Little Penguins heading back to their burrows after a day's out at sea
Few months ago, I made a trip down to Philip Island to view the world famous Penguin Parade and it left a truly memorable natural wildlife experience, a treat never forgotten to me, and I felt I should share this wonderful experience with you.
So what is this Penguin Parade am I talking about?
Well, basically these penguins are called Little Penguins (known by their scientific name as Eudyptula Minor), or other common name such as Fairy Penguin or Little Blue Penguin, and they are the world’s smallest species of penguins.
Each night at sunset, these Little Penguins would emerge from the sea after a day’s fishing at sea, and will waddle ashore to their sand dune burrows. And at Philip Island, visitors like me, would be able to watch this event unfold right before you.
Sounds interesting isn’t it? Well to me it was, watching these Little Penguins coming ashore at dusk really fascinate me, not too sure about you but I hope you do.
Little Penguins coming ashore after a day's out at sea
First, let me give you a brief overview about these Little Penguins, basically they live in burrow unlike their largest Antarctic cousins, the Emperor Penguin, who live in the cold. They are 30 – 35 cm tall and weight 1 kg, unlike the Emperor Penguin which is 1 -1.3 m high with adult males weighting up to 38 kg. They are mostly found along the southern edge of mainland Australia, as well as Tasmania, New Zealand and the Chatham Islands.
Little Penguins is a social bird, and it is the most nocturnal of all penguin species. During the day, they are either hunting at sea or in its nest sleeping. They live in loose colonies, composed of birds of all age. They form small, very vocal groups when coming ashore at night, but then disperse to their respective territories to call it a day.
These Little Penguins usually leave their burrows 1 – 2 hours before sunrise each morning, they travel 15 – 50 km at sea each day and swim at a speed of 2 – 4 km/hr on average (maximum 6.4 km/hr). They forage only in daylight returning ashore at sunset.
From what I heard from one of the ranger who was on duty that day and through some research, these Little Penguins display group behaviour when arriving at the colony or departing to sea. At dusk, small groups of penguins appear in the shallows before making their way to their burrows, and similarly, in the hours leading to sunrise, they congregate in groups within the colony before making their way across the beach towards the ocean.
Having no prior knowledge about penguins or seabirds before my trip to Philip Island, this causes me to wonder why they have to enter and leave the beach in groups and in the darkness. And from the information I found, Little Penguins exhibit such behaviour as a form of predator avoidance strategy because their small stature and limited terrestrial mobility makes them particularly vulnerable to predation during their beach crossing. Both safety in numbers from grouping and moving under the cover of darkness help counteract these threat. Also, Little Penguins will linger within the safety of the vegetation or the ocean until there are enough numbers of penguins for a safe crossing. In the hours before sunset, they will congregate in groups at sea before making their way across the beach in darkness after sunset, towards the colony in groups of 10 – 100.
Again, it makes me wonder whether the groups that these penguins formed when they crossed the beach were composed of the same individual from day to day, or were formed randomly. After some research, I found that these Little Penguins can seek to form groups with the same individuals when arriving or departing from the colony. They display a nonrandom association or sought to parade with the same individuals when forming groups to cross the beach to and from the sea. In years of high breeding success, small groups of penguins form nonrandom groups and studies have shown that up to 25% of the arrivals were with the same individuals, but not in years of low breeding success.
While observing the penguins, I was wondering to myself, do they always enter and leave their nesting area at the same time everyday or do they enter and leave as and when they feel like to. From what I have found, the Little Penguins have the most predictable colony attendance among penguin species with mean arrival and departure times around 75 min after sunset and before sunrise, respectively. In years of low breeding success, Little Penguins tend to arrive on average 30 min later, suggesting a rigorous arrival schedule which could only be delayed if penguins are unable to return home because they are further away or impeded from doing so.
What was interesting was there was a dramatic change in the arrival time of Little Penguins at their breeding colony when a heavy low-level fog that blanket Philip Island on a particular evening. It was noted that, only 5% of penguins arrived at the expected time (compared to other days where it is 88%), and the peak time at arrival was 2 hours behind the usual peak arrival times (the maximum interval in the mean arrival time on normal days was 26 min). It is shown that these Little Penguins were unable or unwilling to return to the colony under the low visibility caused by the fog. It is reported that only half (52%) of the average number of penguins returned to the colony on the evening of the fog. This unusual environmental condition that affects the behaviour of the penguins can provide an insight into their behavioral response to limited depth vision. So why was there a dramatic changed in their arrival time? Several reasons include: the Little Penguins did not come ashore with poor visibility to avoid predation (their inability to detect predators could have kept them at sea) or their visual senses were impaired and were probably unable to find their way back home; or a combination of both.
However, it was noted that 5% of the penguins crossed the beach at the expected arrival time and a further 7% arrived later under thick fog. This can be analyzed using the cost-benefit analysis: as it was the breeding period at the time of the fog, the benefit gained from coming ashore to feed their chicks outweighs the risk of predation.
Thus the visit to Philip Island was indeed a memorable experience as not only do I have a wonderful time watching them but I gain more insights into the lives of these Little Penguins, and managed to find out why they exhibit the various behaviours that I have just mentioned above. And I hope you too, have gain more insights into the lives of these Little Penguins like I do and hopefully have an urge to visit Philip Island some day to watch these Little Penguins waddle ashore to their burrows.
References:
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Chiaradia, A., McBride, J., Murray, T., et al., (2007). Effect of fog on the arrival time of little penguins Eudyptula minor: a clue for visual orientation? Journal of Ornithology, 148(2): 229-233.
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Daniel TA, Chiaradia, A., Logan M, et al., (2007). Synchronized group association in little penguins, Eudyptula minor. The Association for the Study of Animal Behaviour, 74(5): 1241-1248.