Spotted Wood Owl, Big Billed Herons' Courtship, and Mishaps during Camping and Kayaking at North Shore of Singapore

Our enjoyment of  Kayaking on Api Api River  made us want to do it again.

Our misfortunate camping at Pulau Ubin  made us want to try camping again in Singapore. 

This led to the trip plan for a combined camping and kayaking journey:

Camp at Pasir Ris Beach and Park on May 23, 2026, overnight, and go kayaking on Api Api river early next morning. 

We arrived at the park around 6pm. The camp ground is big and smooth, not many campers there at that time. We set up our tent and walked around. We had birds, jungle rooters and a spotted wood owl as our neighbors, plus Sea breeze, setting Sun,... Not bad!

A breezy evening

Spotted Wood Owl

There were many tents by the beach, that's where noisy people were. I hoped they were day campers, and would leave when it was time to sleep.

After our picnic dinner, we walked along the beach away from the noise to the no camping zone. We sat on a park bench by the sea, enjoyed sea breeze, a half Moon in the sky, and the quiet dark Johor Strait. 

We went back to the campsite around 9pm, and was surprised to find tens of lights densely distributed within the campground were turned on, made the campground brighter than earlier in the evening! The noise from the people by the beach was louder than earlier. There was no quiet time restriction. In fact the lights were on the whole night, and noise did not die down until ~ 1 to 2am next day.

Another bad camping experience in Singapore. It was worse than the Pula Ubin camping experience.

our tent

dark and quiet Johor Strait

lit up camp ground, and noise from tents by the beach

We got up early next morning, ~ 6am. There were people jogging and biking at the park already. The sky was still dark, the surrounding was quiet. The restroom for the area was cleaned - thanks to the custodians who got up even earlier. A positive change!

After breakfast, we unset and packed the tent, stored it in our car parked only 100 feet away. 

We inflated our inflatable kayak Emma, and were ready for launching it in about 10 - 15 minutes as usual. It was almost ideal condition for kayaking - the water was calm, the sky was cloudy - the clouds partially blocked the Sun.  But it was low tide this morning at Johor strait. 

inflated kayak

rays of sunshine broke through cloudy sky 

low tide made the beach much larger 

Low tide makes paddling into tidal rivers, such as Api Api, shorter, but poses no other problems for kayaking in wild rivers, such as Sungei Khatib Bongsu. It actually provides some benefits - typically more birds are present at the rivers' bank  - good for bird watching.

Api Api river is a tidal river, it is also a drainage for the residential buildings along its banks.

The water level in Api Api was low - expected, but sections of it smelled like a rotten egg - H2S! We did not see many birds like we saw last time on the river in January. We did not linger, and left the river in less than 45 minutes.

It was still early for the day, we decided to cross the Johor Strait to paddle on Sungai Puaka in Pulau Ubin.

It was a good decision. The low tide provided a different vista of Sungai Puaka.

Fishmen were fishing, in tandem on a boat, or solo on a kayak. 

We were the only people on the river once we passed the fishermen. 

It was quiet except occasional bird chirpings, especially the collared kingfishers. The most endearing part of the kayaking on Sungai Puaka was that we witnessed the courtship of two big billed herons on the riverbank.

Two big billed herons met each other on a bare riverbank, see photos below.

They looked each other and then the heron on the right walked towards the other heron, which did not move at all. Based on typical big billed heron courtship behavior, it was certain that the moving heron was a male.

The male passed the female a step or two, and turned around, then they faced each other with an offset of one step. In a moment, the male then walked a few steps toward an opening in the mangrove, turned around looking at the female again. The female looked around for a moment, then followed the male into mangrove.

two big billed herons met at the riverbank

The heron on the right walked toward the one on the left, which did not move at all

stood side by side but looking at each other 

they looked at each other, and looked around

they decided to go to a private place together 

they disappeared into the mangrove trees  

On the way back to Singapore main island, we paddled around the islet by Pulau Ubin - Pulau Ketam from its northwest tip. The area is primitive, and we saw severe erosion of the shore ... nature at work.

When we were 300 meters to the Pasir Ris Beach, I noticed water in the kayak, and right side air chamber in back (right by my side) was deflated! We did not notice any issues with the kayak when we inflated it.

We paddled to the nearest shore instead of the launch spot. 

A scare but no real consequence - we were on land safely but exhausted.

We will learn from the mishaps (campground light and noise, the kayak leak). In fact we found out the root cause of the leak, and repaired the kayak already at the time of this writing. We paddled the repaired kayak on the rougher water of Sentosa. 

