Magellanic Penguin Research
Students and staff alike are conducting compelling research with Magellanic penguins at Punta Tombo. Below are some of the projects currently being worked on at the Center for Penguins as Ocean Sentinels.
This research, conducted by doctoral candidate Jeff Smith, focuses on the impact of aggressive behavior on penguin fitness. Using aggressive behavior as a proxy, Jeff asks how personalities are maintained in Magellanic penguins, and what effect individual differences in personality have on penguin life-history characteristics including mating, settlement patterns, fitness, and nest protection. Understanding the costs and benefits of different personalities can help us better understand how Magellanic penguins will respond to an ever-changing world.
Additionally, Jeff also studies predation on adult penguins by terrestrial carnivores in an attempt to understand what impact newly recolonized predators may have on the colony at Punta Tombo.
Longevity and Telomeres in Magellanic Penguins
Doctoral candidate Jack Cerchiara is currently conducting research on the maintenance of telomeres (tandem repeating, non-coding sequences that protect the coding regions of DNA during cell replication) to increase longevity in seabirds, specifically Magellanic penguins. For the majority of species, body mass is predictive of longevity, with larger individuals having longer lifespans. Magellanic penguins exceed their mass-predicted lifespan by approximately 26%. In most species, telomeres shorten due to aging and stress. To examine telomere lengths in relation to age, blood samples from 80 wild, known-age adult Magellanic penguins were collected. Wild Magellanic penguins’ telomere lengths did not shorten after 5 years of age. In 2010, Jack re-sampled 36 of the adults sampled in 2007 and telomere lengths showed no evidence of shortening, suggesting that adult Magellanic penguins may not be compromising their longevity by the cost of reproduction. Continual investigation of the aging physiology of seabird species could yield significant clues to understanding the processes of aging in long-lived species and perhaps hold clues to mitigating the pathologies inherent in human aging.
Heritability of Traits from Parents to Young
The passing of morphological traits (heritability) from Magellanic penguin parents to offspring was studied by graduate student Laura Koehn. High heritability is important because without inheritance there is no potential for evolution. Laura estimated heritability for four structural traits (bill length, bill depth, flipper length, foot length) by comparing mid-parent size (the average of both parents’ sizes) and offspring size for each offspring gender. Bill size (depth and length) was significantly heritable from mothers and fathers to sons, and foot length from fathers to sons. No traits were significantly heritable from parents to daughters and flipper length was not significantly heritable for any gender. Bill sizes and feet are important for intrasexual competition among male penguins when fighting to obtain a mate or good quality nest. In contrast, females rarely fight and always get a mate. Morphological traits appear less important for females than males in acquiring a breeding site and a mate. The results suggest intense sexual selection leads to higher heritability for these traits in male offspring.
Climate Change and Reproductive Failure
Penguin Sentinels research scientist Ginger Rebstock, along with lead researcher Dee Boersma, is investigating the impacts of climate change-induced rainstorms on the reproductive success of Magellanic penguins. Large rainstorms can kill a majority of chicks in a seabird colony, causing reproductive failure. Many scientific papers report the effects of single storms on seabird colonies. How will increases in the frequency and intensity of storms, caused by climate change, affect seabirds? They used 28 years of data (1983-2010) from Punta Tombo on causes of chick deaths, chick ages at death, nest characteristics, and daily weather data to analyze the effects of increased storminess on Magellanic Penguins’ reproductive success. Papers published in climate journals show that more rain in the region of Punta Tombo has come from storms with heavier rainfall since 1960 and our daily weather data show an increase in the frequency of rainstorms since 1983. Climate models predict these trends will continue. Chicks die in storms when their down gets wet and they are unable to stay warm. The study showed that chick age, amount of rain, low temperature, and nest type all determine a chick’s probability of dying in a storm. They developed a model to predict the probability of dying and showed that larger storms in the future will kill more chicks and older chicks. The study also showed that a decline in the synchrony of egg laying interacts with storm timing to influence how many chicks die in a storm.
How to Grow a Penguin
Doctoral candidate Olivia Kane studies post-hatching influences on growth and the relationship between growth and successful fledging of Magellanic penguin chicks. How do post-hatching factors such as feeding frequency, brood size, hatch-order and nest type affect growth? Is growth of all body components (mass, bill, flippers, feet, and feathers) affected in the same way? Do chicks sacrifice growth of certain body components over others to increase current survival? For example, if food is limited, do chicks sacrifice growth of flippers and allocate those resources towards feathers so that they may fledge and acquire food independently?
Population Census at Punta Tombo
How many penguins are there at Punta Tombo, and how much has the colony declined since we started monitoring? We have conducted a census at Punta Tombo every field season since 1987. These censuses use the same marked locations each year, making them ideal to detect population trends. In October 2012 we also conducted a stratified random census designed to estimate the number of active nests. We can then apply the relative changes shown by our annual census and estimate the number of active nests in any year that we did a census. We will know not just the relative change in penguins but also the number of penguins that the colony has lost. We are also analyzing the data spatially, by nesting habitat type, to learn how penguins in a declining colony use the habitat.