Haematocrit values in chinstrap penguins (Pygoscelis antarctica): variation with age and reproductive status

We studied haematocrit variation with age and reproductive status in chinstrap penguins (Pygoscelis antarctica) at Deception Island, South Shetlands. There was a significant difference in haematocrit values between different age groups (adults vs nestlings and juveniles). Adults had a higher haematocrit value than juveniles and nestlings and juveniles had higher haematocrit values than nestlings. There was also a significant difference in haematocrit values between adults of different status (breeding vs moulting). Breeding adults had higher haematocrit values than moulting adults. The observed differences between age groups were thought to be the result of different oxygen demands due to exercise. The observed differences between adults of different status could reflect the different demands associated with reproduction and moult fasting.     

Heat loss and site-dependent fecundity in chinstrap penguins (Pygoscelis antarctica)

We study the effects of heat loss and nest site quality on fecundity in a chinstrap penguin (Pygoscelis antarctica) colony on Deception Island, Antarctica. During the austral summers of 1990–1991, 1993–1994, and 1995–1996, 441 randomly selected nests were analyzed. Penguins breeding in the center of subcolonies hatched significantly earlier and had larger broods and than those nesting near or at the edge of the subcolonies. These differences, however, were significantly affected by interaction between year and nest location, being highly significant in colder years, when peripheral nests produce fewer young. Analysis of the rate of heat loss showed that penguins breeding at the edge of subcolonies lost heat twice as rapidly as those breeding in the interior of the subcolony. In a re-occupation experiment, evacuated center nests were re-occupied almost ten times as rapidly as edge nests. An analysis of mean fecundity in the period 1991–1996 and mean wind chill suggested that most of the variability in fecundity among years was related to differences in the rate of heat loss. Subcolonies tend to be as circular as possible, thereby decreasing the proportion of edge nests as the size of subcolony increases. Our results support the site-dependent fecundity hypothesis.     

Parental body size affects meal size in the chinstrap penguin (Pygoscelis antarctica)

Meal size of chinstrap penguins (Pygoscelis antarctica) was estimated through weighing adult breeders before and after food transfer during the crèche phase. Mean meal size delivered by each parent was 630.2 ± 178.3 g and was independent of breeding date, number of chicks and sex. Only body size as estimated by flipper length had a significant effect on meal size, suggesting an advantage of large body size which allows maximization of food carried per visit. Received: 22 September 1997 / Accepted: 16 December 1997     

Experimental assessment of the effects of gastrointestinal parasites on offspring quality in chinstrap penguins (Pygoscelis antarctica)

Parasites reduce host fitness and consequently impose strong selection pressures on their hosts. It has been hypothesized that parasites are scarcer and their overall effect on hosts is weaker at higher latitudes. Although Antarctic birds have relatively low numbers of parasites, their effect on host fitness has rarely been investigated. The effect of helminth parasitism on growth rate was experimentally studied in chinstrap penguin (Pygoscelis antarctica) nestlings. In a total of 22 two-nestling broods, 1 nestling was treated with anthelminthics (for cestodes and nematodes) while its sibling was left as a control. Increased growth rate was predicted in de-wormed nestlings compared to their siblings. As expected, 15 days after treatment, the experimental nestlings had increased body mass more than their siblings. These results show a non-negligible negative effect of helminth parasites on nestling body condition that would presumably affect future survival and thus fitness, and it has been suggested there is a strong relationship between body mass and mortality in chinstrap penguins.     

Population decline of chinstrap penguins (Pygoscelis antarctica) on Deception Island, South Shetlands, Antarctica

Population changes of top predators can provide key indications of environmental quality. In the Antarctic ecosystem, population dynamics of top predators like penguins may yield important information about how the environment is changing. From 1991–1992 to 2008–2009 censuses of the chinstrap penguin (Pygoscelis antarctica), breeding population of Vapour Col in Deception Island (South Shetlands Islands) were carried out. Censuses were conducted on 19 sub-colonies, mainly in December around the time of peak hatching. Nest counts were taken from photographs that were recorded from a standard location. Some censuses were also made in mid-January in 1999, 2006, 2007 and 2008. Our results reveal that the population has declined by 36?% when comparing data from 1991 with those from 2008. The strongest decline occurred since 2000. No temporal trends were detected in reproductive success. Declines of Chinstrap penguin populations constitute a general pattern in the South Shetlands, and it has been suggested to be related to climate change through effects of reduction in sea-ice extent during winter and a consequent decline in the abundance of krill.     

