Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942–2012: current warming hiatus pauses a long-term decline

Morrison, Kyle W.; Battley, Phil F.; Sagar, Paul M.; Thompson, David R.

doi:10.1007/s00300-014-1575-x

Cited by 29 publications

(36 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…), Southern Rockhopper Penguins (Morrison et al. ), and African Penguins (Spelt and Pichegru ). Regardless, sex is often ignored in contemporary research on penguin demographic rates (e.g., Sherley et al.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Sex‐biased survival contributes to population decline in a long‐lived seabird, the Magellanic Penguin

Gownaris

Boersma

2019

Ecological Applications

View full text Add to dashboard Cite

We developed a Hidden Markov mark–recapture model (R package marked) to examine sex‐specific demography in Magellanic Penguins (Spheniscus magellanicus). Our model was based on 33 yr of resightings at Punta Tombo, Argentina, where we banded ~44,000 chicks from 1983 to 2010. Because we sexed only 57% of individuals over their lifetime, we treated sex as an uncertain state in our model. Our goals were to provide insight into the population dynamics of this declining colony, to inform conservation of this species, and to highlight the importance of considering sex‐specific vital rates in demographic seabird studies. Like many other seabirds, Magellanic Penguins are long‐lived, serially monogamous, and exhibit obligate biparental care. We found that the non‐breeding‐season survival of females was lower than that of males and that the magnitude of this bias was highest for juveniles. Biases in survival accumulated as cohorts aged, leading to increasingly skewed sex ratios. The survival bias was greatest in years when overall survival was low, that is, females fared disproportionality worse when conditions were unfavorable. Our model‐estimated survival patterns are consistent with independent data on carcasses from the species’ non‐breeding grounds, showing that mortality is higher for juveniles than for adults and higher for females than for males. Juveniles may be less efficient foragers than adults are and, because of their smaller size, females may show less resilience to food scarcity than males. We used perturbation analysis of a population matrix model to determine the impact of sex‐biased survival on adult sex ratio and population growth rate at Punta Tombo. We found that adult sex ratio and population growth rate have the greatest proportional response, that is, elasticity, to female pre‐breeder and adult survival. Sex bias in juvenile survival (i.e., lower survival of females) made the greatest contribution to population declines from 1990 to 2009. Because starvation is a leading cause of morality in juveniles and adults, precautionary fisheries and spatial management in the region could help to slow population decline. Our data add to growing evidence that knowledge of sex‐specific demography and sex ratios are necessary for accurate assessment of seabird population trends.

show abstract

Section: Discussionmentioning

confidence: 99%

“…]; Southern Rockhopper Penguin, Eudyptes chrysocome [Morrison et al. ]; African Penguin, Spheniscus demersus [Spelt and Pichegru ]), the sex ratio of Magellanic Penguins at Punta Tombo is male biased (Boersma et al. ).…”

Section: Methodsmentioning

confidence: 99%

Sex‐biased survival contributes to population decline in a long‐lived seabird, the Magellanic Penguin

Gownaris

Boersma

2019

Ecological Applications

View full text Add to dashboard Cite

show abstract

“…The decline that was occurring for the rockhopper penguins at the Antipodes Islands appears to have lessened and possibly halted, as is the case with other eastern rockhopper populations (Baylis, Wolfaardt, Crofts, Pistorius, & Ratcliffe, ; Dehnhard et al, ; Kirkwood et al, ; Morrison et al, ; Oehler et al, ). The widespread and largely simultaneous declines of rockhopper penguin populations throughout their range were thought to be the result of a single shared cause.…”

Section: Discussionmentioning

confidence: 95%

“…Climate change has been predicted and observed to significantly alter the world's environment and impact all aspects of the life cycle of marine species (life history traits, phenology, movement, Solomon et al, ). These changes are known to affect penguin population parameters and size (Ainley et al, ; Ainley & Blight, ; Dehnhard et al, ; Demongin, Poisbleau, Strange, & Quillfeldt, ; Morrison, Battley, Sagar, & Thompson, ; Parmesan, ; Parmesan & Yohe, ; Trathan et al, ; Walther et al, ). Climate change is altering weather patterns around the globe, including increasing the frequency and severity of storms, significantly increasing precipitation in some areas, bringing flooding and landslides (Coumou & Rahmstorf, ).…”

Section: Introductionmentioning

confidence: 99%

Significant decline of endangered Antipodes Island penguins: Is extreme weather an additional impact?