The excitement of seeing a new bird species and witnessing big billed herons' courtship made the trip very worthwhile!

erosion of the islet shore

trees fell into water due to severe erosion

Notes

Big Billed Herons' courtship - chat with Google AI

a. (Gender of herons)This photo had two big billed herons, one has darker plumage, they seemed be courting each other. which one is male?

The heron on the right is almost certainly the male.

Because male and female great-billed herons share identical plumage patterns, telling them apart in the wild relies entirely on physical size and behavioral cues during courtship:

• The Larger Size: The heron standing on the right is visibly taller, stands with a more imposing posture, and possesses a heavier build than the heron on the left. In great-billed herons, males average slightly larger and heavier than females.
• The Darker Plumage: During the courtship phase, the male often appears darker or exhibits more pronounced, slicked-down slate-grey plumage contrast, especially while posturing to impress a mate.
• Courtship Dynamics: In typical heron courtship behavior, the larger male takes the lead in displaying, stretching, or approaching the female (on the left) to initiate nesting bonds.

Would you like to know more about the specific courtship displays great-billed herons use, or the best mangrove locations in the region to spot them nesting?

b. that's pretty accurate behavior description of big billed heron courtship compared to my field observation - the darker plumage heron seemed to lead the way into mangroves.

That is a wonderful and incredibly accurate field observation!

The taller, darker heron leading the way into the mangroves perfectly mirrors established great-billed heron nesting biology. In these magnificent birds, the male takes full charge of selecting and securing the nesting territory within the thick, protected mangrove roots or canopy.

Mangrove Courtship & Nesting Roles

• Leading the Way: Once a pair-bond begins to form on the open mudflats, the male will lead the female into the denser mangrove foliage. He is essentially showing her potential, highly secluded spots to build their massive stick nest.
• The "Stick Ceremony": Once inside the mangroves, you might see the male begin to break off small branches and present them to the female. If she accepts the sticks, it seals the courtship bond, and she will handle the actual construction while he continuously gathers materials.
• Security & Seclusion: Great-billed herons are notoriously shy and highly sensitive to human disturbance. They use the deep mangrove systems as a visual shield to keep their massive nests safe from predators and boat traffic.

It sounds like you captured these in a very pristine habitat. To help me share more relevant behavioral insights, could you tell me:

• Did you notice if the male was making any low croaking or roaring vocalizations while leading her?
• Approximately what time of year or what region were these photos taken?

c. I took the photos on May 24 during a kayaking trip. Just had time to write my journal for the trip. Here is my recollection of the observation, with photos: Two big billed herons met each other on a bare riverbank. They looked each other and then the heron on the right walked towards the other heron, which did not move at all. Based on typical big billed heron courtship behavior, it was certain that the moving heron was a male. The male passed the female a step or two, and turned around, then they faced each other with an offset of one step. In a moment, the male then walked a few steps toward an opening in the mangrove, turned around looking at the female again. The female looked around for a moment, then followed the male into mangrove.

That is an exceptionally well-documented field observation! Your journal entry perfectly captures the subtle, step-by-step choreography of great-billed heron pair-bonding and mate attraction.

The timeline you recorded (late May) aligns perfectly with their breeding window, when high-stakes territorial and pair-formation behaviors peak in coastal mangroves.

Deconstructing the Behavior You Observed

• The Approach and Standstill: When the male confidently advanced while the female remained completely stationary, he was testing her receptivity. In heron biology, an interested female will stand her ground calmly, whereas an unreceptive bird or competing male would either flee or strike a defensive, spear-like posture.
• The Strategic Overtake and Offset: Walking past her, turning, and standing offset is a classic, non-aggressive ritual. By positioning himself slightly to the side rather than head-on, the male showcases his full profile, physical size, and breeding plumage while intentionally reducing the threat of a direct confrontation.
• The "Follow Me" Recruitment: Moving toward the mangrove opening and looking back is the definitive transition from initial attraction to territory selection. He isn't just moving away; he is actively inviting her to inspect a nesting sanctuary. Her choice to follow confirms she has officially accepted him as a mate.

Your description reads like a professional ethogram (an official catalog of animal behaviors). If you'd like to expand your journal entry, let me know:

• Did you happen to spot any other wetland species nearby during that stretch of the river?
• Would you like me to look up any specific nesting timelines or egg-laying details for great-billed herons during the mid-to-late summer months?

Lake Wolfgang

Lake Wolfgang and the market town of St Wolfgang on its shore are named after Saint Wolfgang of Regensburg. It stretches about 10.5 kilometers from northwest to southeast. It is divided into two parts by a peninsula, called die Enge (the Narrow), roughly in the middle of its southern shore opposite St Wolfgang. 

The lake was the second stop of our Austria excursion on July 25, 2026.

