Our Lii'iiif; Resources — Hawaii 



J79 



by MoLiiilainspnng and Scott (1983) lound a 

 ncgali\'e association between several native and 

 introduced bird species pairs, much more work 

 is needed to understand the significance of these 

 relationships. Similarly, preliminary evidence 

 suggests that arthropods such as the introduced 

 yellowjacket wasps iVi'spiiUi spp.) and several 

 species of ants may seriously deplete the resi- 

 dent arthropods that many native birds eat, par- 

 ticularly during nesting (P. Banko. NBS. per- 

 sonal communication). 



Current Status 



Table 2 summarizes the most recent infor- 

 mation on the status of endemic Hawaiian bird 

 species. The population size for many forest 

 birds conies from the Hawaii Forest Bird 

 Survey. 1976-81 (Scott et al. 1986). While most 

 of these numbers are more than 13 years old. 

 they represent a distribution and abundance 

 baseline upon which subsequent surveys can be 

 based. The trend infomiation in Table 2 is based 

 on population surveys conducted during the 

 past 13 years. 



Seabirds 



Three seabird species are endemic to 

 Hawaii: the endangered dark-rumped petrel 

 (Ptewdroma phaeopygia saiuhvichensis). the 

 threatened Newell's shearwater {Puffinus 

 uewclii). and the Hawaiian noddy (Anoits minii- 

 tus melanogenys). The first two relatively rare 

 species nest in upland forest or subalpine and 

 alpine sites. As with all of the ground-dwelling 

 or nesting birds, the dark-njniped petrel and 

 Newell's shearwater are extremely susceptible 

 to predation by cats. dogs, rats, and mongooses 

 during their long nesting period. A successful 

 predator-control program in nesting areas for 

 the dark-rumped petrel in Haleakala National 

 Park on Maui has resulted in a significant 

 increase in petrel productivity. Recently discov- 

 ered nesting areas for the dark-rumped petrel 

 and Newell's shearwater on the island of Hawaii 

 offer similar opportunities to use predator con- 

 trol to reestablish significant breeding colonies 

 for these species in upland habitats. 



Waterbirds 



Historically, the Hawaiian avifauna includes 

 six waterbird species, five of which are typical- 

 ly found in and around fresh-, brackish-, and 

 saltwater impoundments and estuaries (Engilis 

 and Pratt 1993). The sixth species, the nene or 

 Hawaiian goose (Branta sandwichensis). 

 though occasionally found around water, most 

 typically occurs in upland sites. 



Continued loss of habitat and predation are 



the two biggest threats to the remaining 

 Hawaiian waterbirds. Although the Hawaiian 

 coastal zone formerly contained many large 

 wetland areas, few remain. For example, the 

 resort area known as Waikiki Beach was an 

 extensive wetland that was drained in the early 

 I9()t)'s. Because introduced predators are a 

 major threat to waterbirds in Hawaii, predator 

 control has become essential in all waterbird- 

 management programs. 



An intensive captive propagation and release 

 program has kept the nene from extinction. This 

 ground-nesting goose, however, is extremely 

 vulnerable to predation by introduced mon- 

 gooses, cats, dogs, and possibly rats and is not 

 able to sustain wild populations in most areas 

 (Stone et al. 1983). A recently established pop- 

 ulation on the island of Kauai appears to be 

 thriving, probably mostly because of the 

 absence of mongooses on this island. 



Both duck species endemic to Hawaii are 

 endangered. The Laysan duck (Anas laysanen- 

 sis) is known only from Laysan Island, a small 

 atoll about halfway up the northwest Hawaiian 

 Island chain. Although population levels have 

 been as high as 600 birds over the past 23 years, 

 they dropped to fewer than 50 during 1993 (T. 

 Work, NBS, personal communication). Species 

 confined to such a small geographical area are 

 extremely vulnerable to natural disasters (e.g., 

 hurricane damage) or human-related impacts 

 (e.g., introduction of disease or predators to the 

 island). 



The koloa or Hawaiian duck {A. wyvilliciiui). 

 formerly found on all major Hawaiian Islands, 

 is now relatively rare, with small populations on 

 Kauai. Oahu, and Hawaii. It, too. is extremely 

 vulnerable to predators. Additionally, because 

 koloa on Oahu are hybridizing with feral popu- 

 lations of the closely related mallard (A. 

 pkityrhynchos; Engilis and Pratt 1993), a mal- 

 lard-control program has been recommended to 

 protect the native koloa populations from genet- 

 ic alteration. 



• T'iwi {Vestiaria coccinea). Ttie 



" long sickle-bill of the ' i" iwi 



» enables it to feed on nectar from 



g flowers and to probe for insects. 



