Posted by Dr G. Bittar
The myth that “introduced” or “non-native” species are necessarily bad for an ecosystem has rooted with a decided ideological tone. Thus scientists researching the matter have difficulty publishing when their results stand against the new religion, which can be summarised as “natives good, non-natives bad”.
Here’s a study that came through the net of the politically and bureaucratically correct.
Because so many of Hawaii’s native fruit-eating birds have gone extinct, mainly through hunting and habitat loss, rainforest shrubs have difficulties sending seeds to new sites. But they are now helped in this task by two “introduced” birds, the Japanese white-eye and red-billed leiothrix. They snack extensively on native fruits, dispersing the seeds widely, allowing native shrubs to reclaim the understorey of Hawaiian forests.
Say the authors:
“The Hawaiian Islands have lost nearly all their native seed dispersers, but have gained many frugivorous birds and fleshy-fruited plants through introductions. Introduced birds may not only aid invasions of exotic plants but also may be the sole dispersers of native plants. We assessed seed dispersal at the ecotone between native- and exotic-dominated forests and quantified bird diets, seed rain from defecated seeds, and plant distributions. Introduced birds were the primary dispersers of native seeds into exotic-dominated forests, which may have enabled six native understory plant species to become reestablished. Some native plant species are now as common in exotic forest understory as they are in native forest. Introduced birds also dispersed seeds of two exotic plants into native forest, but dispersal was localized or establishment minimal. Seed rain of bird-dispersed seeds was extensive in both forests, totaling 724 seeds of 9 native species and 2 exotics with over 85% of the seeds coming from native plants. Without suitable native dispersers, most common understory plants in Hawaiian rainforests now depend on introduced birds for dispersal, and these introduced species may actually facilitate perpetuation, and perhaps in some cases restoration, of native forests.”
In conclusion:
“People tend to think of native species as good and exotic ones as bad, but it’s just not that simple.”
From
Alien birds save Hawaiian natives.
New Scientist, 10/6/2007, Vol. 196, Issue 2624
and
Introduced birds and the fate of Hawaiian rainforests
by Jeffrey T. Foster and Scott K. Robinson
Conservation Biology Volume 21, Issue 5, pages 1248–1257, October 2007
Article first published online: 19 SEP 2007
http://onlinelibrary.wiley.com/doi/10.1111/j.1523-1739.2007.00781.x/abstract
DOI: 10.1111/j.1523-1739.2007.00781.x
See also
Garden plants do not have to be native to help most pollinating insects — Garbuzov and Ratnieks 2013