Cindy L. Hull

The effect of carrying devices on breeding Royal Penguins

The impact of Time Depth Recorders (TDRs) and VHF transmitters, deployed on Royal Penguins (Eudyptes schlegeli) to examine foraging behavior, was assessed during all stages of the breeding season. Models of the devices were attached to penguins and compared to control birds with no devices. There were no impacts from transmitters on probability of return from a foraging trip, foraging trip duration, mass gained, water influx, or body composition, but substantial impacts from the TDRs. Attachment of TDRs (1) reduced the likelihood that penguins would continue the breeding attempt, (2) increased foraging trip duration, (3) increased water influx, and (4) decreased fat levels. The effects varied with sex and stage in the breeding season, which appeared to be related to the energetic demands of the stage in the breeding season. TDRs probably increased drag, affecting swimming speed and foraging success. The differential impact of the devices is most likely related to their cross-sectional area and streamlining, with TDRs being larger and less streamlined than transmitters.

The breeding biology and factors affecting reproductive success in rockhopper penguins Eudyptes chrysocome at Macquarie Island

Adult mass changes, egg morphometrics, chick growth rates, fledging masses, reproductive success and reasons for reproductive failure were examined in rockhopper penguins at Macquarie Island from 1993/1994 to 1995/1996. Mean arrival masses, growth rates of chicks and fledging masses exhibited inter-annual variability, while egg morphometrics, hatching success (68.0±6.0%) and reproductive success (47.3±8.3%) were constant between years. Reproductive failures occurred primarily during incubation, with the majority of eggs lost to great skuas. Logistic regressions revealed that no variable significantly explained hatching success, and only in 1994/1995 was fledging success significantly correlated with the position of nest in the colony (those in the centre were more successful than those on the periphery). Reproductive success during this study was relatively high, and therefore an assessment during poor years would be instructive, particularly in relation to aspects of the penguins’ foraging ecology.

The effect of investigators on the breeding success of royal,Eudyptes schlegeli, and rockhopper penguins,E. chrysocome, at Macquarie Island

The impact on reproductive success of investigators studying the breeding biology of royal and rockhopper penguins was assessed. Control and experimental transects were established in a colony of each species and the number of active nests, from egg laying to creche stage, were compared. Experimental nests were those used in breeding biology work, where birds were measured and banded, and nest checks were carried out at least once per week. Control nests were in equivalent locations but birds were not handled, and no contact was made with the nests once breeding had begun. There were no significant differences in the number of active nests between the control and experimental transects (and, therefore, breeding success) in either species. It is concluded that, provided care is taken when working with these species, no impacts on the short-term (up to creche stage, in one breeding season) breeding success of these populations will occur.

Long-term breeding phenology shift in royal penguins

The Earths climate is undergoing rapid warming, unprecedented in recent times, which is driving shifts in the distribution and phenology of many plants and animals. Quantifying changes in breeding phenology is important for understanding how populations respond to these changes. While data on shifts in phenology are common for Northern Hemisphere species (especially birds), there is a dearth of evidence from the Southern Hemisphere, and even fewer data available from the marine environment. Surface air temperatures at Macquarie Island have increased by 0.62°C during the 30-year study period (0.21°C decade−1) and royal penguins (Eudyptes schlegeli) commenced egg laying on average three days earlier in the 1990s than during the 1960s. This contrasts with other studies of Southern Ocean seabirds; five of nine species are now breeding on average 2.1 days later than during the 1950s. Despite the different direction of these trends, they can be explained by a single underlying mechanism: resource availability. There was a negative relationship between the Southern Annular Mode (SAM) and median laying date of royal penguins, such that low-productivity (low SAM) years delayed laying date. This accords with the observations of other seabird species from the Antarctic, where later laying dates were associated with lower sea ice and lower spring productivity. The unifying factor underpinning phenological trends in eastern Antarctica is therefore resource availability; as food becomes scarcer, birds breed later. These changes are not uniform across the region, however, with resource increases in the subantarctic and decreases in eastern Antarctica.

The efficacy of translocating little penguins Eudyptula minor during an oil spill

As a consequence of the ship The Iron Baron running aground at Low Head in northern Tasmania, Australia, an unknown number of little penguins Eudyptula minor were contaminated with bunker fuel oil. Of these, 1894 were brought into captivity and cleaned of oil. The area was still contaminated with oil when the penguins were ready for release and, rather than prolong captivity with its associated risk of disease and stress at a time when breeding was imminent, a translocation strategy was trialled, the results of which are reported here. Twenty-five penguins equipped with VHF transmitters were translocated 360 km to the east coast of Tasmania, and their movements tracked from the air. Two birds returned to the capture site in 3 days, insufficient time for clean-up to be completed, prompting a new release site 120 km further south. A further six penguins were tracked at nearby Ninth Island to monitor foraging behaviour. Fifty-six per cent of the birds released at the translocation sites returned to Low Head in 4 months. This is a conservative estimate, and subsequent monitoring found no differences in the survival rate of translocated and control birds. It was concluded that the translocation strategy was appropriate under the circumstances, and the translocation of a further 863 penguins was prompted. While translocation was effective in this situation, it should be trialled before being implemented in different circumstances or on other species.

Moult in adult Royal Penguins, Eudyptes schlegeli

Abstract Mass change during moult was measured in Royal Penguins at Macquarie Island during 1995, in order to estimate the energetic costs and prey-consumption rates required to fuel the moult. Masses of 30 birds were taken during each of the following stages: upon their return from the pre-moult foraging trips; in the middle of the moult; and at the completion of moulting. During the 36-day pre-moult foraging trip individuals increased in mass by 3 kg, accumulating 83.3 g day−1. The moult lasted 28 days and 99% of birds moulted at their breeding sites. During moult birds lost 46–47% of their pre-moult mass, with males expending an estimated 57997 kJ and females 57229 kJ during this period. It was estimated that 1.39 × 107 kg of food are required to fuel this stage in the life cycle of Royal Penguins at Macquarie Island, which therefore constitutes an important component of their overall energy budget.