Eudyptes Research Articles

The role of allochrony in influencing interspecific differences in foraging distribution during the non-breeding season between two congeneric crested penguin species.

Mechanisms promoting coexistence between closely related species are fundamental for maintaining species diversity. Mechanisms of niche differentiation include allochrony which offsets the peak timing of resource utilisation between species. Many studies focus on spatial and temporal niche partitioning during the breeding season, few have investigated the role allochrony plays in influencing interspecific segregation of foraging distribution and ecology between congeneric species during the non-breeding season. We investigated the non-breeding migrations of Snares (Eudyptes robustus) and Fiordland penguins (Eudyptes pachyrhynchus), closely related species breeding between 100–350 km apart whose migration phenology differs by two months. Using light geolocation tracking, we examined the degree of overlap given the observed allochrony and a hypothetical scenario where the species commence migration simultaneously. We found that Fiordland penguins migrated to the Sub-Antarctic Frontal Zone and Polar Frontal Zone in the austral autumn whereas Snares penguins disperse westwards staying north of the Sub-Tropical Front in the austral winter. Our results suggest that allochrony is likely to be at the root of segregation because the relative profitability of the different water masses that the penguins forage in changes seasonally which results in the two species utilising different areas over their core non-breeding periods. Furthermore, allochrony reduces relatively higher levels of spatiotemporal overlap during the departure and arrival periods, when the close proximity of the two species’ colonies would cause the birds to congregate in similar areas, resulting in high interspecific competition just before the breeding season. Available evidence from other studies suggests that the shift in phenology between these species has arisen from adaptive radiation and phenological matching to the seasonality of local resource availability during the breeding season and reduced competitive overlap over the non-breeding season is likely to be an incidental outcome.

Characterization of the complete mitochondrial genome of the Macaroni penguin Eudyptes chrysolophus from the Barton Peninsula, King George Island, Antarctica

The Macaroni penguin Eudyptes chrysolophus is a small crested penguin. In this study, the complete mitochondrial genome of E. chrysolophus is revealed for the first time. The mitogenome sequence is circular and 17,059 bp in length. It contains 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes similar to other Spheniscidae species. The total nucleotide composition is 30.53% (A), 32.86% (C), 13.96% (G), and 22.66% (T), and 46.81% for overall GC contents. The phylogenetic analysis shows a close relationship between E. chrysolophus and E. schlegeli. Our findings would be useful for further studies on phylogenetics and evolutionary history of the genus Eudyptes.

Ancient DNA of crested penguins: Testing for temporal genetic shifts in the world’s most diverse penguin clade

Human impacts have substantially reduced avian biodiversity in many parts of the world, particularly on isolated islands of the Pacific Ocean. The New Zealand archipelago, including its five subantarctic island groups, holds breeding grounds for a third of the world’s penguin species, including several representatives of the diverse crested penguin genus Eudyptes. While this species-rich genus has been little studied genetically, recent population estimates indicate that several Eudyptes taxa are experiencing demographic declines. Although crested penguins are currently limited to southern regions of the New Zealand archipelago, prehistoric fossil and archaeological deposits suggest a wider distribution during prehistoric times, with breeding ranges perhaps extending to the North Island. Here, we analyse ancient, historic and modern DNA sequences to explore two hypotheses regarding the recent history of Eudyptes in New Zealand, testing for (1) human-driven extinction of Eudyptes lineages; and (2) reduced genetic diversity in surviving lineages. From 83 prehistoric bone samples, each tentatively identified as ‘Eudyptes spp.’, we genetically identified six prehistoric penguin taxa from mainland New Zealand, including one previously undescribed genetic lineage. Moreover, our Bayesian coalescent analyses indicated that, while the range of Fiordland crested penguin (E. pachyrhynchus) may have contracted markedly over the last millennium, genetic DNA diversity within this lineage has remained relatively constant. This result contrasts with human-driven biodiversity reductions previously detected in several New Zealand coastal vertebrate taxa.

Extreme intra-clutch egg size dimorphism is not coupled with corresponding differences in antioxidant capacity and stable isotopes between eggs

Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. In crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. Here, we assessed whether antioxidant and isotopic composition could underlie these differences between eggs within clutches of southern rockhopper penguins (Eudyptes chrysocome chrysocome). The second-laid egg had higher total antioxidant capacity than the first-laid egg, although this was not due to higher antioxidant concentration but to its higher mass. This suggests that resources are allocated by females at a constant rate in both eggs within clutches. Accordingly, we found a strong correlation for isotopic compositions between eggs suggesting that resources were allocated similarly to each egg within the clutch. Overall, we found little evidence for a significant role of antioxidant and isotopic compositions to explain differences in terms of embryo/chick development between eggs in crested penguins. However, since our results suggest a constant rate of antioxidant transfer from females to eggs, limiting the mass of the first-laid egg might represent a strategy for females to spare antioxidant defences and preserve self-maintenance.

