinleyensis_, _E. occulta_, _E. rossii_,
_E. fasciata_, _E. disa_, _Oeneis uhleri_ can be found at various times
during the summer flying in roadside ditches, even though some of these
are more ususally found high on scree slopes or above the forest cover
on steep hillsides.

3) There was an odd occurrence just east of Delta Junction on the Alaska
Highway a few years ago. There is a wide powerline cut there, running north
from the highway along the edge of a dirt road, which had been a good
collecting site for some years, with a very large population of _Erebia
epipsodea_. There was a fair variety of vegetation, from wildflowers to
shrubs, and there were a number of dirt berms left from the landclearing
which provided shelter. Then the local electric utility decided to clean
up the powerline cut--and brought in heavy equipment to level the berms,
and cut all the plants down to a few inches high. The butterflies were
severely impacted (though they are slowly recovering as the plants grow
back)--but the second summer after the cleanup there was an amazing
outbreak of the sphingid _Hyles gallii_. There were thousands of them
flying among the profusion of fireweed--the densest concentration of
that moth that I have ever seen.

							Ken Philip
fnkwp at uaf.edu


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