Human-Altered Tree-Based Habitats and Their Value in Conserving Bird and Bat Diversity in Northeast Luzon, The Philippines - Smallholder Tree Growing for Rural Development and Environmental Services - page 358

cave roosting fruit bat Rousettus amplexicaudatus occurs in all habitat types at all
distances from caves (max 18 km). Other studies show that bats are capable to fly
considerable distances from roosts to feeding sites, up to 10 km in a study in Mexico
in agricultural mosaic habitats for example (Estrada and Coates-Estrada 2002).
There is also evidence that there is differentiation between forest bat species that are
sensitive to deforestation and species that are more tolerant to forest fragmentation
and isolation and readily fly over, and make use of resources in open areas (Law et
al. 1999). A recent study in Brazil suggests, for most bat species, no significant dif-
ference in abundance between forest, forest fragments and surrounding savanna
vegetation although some species are restricted to forest and others to savannas.
Furthermore, the open savannas seem not to act as an ecological barrier to bats
(Bernard and Fenton 2007). Our study shows that human-altered habitats in Cagayan
Valley do offer suitable conditions for a moderate number of bats found in the region
including several endemic and forest bat species. Forest bat species are however
restricted to a maximum distance to contiguous forest.
Reforestation with mono-culture Gmelina arborea is of little direct value in
terms of bird and bat conservation in the Cagayan Valley. Yet elsewhere, plantations
of exotic tree species do provide conservation benefits, such as the mono-cultures
of Chinese ash Fraxinus chinensis in the Colombian Andes serving, in addition to
watershed reforestation, as a habitat for birds comparable to that of natural regen-
erating forest (Duran and Kattan 2005). In addition, fast-growing trees like the
Chinese ash act as catalysts for recovery of degraded habitats, something that will
be hard to attain with slow-growing native tree species. Gmelina arborea can play
a similar role as a catalyst in reforestation of degraded forest land in the Philippines
and elsewhere.
16.5 Conclusions
The human-altered Cagayan Valley in northeast Luzon provides a habitat for a
moderate number of resident bird species of the region, including several endemic
and one threatened ( Anas luzonica ) open area bird species. For bats, the valley
offers slightly better conditions. Forest birds and bats are restricted to a human-
altered zone bordering the contiguous forest of the Sierra Madre mountains
although forest bats venture further away than birds. For most of the forest, endemic
and globally threatened lowland bird and bat species in northeast Luzon, homegar-
dens and Gmelina arborea forest plantations, and the surrounding shrub-land, in
their present state fail to serve as alternative habitats for closed-canopy forest. Yet,
further studies are needed to understand why Gmelina forest plantations have a
much lower conservation value for birds compared to exotic tree plantations else-
where. Likewise, studies on habitat diversification such as enrichment planting in
Gmelina forest plantations are needed to determine whether more diverse and com-
plex forest plantations offer a higher conservation value for both forest bird and bat