Gynandromorphs of New Zealand Austrosimulium spp. (Diptera: Simuliidae)

Investigations in the 1970s of Leucocytozoon tawaki Fallis, Bisset & Allison, a blood parasite of New Zealand’s Fiordland Crested Penguins (Eudyptes pachyrhynchus Gray) parasites normally transmitted by female simuliids resulted in the trapping of some 20 thousand female Austrosimulium (Austrosimulium) adults, attracted to captive penguins. Three species were involved: Austrosimulium (A.) australense (Schiner), A. (A.) dumbletoni Crosby and A. (A.) ungulatum Tonnoir. Of those adults trapped, 24 were gynandromorphs; one other was obtained from elsewhere. Austrosimulium dumbletoni has only its female adult described; the two other species have all their stages known. Eight gynandromorphs of A. dumbletoni have been identified and elsewhere will be used formally to describe, for the first time, the male of this species. Here, synoptic descriptions of the gynandromorphs are provided.

Preferential incubation positions for different sized eggs and their influence on incubation period and hatching asynchrony in Snares crested (Eudyptes robustus) and yellow-eyed penguins (Megadyptes antipodes)

In crested penguins (Eudyptes spp.), second-laid eggs typically hatch before first eggs. Amongst a variety of factors that have been considered as mechanisms underlying this reversal, has been the idea that crested penguins can adjust the degree of hatching asynchrony by manipulating egg positions (i.e. placing the smaller first egg in the supposedly thermally disadvantaged anterior position) during incubation (termed Preferential Incubation Hypothesis). We tested this in the Snares crested penguin (Eudyptes robustus) and the closely related, but synchronously-hatching, yellow-eyed penguin (Megadyptes antipodes). Snares crested penguins were more likely to place their first eggs, which are smaller than second eggs, in the anterior incubation position than were yellow-eyed penguins, which have a clutch of two similar-sized eggs. But when yellow-eyed penguins, a non-brood reducing species, were provided with an artificial size-dimorphic clutch, they also placed smaller eggs more frequently in the anterior position, suggesting that a general preference exists among penguins to place smaller eggs in the anterior position. Egg temperatures of small first eggs of Snares crested penguins were higher in the anterior than in the posterior position. Large first eggs in lesser size-dimorphic clutches experienced high temperature differences in relation to position, while small first eggs in greater size-dimorphic clutches were incubated at similar temperatures. In yellow-eyed penguins, large eggs within clutches generally had higher egg temperatures than small eggs. Incubation periods of second eggs declined with increasing egg size. Egg-size variation, rather than egg positioning behaviour, influenced hatching patterns in Snares crested penguins. In lesser size-dimorphic clutches, second eggs were more likely to hatch first while in greater size-dimorphic clutches, small first eggs were more likely to hatch at the same time or before the second eggs. This was similar in yellow-eyed penguins, where second eggs hatched earlier in clutches with large first eggs. Our data contradicts the Preferential Incubation Hypothesis and we conclude that this hypothesis is unlikely to explain the reversed hatching asynchrony in crested penguins.

The Reproductive Endocrinology of Fiordland Crested Penguins Eudyptes pachyrhynchus

SummaryPlasma concentrations of progesterone (males and females), 17α-hydroxyprogesterone (males and females), oestradiol (females) and testosterone (males) were measured in Fiordland Crested Penguins at different stages from courtship to late in the incubation period. Plasma levels of oestradiol and testosterone were high during courtship, had declined to low levels by the time eggs were laid, and remained low in incubating birds. Progesterone was also highest during courtship in both males and females, but remained at relatively high levels following egg laying and during incubation. However, males returning from foraging towards the end of the incubation period had significantly elevated testosterone levels and lowered progesterone levels. Plasma levels of 17α-hydroxyprogesterone remained constant in both sexes through all stages of the breeding cycle examined here.

Multiple Mechanisms of Reversed Hatching Asynchrony in Rockhopper Penguins

Brood reduction in birds is frequently associated with hatching asynchrony, wherein incubation commences before clutch completion, causing last-laid eggs to hatch after earlier eggs. In crested penguins (Eudyptes spp.), second-laid eggs typically hatch before first-laid eggs, but the mechanisms behind this reversal are unknown. Through a multifactor field experiment with rockhopper penguins (Eudyptes chrysocome Forster 1781), I examined several factors that might influence incubation length : laying order (smaller first-laid eggs vs. larger second-laid eggs) ; incubation onset (exposure to immediate vs. delayed incubation) ; intraclutch dimorphism (incubated with an equal-sized vs. larger nest mate) ; laying date ; egg mass ; and egg composition (yolk and albumen content). Three of these factors - laying order, intraclutch dimorphism and laying date-contributed significantly to variation in incubation length ; first-laid eggs produced early in the season and incubated with a larger nest mate took longest to hatch. Differences in incubation onset did not contribute to incubation length when tested independently. The albumen content of both first and second eggs increased in proportion to fresh egg mass, but egg mass had no effect on incubation length. Although Eudyptes parents can potentially adjust the degree of hatching asynchrony through variation in egg position, the effects of laying date and laying order are probably beyond facultative control. Together, these effects may contribute to the unique reversal in both hatching asynchrony and egg-size dimorphism characteristic of crested penguins.

