Duck Family Routines, Startle Responses to Carp, and a Weir-Slip Incident in Eastern Spot-billed Ducks
A young family of Eastern Spot-billed Ducks was observed moving repeatedly between feeding areas, shallow streams, resting sites, and riverside vegetation. The footage documents several aspects of ordinary duck-family behavior, including ducklings reacting suddenly to a large carp, a mother waiting for a slower duckling, repeated attempts to settle at a resting place, and another mother duck unexpectedly sliding down a weir.
These events may appear minor compared with dramatic predation or rescue scenes, but repeated daily routines can provide valuable clues about how wild duck families use familiar routes, respond to disturbances, and coordinate their movements in an urban river environment.
This article is based on continuous field observation and chronological video records. The behavioral interpretations presented here are personal observations by a non-specialist wildlife enthusiast and should not be treated as formal scientific conclusions.
Field Observation Video
Main Species Featured
カルガモ — Eastern Spot-billed Duck — Anas zonorhyncha
A resident East Asian duck frequently found in rivers, ponds, canals, and other urban wetlands. Mothers guide their ducklings between feeding, resting, and sheltering areas while responding to changing water conditions and potential threats.コイ — Common Carp — Cyprinus carpio
A large freshwater fish commonly found in Japanese urban rivers. Its sudden movement near the surface can startle small ducklings, even when it presents no direct threat.アメンボ類 — Water Strider — Family Gerridae
A surface-dwelling insect that moves across the water using hydrophobic legs. One individual appeared to react quickly when approached by the mother duck.アオサギ — Grey Heron — Ardea cinerea
A large wading bird that hunts fish, amphibians, and other aquatic animals. A flying Grey Heron was recorded near the end of the observation.カワウ — Great Cormorant — Phalacrocorax carbo
A large diving bird specialized for pursuing fish underwater. One individual was seen standing near the river while the Grey Heron flew past.ナマズ類の可能性がある未確認魚 — Possible Catfish Species — Order Siluriformes
A fish-like shape was briefly visible immediately before the ducklings showed a sudden startle response. The image was unclear, so its identity could not be confirmed.
Daily Observation of Duck Family キf4-9
At the beginning of the main observation period, many adult ducks were resting together. Some may have been members of families that had already reached a stage at which the young birds were difficult to distinguish from adults.
After searching the tributary and downstream areas without locating any obvious young families, I eventually found duck family キf4-9. This code indicates the mother identified as キf, accompanied by four ducklings estimated to be nine days old.
The family soon moved into dense vegetation, so I changed position and continued observing from the opposite bank. Because no other families were readily visible and the surrounding area offered few obvious weirs or dramatic obstacles, I decided to record the family’s ordinary behavior at relatively close range.
The four ducklings swam closely behind their mother. At this age, their tendency to remain tightly grouped may help them maintain visual contact with her and reduce the risk of becoming separated in vegetation or flowing water.
An Unexplained Startle Response
At approximately 05:15 in the video, the ducklings suddenly reacted to something in the water.
Even after reviewing the footage in slow motion, the cause remained unclear. A horizontally shaped form resembling the closed mouth or upper body of a catfish may be visible for a moment, followed by movement downstream. However, the same image could also have been produced by reflected light or turbulence.
One possibility is that a duckling unexpectedly touched or moved over the back of a submerged fish. This remains speculation. The mother duck did not show an intense alarm response afterward, suggesting that she may not have interpreted the event as an immediate danger.
Because the visual evidence is insufficient, the possible fish should be regarded as unidentified rather than recorded as a confirmed catfish.
Ducklings Startled by a Common Carp
Soon afterward, a Common Carp appeared near the family and caused the ducklings to flee suddenly.
The contrast between the ducklings and their mother was striking. The young birds reacted immediately and moved away together, while the mother remained comparatively calm and watched them.
Young ducklings may respond strongly to sudden underwater movement because they have limited experience distinguishing harmless large fish from genuine threats. Their rapid escape response may be useful in an environment where danger can emerge from below the surface.
The mother’s calmer behavior may reflect greater familiarity with large fish. However, it is not possible to determine from the footage whether she had identified the carp specifically or had simply judged that no urgent action was required.
Foot Movement and Surface Activity
The footage also provides a close view of the mother duck’s webbed feet opening and closing as she moved through shallow water.
