The extreme variation in counts even during the 

 same year shows the difficulty of observing all 

 birds present, probably due to the secretiveness 

 and nocturnal habits of the species noted by 

 Warner (1963). 



There is a captive population of over 150 in 

 zoos and private collections (King in press). 



REPRODUCTION 



H. M. Smith found 7 downy young in broods 

 of 3 and 4 in 1950 (Brock 1951). Fisher (1903) 

 found 6 eggs in a nest. The species breeds readily 

 in captivity (Ripley 1960). 



The nesting cycle is evidently an extended 

 one. Pairing is first observed in early March and 

 continues until mid-summer. There seems to be 

 no published report of courtship behavior (Ely 

 and Clapp 1973), Warner 1963). Usual clutch 

 size is 5 or 6. The earliest recorded hatching date 

 is 19 May (Fisher 1903). Most eggs are laid in 

 May, but the season extends through July. 

 Incubation takes 27 to 28 days, The drake 

 guards the incubating female. The chicks remain 

 in the nest with the female for 2 days. In the 

 wild, males sometimes tend the brood (Warner 

 1963, Ely and Clapp 1973). 



High chick mortality, which reduced brood 

 size from an average of 3 at hatching to about 1 

 or less at 1 month, strongly suggests that this 

 may be a limit on population growth (Warner 

 1963). 



Warner (1963) considered destruction of 

 eggs by Laysan finches and young by frigate- 

 birds a possible but unproved limiting factor on 

 population; Ely and Clapp (1973) thought it to 

 be probably negligible. 



MANAGEMENT AND CONSERVATION 



The entire range (Laysan Island) is within 

 the Hawaiian Islands National Wildlife Refuge. 

 Landings on the island are restricted by permit. 

 The species is protected by Federal and State 

 law, and Listed in Appendix 1 of the 1973 Con- 

 vention on International Trade in Endangered 

 Species of Wild Fauna and Flora. A census is 

 conducted periodically by the U.S. Fish and 

 Wildlife Service. Conservation measures pro- 

 posed by King (in press) are: 



1. Increase patrols of Laysan Island to 

 prevent unauthorized landings and to prevent 



introduction of additional pest plants, in- 

 sects, and predators such as dogs, cats, and 

 rats. 



2. Introduce captive-reared Laysan ducks 

 to another Pacific island with suitable habi- 

 tat (Fish and Wildlife Service, King in press). 



Introduction attempts include a release of 

 24 or 25 in the Kewalo marsh on the outskirts 

 of Honolulu in 1894 by a Mr. Whitney, but none 

 have been taken since (Ely and Clapp 1973). In 

 March 1968, 12 were transported from Laysan 

 to Southeast Island, Pearl and Hermes Reef, by 

 Fish and Wildlife Service personnel. All disap- 

 peared soon after introduction (Ely and Clapp 

 1973, E. Kridler 1974 in King in press, Fish and 

 Wildlife Service 1973). Beginning with 44 cap- 

 tured birds, rearing in captivity has been very 

 succesful in the Hawaii zoo and numerous main- 

 land aviaries (Warner 1963, Ripley 1960). A re- 

 covery team has been appointed and a recovery 

 plan for the Laysan duck is now in progress. 



AUTHORITIES 



Eugene Kridler 

 835 Akumu Street 

 Kailua, Hawaii 96743 



Richard Warner 

 Building 737 IFAS 

 University of Florida 

 Gainesville, Florida 32611 



PREPARER'S COMMENTS 



The great variation in population estimates 

 at different times, even during the same year, is 

 evidence of the inadequacy of present inventory 

 methods. Also, the almost complete lack of in- 

 formation on the factors that limit the population 

 indicates a definite need for additional research 

 on both of these problems in particular. 



Introduction of predatory or competing ani- 

 mals, particularly rats, on Laysan Island as a 

 result of unauthorized or unknown landings re- 

 mains the greatest threat to the continued sur- 

 vival of the duck, so the sooner another popu- 

 lation can be established on another island, the 

 safer it will be from such accidents.— John W. 

 Aldrich. 



