Size of the overwintering monarch populations - published data.
Chip Taylor
chip at ku.edu
Mon Oct 13 13:32:48 EDT 2003
>
>
>My take on the concern is that if %-mortality becomes very high, then in one
>of the down reproductive years, essentially the entire overwintering
>population could be wiped out, erasing the phenomenon (but not the species).
John: Your conclusion doesn't really differ from the one I offered in
response to Stan. If the returnees are low in number, sooner or later
the population will crash.
>Some quantitative measure of percent mortality over many years would be
>required to get at this basic question - is anyone working on that angle?
No. There has been no emphasis on the overall survival of the
wintering populations. The winter clusters are not static and their
density changes through the season and with the weather. This
presents a conundrum as to how to measure the mortality of the
wintering butterflies. It would take a well funded and well designed
program to track this mortality for an entire season. Surprisingly,
it's been almost 15 years since any trained scientist has spent more
than a few weeks studying the overwintering population. Most of the
studies at the overwintering sites, and there are only a few, are
conducted by Mexican students. Some of these projects are well
supervised and will produce good results and others will not. Some of
the funding for these projects comes from donations. There are no
grants involved that I am aware of.
Chip
--
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