Chilvers

Hiscock

2019

Aquatic Conservation

View full text Add to dashboard Cite

Worldwide, most crested penguin species (Eudyptes spp.) are in decline. New Zealand's subantarctic Antipodes Islands are of international significance for erect‐crested (Eudyptes sclateri) and rockhopper (Eudyptes filholi) penguins. Between 1995 and 2011, a 23% decline was recorded in the two penguin species on the Antipodes Islands. In October 2014, nest abundance counts on Antipodes Island were undertaken to determine if this decline was continuing, particularly in light of a significant storm event that hit the Antipodes area in January 2014 causing massive landslides during the penguin breeding season. All penguin colonies ground counted in 2011 were preferentially ground counted in 2014 or, if time or weather did not allow, were checked with binoculars to confirm colony presence or absence. Seventy‐three per cent of the colonies and the equivalent of 82% of all nests counted in 2011 were recounted in 2014. Overall, there was a 19% decline in erect‐crested penguin nests between 2011 and 2014. Rockhopper penguins showed a slight increase (2.6%). Landslides affected 11% of the main islands’ land area and 44% of surveyed nesting colonies. Erect‐crested penguin colonies with approximately 75% or greater of their area impacted by landslides showed a significantly greater decline than unaffected or only partially impacted colonies. Landslides showed a minimal effect on rockhopper nest numbers. There continues to be a significant decline of erect‐crested penguins at the Antipodes Islands. An increasing occurrence of extreme weather events are predicted with climate change and have the potential to increase land‐based flooding and landslides, adding additional impacts to terrestrial breeding marine species. Greater understanding of what is causing erect‐crested penguin decline is needed to prevent this endangered species from extinction.

show abstract

“…In 1939, Mayr called for more research into sex ratios and their variability, but this topic remains understudied, particularly in long‐lived organisms (Mayr , Székely et al , Carmona‐Isunza et al ). Though male‐biased sex ratios are frequently reported in penguins (Yellow‐eyed Penguin Megadyptes antipodes [Richdale ], Adélie Penguin Pygoscelis adeliae [Ainley and Demaster ], King Penguin Aptenodytes patagonicus [Olsson and van der Jeugd ], Galápagos Penguin Spheniscus mendiculus [Boersma et al ], Southern Rockhopper Penguin Eudyptes chrysocome [Morrison et al ], African Penguin Spheniscus demersus [Spelt and Pichegru ]), generally only static estimates of sex ratio are available for these species (see Richdale , Ainley and Demaster , Weimerskirch et al , Gownaris and Boersma for age‐related trends). We leveraged a long‐term data set on two Magellanic Penguin colonies to examine how OSR varies at several temporal scales (long term, interannually, intraannually) and to explore how this variation influences breeding behavior and success in this long‐lived, monogamous species.…”

Section: Discussionmentioning

confidence: 99%

Sex ratio is variable and increasingly male biased at two colonies of Magellanic Penguins

Gownaris

Borboroglu

Boersma

2020

Ecology

View full text Add to dashboard Cite

Sex ratios are commonly skewed and variable in wild populations, but few studies track temporal trends in this demographic parameter. We examined variation in the operational sex ratio at two protected and declining breeding colonies of Magellanic Penguins (Spheniscus magellanicus) in Chubut, Argentina. Penguins from the two colonies, separated by 105 km, migrate north in the non‐breeding season and have overlapping distributions at sea. Conditions during the non‐breeding season can impact long‐term trends in operational sex ratio (i.e., through sex‐specific survival) and interannual variation in operational sex ratio (i.e., through sex‐specific breeding decisions). We found an increasingly male‐biased operational sex ratio at the two disparate colonies of Magellanic Penguins, which may contribute to continued population decline. We also found that the two colonies showed synchronous interannual variation in operational sex ratio, driven by variation in the number of females present each year. This pattern may be linked to sex‐specific overwintering effects that cause females to skip breeding, i.e., to remain at sea rather than returning to the colony to breed, more often than males. Contrary to our predictions, colony‐wide reproductive success was not lower in years with a more male‐biased operational sex ratio. We did find that males showed more evidence of fighting and were less likely to pair when the operational sex ratio was more male biased. Our results highlight an indirect mechanism through which variation in the operational sex ratio can influence populations, through a higher incidence of fighting among the less abundant sex. Because biased sex ratios can reduce the size of the breeding population and influence rates of conflict, tracking operational sex ratio is critical for conservation.

show abstract

Population dynamics of Eastern Rockhopper Penguins on Campbell Island in relation to sea surface temperature 1942–2012: current warming hiatus pauses a long-term decline

Cited by 29 publications

References 43 publications

Sex‐biased survival contributes to population decline in a long‐lived seabird, the Magellanic Penguin

Sex‐biased survival contributes to population decline in a long‐lived seabird, the Magellanic Penguin

Significant decline of endangered Antipodes Island penguins: Is extreme weather an additional impact?

Sex ratio is variable and increasingly male biased at two colonies of Magellanic Penguins

Contact Info

Product

Resources

About