Aspects of the breeding biology of the southern rockhopper penguin <Emphasis Type="Italic">Eudyptes c. chrysocome</Emphasis> and new consideration on the intrinsic capacity of the A-egg

The rockhopper penguins Eudyptes chrysocome have recently been split into the northern E. moseleyi and the southern E. chrysocome rockhopper penguin. It is therefore crucial to have a comprehensive understanding of the biology of each species in order to develop appropriate conservation measures. We investigated the breeding biology of the southern rockhopper on New Island, in the western part of the Falklands Islands, by following the breeding attempt of 160 pairs during the 2006/2007 season and examining the effect of lay time and colony habitat on breeding success. Specifically, we compared survival and growth parameters between A- and B-eggs and chicks from non-manipulated and artificially manipulated nests to investigate why southern rockhopper penguins in the Falkland Islands are more able to fledge an A-egg (first laid) than conspecifics elsewhere. Breeding was highly synchronous, with no significant difference in the breeding success between early and late breeders or between pairs breeding in different habitats. We demonstrate for the first time that the A-egg produced by the southern rockhopper penguin has, when alone, the same theoretical intrinsic potential to lead to a fledged chick as the B-egg. In contrast, the hatching success and survival of the B-chick was similar when alone or in a two-egg clutch.     

Short-term responses of king penguins Aptenodytes patagonicus to helicopter disturbance at South Georgia

The short-term behavioural effects of helicopter overflights on breeding king penguins Aptenodytes patagonicus at South Georgia were examined. Seventeen helicopter overflights were made at altitudes between 230 and 1,768 m (750–5,800 ft) above ground level. Noise from the aircraft engines and helicopter blades increased sound levels in the colony from a background level of 65–69 dB(A) to a maximum mean peak level of 80 dB(A) during overflights. Penguin behaviour changed significantly during all overflights at all altitudes compared to the pre- and post-flight periods. Pre-overflight behaviour resumed within 15 min of the aircraft passing overhead and no chicks or eggs were observed to be taken by predators during overflights. Non-incubating birds showed an increased response with reduced overflight altitude, but this was not observed in incubating birds. Variability in overflight noise levels did not affect significantly the behaviour of incubating or non-incubating birds. Penguins exhibited a reduced response to overflights as the study progressed (despite later flights generally being flown at lower altitudes) suggesting some degree of habituation to aircraft. To minimise disturbance to king penguins we recommend a precautionary approach such that overflights are undertaken at the maximum altitude that is operationally practical, or preferably are avoided altogether.     

Low genetic diversity and lack of population structure in the endangered Galápagos penguin (<Emphasis Type="Italic">Spheniscus mendiculus</Emphasis>)

Long-term monitoring of the endangered Galápagos penguin (Spheniscus mendiculus) has indicated poor reproductive periods and severe population fluctuations in association with El Niño – Southern Oscillation events. An earlier mark and recapture study indicated that adults exhibit some degree of breeding-site and mate fidelity, and that juveniles potentially move more frequently than adults; however, the extent to which migrants and gene flow occur between islands within the Galápagos archipelago is largely unknown. This study tested the hypothesis that geographic isolation and adult breeding philopatry has led to a degree of genetic differentiation between island subpopulations within the archipelago. We examined the genetic diversity within and among different subpopulations and the extent to which gene flow occurs between island subpopulations. Estimates of allelic richness and gene diversity were not significantly different between subpopulations. Tests to detect genetic heterogeneity failed to reject the H ₀ of no difference in allele frequencies for chi-square (P = 0.28) and Fisher’s exact test (P = 0.19). All pairwise values of the F _ST variant θ were not significant, while a power analysis revealed a >99% probability of detecting a biologically true F _ST of 0.05. Migration estimates in BAYESASS+ suggest symmetrical gene flow throughout the species’ distribution. Our results indicate a low level of genetic diversity throughout the population and a seemingly high level of gene flow between subpopulations. We argue that the Galápagos penguin should be managed as one panmictic population and we discuss the risk of disease threats in the archipelago.     

Isolation and characterization of microsatellite loci from the yellow-eyed penguin (Megadyptes antipodes)

Twelve microsatellite loci were isolated and characterized in the endangered yellow-eyed penguin (Megadyptes antipodes) using enriched genomic libraries. Polymorphic loci revealed two to eight alleles per locus and observed heterozygosity ranged from 0.21 to 0.77. These loci will be suitable for assessing current and historical patterns of genetic variability in yellow-eyed penguins.     

