Leach 's Storm -Petrel (Oceanodroma leucorhoa) 



Leach's Storm-Petrels are the most abundant 

 of the storm-petrels breeding in California and are 

 probably the most pelagic of the four species. 

 Although breeding colonies are confined to the 

 northern hemisphere, wintering birds range south 

 to tropical waters in both the Pacific and Atlantic 

 Oceans (Palmer 1962). 



Like all storm-petrels, Leach's Storm-Petrels 

 are nocturnal on the breeding colonies, an 

 adaptation which reduces their susceptibility to 

 diurnal predators such as gulls. Nests are ususally 

 located in burrows or, less frequently, in rock 

 crevices (Palmer 1962). Leach's Storm-Petrels 

 have a well-developed olfactory system (Bang 

 1966, Stager 1967) and Grubb (1973, 1974) has 

 suggested that these birds, which often nest in 

 crowded colonies in dense spruce forests, may 

 locate their burrows by odor. 



Like most seabirds, Leach's Stonn-Petrels 

 exhibit relatively long lifespans and low mortality 

 rates for their size. Individuals that survive the 

 hazardous first year of life can live up to 24 years 

 and possibly longer (Graham 1980). Additional 

 references on this well-studied species include 

 Ainley et al. (1974, 1976) Ainslie and Atkinson 

 (1937), Gross (1935), Harris (1974), Huntington 

 (1963), Morse and Buchheister (1979), Threlfall 

 (1974), and Wilbur (1969). 



CALIFORNIA COLONIES 



Leach's Storm-Petrels are known or suspected 

 to breed at 13 sites along the California coastline. 



While most sites are located in the northern part 

 of the state, recent evidence suggests that small 

 numbers of Leach's Storm-Petrels may also nest 

 in the Channel Islands (Hunt et al. 1979). 



The largest colony in California is located at 

 Little River Rock (325 035), which has 10,000 

 birds (Harris 1974). Other major colonies are 

 Castle Rock (325 006) with 5,000 birds, the 

 Farallon Islands (429 012) with 1,400 birds, 

 Trinidad Bay Rocks (325 054) with 1 ,640 birds, 

 and Prisoner Rock (325 027) with 160 birds. 



Colonies are suspected to exist at Fish Rocks 

 (404 003), Prince Island (325 003), and Tolowa 

 Rocks (325 007), although nests of this species 

 have not been found at these locations. On both 

 Fish Rocks and Prince Island suitable nesting 

 habitat is available and Leach's Storm-Petrels with 

 clearly visible incubation patches have been 

 mist-netted and banded. We are confident that 

 Leach's Storm-Petrels breed at Fish Rocks because 

 of our recapture of banded birds there and 

 the island's isolation from other known Leach's 

 Storm-Petrel colonies. At Prince Island no 

 recaptures of banded birds were made and it is 

 possible that the birds we caught were from 

 nearby colonies at Castle Rock (325 006) and 

 Goat Island, Oregon. At Tolowa Rocks, the less 

 common Fork-tailed Storm-Petrels were found 

 nesting in burrows. Many unexamined burrows 

 were present and it seems likely that Leach's 

 Storm-Petrels nest there. 



All major colonies of Leach's Storm-Petrels 

 in California have probably been identified, but 



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