(1972) estimates from historical records that 

 20,000 storm-petrels (Leach's and Fork-tailed 

 Storm-Petrels), along with Western Gulls, Pigeon 

 Guillemots, and Black Oystercatchers, nested on 

 Whaler Island. Loss of this nesting island may 

 have substantially reduced the number of nesting 

 Leach's and Fork-tailed Storm-Petrels in 

 California. 



Several seabird species nest in burrows dug 

 into the ground. No one should walk on these 

 burrow areas since they can easily collapse under 

 the weight of a person. Birds may then abandon 

 the burrow. Burrow destruction can also accelerate 

 the serious problem of soil erosion from offshore 

 rocks. Most islands along the California coast 

 were once part of the mainland and soil is primarily 

 or entirely a remant from before the islands broke 

 away. 



In California, burrow nesting species are: 

 Black, Leach's, Fork-tailed, and Ashy Storm- 

 Petrels, Xantus'Murrelets,Cassin'sand Rhinoceros 

 Auklets, Tufted Puffins, and, in some instances, 

 Pigeon Guillemots. Of these, Rhinoceros Auklets, 

 Tufted Puffins, and Black and Fork -tailed Storm- 

 Petrels are present only in very low numbers. 

 None of these species' California populations 

 exceed 400 birds, and none of these species is 

 present at more than 14 sites in the state. While 

 Cassin's Auklets and Leach's and Ashy Storm- 

 Petrels are present in greater numbers in California, 

 they are also limited to very few nesting loca- 

 tions. Any disturbance to burrow-nesting species 

 would be particularly unfortunate. 



Whaler Island (325 045) was an important 

 seabird colony until the island was quarried and 

 a breakwater was constructed. Few seabirds 

 nest there now. Photo by Art Sowls 



SPACE SHUTTLE 



The following account is drawn largely from 

 Potential impact of space shuttle sonic booms 

 on the biota of the California Channel Islands: 

 literature review and problem analysis (Evans et 

 al. 1979). 



Channel Island seabird populations may be 

 subjected to a new disturbance during the 1980's. 

 The U.S. Government has selected Vandenberg 

 Air Force Base (VAFB), just north of Point 

 Conception, as launch site for the Space Shuttle. 

 Most of these launches will be directed west over 

 the open Pacific, but approximately six launches 

 planned for polar orbit will pass directly over the 

 Channel Islands. These launches will produce 

 sonic boom pressure waves of up to 30 pounds 

 per square foot (psf), considerably greater than 

 the 2.0 to 2.5 psf produced by aircraft sonic 

 booms. Depending on weather and other factors, 

 sonic booms produced by the Space Shuttle will 

 be at maximum intensity over San Miguel Island 

 (Figure 1). Areas south and east of San Miguel 

 Island will be subjected to intense, though less 

 potentially devastating sound pressures. In addi- 

 tion, all of the estimated 129 Space Shuttle re- 

 entries will pass directly over the Channel Islands. 

 Sonic booms from these flights will be similar to 

 those from military aircraft, and 18 per year are 



SAN LUISOBISPO 



Zon* of maximum 

 sound intaowty 30 



LOS 

 ANGELES 



A 



^-SAN CLEMENTE IS. 



GROUNDTRACK 



Figure 1. Predicted lines of maximum sonic 

 boom pressures in pounds per square foot (psf) at 

 sea level resulting from Space Shuttle launches 

 into polar orbit from Vandenberg Air Force Base 

 (modified from U.S. Air Force, 1978. Final 

 Environmental Impact Statement, Space Shuttle 

 Program, Vandenberg Air Force Base, California). 



