Dispersal, migration and management - Ecological Applications: Toward a Sustainable World - page 89

4.3 Restoration and
species mobility

Managers sometimes want to restore populations of endangered species to locations
where they have gone extinct, or to restore whole communities of plants and
animals. Once again, without detailed knowledge of migratory and dispersal behav-
ior, efforts to manage endangered animals may be doomed to failure (Section 4.3.1).
And when it comes to plant community restoration, an intimate knowledge of the
dispersal ability of seeds (whether through space or time) can be equally critical
(Sections 4.3.2, 4.3.3).

4.3.1 Behavior
management

Attempts to restore populations of migratory species must, of course, take their
migratory behavior carefully into account. Europe's lesser white-fronted goose
( Anser erythropus ) moves between widely separated locations, and Sutherland (1998)
tells a fascinating story where knowledge of migratory behavior has proved useful
for management. A scheme was devised to alter the migration route of the lesser
white-fronted geese from southeastern Europe, where they tend to get shot, to spend
their winters in the Netherlands, where hunting is not a problem. A population of
captive barnacle geese ( Branta leucopsis ) breeds in Sweden at Stockholm Zoo but
overwinters in the Netherlands. Some were taken to the wilds of Swedish Lapland
where they nested and were given lesser white-fronted goose eggs to rear. The young
geese then fl ew with their adoptive parents to the Netherlands for the winter, but
next spring the lesser white-fronted geese returned to Lapland and bred there, sub-
sequently returning again to the Netherlands. (Saved from the hunters, one wonders
whether the geese might meet an equally unpleasant end in one of Maria's wind
farm turbines?)
Another example where restoration effort has benefi ted from an intimate knowl-
edge of animal behavior involves reintroduction of captive-reared Phascogale tapoa-
tafa , a small carnivorous marsupial that has disappeared from part of its range in
Australia. Soderquist (1994) found that if males and females were released together,
the males quickly dispersed from the area and females could not fi nd a mate. Much
more successful was a 'ladies fi rst' release scheme; this allowed the females to estab-
lish a home range before males came and joined them.

4.3.2 Bog restoration
- is assisted
migration needed for
peat's sake?

Peat is a valuable commodity, for fuel and garden supplies. Many Sphagnum peatbogs
in eastern Canada, as elsewhere, are exploited for peat for several decades before
they are abandoned, leaving fl at surfaces up to 5 km 2 in area that are intersected by
dense networks of ditches. A relatively thin organic peat substrate, 1 m or more deep,
usually remains, but this is acid and poor in nutrients. There is no persistent seed-
bank in these highly disturbed sites, so 'migration through time' is not possible
(Box 4.1). However, unexploited peatbog habitat will usually be found at the edges
of the disturbed areas. Subsequent recolonization of exploited sites from these
healthy fragments is very slow, partly because of unfavorable physicochemical con-
ditions, but also because of restricted powers of dispersal of some of the peatbog
plants. Campbell et al. (2003) wanted to distinguish between these two causes of
poor recovery so that restoration management could be focused for maximum
effect.
They assessed the wind-dispersal ability of a wide range of peatbog plants, includ-
ing mosses, herbaceous plants, shrubs and trees. For each species, three components
of wind dispersal were determined for plants growing in the wild, namely 'propagule
release height' (those released from greater height are generally exposed to higher