Scientific name:Synthliboramphus craveri
Until Recently: Endomychura craveri
Spanish: Pato Nocturno

Although a few Craveri's Murrelets have been found breeding on the western shores and islands off Baja California as far north as San Benitos they primarily breed on the islands of the Gulf of California where it is the only species of alcid. The species was first described in 1865 by Salvadori who collected it from Natividad Island on the west side of Baja California, and named it after Federico Craveri, a nineteenth century meterologist. Since then some argument has persisted as to whether the Craveri's Murrelet should be classed as a distinct species or listed as a subspecies of the Xantus' Murrelet. (See Chapter 10.) Unlike the Xantus', the Craveri's Murrelet is more uniform in appearance throughout its geographical range. It is the most tropical of all the auks.

Brief studies of the breeding biology of the Craveri's Murrelet on the islands of the Gulf of California indicate that it gathers near the islands in December and occupies nests from February to May each year. Eggs have been found from 6 February through 30 April.¹⁵⁶

The Craveri's Murrelet nests in crevices among rocks or vegetation, tending to stay close to the water just above the high tide zone. A few may nest on cliffs. Two is the usual number of eggs laid per clutch although on rare occasions, three eggs have been recorded. Ornithologists Lawrence DeWeese and Dan Anderson noted that the average number of chicks convoyed at sea by parent birds was 1.5 in 1972, and 1.3 in 1974. These figures indicated favorable success rates for those seasons. In 1973 however, very few chicks were seen at sea indicating an unexplained very poor season.¹⁵⁶ In other words, in 1972, 74 percent of the adult pairs convoyed young, while in 1973 only 12 percent were seen with chicks at sea. Of interest is the fact that in the same year other seabirds were also less successful. Lowering of food availability due to changes in oceanic currents may account for the observed differences. Whatever the causes, it is obvious that breeding success varies from year to year and that figures based upon one year's study are not sufficient for accurate information on the life history of a species. An unusual southerly sighting of the Craveri's Murrelet off the coast of Guatemala was recorded in 1973 when breeding was unsuccessful further north.²⁹⁸ This emphasizes the possibility that food was scarce for seabirds that year, forcing them away from their breeding grounds.

The Craveri's Murrelet, like the Xantus', is mated before it arrives at its breeding island. Since they are usually seen as pairs even during the winter months, it is thought that they stay mated all year. Both sexes share in the incubation duties, changing shifts in darkness. Two well-defined incubation patches are present on the bellies of both male and female during the breeding period. Only when it is incubating is the Craveri's Murrelet seen on land - all of its other activity and behavior occurs at sea. Its shrill clear calls are heard on the water near its breeding islands from December to February, but no one has ever observed its mating behavior which is presumed to take place at night. Consequently, our knowledge of the life history is incomplete.

In color, texture, and size the egg closely resembles that of the Xantus' Murrelet, but it is slightly smaller, as is also the body of the bird. The incubation period is unknown but is undoubtedly about the same as that of the Xantus', thirty-two to thirty-four days.

The young move to sea two to four days after hatching, and are cared for by both parents until fully grown. The young can be distinguished from their parents until they are about three-quarters grown. Solitary Craveri's Murrelets are rarely seen. Family units gradually move out to sea where, in June and July, they wander north along the coast of California or south along the coasts of Mexico. It was once thought that the Craveri's Murrelet raises two broods each year, but recent observations do not support this. Early seasonal egg losses may be replaced but, once a chick is reared, no second nesting occurs in the same year.

The Craveri's Murrelet forages at or near the surface over deep water and takes as food, larvae, small fish, and invertebrates.¹⁵⁶ Adult birds have been seen to pass small fish, 4 to 7 centimeters long, to their chicks. Unlike other alcids, which often mix together, the Craveri's Murrelet does not flock.

By July most of the murrelets have left the Gulf and numbers are seen as far north as Monterey Bay and, infrequently, up to the Oregon coast. Some may winter to the south along the Mexican coast.

Peregrine Falcons and Barn Owls have been known to prey upon the Craveri's Murrelets and, along with fish which are bound to take their share, these may be their chief predators. It is also a possibility that rats and feral cats have lowered breeding success on some islands in the Gulf of California. These animals should be exterminated on all islands where birds may potentially breed. Gulls inhabiting the same islands apparently do not prey upon murrelets as do the Western Gulls on auklets to the north. At least their effect is apparently minimal. Providing that curious boaters and souvenir seekers leave its breeding islands alone, the Craveri's Murrelet, although among the least numerous of all alcids, should continue to grace the waters of Baja California for some time to come. Its breeding places are warm, sunny isles that belong to the murrelets, at least during the weeks when they are nesting.