A water strider was later seen moving rapidly across the surface near the mother. Its sudden change of direction made it appear as though it had detected the approaching duck and escaped.
This brief interaction illustrates how even a small area of river surface can contain multiple layers of activity: birds moving above and through the water, fish below the surface, and insects occupying the boundary between air and water.
Moving Through a Stream-Like Channel
The family entered a narrow, stream-like section of the river. At several points, the mother adjusted her pace when one of the ducklings fell behind.
At approximately 12:07, she appeared to wait until the fourth duckling had approached before continuing.
This type of pause can easily be missed when watching only dramatic scenes. In continuous observation, however, repeated waiting behavior may reveal how a mother regulates the spacing of her brood.
It would be difficult to prove that every pause was deliberately directed toward a particular duckling. Nevertheless, the timing repeatedly appeared consistent with visual monitoring of the group.
Arrival at a Familiar Resting Site
The family reached a resting area at approximately 13:25.
This location has additional significance because one of the ducklings from this family had previously disappeared in the same general area under circumstances consistent with predation. Returning to the site therefore created a complicated impression from the observer’s perspective, even though the ducks themselves may have continued using it because it remained part of their familiar route.
The mother came ashore, apparently preparing to rest. The ducklings, however, remained active and did not immediately settle.
One duckling briefly displayed a posture that looked as if it was about to sleep, while the mother appeared increasingly uneasy. Eventually, the ducklings approached, but the family still did not remain calm for long.
An unrelated adult duck nearby completed bathing behavior and performed a vigorous wing-flapping movement.
Conflicting Motivations Within the Brood
After leaving the resting site, the mother remained in shallow water while the ducklings displayed different levels of activity.
Some appeared interested in continuing to move, while others seemed tired. These differences gave the brood a visibly individual character, despite all four ducklings remaining part of the same coordinated family unit.
The mother appeared willing to rest, but the ducklings eventually moved onward. The family then followed the same route they had used to reach the resting site, but in the opposite direction.
This repeated movement suggests that the family may travel around a relatively stable circuit several times during the day. The route appears to include feeding areas, flowing water, vegetation, shallow resting places, and sheltered sections.
Repeated Use of a Daily Route
The approximate activity range of family キf4 had already become increasingly clear through observations on different days.
The mother had previously approached a weir twice and had also visited the area in front of a small sluice gate. On two occasions, she had flown away temporarily while the ducklings remained behind.
These earlier events suggested that she may have been attempting to move the family to another location. Another possibility is that she was continuing to revisit areas connected with the duckling that had disappeared.
There is not enough evidence to distinguish between these explanations. Repeated movement may simply be part of normal daily foraging and habitat use.
At approximately 28:26, the ducklings entered a fast-flowing section and appeared comfortable playing or feeding in the current. Although the scene looked refreshing, this area has conditions that can separate small ducklings, so I continued watching carefully.
One duckling later entered vegetation while the mother remained outside and watched. The mother then gathered the ducklings and moved downstream.
The family eventually returned to approximately the same area where I had first encountered them. This strengthened the impression that they may repeat a familiar route rather than travel in a single direction throughout the day.
Observation of Family Of2-49
Later, another family was found near two unrelated adult ducks.
This caused temporary confusion because the grouping initially appeared to contain four young birds. After closer observation, the family was identified as Of2-49: mother Of with two young birds at approximately 49 days old.
The family approached a weir, and the mother appeared likely to descend. I continued recording because her position strongly suggested an imminent movement down the structure.
Instead, the situation remained unchanged for several minutes.
At approximately 38:33, the mother unexpectedly lost her footing or balance and was carried or slid down the weir by the water. One of the young birds initially appeared ready to follow but ultimately remained above.
The event differed from a deliberate jump or controlled descent. The mother’s movement seemed accidental, although the exact influence of footing, current strength, and body position cannot be determined from the footage alone.
A Possible Waiting Strategy
After the mother descended, the young birds still did not follow.
During previous observations of the same family, the mother had often remained in position for long periods while waiting for the young birds to become willing to climb or move.
This raises the possibility that Of mother frequently uses a patient waiting strategy rather than repeatedly calling, circling, or immediately abandoning an unsuccessful route.