The town of St. Wolfgang is about 50 km away from Salzburg, 1/3 of the distance is along the lake shore. We got there in less than an hour from Salzburg. Alpine mountains on both sides of the narrow long lake. The crystal-clear turquoise water was mesmerizing.  

We had a short tour of the town before a 45 minute lake cruise.

Lake Wolfgang viewed near the town of St. Wolfgang

The buildings in the town are very colorful, like in a children's cartoon movie! We stopped at the Parish and Pilgrimage Church of St. Wolfgang. Instead of going in, we walked into its yard. The windows on the wall of the yard serve as frames to beautiful pictures.

Parish and Pilgrimage Church of St. Wolfgang

The lake cruise was relaxing and provided different views of the splendid beauty of Lake Wolfgang. Quite a few interesting stories about some landmarks. Mountain Schaferberg, which has a famed north cliff which is a nearly vertical, jaw-dropping limestone wall that plunges sharply toward the Mondsee and Attersee lakes below. From south, on lake Wolfgang, we could not see this cliff. There is dramatic story about a tiny islet in the lake, Butcher's island, where there is a Ox Cross.

Legend of a butcher and his ox ('Metzgerinsel'), wayside shrine 1579 and 1669:

According to legend, a farmer from Abersee drove his ox to St. Gilgen to be slaughtered. This took place on a narrow path along Lake Abersee. (Abersee was the former name of Lake Wolfgangsee). The ox suddenly shied and panicked due to falling stones. The farmer couldn't swim, but didn't want to lose his ox, which had fallen into the lake in the meantime. The farmer rushed after him and managed to grab the ox by the tail. The ox then pulled him across the entire lake to this small island. Out of joy and gratitude, he had this small wayside shrine erected.

Instead of legends, we could use our own imagination - a vertical limestone cliff, Falkensteinwand, by the lake resembles an elephant, we called it Elephant Rock!

Lake Wolfgang is an oasis for relaxation, water sports and enjoying nature at the same time. The surrounding area, e.g. Schafberg, Falkensteinwand, is great for outdoor adventure. 

Parish and Pilgrimage Church of St. Wolfgang

Schafberg - mountain peak

Summer retreat of Katharina Schratt, confidante of Emperor Franz Joseph I

Elephant Rock 

Metzgerinsel (Butcher's Island)

Illusion On the Water by Sentosa

Lily and I went kayaking by the shore of Sentosa on August 16, 2026. It is our second paddling trip there, the first time was more than 4 years ago, on March 19, 2022. 

During our 2hour 40 minutes, 9km paddling journey from Tanjong Beach to Labrador Nature Park, and return, we saw a group of swimmers swimming in the ocean, rowers in two row boats practicing, and the constant presence of many giant Shipps waiting for port clearance. There were birds as well, a collared kingfisher flying around the shoreline near Tanjong  Rimau, a white bellied sea eagle overhead. We paddled across Pulau Renggis near the Keppel island, and into Berlayar Creek -  no need to paddle though, the nature did the work, rising tide pushed us in, so we could just enjoy the surrounding - listening to bird chirps, and trying to locate them. We paddled along the shoreline of Labrador Nature Park before returning. 

swimming in the ocean

                                                                       Collared Kingfisher

white bellied sea eagle

                                                                            Rowing 

inside Berlayar Creek - looking out

Those were not the most interesting experience!

The most interesting and intriguing observation was about the movement of a giant ship NYK Line.

On the way to Labrador Park (northwest direction), we paddled away from the shoreline, toward the tiny islet Pulau Palawan. We noticed the giant ship NYK Line. As we got closer to the islet, we noticed the ship was moving in the same direction as we did. On the return, we saw that NYK was far away to the northwest of the islet. Our hypothesis was confirmed!

As we continued our return trip in the southeast direction, we noticed that NYK Line was moving with us again !? I realized that what we observed was optical illusion. 

I believed that the big ship was somewhere behind the islet in the southwest direction, anchored, i.e. not moving. But how could this illusion form?

One factor is the distance, the anchorage zone is about 400 meters southwest to the islet, and the islet is 200 meters from Sentosa shore. The other factor is that we were moving, paddling, our view angle changes and used the islet as a reference point. See illustration. I thought I got the physics (optics) right.

Paddling toward the islet Pulau Palawan

NYK position when we were paddling back to Tanjong Beach

                                                NYK Line followed us again on the return trip?!

Reason for the Optical Illusion

I uploaded the gif of the NYK and my illustration to Google. My reasoning is confirmed, and  the illusion has a scientific name  - motion parallax. 

Motion parallax is a visual cue that helps us perceive depth. When we move, nearby objects appear to move across our field of view much faster than distant objects. Our brains use this difference in apparent motion to estimate how far away things are.

