California Colonies 



Catalog Total 



3,500 birds 

 = colony sites 



Percent of California 

 Breeding Population. 



Breeding Chronology 



Northern California 



Clutch- 1 2 



Incubation Period - 41 days 



Nill.r>g Period 2 dYl 



(38,29) 



Not Branding 



Ituiabers Jn parentheses correspond to the 

 references from vhlch tre obtained the data. 



Central California 



NotBrMding 



Channel lilimdl 



eoglaying 



(28,29) 



Jan. | Feb. | Mar. | Apr. | Miy | Jun | July | Au,. | Sp. | Oct. | No. | Qac. 



(524 001) with two birds. Xantus' Murrelets 

 probably also breed at Scorpion Rock (502 010) 

 and Castle Rock (501 005), and small numbers 

 may occasionally breed at other locations in the 

 Channel Islands (Hunt et al. 1979). 



HISTORICAL STATUS AND VULNERABILITY 



The population of Xantus' Murrelets on 

 Santa Barbara Island is apparently recovering 

 from a drastic decline. Between 1897 and 1908, 

 feral cats (Felis catus) were introduced onto 

 Santa Barbara Island. Few data on the size of the 

 murrelet population prior to the cats' introduction 

 exist, but Sumner (1939) states, "At one time 

 large colonies of auklets and murrelets were 

 present on the island, but none have been recorded 

 in recent years and it is supposed that they have 

 been exterminated by these feral cats". By 1975 

 the population of cats was reduced to perhaps 

 a single animal and Xantus' Murrelets are now 

 some of the most abundant of breeding seabirds 

 on the island (Hunt et al. 1979). 



Natural predators of Xantus' Murrelets 

 include the Peregrine Falcon (Falco peregrinus), 

 Deer Mouse (Peromyscus maniculatus), and 

 the Island Fox (Urocyon littoralis). Peregrine 

 Falcons were once common residents of the 

 Channel Islands, but now are only present as 

 migrants. Their decreased presence may have 

 contributed to the Xantus' Murrelet recovery on 



Santa Barbara Island (Hunt et al. 1979). 



An insular subspecies of Deer Mouse resides 

 on each of the eight large Channel Islands (Nelson 

 and Goldman 1931). They are known to prey on 

 eggs and possibly chicks of the Xantus' Murrelet, 

 but their presence is not a deterrent to successful 

 reproduction (Hunt et al. 1979, Winnet et al. 

 1979). 



The Island Fox is present on all large Channel 

 Islands, except Anacapa and Santa Barbara 

 Islands, the only two islands with large seabird 

 colonies. The presence of foxes on the other 

 large islands may account for small populations of 

 seabirds there. 



Because Xantus' Murrelets, like other alcids, 

 spend a lot of time on the water and dive for 

 food, they are vulnerable to oil spills. Location 

 of spills in the California Bight during the breeding 

 season would be the most critical, since adults 

 and recently hatched flightless chicks would be 

 concentrated near their colonies. 



Xantus' Murrelet Chick 



47 



