[Pollinator] New Paper: Western Monarch Population Plummets: Status, Probable Causes, and Recommended Conservation Actions

[Jenni Denekas]

Western monarch butterflies dropped by ~97% of their average historic
abundance between the 1980s and mid-2010s. In winter 2018–2019, the
population plummeted even farther, to fewer than 30,000 monarchs, which
represents a single year drop of 86% and a drop of >99% since the 1980s.
The population may now be hovering at its quasi-extinction threshold. In
this Perspectives piece, we: (1) Place the current status in context, (2)
Highlight the most likely window during the annual life cycle when the
population declined, (3) Review probable causes of long-term declines, and
(4) Recommend steps that the public, policy makers, and land managers can
take to recover western monarchs. The available studies reinforce the
hypotheses that overwintering habitat loss and loss of central California
breeding habitat, as well as pesticide use, are likely important
contributors to the western monarch's long-term decline. The most limiting
part of the migratory cycle appears to be concentrated during the
overwintering stage and/or in early spring. If western monarchs are in fact
entering an extinction vortex, they need extraordinary efforts—focused on
the most vulnerable periods of the annual cycle— to save the migration.
Critical short-term conservation priorities are to (1) Protect, manage and
restore overwintering habitat, (2) Protect monarchs and their habitat from
pesticides, (3) Restore breeding and migratory habitat in California, (4)
Protect, manage, and restore summer breeding and fall migration monarch
habitat throughout the western monarch's range, and (5) Fill research gaps
to inform western monarch recovery strategies.

-- 

*Jenni Denekas*

Web and Communications Coordinator

jenni.denekas at xerces.org

(503) 232-6639 x105

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<https://www.bottomline.org/content/support-gender-inclusive-pronouns>


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