Ely and Clapp 1973, Berger 1972, Warner 1963, 

 Ripley 1960). More recent counts have varied 

 from 69 in July 1974 to 287 in August 1976. 

 The last count w^as 240 in August 1977, so the 

 present status is relatively good (Eugene Kridler 

 personal communication). 



Reasons for the rapid and extreme population 

 fluctuation in recent years are evidently unknown, 

 but the main one is probability inability to count 

 all birds present (Eugene Kridler pers. comm.). 

 Ely and Clapp (1973) say adults have no known 

 enemies on the island and destruction of eggs by 

 Laysan finches and young by frigatebirds is prob- 

 ably negligible. The limiting factor in the past and 

 now must have been the environment. 



PRIORITY INDEX 



33 



DESCRIPTION 



The Laysan Duck is a small, dark brown duck 

 similar to the Hawaiian duck, but smaller and 

 redder; head and neck are blackish, often 

 speckled irregularly wdth white almost around the 

 bill and on the face and chin; there is always a 

 white ring around the eyes. The speculum is green 

 and black, bordered with white posteriorly. The 

 bill is narrow. Females are more boldly marked 

 than males; the speculum is sooty brown, some- 

 times with a little green (Delacour 1956). 



Size — Male: wingspan 192-210 mm, tail 100- 

 105 mm; culmen 39-40 mm; tarsus 37-39 mm; 

 Female: wingspan 190-196 mm; tail 90 mm, 

 culmen 38-39 mm; tarsus 35-38 mm (Delacour 

 1956). 



The downy young are like those of the com- 

 mon mallard, but smaller and redder above and 

 cinnamon below; markings on upper parts are 

 indistinct (Delacour 1956). 



Eggs are greenish white, 55 by 38 mm (Fisher 

 1903). 



RANGE 



Laysan Island (4 km ), in the northwestern or 

 leeward Hawaiian Islands, is the only known 

 range. According to von Kittlitz in Phillips 

 (1923), it also occured on adjoining Lisianski 

 Island in 1928, but this statement has never been 

 verified and is considered almost certainly er- 



roneous (King in press, Ely and Clapp 1973, 

 Berger 1972). Although 525 individuals have been 

 banded since 1958, no natural occurrences away 

 from Laysan Island have been recorded (Ely and 

 Clapp 1973). The details of published records of 

 Laysan ducks on Laysan Island from 28 March 

 1928 to 9 September 1960 are given by Ely and 

 Clapp (1973). 



RANGE MAP 



Total Range (Ely and Clapp 1973). 



STATES /COUNTIES 



Hawaii Leeward Islands 



HABITAT 



All plant associations on Laysan Island are 

 used, but concentrations are found in low sedges 

 and vines around the central lagoon (Ely and 

 Clapp 1973, Warner 1963, E. Kridler in King in 

 press). Fisher (1903) and Bailey (1956) found 

 birds concentrated at a small brackish or fresh- 

 water pond near the southwest corner of the 

 lagoon, always a favorite spot until its disappear- 

 ance in the 1920's. They rarely occur on the 

 hypersaline and almost lifeless main lagoon and 

 almost never on the ocean (Warner 1963, Ely and 

 Clapp 1973). A. Wetmore in Ely and Clapp 

 (1973) noted that birds rested among rocks 

 during the day, and at night walked inland to 

 the lagoon margin and patches of vegetation 

 which probably provided food. More recently, 

 ducks have concentrated around slightly brackish 

 water available at several points following heavy 

 rains. They apparently survive long periods when 

 neither fresh nor slightly brackish water is avail- 

 able. The home range of each pair usually con- 

 tains a strip of lagoon shore (Woodside and 

 Kramer in Ely and Clapp 1973). Ducks occur 

 throughout the island, but most of them are 

 found in the beach morning glory near the 

 lagoon during the day (Ely and Clapp 1973). 



They formerly used permanent freshwater 

 areas that are now filled with sand as a result of 

 the rabbits' destruction of the vegetation cover 

 (Warner 1963), complete except for three patches 

 of sesuvium that may have enabled the remnant 

 population of ducks to survive (Warner 1963). 

 Now that vegetation has recovered, the sesuvium 



