Duck Family 0628F: A 50-Day Urban Duck Family Record, Practice-Like Wing Flapping, House Martins Nesting, and an Unidentified Bird Call

 

On June 28, 2025, I recorded another long-form observation of Eastern Spot-billed Duck families and other urban wildlife along the river. This video is part of my daily field-recording archive, filmed with a super-telephoto compact camera, mainly Nikon P1100 and P950. The footage is published almost as recorded, not only for viewers, but also as a personal field archive and as date-based evidence that cannot easily be altered later.

I am not a professional ornithologist. These notes are written from the perspective of a long-term amateur observer who has continued filming the same river system almost every day. Because of that, individual observations may remain uncertain, but the strength of this record lies in continuity: repeated daily filming, family identification codes, timestamps, and comparison with the previous and following days.

This day was especially meaningful because the Af family, the first duck family I had seen this season, reached 50 days old. The ducklings now looked almost adult in body size, yet they still appeared unable to fly fully. When the family descended a weir, several young ducks used strong wing-flapping movements. This may have been part of ordinary balance and landing behavior, but it also looked like a transitional stage toward flight practice.

Species Observed

- カルガモ / Eastern Spot-billed Duck / Anas zonorhyncha  

  The main subject of this record. Multiple mother-and-duckling families were observed, including Af13-50, Mf1-30, Bf orphan 1-47, Hf2-38, Tf8, エf5, and others.

- イワツバメ / Asian House Martin / Delichon dasypus  

  Several nests were found under a structure. Some birds entered nests, while others approached different nests, possibly due to pair activity, nest confusion, or territorial interaction.

- ウグイス / Japanese Bush Warbler / Horornis diphone  

  Its song was heard clearly from nearby vegetation. The bird itself was not clearly seen, but the song was prominent in the riverside habitat.

- カワラバト / Rock Dove / Columba livia  

  A pair was observed in close social behavior, offering a quiet moment between duck-family observations.

- スズメ / Eurasian Tree Sparrow / Passer montanus  

  A sparrow was seen bathing, showing typical small-bird behavior in the urban riverside environment.

- クサガメ / Chinese Pond Turtle / Mauremys reevesii  

  A small individual was observed near the river, suggesting the presence of freshwater reptiles within the same urban ecosystem.

- アオサギ / Grey Heron / Ardea cinerea  

  The Af family reacted to a heron passing overhead. I could not clearly film the bird at that moment, but the call helped identify the situation.

- カラス類 / Crow species / Corvus spp.  

  Crow activity was observed near a nest. Based on the season and behavior, it may have involved Large-billed Crows and Carrion Crows, but this remains uncertain.

- カワセミ / Common Kingfisher / Alcedo atthis  

  A female kingfisher was briefly recorded, adding another species to the day’s river wildlife record.

Observation Record

The day began with confirmation that Af13 had reached day 50. This was a satisfying milestone. The young ducks had grown dramatically, and their bodies appeared close to adult size. However, they were not yet truly flying. Later, when the family descended the weir, several juveniles flapped strongly while dropping down. This behavior may be an important developmental stage: not yet full flight, but no longer the simple jumping or sliding behavior of younger ducklings.

Bf orphan 1, now 47 days old, was also confirmed safe. This individual had returned to the lower weir area where it had previously been seen, making it easier to relocate. Unlike the other ducklings, this bird was alone without a mother. Its continued survival is therefore especially important as a long-term observation subject.

Mf1, now 30 days old, was seen with its mother. The single duckling even seemed to lead the departure. Later, Mf1 encountered Bf orphan 1. Both were single-duckling cases, but their social situations were completely different: one still had a mother, while the other was alone. This contrast made the encounter especially interesting.

Further downstream, Hf2-38 was observed feeding peacefully. A Japanese Bush Warbler was singing nearby, and its voice became one of the notable sound records of the day. I walked farther downstream than usual, hoping to find families that had not been seen recently, but I could not locate Zf1, ウf5, or several other missing families. It is possible that I simply missed them, but this downstream area seemed less favored by duck families this year.

