Although WAA's purpose for this outing was to give people a taste of bird-watching, Ron pointed out that timing is important. Birders have their best luck in the early morning and evening, and during the winter when most migratory birds visit Hawai‘i.

Introduced Birds
We learned that most of Hawai‘i's birds were intentionally introduced, and had no trouble finding examples (e.g. Japanese white eyes, waxbill finches, laceneck doves, bar doves & ducks). Introduced birds compete with native species for food and habitat, and in some cases, feed on the native species directly (e.g. egrets are known to eat native waterbird chicks).

Mallards were common on this walk and are a great example of one of the indirect impacts of introduced birds. Mallards and domestic ducks are similar enough to the Koloa (the Hawaiian duck) that they can interbreed, producing "hybrids". This is a problem because the hybrids share only half their genes with the native stock. After several generations, the offspring can not really be considered native. In fact, Ron told us that pure Koloa are essentially nonexistent on O‘ahu -- all ducks are considered hybrids.

Introduced Aquatic Species
We made our way down to the lake and learned that it is home to cichlids and tilapia from Africa, as well as mosquito fish and small-mouth bass from the mainland USA. We were happy to find several native Hawaiian coots (‘alae ke‘oke‘o) nesting on the lake but were again reminded of the problems with introduced species when we learned that the coot chicks are preyed upon by the small-mouth bass!

Perhaps the most evident introduced species in the lake was Elodea, an aquatic plant thought to have been released into the lake from somebody's aquarium. Elodea is everywhere in the lake, but unlike the floating Salvinia that recently took over Lake Wilson, Elodea is rooted to the bottom. When workers try to remove it, the roots often remain and parts that break off can produce new plants!

The walk was relatively short, so we we didn't get a chance to use KBAC's awareness survey, but we all left with a great lesson in how invasive animals can impact Hawai‘i's native species.