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- Local topography and microclimate have a dramatic impact on
population dynamics, but the year-to-year variation in regional
climate has a far larger impact.
- Habitat ``quality'' plays a role in patch occupancy, but patch
distance from a large, persistent reservoir population plays a larger
role.
- Key conservation goal: protect the habitat areas
that supports the reservoir populations in Santa Clara and San Mateo
Counties.
- Protection of habitat patches
7 km from reservoir population
may not be necessary, but protection of patches
7 km is, even
though those colonies may be subject to relatively frequent local
extinctions. Protection of small, relatively low quality patches
close to the reservoir population may be more important than
protection of larger, higher quality patches further
away.7
- Even with three decades of research behind it, much remains to be
done be for an accurate, predictive model of population
dynamics8 is available.
- Successful parameterization of key factors affecting population
persistence, but no estimates of variances - particularly difficult
when year-to-year variation may be an order of magnitude or more
- Factors other than topography affect resource availability, but
they are poorly understood
- Metapopulation dynamics are critical, but factors promoting
successful colonization and the characteristics of effective
dispersal corridors have not been established
- Focusing on genetic or local demographic factors in efforts to
preserve populations with high local densities is often a
misallocation of effort. Instead
- Focus on identifying habitat features and resources that
determine occupancy.
- Distinguish between temporarily empty habitat and unsuitable
habitat.
- Find out why suitable habitat is unoccupied. (Recall that in a
true metapopulation model, unoccupied but suitable habitat may be
critical to long term persistence of a population.)
- Do we really need a detailed, numerically accurate, predictive
model of population dynamics in order to make reasonable conclusions
about management right now?
Next: Bibliography
Up: Population Viability Analysis Bay
Previous: Local Extinction
Kent Holsinger