28 November 2010

Mangroves at Pasir Ris with high tide surprises

Pasir Ris mangroves is so colourful with the seasonal yellowing leaves of the Buta-buta mangrove trees (Excoecaria agallocha).
The Bird Ecology Study Group recently shared that herons were nesting at Pasir Ris mangroves. Yesterday, after the Chek Jawa walk, Ley Kun, Ivan and I decided to check this out. On the way, we bumped into Andy and his friend and we all headed out for a lovely stroll.

Among the first things we saw was a humungous Atlas moth caterpillar, slowly chewing up every single leaf within its reach on the host plant. Nearby, there were denuded branches with a few cocoons.
Heading onto the boardwalk, I realised the tide was really high! With water rushing right into the back mangroves.
The high water made the mangroves quite lively! Pasir Ris is crawling with huge crabs. Almost every burrow had one peering out or lurking nearby. These are mostly Tree climbing crabs (Episesarma sp.).
And there were plenty doing just that, climbing trees. To get out of the high water where nasty crab-eating predators might be lurking. At the same time, they are careful not to climb too high up the tree to avoid equally crab-loving predators like birds. In fact, whenever we got too close to trees with crabs, the crabs promptly jumped back into the water!
All kinds of snails were also crowded up on the tree trunks. These include marble-shaped Nerite snails (Family Neritidae) and more oval-shaped Chut-chut snails (Family Potamididae). Little mudskippers also clung onto tree trunks and branches.
Pasir Ris is a great place to spot really HUGE Giant mudskippers (Periophthalmodon schloserii). These two were huddled together, clinging to a root in the high water. These quarrelsome fishes are usually well separated, so it's an unusual sight.
In the flooded mangroves, there were several jellyfishes with fat arms (Acromitus sp.), vigorously swimming to and fro.
Wow! We saw several Dog-faced watersnakes (Cerberus rynchops) swimming about in the high water. One of them was very long and rather fat around the middle. Perhaps a Big Mama full of babies? These snakes give birth to live young. Or perhaps just had a big lunch?
I also saw a slender snake draped on a mangrove tree! From Nick Baker's awesome website, my guess is that it's a Painted bronzeback (Dendrelaphis pictus).
Finally we got to the viewing platform near the heron nesting site. In the distance, there were a few herons. We could hear their calls throughout our trip. But when we got to the nesting site, they seemed all quiet. Perhaps it was because of the incoming rain.
There was one nest on a tree nearer the viewing platform. But I'm not sure if it is currently in use. Throughout the trip, the mangroves are filled with the blare of music and noise from the nearby chalets and entertainment centre. And the nesting area is very close to all the noise. How surprising! As usually we are told to hush and be quiet near nesting sites. More about the new heronry on the Bird Ecology Study Group blog.
Since I was there, I quickly checked out the area where some rare mangrove trees have been planted. The area is usually dry but during the trip it was flooded. How nice!
The Gedabu trees (Sonneratia ovata) were growing nicely taller and one was fruiting! These trees are planted (as I understand, from stock from Thailand). The trees are rare in Singapore and listed as Critically Endangered. This Sonneratia can be distinguished by the calyx which clasps the fruit.
The pool with the Berembang trees (Sonneratia caseolaris) was also flooded with the tide. Apparently it's connected to the sea!
In this Sonneratia, the calyx is held away from the fruit and its leaves are more eye-shaped and held on 'weeping' branches that resemble the weeping willow. Berembang is also listed as Critically Endangered.
Another rare tree is the Dungun (Heritiera littoralis), it is listed as Endangered. There are several planted near the mangroves and one of them was blooming!
Here's a closer look at the pretty fuzzy pink bell-shaped flowers.
In the Park, there was a planted Yellow Flame (Peltophorum pterocarpum) that was still nice and short. A great opportunity to get better photos of the flowers, which are usually well out of reach on a fully grown tree. This tree is native to Singapore.
There were of course lots of other plants and interesting sightings. I find it is actually more fun to visit a boardwalk at a high and incoming tide!

More about Pasir Ris on wildsingapore. There are regular walks at the Pasir Ris boardwalk, the next ones are on 4 Dec (Sat) and 18 Dec (Sat) and plenty of fun activities for kids at Pasir Ris this coming December holidays!

The sea shores of Pasir Ris are also very much alive, despite the massive coastal works going on there. See Kok Sheng's post on his recent trip there.

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