Over-wintering strategies of the Lesser Sheathbill Chionis minor in an impoverished and insular environment.

The Lesser Sheathbill Chionis minor is an opportunistic predator and scavenger that breeds on sub-Antarctic islands during the summer season, when many other seabirds are present, especially penguins on which it is kleptoparasitic. It is a poor flyer and over-winters on its breeding grounds, where it faces a diminished food supply and low temperatures. Its foraging behaviour was suspected to be plastic enough to respond to such a variable environment, and we show how this species enlarged its niche to survive in winter. Population movements, dietary changes and monthly weight gains were quantified during a 13-month period of observation. Mortality rates, calculated over a 19-year period of banding, appeared to be age dependent: they decrease, due to competition, from juveniles to subadults, adult non-breeders, and breeders. One of the survival strategies described here is, to our knowledge, unique among birds. After the Crested Penguin colonies have been deserted, some adult sheathbills (mainly females) remained territorial, extending their territory size and diet while their partners moved to previously undefended zones in King Penguin colonies (permanent and large in the Crozet archipelago), where they competed for a winter territory and subsequently associated with another mate. After this winter mating, mobile sheathbills returned the following summer to their breeding territory and previous mate.

Growth and Survival in Macaroni Penguin, Eudyptes chrysolophus, A- and B-Chicks: Do Females Maximise Investment in the Large B-Egg?

In crested penguins, Eudyptes spp., the first-laid (A) egg is smaller than the second-laid (B) egg and although viable rarely survives to hatching. I studied survival and growth to fledging of A- and B-chicks at experimentally-manipulated nests, and individual variation in relative investment by adult females in A- and B-eggs, in macaroni penguins, E. chrysolophus

Recognition of Parents' Calls by Chicks of the Snares Crested Penguin

Recognition of Parents' Calls by Chicks of the Snares Crested Penguin

Diets of yellow-eyed, Fiordland crested, and little blue penguins breeding sympatrically on Codfish Island, New Zealand

Diets of sympatrically breeding yellow-eyed (Megadyptes antipodes), fiordland crested (Eudyptes pachyrhynchus), and little blue penguins (Eudyptula minor) were examined over 1 week in late October ...

Aggression, Incubation Behaviour and Egg-Loss in Macaroni Penguins, Eudyptes Chrysolophus, at South Georgia

In crested penguins Eudyptes spp., the first-laid (A) egg is very much smaller than the second (B) egg and, although viable, rarely survives to hatching. I tested the recent hypothesis that this is an adaptation to cope with the high degree of egg loss resulting from selection for male aggression. In 60 nests of macaroni penguins 60% of A-eggs were lost on the same day and 23% on the day before the B-egg was laid. During the laying interval adults spent increasing time incubating prone (i.e. providing maximum protection for the A-egg). Aggression rates peaked before A-eggs were laid. Both results are contrary to the suggestion that intra-specific aggression and poor egg protection cause high A-egg loss and are the main factors favouring egg-size dimorphism. It is hypothesised that successful laying of the B-egg may have a causal effect on A-egg loss and that the A-egg may function as insurance against unsuccessful laying (immediate loss) of the B-egg.

The Clutch Size of Macaroni and Rockhopper Penguins

Williams, A.J. 1981. The clutch size of Macaroni and Rockhopper Penguins. Emu 81: 87–90.Published claims that Macaroni Penguins Eudyptes chrysolophus and Rockhopper Penguins E. chrysocome lay clutc...

Remarks on the Nomenclature and Taxonomy of the Crested Penguins

"Remarks on the Nomenclature and Taxonomy of the Crested Penguins." Emu - Austral Ornithology, 80(1), p. 38

The Crested Penguins of New Zealand

(1953). The Crested Penguins of New Zealand. Emu - Austral Ornithology: Vol. 53, No. 2, pp. 185-187.

The Correct Name of the Crested Penguin

The Correct Name of the Crested Penguin

Another Specimen of the Crested Penguin in Western Australia

Another Specimen of the Crested Penguin in Western Australia

On the occurrence of the Crested Penguin (Eudyptes chrysocome) in Australia, with notes on its range, and on the history of its original discovery

On the occurrence of the Crested Penguin (Eudyptes chrysocome) in Australia, with notes on its range, and on the history of its original discovery

Moulting in the Crested Penguin.

Moulting in the Crested Penguin.