Abstract:
One speaks of ecological substitutes when an introduced species performs,
to some extent, the
ecosystem function of an extirpated native species. We suggest that a
similar case exists for habitats. Species evolve within ecosystems, but habitats can be destroyed or modified by
natural and human-made causes. Sometimes habitat alteration forces animals to move to or remain in a
suboptimal habitat type. In that case, the habitat is considered a refuge, and the species is called a
refugee.
Typically refugee species have lower population growth rates than in their original habitats. Human action
may lead to the unintended generation of artificial or semiartificial habitat types that functionally
resemble the essential features of the original habitat and thus allow a population growth rate of the same
magnitude or higher than in the original habitat. We call such areas substitution habitats and define them as
human-made habitats within the focal species range that by chance are partial substitutes for the species’
original habitat. We call species occupying a substitution habitat adopted species. These are 2 new terms in conservation
biology. Examples of substitution habitats are dams for European otters, wheat and rice fields for many
steppeland and aquatic birds, and urban areas for storks, falcons, and swifts. Although substitution habitats
can bring about increased resilience against the agents of global change, the conservation of original habitat
types remains a conservation priority
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| Photo: Martínez-Abrain, A. |