Factors that affect hatching asynchrony in the chinstrap penguin (Pygoscelis antarctica)

We examined if laying intervals and hatching asynchronies are related in a chinstrap penguin (Pygoscelis antarctica) population in the South Orkneys. The lack of association between the two variables, as well as data on brood patch development, indicated that incubation did not begin immediately after the first egg was laid. This suggests that longer laying intervals may be compensated by longer delays in the onset of full incubation. Hatching asynchrony increased with within-clutch egg size asymmetry, decreased with breeding date, and was related to the laying order of the eggs according to size. However, only egg-size asymmetry remained significant when controlling for the other variables. We conclude that more asymmetric clutches were more asynchronous, although a large part of the variation in hatching asynchrony remains unexplained.     

Absence of haematozoa in a wild chinstrap penguin Pygoscelis antarctica population

No haematoza were detected in 40 adult and 58 nestling wild chinstrap penguins (Pygoscelis antarctica) from Antarctica examined by blood smear. Received: 27 November 1996 / Accepted: 24 March 1997     

Breeding time, health and immune response in the chinstrap penguin Pygoscelis antarctica

Health status and immunocompetence have been proposed as important factors affecting individual variation in the attainment of breeding condition in birds. We studied individual variation in serological variables indicating health status (blood sedimentation rate, haematocrit, `buffy coat' layer, proportions of different types of leucocytes) in two groups of breeding chinstrap penguins Pygoscelis antarctica with breeding dates 9 days apart. We sampled these individuals shortly after hatching of their young and at the end of the chick-raising period. A group of failed breeders was also sampled. Birds of both sexes were included. We also measured the T-cell-mediated immune response as indicated by an in vivo hypersensitivity response to an intradermal injection of a mitogen (phytohaemagglutinin) in early and late breeders. Sex had no significant effect on most variables. Late breeders had poorer health (more leucocytes, especially heterophils and lymphocytes) and a lower T-cell-mediated immune response than early breeders. Failed breeders were more similar to late than to early breeders. Early breeders suffered a decline in health status throughout the chick-raising period. The impact of pathogens on variation in life history traits in avian populations may be important even in extreme Antarctic environments. Received: 18 December 1997 / Accepted: 1 March 1998     

Adult aggression during the post-guard phase in the chinstrap penguin Pygoscelis antarctica

We report an observational study of aggressive behaviour by adults during the post-guard phase in the chinstrap penguin. The study was carried out in one subcolony where all the individuals (breeders, chicks and failed breeders) were banded, as well as in nine other subcolonies where individuals were not identifiable. Breeding adults were more aggressive towards unrelated chicks when they were feeding their own chicks than in other contexts. Chicks were also attacked at high rates by adults that did not belong to their own subcolonies. The evidence suggests that some aggressions to chicks by adults may function to avoid interference from unrelated chicks during food transfers, but our data also show that aggressive interactions are common in contexts other than chick feeding. However, aggression by adults did not show any clear spatial directionality or purpose of shepherding the chicks, and these tended not to move in any particular direction when attacked.     

Chinstrap penguins (Pygoscelis antarctica) nesting on Sabrina Islet, Balleny Islands, Antarctica

Although the majority of chinstrap penguins (Pygoscelis antarctica) inhabit the Scotia Arc, a minuscule population of ten breeding pairs has been reported several times from Chinstrap Islet, in the Balleny Islands, 5,000 km distant on the opposite side of Antarctica. An aerial photographic census (December 2000) reveals that the overall penguin population of the Balleny Islands has declined by 8% since the last census 16 years ago, while the combined populations of the two largest colonies, Chinstrap Islet and Sabrina Islet, have increased by 11%. A ground visit confirmed for the first time that chinstrap penguins also breed on Sabrina Islet, occupying 20-24 nests on the margins of the Adélie colony (3,790 pairs in all). The small size and anomalous location of the Balleny Islands chinstrap population clearly warrant further study and the strongest protective measures.     

Limited effects of egg size on chick growth in the chinstrap Penguin Pygoscelis antarctica

We studied the effect of egg size on chick growth in the chinstrap penguin under natural non-manipulative, conditions. The influence of egg size on chick mass at hatching, 15 and 45 days of age was analysed controlling for the effect of hatching date, as hatching date has been repeatedly associated with chick growth in this species. Egg volume explained 20% of the variation in the body mass of chicks at hatching. Its effect disappeared as chicks grew, being statistically not significant at the age of 15 and 45 days. Egg volume asymmetry also had no role in determining chicks' growth asymmetries. Accepted: 6 June 1998     

The food and feeding ecology of Adélie penguins (Pygoscelis adeliae) and Chinstrap penguins (P. antarctica) at Signy Island, South Orkney Islands

Adélie Pygoscelis adeliae and Chinstrap P. antarctica penguins are important consumers of Southern Ocean marine resources. The stomach contents of adult penguins at Signy Island, South Orkney Islands, were analysed quantitatively throughout the chick-rearing period. They consisted almost exclusively of Antarctic krill Euphausia superba , Adélies eating 35–63% by number and 23–28% by weight of juvenile krill and Chinstraps 72–87% by number and 90–95% by weight of mature krill, as well as small amounts offish and amphipods. Interspecific dietary differences may partly be attributable to Adélies starting breeding one month before Chinstraps but, as they persist when both are simultaneously rearing chicks, the two species may also forage in somewhat different areas.
Krill data from net hauls indicate a substantial overlap in the size of krill taken by scientific, and probably also commercial, operations and by Adélie and Chinstrap penguins.
Chicks were fed c. 300 g of food 0–5-0-8 times per day, Chinstrap chicks without a sibling being fed most frequently. Chicks of both species were most often fed in the late afternoon, and from estimates of swimming speed and feeding frequency adults may feed quite extensively at night.     

