Little Penguins: Dive Shape Versus Coastline Health
by Sian Liversage
Little Penguins, otherwise known as Kororā in Moari and commonly called Blue Penguins or Fairy Penguins, are found all around the coast of New Zealand. As their name suggests, they are the world’s smallest penguin weighing in at a mere 1kg and 25cm tall. They have a varied diet composed of small fish, squid, and crustacean species.
A Little Penguin near its burrow.
Primarily nocturnal on land, they can sometimes be found close to human settlements, in and around buildings, keeping the neighbours awake with their vocal displays. A recent article was published about a sushi store in Wellington who found out first hand just how noisy Little Penguins can be! The pair had decided to cross two main roads to nest underneath the sushi store. Perhaps it was the smell of the fresh fish that had enticed them in? Unfortunately for them though, they had chosen an awkward spot, so the Department of Conservation had to step in to relocate them. They have since decided to keep away from the area, and the hope is they have chosen a nest box located along the wharf instead.
Little Penguins Commonly Nest in Coastal Areas with Heavy Automobile Traffic
This pair were lucky not to get hit by any cars when they decided to cross main roads to nest. Sadly, many penguin colonies around the world are in decline, and thanks to an abundance of media stories in recent years just like the one mentioned, we are now more aware that our coastal areas are severely affected by humans due to an increase in shipping, fishing pressures, and coastal land development. This awareness hopefully will encourage councils and governments to either protect whole areas or at least provide wildlife-friendly areas that allow penguins to go about their natural behaviours.
Because Little Penguins depend on these coastal areas for food, they offer an easy and convenient way to study the health of marine ecosystems around New Zealand. And thanks to their predictable behaviour, where every night they will return to the same location, it makes it even easier for scientists to research them.
Little Penguins Exhibit Varied Hunting and Diving Behaviour
A study conducted by the Department of Conservation marine scientists monitored hunting trips of 8 Little Penguins using tiny electronic data loggers2. These small devices are carefully attached to the penguins’ tail feathers for 2-4 days, where they record the length and depth of each dive. These scientists were able to find differences in Little Penguin diving techniques dependent on the environment in which the penguins lived. In areas with plenty of prey, “V-shaped” dives were made for short shallow hunts, “U-shaped” dives meant they had to work a bit harder searching the ocean bottom for food, and finally “W-shaped” dives meant it took them approximately a quarter of their time to hunt for their prey. This research showed that Little Penguins have a variety of diving techniques when hunting, which is dependent on the abundance of prey and their location. So, can it be assumed that studying the diving technique of Little Penguins can determine the health of the marine ecosystem in which the penguins live?
Fortunately, Little Penguins are Adaptable
To support this assumption, another recent study was conducted which also looked at diving behaviours and diets in Little Penguins off Motuara Island3. They concluded that the species appear to be highly adaptable to local environments, given the variability in diving behaviours as well as in prey. These results therefore suggest that some locations would naturally be more difficult to adapt to than others, reflected in longer and deeper dives (aka “W-shaped” dives). Therefore, these penguins may prove to be useful environmental monitors for changes in the specific sites in which the individuals live. And with the combination of long-term site monitoring and population trend monitoring, it could lead to enough evidence to show that the coastline requires more protection if the ecosystem changes for the worse.
Some studies have already proven that a variation or lack in availability of food can result in problems for the penguins4. Results showed delays to the start of breeding, a reduced likelihood that a second clutch will be produced, and a higher chance of chick mortality. In addition to this, researchers have found that adult and chick body conditions are poor, resulting in the chicks’ immunity being reduced and causing the fledging period to become longer. Therefore the parents must work harder for longer. Without the varied diet that they require, these issues could cause a population to decline in the future, so perhaps by continuing the research into penguin diving techniques around the New Zealand coastlines, we can determine whether the area requires environmental protection or not.
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References:
- RNZ News. 2019. Web: https://www.rnz.co.nz/news/national/394557/little-blue-penguins-move-on-from-sushi-shop
- Department of Conservation Marine Ecosystems Team, Science and Policy. 2015.
- Chilvers L. 2019. Variability of little blue penguin diving behaviour across New Zealnad. New Zealand Journal of Ecology, Vol. 43, No. 2, 2019
- Dann P, Norman FI, Cullen JM, Neira FJ, Chiaradia A 2000. Mortality and breeding failure of little penguins, Eudyptula minor, in Victoria, 1995–1996 following a widespread mortality of Pilchard Sardinops sagax. Marine & Freshwater Research 51: 355–362.
