Female Penguins Research Articles

Humoral immune responses of black-footed penguins (Spheniscus demersus) after DNA-mediated immunization with a beta-galactosidase reporter gene.

Humoral immune responses of black-footed penguins (Spheniscus demersus) to DNA-mediated immunization with a beta-galactosidase reporter gene expression plasmid were evaluated. Six male and 6 female adult penguins received either test plasmid, pCMV-beta, containing the beta-galactosidase gene or control plasmid, pCI, lacking a gene for expression. Three birds from each group were used previously in a diluent control group and given one injection of sterile saline. All samples were screened for anti-beta-galactosidase antibodies by indirect enzyme-linked immunosorbent assay with anti-chicken immunoglobulin G as secondary antibody. Antibodies to beta-galactosidase were detected in the sera of pCMV-beta-inoculated penguins, with a peak response on day 21. Antibody titers of the test plasmid group versus both control groups on days 21, 28, and 42 differed significantly. These results demonstrate that black-footed penguins can be safely transfected with the gene encoding beta-galactosidase and will mount a humoral response against the in vivo-expressed protein. Knowledge from this initial study can be applied to the development of DNA-mediated vaccines against specific infectious diseases of penguins.

Effects of Feeding on Plasma Uric Acid and Urea Concentrations in Blackfooted Penguins (Spheniscus demersus)

Preprandial and postprandial plasma uric acid concentrations were evaluated in 12 healthy blackfooted penguins (Spheniscus demersus). Five male and 7 female penguins were fasted overnight, and blood was collected the next morning. Four days later, the same group of birds was given a morning feeding of fish ad libitum. Each bird's food consumption was recorded over a 2-hour feeding period. A blood sample was collected from each bird after removal of the fish (0- to 2-hour postprandial sample) and again 4 hours later (4- to 6-hour postprandial sample). Plasma samples were analyzed for uric acid and blood urea nitrogen (BUN) concentrations. In the 8 birds that consumed food during the 2-hour feeding period, plasma uric acid concentrations were significantly higher in both the 0- to 2-hour and 4- to 6-hour postprandial samples than in the preprandial samples. Uric acid concentrations were significantly lower in the 4- to 6-hour postprandial samples than in the 0- to 2-hour postprandial samples. Preprandial uric acid concentrations were <10 mg/dl, and 0- to 2-hour postprandial concentrations were >13.4 mg/dl (mean concentration = 21.2 mg/dl). No significant differences were found between preprandial and postprandial BUN concentrations. In penguins, uric acid concentrations must be measured after a fast to avoid a possible misdiagnosis of renal disease or gout.

Fidelity and breeding success of the blue penguin Eudyptula minor on Matiu‐Somes Island, Wellington, New Zealand

A study of the nesting habits and breeding biology of blue penguin Eudyptula minor was undertaken over the 1995–96 and 1996–97 breeding seasons on Matiu‐Somes Island, Wellington, New Zealand. Male and female blue penguins tended to be faithful to both mates and nest sites, although there was insufficient evidence to detect any association between a bird's breeding success in 1995 and a subsequent change of mate or nest in 1996. Over the 1995 and 1996 seasons the recorded hatching success (0.51 ±0.11 and 0.63 ± 0.10 respectively), fledging success (0.81 ±0.12 and 0.85 ±0.10 respectively) and reproductive success (0.41 + 0.11 and 0.54 ± 0.11 respectively) were similar each season. There was no significant difference between the proportion of eggs laid, or eggs hatched and chicks fledged, between the two seasons. The mean number of chicks raised over the two seasons was 0.94 ± 0.05 per nest. Replacement clutches were laid by 11 per cent of failed breeders in each season, but only in 1996 were they successful in fledging chicks. No significant difference was found between the breeding success of the Matiu‐Somes Island blue penguin colony recorded during this study and a previous study undertaken on the island 40 years ago.

Sex differences in Adélie penguin foraging strategies

Consistent sex differences in foraging trip duration, feeding locality and diet of breeding Adelie penguins (Pygoscelis adeliae) were demonstrated at two widely separated locations over several breeding seasons. Differences in foraging behaviour were most pronounced during the guard stage of chick rearing. Female penguins made on average longer foraging trips than males, ranged greater distances more frequently and consumed larger quantities of krill. In contrast, males made shorter journeys to closer foraging grounds during the guard period and fed more extensively on fish throughout chick rearing. Mean guard stage foraging trip durations over four seasons at Bechervaise Island, Eastern Antarctica and over two seasons at Edmonson Point, Ross Sea ranged between 31 and 73 h for females and 25 and 36 h for males. Ninety percent of males tracked from Bechervaise Island by satellite during the first 3 weeks post-hatch foraged within 20 km of the colony, while the majority (60%) of females travelled to the edge of the continental shelf (80–120 km from the colony) to feed during this period.

Maximum diving depths of northern rockhopper penguins ( Eudyptes chrysocome moseleyi ) at Amsterdam Island

The mean maximum dive depth from 49 foraging bouts by northern rockhopper penguins, measured using capillary-tube depth gauges, was 66±4 m (12–168 m). There were no differences in the maximum dive depths between male and female penguins. Northern rockhopper penguins dived deeper in early than in late creche stages (83±7 vs 57±4 m), and this was associated with probable dietary changes, squid dominating the diet by mass (44%) in November, and fish (64%) in December 1994 at Amsterdam Island.

Discrimination by adélie penguins, Pygoscelis adeliae, between the loud mutual calls of mates, neighbours and strangers

Playback experiments were conducted during the incubation period to test the responses of 10 male and 14 female penguins to recordings of the Loud Mutual Calls of their mates, neighbours and strangers. Loud Mutual Calls are given at the nest-site by lone birds, towards an opponent or as part of a display with mate or offspring and are individually distinctive. Both males and females discriminated between the calls of their mates and strangers. Males, but not females, discriminated between the calls of neighbours and strangers. This is the first time an ability to discriminate between the calls of neighbours and strangers has been demonstrated in a colonially breeding seabird. The greater fidelity of males than of females to nest-sites probably results in a more stable ‘vocal environment’ for males than for females. Males may thus have greater opportunities than females to learn the calls of their neighbours.