At around 09:58, I heard a loud, repeated, unidentified bird call from riverside vegetation. I waited for a long time but could not see the bird. At first, I wondered whether it might be a Ruddy-breasted Crake, a bird said to have existed in the area for years but which I have never seen. After checking the sound, however, it did not seem to match. During this waiting period, I also thought I heard duckling calls from inside the vegetation, possibly from ウf5, but I could not visually confirm the family.

A major discovery came soon afterward: Asian House Martins were nesting. From the opposite bank on a previous day, I had seen only an old-looking nest and assumed they were not nesting there this year. But from this angle, several nests were visible. One pair was sitting neatly inside a nest, and other birds arrived and departed. Some individuals seemed to approach nests other than their own, which may have been territorial behavior, nest checking, or simple confusion. Because I am not a specialist, I cannot conclude the reason, but the behavior was worth recording.

The middle part of the observation returned to the duck families near the weir. Mf1 descended first, with the duckling going down before the mother. Af13 later became active and also descended the weir. This was the most important duck behavior of the day. Several Af juveniles flapped while descending, suggesting a stage where their wings were becoming functionally important, even if they could not yet fly.

Af13 then moved across the river toward the area where Mf1 had been resting. This created a rare scene where a large family approached a one-duckling family. Mf mother seemed aware of the large group and moved toward vegetation, while the young ducks themselves did not appear especially concerned. Lf4-29 also passed unexpectedly in front of Af and Mf, making the scene more complex.

Bf orphan 1 was seen resting on a sunny small island for a long time. I wondered whether it was not too hot, but the bird remained there. Later, when one Af juvenile moved leftward, Bf orphan 1 came out as if avoiding the situation. These small interactions are not dramatic in a cinematic sense, but they are valuable as behavioral records.

Later observations confirmed more families: Df orphan 4-42, Cf3-47, イf4-26, Tf8, Uf1-18, Gf7-44, Xf5-18, Ef6-41, and アf3-10. The second encounter with イf4 was especially exciting because this family had only been seen once before, three days earlier. Their appearance raises questions about where they had been raising ducklings before arriving in this area. It may resemble cases where ducklings grow for some time in rice fields before moving into the river.

One of the most puzzling observations involved エf. This family had been recorded with four ducklings on the previous days, but today there appeared to be five. The ducklings were similar in size, and because this was one of the youngest families, it was difficult to explain as a simple mixed-duckling case. In many years, I have seen patterns where a lost duckling is found first and later reunites with a main family. This year, however, there have been cases where the number of ducklings increases without my previously finding the missing individual. Df also showed a similar increase, although that case may be partly explained by rice-field movement. For エf, the reason remains genuinely mysterious.

Tf8 also showed a familiar problem: one duckling became separated, called, and the mother flew back quickly. However, while she responded to one duckling, others also began to wander. This repeated pattern suggests that as ducklings grow more mobile, the mother’s ability to control the whole group may become more difficult.

Conclusion

This day did not produce a single dramatic rescue or predator event, but it was one of the most valuable types of observation days: slow, continuous, and rich in small details. Af13 reaching 50 days old provided an important developmental milestone. The wing-flapping descent at the weir may represent a transition toward flight ability. The nesting Asian House Martins added a separate urban-bird record, and the unidentified call remains an unresolved question for future observation.

The day also reminded me why daily records matter. A single video may only show ducks resting, feeding, or moving quietly. But when connected across days, these records reveal growth, survival, disappearance, reunion, possible adoption, changes in family size, and the shifting use of river habitat.

This is not a formal scientific study. It is a field diary built from repeated observation, timestamps, and unedited video evidence. Still, I believe such records can preserve valuable details of urban wildlife behavior that might otherwise go unnoticed.