Search the SPREP Catalogue

Between 1892 and 1930, 58 percent (30 taxa) of Hawaiian endemic forest birds either were greatly reduced or became extinct. The order in which the islands experienced major declines ofseveral forest birds is Oahu (ca. 1873-1887), Hawaii (1892-1900), Mo10kai (1893-1907), Maui (18941901), Kauai (after 1900), and Lanai (1926-1932). Loss of habitat, reduced food supply, introduced avian diseases, as well as predation by man, feral cats, mongooses, and Norway rats (Rattus norvegicus) all appear to have reduced some species ofbirds, but none ofthese factors adequately explains the accelerated rates ofdecline offorest birds that occurred after 1892. Although it has been assumed that roofrats (Rattus rattus) reached Hawaii with the first European ships at the end of the 18th century, there is circumstantial evidence, independent of the bird decline data, that indicates that this rat did not arrive until after 1840, probably between 1870 and 1880. The hypothesis is advanced that after its establishment on Oahu in the 1870s, R. rattus spread to the remaining large islands in the group, resulting in a stepwise accelerated decline offorest birds on each island in turn. Hawaii thus parallels some other Pacific islands where major reductions of birds have followed the establishment of R. rattus. The need for precautions to prevent rats from reaching rat-free islands in the Hawaiian group is emphasized.

Flourescein dye was used to trace water movements and to determine flow velocities and volume transports on two Guam fringing reef flats. Wave-driven water crossed most portions of the reef margin in a direction roughly perpendicular to the shoreline. As it moved across the reef flat it gradually changed direction until it was flowing as a longshore current in a deepened moat zone adjacent to the shoreline. After flowing in this longshore current for distances up to 1500 m, the water gradually moved seaward in a more dispersed pattern and exited the reef flat through major cuts in the reef margin. Smaller, more restricted portions of both reef flats had very sluggish water movements with less distinct patterns. Of the total water volume crossing transects which extended perpendicularly from the shoreline, 10-100% flowed in the moat zone within 80 m of the shore. Flow velocities ranged up to 0.6 m sec1. Mean volume transport across entire transects was up to 61.6 m3 sec1. and in the moat zone alone was up to 23.5 m3 sec-1. There was a significant correlation between surf and flow velocity, as well as between surf and volume transport in the moat, at all transects and tidal states tested in one bay; but the correlations were less conclusive in the other bay. Velocity was more strongly correlated with surf than was volume transport in the moat for most of the correlation analyses.