123 



by exposing managed herbaceous wetland complexes (a threatened plant community 

 type m river floodplains) to the negative impacts of carp, siltation, woody plant inva- 

 sion, and unnatural flooding episodes. We would urge the Federal Government to 

 consider the possible impact of carp on Federal lands that would be converted from 

 managed impoundments to nonstructural management. 



Exotics in Hawaii 



Although the incidence of non-native plants is great in California, Texas, and 

 Florida, m no State is it more obvious than Hawaii. Estimates suggest that five to 

 eight new exotic species of vegetation arrive in this State each year despite control 

 efforts by the U.S. Department of Agriculture. DU's program in Hawaii has empha- 

 sized restoration of quality habitat for North American and Asian waterfowl species, 

 which winter on the islands, and for four federally endangered waterbirds. Our cur- 

 rent projects include work with the U.S. Fish and Wildlife Service on Oahu and 

 Kauai, a cooperative effort with the Parker Ranch, Hawaii Department of Forestry 

 and Wildlife (DOFAW), the Fish and Wildlife Service on Big Island, and work on 

 Hamakua Canal wetland with Kaneohe Ranch and DOFAW. 



Threats to the four endangered waterbirds come from a host of non-native species 

 which include plants, feral mallards, and introduced mongoose (Herpestes 

 auropunctaus). Exotic plant species, such as California grass {Brachiaria mutica), 

 water hyacinth (Eichhornia crassipes), pickleweed (Batis maritima), and red man- 

 grove (Rhiszophora mangle) all present serious problems in many wetlands by elimi- 

 nating interspersion of open water and vegetation and by outcompeting more desir- 

 able native vegetation. Where the U.S. Fish and Wildlife Service eradicated Cahfor- 

 nia grass and other exotic plant species on James Campbell NWR on Oahu and 

 Hanalei NWR on Kauai, and then replicated shallow seasonal flooding, response by 

 native and migrant waterbirds was substantial. At Hanalei NWR alone, clearing of 

 exotic vegetation on two 40-acre impoundments in the late 1980s resulted in the 

 habitat use by more endangered Hawaiian duck (Anas wyvukkuaba) than were 

 thought to exist on the entire islands. 



Introductions of exotic mammahan predators have negatively affected waterbird 

 populations across the Pacific Islands, and Hawaii has not escaped this catastrophe 

 The mongoose was first introduced to Maui, Molokai, and Oahu to control rats in 

 sugarcane fields. Unfortunately, rats are nocturnal and mongoose are diurnal, so 

 they rarely interact. Mongoose has been implicated as a very serious predator on 

 native waterbirds and their nests. Feral cats and dogs also may prey on waterbirds 

 on marginal habitats, as quality waterbird habitat has been reduced on the islands. 

 Federal and State dollars are needed to improve the quality of existing wetlands 

 and restore certain key wetland complexes. An example of such a success is the use 

 of coastal wetland dollars by DOFAW, USFWS, and DU to enhance the Hamakua 

 Canal Wetland. 



Feral mallards, distinct from migrants that enter the State, have become a para- 

 mount problem for the Hawaiian duck (or Koloa). Recent evidence suggests that 

 feral mallards on Oahu, the west coast of Big Island, and Kauai interbreed with the 

 native Hawaiian duck. Recent genetic studies have shown that a high percentage 

 of Oahu 8 Hawaiian ducks are hybrids. The Federal Endangered Species Act pro- 

 vides no protective status for hybrids. Feral mallards on Kauai and Big Island are 

 mostly concentrated in urban or hotel ponds. A ban on mallard importation to Ha- 

 wau and the eradication of existing feral mallards are necessary. 



We encourage Federal and State agencies to address problems with exotic mam- 

 malian populations on all islands. We especially urge these agencies to monitor 

 Kauai so that mongoose do not enter the island. An interagency workshop for State 

 and Federal biologists on wetland and waterbird management would be most timely 

 for Hawaii. '' 



Summary 



Millions of dollars have been expended by conservation organizations and agencies 

 to protect and preserve wetland habitats for endangered species, waterfowl and 

 other wetland wUdUfe. Exotic species often drasticaUy reduce the biological capabil- 

 ity of publicly purchased lands which, in effect, reduces the economic benefits that 

 local communities receive from outdoor recreation-based activities and the quality 

 ot lite that all eryoy from an abundant and ecologically diverse wetland ecosystem 



For more information, contact Eric Schenck, Manager Of Agricultural Pohcy (202) 



^r^S?^l!^li^^J^'^' Biologist, (916) 363-8257; or Roger Pederson, RegionalBiolo- 

 gist, (612) 683-0441. 



