236 



S. Kim Nelson Testimony on H.R. 2866 3 



between murrelets and other alcids include their choice of 

 nesting sites and adaptations to avoid predation. 



Muxxelets lay a single egg on the flat suxf ace of large moss 

 ox duff covered coniferous tree limbs. • Nesting occurs between 

 April and September. Eggs are incubated for 30 days, and chicks 

 fledge after an additional 28-36 days {Hirach et al. 1981, 

 Nelson, 1991, 1992; Nelson and Hardin 1993a) . Both adults 

 participate ^ in incubation on a 24 -hour schedule . Exchanges occur 

 before sunrise, in the cover of darkness or dawn. Adults enter 

 the nest silently and rapidly in order to avoid detection by 

 predators- When the chick hatches, adults brood it for one day; 

 after that the chick is left alone on the nest. The chicks 

 camouflage plumage is their only protection from predators, other 

 I'ihHTT cover above and near the nest site. Adults make 1 to 3 

 trips a day (at dawn, dusk and mid-day) between ocean feeding 

 areas and j-nTarir? nesting sites to feed the chick (Nelson 1991, 

 1992; Nelson and Hardin i993a) . These birds fly approximately 50 

 mph on their trips to and from the ocean. Chicks pluck their 

 feathers to reveal a distinctive black and white juvenile plumage 

 24-48 hoiirs before leaving the nest. C3iicks fly directly to the 

 ocean from the nest site (Earner and Cummins 1990) . 



Marbled Murrelets do not nest in dense colonies, however 

 they nest primarily in loose aggregations in forest stands. 

 Marbled Murrelets have high site fidelity; birds return to the 

 same forest stand year after year (Nelson, ui^ublished data; S. 

 Singer, T. Hamer, pers- comm.) . Occupancy of forests stands may 

 be historical in nature with yoxmg returning to the same stand 

 v^ere they hatched. High site fidelity and historical occupancy 

 are common among seabirds in the Auk Family (puffins, murrelets, 

 murres, auklets, etc.) (Nettleship a-r^r^ Bir^khead 1985) . 



Longevity, survd.val and mortality ra.tes are unknown. Age of 

 first breeding is thought to be three years (S6aly 1975b) - 

 Recruitment rates are very low because they lay only one egg, and 

 predation at nest sites is high. In addition, murrelets may not 

 nest or be successful in nesting during years of poor food 

 ava±lability (e.g. during El NiSo currents) . T>ia - arinl t-./jV-rg t»TTi 1 «» 

 ratios from counts along the central coast (Nelson and w•aT^^^T^ 

 1993b) indicate a recruitment rate of less than 5% each year 

 between 1989 and 1992; low numbers of juveniles (1-5%) have also 

 been documented in California and Alaska- (C.J. Ralph; ti. Kuletz, 

 pers. comm.). Of 45 tree nests found before 1993, at least 73% 

 fciiled to fledge a chick (see Threats section) . 



Habitat Selection 



All data collected to date on this species substantiate 

 their tise and selection of older-aged forests (Paton and Ralph 

 1988, 1990; Nelson 1989, 1990; Hamer and Cummins 1990, 1991) . In 

 Oregon, Marbled Murrelets have been found to select old-growth 

 and ma.ture forests with an old-growth component (Nelson 1989, 



