Penguin Island¦December 2019

December KRM Branch Excursion

After our last two outings were rain affected the weather gods were finally with us for our outing to Penguin Island and 13 attendees met at the ticket kiosk on a warm sunny morning. Upon arrival on the island we spotted large numbers of Bridled Terns near the jetty and gliding overhead. In the vegetation along the path up to the picnic area we saw large King’s Skinks in good numbers. It was good to see that their numbers have bounced back after being severely impacted by the Black Rat invasion a few years ago. We walked along the track towards the western beach. On the way we stopped off at a lookout point to see whether there were any Caspian Terns nesting. Only one pair was visible amongst the vegetation but it was not possible to see whether there were any chicks. Approaching the beach on the western side it was evident that the Wild Grape (Nitraria billardierei) had benefited from the wet winter/spring and was very healthy with lots of seeds. As we made our way onto the beach we noticed Little Blue Periwinkles (Nodilittorina unifasciata) in cavities high up on the rocks. These are nocturnal feeders and move around the spray zone of the rocks grazing on algae. On the beach we found that the tide was very low and a lot of seaweed had been washed up. A pair of Pied Oystercatchers were seen probing the sand along the edge of the kelp.

Crested Tern chicks had been taken down onto the beach by their parents and we were once again treated to the spectacle of adult Crested Terns returning to the beach with a small fish to feed its chick and having to run the gauntlet of Silver Gulls.

It is always amazing to see how they are able to pick out their chick amongst the large number of birds on the beach. It was evident that not all chicks were at the beach as many adult terns delivered food to their nest site up in the vegetation. These generally suffered less from harassment by the Silver Gulls. The Bridled Terns also had nests up in the vegetation, which made it difficult to see if they had chicks. One chick was seen under the boardwalk at the southern end of the beach. After watching the spectacle for a while we made our way towards the stairway that would take us off the beach.

As we approached it we noticed a lone Pelican making its way through a fairly thick patch of Nitraria quite a distance from the Pelican nesting area. As it did so, both Silver Gulls and Bridled Terns were constantly harassing it.

This made us wonder if it was looking for unattended chicks in nests. After a while it appeared to give up and made its way back to the nesting area. We walked up the boardwalk and made our way to a viewing platform. This afforded views of the Pelican Rookery on the southern end of the island, a relatively bare patch in contrast to the healthy shrubbery elsewhere, highlighting the impact these rookery areas have on the vegetation. To the east of the island as we came back over the ridge we spotted a group of Pelicans fishing; they appeared to be chasing a school of whiting. Throughout our walk we had noticed a large number of Silver Gull carcases, possibly due to botulism picked up when feeding on the mainland. It did not appear to have affected the terns, however. Following the boardwalk around, we returned to the picnic area for a drink and snack. Around the Penguin Display and picnic area Scaevola crassifolia was in flower, Rhagodia baccata was in bud and both species of Tetragonia, the introduced Sea Spinach (Tetragonia decumbens) and the native Bower Spinach (Tetragonia implexicoma) were also in flower. Coastal Pigface (Carobrotus virescens) was also seen in flower during our walk.

With our interest being the birds we did not record many invertebrate sightings. Invertebrates that were noticed included an Orb Weaver spider (only the abdominal side was in view so it could not be identified), many small insects (Kelp Flies?) around the seaweed wrack on the western beach, a Monarch Butterfly, an unidentified native butterfly plus a tiny jumping spider found at the picnic area.

All too soon it was time to catch the ferry back to the mainland and we headed back to the jetty. The incoming ferry was full of visitors, highlighting how popular a day trip across to Penguin Island is for Perth residents and tourists. Our entire group certainly enjoyed our outing.

Colin Prickett