Abstract
Between 11/2/84 and 11/14/84 research was carried out by a Sea World field team on Isla Noir, Isla Magdalena and Isla Marta in southern Chile. In addition to the scientific commitments, the prime objective was to acquire a number of fertile penguin eggs (as well as those of several other avian species), which would be subsequently hatched in San Diego, California. Sea World has been deeply committed to polar penguin research for the past 12 years and maintains the largest colony of controlled environment subantarctic and Antarctic penguins in the world. The techniques used for egg acquisition and transport were prototyped during the 1983/84 season in the Antarctic in conjunction with the Chilean Antarctic Institute, Chilean Air Force and the University of Chile. The success of that venture formed the basis for the current project.
Isla Noir: This remote island is located some 200 miles to the northwest of Cape Horn and has been visited by very few naturalists, or anybody else for that matter. The island was extremely difficult to reach and conditions there were less than hospitable. Isla Noir (Black Island) was larger than any chart available indicated and was far more rugged than anticipated. This greatly hampered our ability to accomplish all of the scientific objectives. Several of the science projects had to be scaled down even more due to extreme climatic conditions. At times, the wind speed exceeded 90-100 mph and the sea state generally was in excess of 20 feet. As a result, landings in a small rubber zodiac were extremely difficult, not to mention hazardous. Additionally, the unbelievably dense vegetation precluded accurate census work since penetration through the thick growth was essentially impossible. For an accurate avifauna census to have been accomplished, dozens of qualified people working continuously for several weeks would have been required.
Rockhopper penguin (Eudyptes crestatus): This was a common nesting species on Isla Noir. However, they were difficult to reach because the penguins tended to favor rough coasts, nested high on the steep slopes (200 meters or more), and the rookeries were usually located in dense vegetation. Rockhoppers were abundant all along the southeast coast but some were also observed on the north side of the extreme eastern coast. However, they were not nearly as numerous in this sector, undoubtedly because of the vertical cliffs.
The specific rookery we· ultimately selected was somewhat difficult to reach, but it was one of the more accessible. This small rookery consisted of 300-500 pairs of rockhoppers, but many other rookeries dotted the hillside. We estimated in this area alone, at least 5, 000 pairs were nesting. However, due to the visual restrictions of the thick vegetation, the number could easily have been five times that amount.
The eggs were collected without incident because the rockhopper penguins tended to be very nervous and would move off the nest when approached. This was curious, since it did not conform to the behavior of E. crestatus I have worked with elsewhere; i.e., Falkland Islands, MacQuarie Island, etc. Generally, these are very aggressive, territorial and defensive birds which are not hesitant to attack and bite viciously. In addition, the nesting penguins were scattered, rather than in dense concentrations as is more typical elsewhere.
Crested penguins are of great interest since they produce a clutch of two dissimilar sized eggs. The first egg laid (alpha egg) is approximately one-third smaller than the second egg (beta egg). Why the small egg is laid first when the reverse appears to be more logical is not known. We were anxious to determine the viability of the alpha egg and wanted to know if egg size is related to sex determination. To accomplish this, 50 double egg clutches were collected along with an additional 30 beta eggs.
Crested penguins, while sometimes hatching two chicks, are not capable of fledging more than one young. This fact has been documented repeatedly.
In order not to compromise reproductive potential, one egg from nests we did not collect from was placed in nests where the two-egg clutches were acquired. Despite the fact that the territories were temporarily abandoned during collecting activities, and since penguin eggs are quite tolerant of cooling, the egg switch should have been successful.
Based on the behavior of the birds, combined with the fact most eggs in the colony did not exhibit extensive nest staining, we estimated that incubation had been in progress for approximately two weeks. The eggs were transported in portable, forced air, battery-operated field incubators. The temperature was maintained at a constant 96.5 °F. The transport of the eggs by boat back to the anchorage was extremely traumatic for us. The high winds and heavy seas (with 20 + foot swells), pounded the little 39-foot fishing boat to such a degree that we were doubtful the eggs could survive. During the early stages of incubation, developing embryos are particularly sensitive and any kind of shaking can cause development to terminate.
Once back in San Diego, the eggs were transferred to the stationary incubators within the USDA-approved quarantine freezer facility. We have since determined that both the alpha and beta eggs are indeed viable and while some of the alpha egg chicks were tiny (45 grams), the young were reared without major incident. It is also possible for researchers to analyze the remains in the discarded shell for hormonal traces and this data will enable us to sex each chick.
It will then be possible to answer the question of whether or not egg size is related to sex. The peak of hatching occurred on December 1 and since the incubation period is 32-34 days, we can fairly accurately determine when the Isla Noir rockhoppers commenced laying-the last week of October. A force in excess of 80 volunteers was required to assist with the hand rearing since feeding was necessary 24 hours a day, seven days a week. Ultimately 88 rockhopper penguins were fledged out of 92 hatched.