Morphometric and genetic evidence for four species of gentoo penguin

Gentoo penguins (Pygoscelis papua) are found across the Southern Ocean with a circumpolar distribution and notable genetic and morphological variation across their geographic range. Whether this geographic variation represents species‐level diversity has yet to be investigated in an integrative taxonomic framework. Here, we show that four distinct populations of gentoo penguins (Iles Kerguelen, Falkland Islands, South Georgia, and South Shetlands/Western Antarctic Peninsula) are genetically and morphologically distinct from one another. We present here a revised taxonomic treatment including formal nomenclatural changes. We suggest the designation of four species of gentoo penguin: P. papua in the Falkland Islands, P. ellsworthi in the South Shetland Islands/Western Antarctic Peninsula, P. taeniata in Iles Kerguelen, and a new gentoo species P. poncetii, described herein, in South Georgia. These findings of cryptic diversity add to many other such findings across the avian tree of life in recent years. Our results further highlight the importance of reassessing species boundaries as methodological advances are made, particularly for taxa of conservation concern. We recommend reassessment by the IUCN of each species, particularly P. taeniata and P. poncetii, which both show evidence of decline.     

Pinguine – Überlebenskünstler in der Antarktis. Klimawandel

The future of penguin population development in the Western Antarctic Peninsula (= WAP) is largely depending on ecological factors like food availability (mostly krill) due to primary production of algae which itself depends on sea ice conditions, water‐ and air temperature and salinity. The extraordinary rise in temperature in the WAP area seems to cause a change in population numbers of Adelie and Gentoo Penguins: Adelies are declining in the north and Gentoos were occupying these sites instead. Gentoos have already reached the southern polar circle. These trends occurred in parallel with regional long‐term warming and significant reduction in sea ice extent. There is a lack of available information for penguin populations breeding possibly more south in the WAP area. We still have large gaps in our present knowledge in Adelies and Emperor Penguins southernmost breeding distribution.     

Krill-feeding behaviour of gentoo penguins as shown by animal-borne camera loggers

Animal-borne camera loggers were used to examine the patterns of prey encounter and feeding behaviour of gentoo penguins at King George Island, Antarctica. The still images from the camera loggers showed that the penguins encountered the swarms of krill for 25.5% (range: 8–38%) of their dives (>5 m) on average, during their foraging trips (mean duration of 5.4 h, n = 7 trips). They encountered krill swarms during the dives to 10–70 m depth, in pelagic as well as benthic habitats. In the benthic habitat, the penguins swam just above the sea floor and headed downward over a krill swarm, probably using the sea floor to assist them to feed on mobile swarms. The shallow coastal waters would be the important foraging habitat of gentoo penguins breeding in King George Island.     

Population variability in heat shock proteins among three Antarctic penguin species

Heat shock proteins (HSPs) are synthesised under stressful conditions such as exposure to elevated temperatures, contamination, free radicals, UV light or pathophysiological states resulting from parasites and/or pathogens. HSPs function to protect cells by means of modulation of protein folding. In Antarctica, these proteins have been studied in such organisms as protozoa and fishes, without attention to geographical variation. We studied the variation of HSP70 and HSP60 levels in Gentoo, Adelie and Chinstrap penguins among different populations along the Antarctic Peninsula from King George Island (62°15′S) to Avian Island (67°46′S). Our results show that the northern population of Gentoo penguin showed higher levels of HSP70 and HSP60 than the southern population. High temperature, human impact and immunity as a proxy for parasites and diseases in northern locations could explain such variation. Adelie penguin only showed significant geographical variation in HSP70, increasing north to south, a pattern perhaps related to increased UV radiation and decreased temperatures from north to south. Chinstrap penguin shows no population differences in the variation in neither HSP70 nor HSP60, although HSP70 showed marginally significant differences. Sexual differences in the level of these proteins are also discussed.     

Annual variation in reproductive parameters of Adélie penguins at Edmonson Point,Victoria Land,Antarctica

Annual egg and chick production and breeding success at the Adélie penguin (Pygoscelis adeliae) colony Edmonson Point (74°21′S–165°10′E), Victoria Land, is presented for eight breeding seasons between 1995 and 2005. During this period the colony consisted of 10–13 subcolonies and averaged 2098 ± 278 breeding pairs. A sample of over 100 nests (114–150), belonging to two subcolonies, was monitored each year. Some breeding parameters remained constant while others showed substantial annual variation. Laying date showed little variation, and laying was highly synchronous: 82.5% of clutches were initiated in a 10-day period, 9–18 November. In contrast, clutch size (1.77–1.97) and incubation period (34.4 ± 2.5) varied significantly. Variation among years was also recorded in hatching success (from 58 to 86%) and breeding success. This last parameter, measured as number of chicks reared to crèche per nest with eggs, varied between 0.34 and 0.97.     

The influence of thermoregulatory demand on contact crèching behaviour in Adélie Penguin chicks

(1) We tested the hypothesis that contact behaviour in Adélie Penguin (Pygoscelis adeliae) chicks of crèching age is strongly influenced by thermoregulatory demand. (2) Estimated thermoregulatory costs (% minimal metabolic rate) for early crèche stage (1 kg) chicks were much higher (13.4–121.0%) than for late crèche (3 kg) chicks (0–45.1%). The incidence of contact behaviour was high during early crèche, but uncommon during late crèche. (3) Both the percentage of early crèche chicks forming contact groups and the mean number of chicks per group increased significantly as thermoregulatory demand increased. (4) Thermoregulatory costs were significantly higher when late crèche chicks exhibited contact behaviour than when they did not. (5) Contact behaviour in Adélie Penguin chicks therefore appears to perform a thermoregulatory function and probably confers important energy savings in terms of maintaining a favourable daily energy budget and maximum fasting duration.     

Practical method of estimating fresh mass of Adélie penguin eggs

Fresh egg mass (FEM) is an important measure as it relates to many allometric relationships. Adélie penguin (Pygoscelis adeliae) eggs, as other bird eggs, begin to lose weight as soon as they are laid but their linear dimensions remain constant. The FEM of an Adélie penguin’s egg can be estimated within 1% from the relationship FEM = 0.564 × LW ², where L is the length and W is the width. The constant 0.564 was calculated by weighing the eggs after replacing the air cell with water. The calculated mean egg mass agrees well with that obtained by weighing eggs after replacement of the air cell with water (r ² = 0.996). This method of estimating FEM based on linear measurements is easily applicable in the field.