SOS Penguins

Reporter: Belinda Wilkinson

Whilst breeding seemed to start as usual this year, it all fell in a heap! Many fewer eggs than usual were laid, especially in June and July, when normally the highest number of eggs are laid. In contrast, the most eggs were laid in September this year, and the incubation shifts by the penguin parents were also much longer. Normally, one parents shift on the eggs will last for 3-5 days. During this time the other parent remains at sea, feeding and when that penguin returns to the nest, it is time for the other hungry penguin to spend time at sea. But this year, the maximum recorded shift was 13 days! This means one penguin is sitting on the eggs for 13 days without eating. The longer a penguin incubates eggs for, the more likely it is to abandon those eggs to ensure its own survival. Throughout this year, particularly in September, many of the eggs or young chicks were abandoned. Of 38 eggs laid in the nest boxes in September, only 3 chicks have so far survived. This success rate is much lower than normal.

The few fledglings that have survived and grown their adult feathers are also much lighter than average, often up to half the weight that fledglings have been in previous years. Once the fledglings leave the nest, their chance of survival is closely tied to their weight. Remember, these fledglings are not shown where to catch fish, or how to catch them. So the heavier they are, the more likely they are to survive while they develop their hunting skills. The chance of these much lighter fledglings surviving is therefore very low.

So, why the late breeding, longer incubation shifts, fewer pairs breeding and poorer success at raising chicks? It seems likely that the fish the penguins prey on while breeding, particularly whitebait, were not as abundant in the nearby areas the penguins usually feed in. This year the penguins travelled long distances, such as to Binningup, over 100km south from Penguin Island! This information was obtained by attaching satellite tags to several penguins during incubation. The penguin that swam to Binningup took two days to swim there, and then remained in front of Binningup and within 5 km of the coast for 9 days. He must have found a good supply of fish down there.

Once the eggs have hatched, the penguins need to stay much closer to home as they need to be able to return to the island every evening to feed the chicks. For the penguins at Penguin Island, this means they can't travel much past Mandurah if they are to return that same night. As it happened, a few penguins did travel further south than this, and not surprisingly, they did not return the same evening. Their chicks therefore went at least one day without food. If this continuously happens, the chicks grow more slowly, some may die depending on the size of the meals brought back to them, and the parents themselves lose weight. This is because they have to put a lot of energy to swim to feeding areas further away, and the may catch less food, or food of poorer quality. The penguins can't continue to sustain such practices, and will eventually abandon their chicks in order to survive. In short, penguins need a reliable supply of fish that are close by to their nesting grounds.

The penguins mainly eat the whitebait while they are raising chicks, and we know they feed on whitebait that comes from a nursery at Becher Point. So the biggest threat to the penguins from Penguin Island is the long term survival of this nursery. We also know that it is the most productive nursery in Warnbro Sound and Comet Bay. Without the fish that originate from this nursery, we are likely to continue to see the events that happened this year - fewer penguins breeding, later breeding and fewer chicks being successfully raised. We must therefore protect this nursery if we want to continue to enjoy having the most western colony of Little Penguins in the world.