This interpretation is based only on repeated visual impressions. To evaluate it more reliably, similar behavior would need to be compared across many families and multiple situations.
Other Birds and Large Duck Gatherings
Near the end of the observation, a Grey Heron flew past while a Great Cormorant stood nearby.
A large number of ducks were also gathered beneath a bridge. Ducks occupied both sides of the riverbank, creating a dense resting group.
I examined several females in an attempt to identify previously recorded mothers. One bird resembled Lf mother, but closer inspection indicated that it was a different individual.
This illustrates one of the central difficulties of long-term duck-family observation. Once ducklings grow and family groups begin mixing with unrelated adults, visual identification becomes much less reliable.
An Uncertain Family Identification
A mother accompanied by three large young ducks was later recorded.
The group initially appeared numerically consistent with Yf3-48. However, the mother’s feather pattern did not seem to match Yf mother.
Another possibility was that the group belonged to Tf8-44, with the other five young birds resting out of sight. The plumage and apparent development of the three visible young birds also seemed less advanced than that of the approximately 49-day-old Of young birds.
For these reasons, Tf appeared to be the more likely identification, but the evidence was insufficient for certainty.
Rather than forcing a definite identification, the record is preserved as uncertain. Maintaining that uncertainty is important because long-term behavioral records can become misleading when tentative identification is later treated as confirmed fact.
Limits of Detection in Dense Summer Vegetation
Despite searching several sections of the river, relatively few duck families were visible during this observation.
This does not necessarily mean that the families had disappeared. Summer vegetation along the tributary was dense, and direct sunlight made it difficult to inspect shaded resting areas.
The absence of family ケf2 near the small sluice gate remained notable, but the available evidence could not establish whether the family had moved elsewhere or was simply hidden.
Families using nearby rice fields were also searched for regularly. They may rest on strips of land between the fields, but no clear sightings had been obtained during this period.
These detection limits are an important part of the record. A family that is not seen should not automatically be recorded as absent, lost, or dead.
Observational Interpretation
The most informative aspect of this day was not a single dramatic event but the repeated sequence of ordinary actions.
Family キf4 appeared to move through a familiar cycle:
close following behind the mother
reactions to sudden movement in the water
travel through shallow and flowing sections
pauses for slower ducklings
attempts to rest
renewed activity initiated by the ducklings
movement through vegetation
return along a previously used route
These repeated routines may help a young family learn the spatial structure of its habitat.
The ducklings’ strong reaction to a Common Carp also suggests how experience may shape responses to harmless but unfamiliar animals. In contrast, the mother’s calm behavior may reflect greater knowledge of the local aquatic environment.
The accidental-looking descent of Of mother provides a separate reminder that not every movement at a weir is a planned behavioral decision. Flowing water, slippery surfaces, and momentary loss of footing can influence what observers see.
Nature of This Record
I am not a professional ornithologist or behavioral ecologist. The interpretations in this article are those of an independent wildlife observer reviewing field footage collected during repeated visits.
My aim is to preserve what was visible, distinguish observation from speculation, and avoid presenting uncertain identification or behavior as established fact.
These records are part of a continuous project in which I film local wildlife almost every day. Recording dates, video publication dates, family codes, feather patterns, brood sizes, and estimated duckling ages are compared across multiple days.
Because the observations extend across different dates, the archive also provides chronological supporting evidence. Events recorded on one day can be compared with the same family’s condition, brood size, route use, and behavior before and after that date.
The videos are kept largely unedited, with minimal explanation, so they can remain useful as primary visual records even when later interpretations change.
Observation Codes
The date code for this recording is 0720F.
In this coding system:
0720 represents July 20.
F represents the year 2025.
Duck-family codes record the identity assigned to the mother, the number of visible ducklings, and their estimated age in days.
Examples from this observation include:
キf4-9: mother キf, four ducklings, approximately nine days old
Of2-49: mother Of, two young birds, approximately 49 days old
The symbol キ is written in Japanese katakana and must not be converted into the Roman letter K. Katakana mother codes and alphabetic mother codes are separate identifiers.
