Outline of Quino Recovery Plan - The Xerces Society

population of prediapause larvae. Larger host patches could accommodate more
egg clusters, but no evidence exists to suggest that Euphydryas edithas spatially
distribute egg masses in a manner that would maximize offspring survival. On
the contrary, individual females often apparently independently select the same
oviposition sites, leading to high mortality of larvae from competition (Rausher
et al. 1981, Boughton 1999).
Each successful post-diapause larva consumes several hundred Plantago
seedlings, and the impact on a plant population can be severe. Thus
post-diapause larval feeding has three consequences for habitat assessments: 1)
Plantago density estimates made during seedling stages, when post-diapause
larvae have not yet finished feeding, must consider future post-diapause feeding
needs, 2) the number of plants in a Plantago population that currently support
Quino checkerspot larvae will be lower than the number in the same population
without the butterflies, and 3) measurements of Plantago density in unoccupied
habitat may overestimate the ability of habitat patches to support a butterfly
population. Also, if larvae commonly re-enter diapause during dry years,
hostplant density (habitat suitability) may be underestimated due to low
germination rates that do not affect the population of larvae. Note that a
substantial amount of food, primary or secondary hostplants, must remain after
the post-diapause larvae have finished feeding if a habitat patch is to support
clusters of pre-diapause larvae clusters. If too few primary hostplants remain,
adults must disperse to seek new habitat patches for oviposition.
Local habitats alone are generally not sufficient to ensure the long-term
persistence of the butterfly. A local population may be expected to persist on the
time scale of years. Persistence for longer terms derives from the interaction of
sets of local habitat patch populations at larger geographic scales. These sets of
populations are known as metapopulations. For the bay checkerspot butterfly, a
metapopulation was described as: "...a set of populations (i.e., independent
demographic units; Ehrlich 1965) that are interdependent over ecological time.
That is, although member populations may change in size independently, their
probabilities of existing at a given time are not independent of one another
because they are linked by processes of extirpation and mutual recolonization,
processes that occur, say, on the order of every 10 to 100 generations." (Harrison
et al. 1988). The ability and propensity of larvae to undergo multiple-year
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