In nature, many animals invest time and energy into raising their young to ensure that they can survive into adulthood. However, there are always a slew of challenges that parents face during the breeding season, including adverse weather conditions, an inconsistent food supply or difficulties inherent in raising offspring. Adélie penguins (Pygoscelis adeliae) are no exception, and although these birds breed between October and March, they still face harsh conditions in Antarctica. This led Madi McLatchie, Louise Emmerson, Simon Wotherspoon and Colin Southwell of the Department of Climate Change, Energy, the Environment and Water, and University of Tasmania (both in Australia) to conduct a 10-year study examining a wide range of factors that determine how successful Adélie penguins are at building their nests and raising their chicks.
For their study, the team researched a population of Adélie penguins located on the Windmill Islands in East Antarctica. The scientists set up five remotely operated cameras at four known breeding sites in 2011/2012 to take photos of the nesting penguins. The cameras were automated to take pictures once per hour for 10 daylight hours of the penguins’ breeding season each year, for 10 years. The team collected images of 450 nests throughout their 10-year study period, and randomly selected 10 nests from each camera site every season that had at least one penguin to analyse the behaviours of the parents. Some of these included the date that the nest was occupied by a parent penguin (where they were at the nest for at least 5 days), the nest structure (based on how well it was constructed out of stones) and its location within the penguin colony, and the date the female penguin left the nest to find food, while the male stayed behind to sit on the egg. Next, the team collected environmental measurements including air pressure, the movement of the continuously blowing westerly winds in the atmosphere (which can impact snow or rainfall amounts), the amount of ice attached to land, and possible overlap in penguin feeding grounds with neighbouring colonies to see whether any of these affected how successful the parents were at raising their chicks. The team also included more local factors such as snow cover, ground moisture and windchill.
The scientists found that parents successfully raised their chicks 313 times, but, unfortunately, were unsuccessful 137 times and the chicks did not survive. Of all the factors the researchers examined, the most important was for the penguins to occupy a nest at an earlier date in the breeding season, thereby allowing them to construct a high-quality nest – one that is raised off the ground and made with more stones – to raise their chicks in. This was especially true during the early part of the breeding season, which led the researchers to conclude that high-quality nests function to protect young and vulnerable chicks from adverse weather conditions and from water on the ground resulting from the snow melt in Antarctica. However, if the parents were late in the season to occupy and build their nests, their chick was less likely to survive.
Through their 10-year study, the team of researchers discovered which factors impact whether Adélie penguins can successfully raise their chicks. While many researchers in wildlife studies may focus solely on environmental factors affecting the ability for parents to raise their offspring, it is important to look at a range of factors that influence whether their young survive. In this study, McLatchie and colleagues showed how a parent's behaviours can impact their young, and the importance of punctuality in penguins.