Detailed explanations of the date codes, duck-family identification system, feather-pattern comparisons, and the purpose of this long-term observation project are available here:
https://okasinaikimono.blogspot.com/p/welcome-to-wild-duck-diaries.html
A visual identification table for the duck families recorded during this period is also available here:
https://okasinaikimono.blogspot.com/2025/07/0720f.html
Chronological Continuation
The next day’s field record is available here:
00:00 Highlights (unordered)
* It happened right after the previous mystery surprise, so it was extra scary.
06:24 The mother duck’s webbed feet moving—open and close
06:43 A water strider dancing—then noticed by the mother and fled
08:35 The duck family proceeds through a stream-like spot
* At one point, the mother noticed a duckling wasn’t following and waited. I tried to document these moments of waiting for slow ducklings today, but couldn't capture them well.
12:07 Mother duck waits for the 4th duckling to arrive before moving on
13:25 Reached sleeping spot – Will they sleep? Ducklings won’t settle The mother watches over them
* As always… this is the spot where a Kf duckling was once preyed upon, so it’s complicated.
16:13 Mother duck comes ashore. Will she get a nap!?
16:36 A duckling looking sleepy—but still cute 
17:39 Ducklings came to sleep too, but the mother looks uneasy. Might move.
18:17 Another duck (not part of a family) flaps wings after a bath!
18:37 Kf4 suddenly sets off. A duckling stretches while swimming—so cute
19:44 The mother relaxes in shallow water… but ducklings can’t touch the bottom
20:01 One duckling wants to move, another wants to nap… so unique
22:24 Mother seems like she wants to rest, but the ducklings wander off anyway
26:43 They swam the route to the sleeping area—then went back the same way
* Unnoticed, several other ducks had arrived
* Kf4’s activity range is mostly confirmed. However, they’ve challenged the weir twice, visited the small floodgate once, and I’ve seen the mother leave them behind and fly off twice. She may be trying to relocate. Perhaps she's still searching for the duckling that disappeared on the tragic day.
28:26 Ducklings enjoying the rapids
* It looks refreshing, but this area is easy to get lost in, so I’m a little worried
30:02 Duckling enters bushes—mother watches over
31:18 Suddenly, mother gathers the ducklings and heads downstream
* Likely the same area where we first encountered them today. Seems like they go through this loop several times a day.
32:45 Of2 and two other ducks nearby—confusing to distinguish
* At first, I mistook them for the 4-duckling group Lf4 or イf4, and it took time to realize.
33:37 Of2-49 – Looks like they’re going down the weir but… they don’t
* I was sure they would, so I waited…
38:33 ★ Of mother, unexpectedly swept away Ducklings tried to follow… but didn’t.
* I waited longer after this too… but nothing changed, so I gave up. Like when climbing, Of mother seems to often just wait until the ducklings are motivated.
* I looked for other families too… I assume they’re sleeping, but I couldn’t confirm due to bushes or sunlight… gave up.
41:15 A flying grey heron and a standing great cormorant
41:31 Lots of ducks under the bridge! A closer look reveals… even more ducks!
42:28 Ducks packed under the bridge on both banks
* I checked for familiar mothers but didn’t recognize any. There was one on the left bank that looked like Lf mother so I filmed her, but it was someone else.
43:50 A grown-up duckling trio with a mother… probably the Tf family
▲▲▲ End of timestamps
* Based on numbers, it seemed like Yf3-48, but the mother’s feathers looked different… Yet there are few families with 3 ducklings of that size, so I’m unsure. It could be Tf8-44 with the other 5 ducklings sleeping somewhere ← probably more likely Tf. Judging by the ducklings’ plumage, Of is 49 days old, Yf 47 days, Tf 44 days. Compared to Of, these ducklings seem younger—so probably not Yf!
So… today I barely found any duck families. I luckily encountered the young Kf4 family and filmed them a lot. That first encounter with what looked like a catfish was pretty scary on review, but since the mother wasn’t alarmed, it was probably fine. I haven’t seen Kf2 near the small floodgate either, which worries me—but this year, the tributary has thick vegetation, so I can’t even tell if they’re there or not... Oh, and there’s also the rice paddy family—I do look for them every day (they usually sleep on the land between paddies), but I haven’t found them this year.
* To keep track of the many duck families, I use the mother duck’s wing pattern (tertials) and family code system. [List here ↓] https://okasinaikimono.blogspot.com/2025/07/0720f.html
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