It is something we experience constantly without consciously noticing it. The same principle is also important in technologies such as video games, computer graphics, and virtual reality, where it helps create the perception of three-dimensional depth.

What fascinated me was that I had encountered this phenomenon not in a textbook or laboratory, but simply by paddling a kayak around an island.

The optical illusion turned out to be the most interesting part of the entire paddling trip.

A simple observation became a puzzle. The puzzle led me to think about distance, movement, and reference points. I formed a hypothesis, tested it, and rediscovered an established scientific principle—one that I had encountered in a completely unexpected context.

That is one of the things I enjoy most about exploring nature.

I enjoy the sights and sounds, of course. But I also enjoy the questions that nature quietly presents.

Sometimes I notice something unusual.

Then I wonder why.

The curiosity leads to a mystery, the mystery leads to investigation, and the investigation often leads to a little discovery—sometimes in a field far outside my own expertise.

And that, to me, is part of the fun of exploring nature.

Explore Nature. Have Fun!

 

Appendix 

A. Here is the Google AI explanation of the observation in the GIF and my diagram:

Why the Ship Appears to Move with Your Kayak

What you are experiencing in your GIF is a classic optical phenomenon known as motion parallax:

• The Setup: The small green islet sits close to you (the foreground), while the massive NYK Line freight ship is significantly further out in the deep shipping lanes of the Singapore Strait (the background).
• The Illusion: As you kayak from right to left, you are actively changing your angle of view relative to the nearby islet. Because the islet is so close, it appears to shift backward (to your right) very quickly against the distant background.
• The Result: Because the ship in the background stays relatively fixed in your field of vision due to its extreme distance, the rapid backward movement of the nearby island makes the ship look like it is drifting or moving forward along with you toward the left.

The illustrtion is a fantastic, highly precise geometric breakdown of the illusion! Your diagram perfectly illustrates why it fooled you on the way out and revealed itself on the way back.

Why Your Diagram Explains It Perfectly

By tracking the intersection lines from the moving kayak through the edges of the stationary islet, your illustration beautifully maps out the changing sightlines:

• The Focal Point: As your kayak (the dots moving left) approaches and passes the islet, your line of sight has to swing backward to keep the islet centered in your vision.
• The Background Shift: Because the ship sits far behind that pivot point, the sightlines intersecting the islet project onto the distant background at a faster rate than you are actually moving forward.
• The "Anchored" Clue: Discovering that it happened in both directions is the ultimate proof of a stationary object. If the ship had actually been moving, it would have separated from the islet on your return journey. Instead, it stayed locked in that geometric dance.

Many ships anchor in that exact southwest zone of the Singapore Strait while waiting for port clearance, making them the perfect stationary backdrops for this exact parallax trick. It's a brilliant real-world observation and an excellent piece of diagramming!

B. Motion Parallax in applications

In video game design and virtual reality (VR), motion parallax is a critical tool used to create a sense of 3D depth on flat screens and prevent motion sickness in immersive headsets.

Here is how developers use it across different mediums:

1. 2D Video Games: Parallax Scrolling

In 2D games, developers stack art assets into independent, layered backgrounds that move at different speeds relative to the camera.

• Foreground layers: Move incredibly fast (e.g., leaves, lampposts passing close to the screen).
• Midground layers: Move at a moderate speed where the playable character usually resides.
• Background layers: Move very slowly (e.g., distant mountains, clouds, or stars) to simulate massive distance.

2. 3D Video Games: Camera Control & Scale

Modern 3D engines handle motion parallax automatically through the camera's field of view (FOV), but developers fine-tune it to manipulate player perception.

• Speed Perception: Placing objects close to the camera (like narrow canyon walls) increases the sensation of high speed. Wide open landscapes make the player feel like they are moving slower.
• Skyboxes: The sky and distant horizons are programmed to move perfectly with the camera's coordinates so they never get closer, creating an illusion of infinite distance.

3. Virtual Reality (VR): Head Tracking

In VR, motion parallax is the boundary between a highly immersive experience and immediate nausea.

• 6 Degrees of Freedom (6DoF): Modern VR headsets track your exact head movements in space. When you lean left or right, the virtual objects close to your face shift dramatically, while the background shifts minimally.
• Comfort & Realism: This real-time calculation mimics how our eyes naturally perceive the physical world. Without accurate motion parallax, your brain detects a mismatch between your inner ear (vestibular system) and your eyes, leading to severe motion sickness.

To help tailor this further, let me know:

• Are you looking for programming concepts (like how to implement a parallax script in Unity or Unreal Engine)?
• Would you like examples of classic games that pioneered this technique?
• Are you designing your own VR or game project?