Genetic diversity in populations of Gentoo penguins (Pygoscelis papua)

RAPD analysis was used to examine the extent of genetic polymorphism in two populations of Gentoo penguin (Pygoscelis papua) from Antarctic Islands (Petermann and Livingston). The chosen two of three 10 mer oligonucleotide primers accordingly to preliminary results showed different levels of polymorphism in Gentoo penguins at Petermann Island (from 23.53 to 42.86%) and Livingston Island (from 52.94 to 57.14%). Nei's similarity coefficients were in range from 0.5606 (when Gentoo genome profiles were compared with RAPD profiles of two related penguin species: Pygoscelis adeliae (Adelie) and Pygoscelis antarctica (Chinstrep)) to 0.9281 among observed Gentoo penguin populations. Nei's distances values ranged from 0.0746 to 0.5787 among the populations and species. The obtained results will be used for further estimation of genetic diversity of Gentoo penguins and determination of their taxonomic status.     

Physiological condition and reproductive consequences in adelie penguins

Animals must make "decisions" (e.g., when or whether to breed,the effort to put into a breeding episode) by integrating physiological,environmental and social inputs. This integration can be studiedonly in a field context. In Adélie penguins (Pygoscelisadeliae) reproduction is constrained by foraging ecology, modeof transport, and the extreme latitude at which they live. Thedecision whether to breed in a given year is influenced by bodyconditions. Adélie penguins must fast for several weeksduring the early reproductive stages and use stored fat formetabolic energy. Females that return to the colony, but donot breed, are 10–12% lighter than females that do breed.Birds that are relatively low in body mass tend to have lowerreproductive success than heavier birds, and an individual'sreproductive success is positively correlated with the bodyfat stores it had on arrival. After eggs are laid, parents alternatein attending the nest. Nest failure occurs if one parent doesnot make a timely return and its fasting partner must eventuallyleave. During normal-length fasts plasma corticosterone andglucose levels do not change. Blood ß-hydroxybutyratelevels gradually increase during the fast while uric acid levelsremain low, but in birds with the longest fasts (>50 days),ketone levels may fall and uric acid levels increase, indicativeof a switch from using fat to using body proteins for metabolism.In incubating males, hematocrit and hemoglobin concentrationsalso increase, suggesting dehydration can accompany energy stressduring the breeding fast.     

Plasma proteins and immunoglobulins in penguins (Pygoscelis adeliae).

Total and fractionated proteins were evaluated in the serum of normal penguins. Four proteins with antibody activity, determined by passive haemagglutination, were isolated by Sephadex G-200 filtration and DEAE-cellulose chromatography, from the serum of penguins (Pygoscelis adeliae) inoculated with dinitrophenylated human gamma-globulin. Immunoelectrophoresis and immunodiffusion showed that all these proteins exhibited both their own and shared antigenic determinants. On account of their electrophoretic mobility, elution conditions and characteristics of the precipitation arcs, they have been tentatively denominated IgG2 (gamma2), IgG1 (gamma1), IgM (gammam) and IgX (probably IgA).     

Nest maintenance and stone theft in the Chinstrap penguin (Pygoscelis antarctica)

The intensity of stone collection and stone theft by breeding Chinstrap penguins was measured, and estimations made of the number of stones per nest in large (> 400 nests) and small subcolonies (< 50 nests) in the large Vapour Col colony on Deception Island, South Shetland Islands. Stone availability was significantly higher both inside and outside small subcolonies. Penguins carried stones to the nest at the same rate in large and small subcolonies, but stole more intensively in large subcolonies. Stones obtained by theft were significantly larger than those collected elsewhere. When stone availability was increased experimentally, individuals of large subcolonies collected more intensively than control individuals in large and small subcolonies, and stole significantly less than control individuals in large subcolonies, and as much as individuals in small subcolonies. The greater theft pressure in large subcolonies was accompanied by more aggressive defence by nest owners and by reduced succession stealing. However, the reduced availability of stones on the ground near large subcolonies led to a significantly lower number of stones per nest than in small subcolonies. These results are interpreted in the light of the geometric effects of breeding group size (perimeter to surface ratio) on stone accessibility.