A comparison of genetic diversity between the Galápagos Penguin and the Magellanic Penguin

The Galápagos Penguin (Spheniscusmendiculus) is a United States federallylisted endangered species with populations onthe Galápagos Islands of Fernandina andIsabela. Although the waters around theislands are normally productive, lowproductivity during El Niño years resultsin high adult penguin mortality and lowrecruitment in following years. We usedmicrosatellite markers developed for Spheniscus penguins to study the long termgenetic effects of serial bottleneck events inthe Galápagos Penguin, and compared thisvariation to that of its congener, theMagellanic penguin (Spheniscusmagellanicus). The observed heterozygosityfor the Galápagos Penguin was 3%,significantly lower than the 46%heterozygosity of the Magellanic Penguin. Thislow level of heterozygosity is directly relatedto its low effective population size. Whilethis population has survived long term,presumably without high levels of geneticvariation, we feel that the greater frequencyof El Niño events, coupled with increasedhuman impacts such as introduced disease, oildischarge, and competition with fisheries, mayput the species in particular danger ofextinction.     

Semen collection,characterization, and cryopreservation in a Magellanic penguin (Spheniscus magellanicus)

A cooperative method was developed for collecting semen from a Magellanic penguin. Ejaculate parameters and semen production during a breeding season were characterized. Experiments were performed to study the effect on penguin spermatozoa of two temperatures (4°C and 21°C) for short‐term storage, and two cryoprotectants (dimethylsulfoxide [DMSO] and ethylene glycol [EG]) for long‐term storage (cryopreservation). All dilutions were made using modified Beltsville Poultry Semen Extender. Sperm quality was assessed by evaluating motility and forward progression (sperm motility index [SMI]), viability, and morphology. A total of 39 ejaculates was collected over the 40‐day study period. Thirty‐eight ejaculates contained spermatozoa, but semen quality decreased toward the end of the study period. Varying levels of urate contamination were present in all ejaculates. Sperm quality parameters were similar for diluted samples held at 4°C and 21°C, and samples maintained high numbers of viable (77.8 ± 5.4%) and morphologically normal (67.9 ± 2.5%) spermatozoa at 3 hr. SMI and percentage of viable sperm decreased (P < 0.05) and the number of spermatozoa with a bent head or midpiece increased (P < 0.05) for both temperature groups over the 3‐hr storage interval. DMSO and EG were equally effective in maintaining penguin sperm quality parameters during the cryopreservation and thawing process. Frozen‐thawed semen maintained 69 ± 5 and 78 ± 3% of its pre‐freeze SMI and viability, respectively. SMI and viability decreased slightly during the cooling and equilibration phases but remained relatively stable during the 3‐hr storage interval post‐thaw. Frozen‐thawed semen also exhibited an increase (P < 0.05) in spermatozoa with a bent head or midpiece over time. The pre‐freeze SMI was higher (P < 0.05) for ejaculates with low levels of urates (clean ejaculates) compared with ejaculates with high levels of urate contamination, but sperm viability and morphology were similar (P > 0.05). Both SMI and viability of frozen‐thawed spermatozoa were higher (P < 0.05) for clean than for contaminated ejaculates. This is the first report on penguin ejaculate parameters, semen production, and preliminary methods for short‐ and long‐term semen storage. Zoo Biol 18:199–214, 1999. © 1999 Wiley‐Liss, Inc.     

A retrospective analysis of mortality in captive Magellanic penguins (Spheniscus magellanicus) in the United States, 2008–2018

Mortality data for Magellanic penguins (Spheniscus magellanicus) housed in zoos and aquariums in the United States has not previously been published. Necropsy and histopathology records were examined for Magellanic penguins housed at 12 Association of Zoos and Aquariums institutions from 2008 through 2018. If birds lived through the first year, the mean longevity was found to be 18.9 years of age (standard deviation: 7.9). Prefledge chicks and geriatric penguins experienced the highest mortality rates. Aspergillosis was a major cause of death in this species. There was no significant difference in mortality between males and females. Based on these data, recommendations for the husbandry and veterinary care of captive Magellanic penguins can be made.     

Landfast ice: a major driver of reproductive success in a polar seabird

In a fast-changing world, polar ecosystems are threatened by climate variability. Understanding the roles of fine-scale processes, and linear and nonlinear effects of climate factors on the demography of polar species is crucial for anticipating the future state of these fragile ecosystems. While the effects of sea ice on polar marine top predators are increasingly being studied, little is known about the impacts of landfast ice (LFI) on this species community. Based on a unique 39-year time series of satellite imagery and in situ meteorological conditions and on the world''s longest dataset of emperor penguin (Aptenodytes forsteri) breeding parameters, we studied the effects of fine-scale variability of LFI and weather conditions on this species'' reproductive success. We found that longer distances to the LFI edge (i.e. foraging areas) negatively affected the overall breeding success but also the fledging success. Climate window analyses suggested that chick mortality was particularly sensitive to LFI variability between August and November. Snowfall in May also affected hatching success. Given the sensitivity of LFI to storms and changes in wind direction, important future repercussions on the breeding habitat of emperor penguins are to be expected in the context of climate change.