Sparrowhawk Nest Feeding, Duck Family Habitat Restoration, and Urban Bird Breeding Behaviors: A Field Observation Record of Multiple Wild Species

 Urban rivers can support an astonishing diversity of wildlife during the breeding season. On this observation day, I documented a wide range of behaviors, including food delivery to Sparrowhawk nestlings, several Eastern Spot-billed Duck families at different stages of growth, nesting Azure-winged Magpies, close-up observations of Brown-eared Bulbuls, Common Kingfishers, Japanese Wagtails, butterflies, softshell turtles, and even changes to an artificial river structure that had previously become known for repeated duckling fatalities.

Among the most remarkable moments was an adult Japanese Sparrowhawk (*Accipiter gularis*) returning to its nest with a freshly captured bird. The prey was carefully divided into smaller pieces before being fed to the white nestlings, illustrating the specialized feeding behavior required during the early nestling stage.

The observation also documents improvements made to a concrete river block section where ducklings had repeatedly become trapped or separated from their mother in previous years. Because I have recorded this river almost daily over many breeding seasons, this location provides valuable chronological evidence of how changes to artificial habitats can directly influence wildlife movement.

This article summarizes one day's field record as part of a long-term visual documentation project. While some behavioral interpretations include my own observations and hypotheses, they should be regarded as those of a dedicated wildlife observer rather than formal scientific conclusions.

Main Species Featured

• Japanese Sparrowhawk
  • 日本語: ツミ
  • Scientific name: Accipiter gularis
  • Japan's smallest breeding hawk. During the nesting season, adults frequently deliver small birds to their chicks, carefully tearing prey into manageable pieces before feeding.
• Eastern Spot-billed Duck
  • 日本語: カルガモ
  • Scientific name: Anas zonorhyncha
  • A common resident duck throughout East Asia. Long-term observation of family groups reveals remarkable parental care, movement strategies, and responses to urban environments.
• Brown-eared Bulbul
  • 日本語: ヒヨドリ
  • Scientific name: Hypsipetes amaurotis
  • One of Japan's most familiar urban birds. Close-up observations reveal subtle facial expressions and feather details that are often overlooked.
• Azure-winged Magpie
  • 日本語: オナガ
  • Scientific name: Cyanopica cyanus
  • A highly social corvid known for cooperative behavior and loud group communication during the breeding season.
• Common Kingfisher
  • 日本語: カワセミ
  • Scientific name: Alcedo atthis
  • A small fish-eating bird that inhabits clean rivers and ponds, often serving as an indicator of healthy aquatic ecosystems.
• Japanese Wagtail
  • 日本語: ハクセキレイ
  • Scientific name: Motacilla grandis
  • Frequently seen along riversides, constantly searching for aquatic insects while displaying characteristic tail-wagging behavior.
• Oriental Turtle Dove? Wait no (not included)
• Rock Pigeon
  • 日本語: カワラバト
  • Scientific name: Columba livia domestica
  • Common in urban environments, displaying a variety of behaviors including bathing, courtship feeding, and foraging.
• Eurasian Tree Sparrow
  • 日本語: スズメ
  • Scientific name: Passer montanus
  • One of Japan's most familiar small birds and an important prey species for several urban raptors.
• Chinese Softshell Turtle
  • 日本語: スッポン
  • Scientific name: Pelodiscus sinensis
  • An aquatic turtle that inhabits slow-moving rivers and ponds, often remaining hidden beneath the substrate.
• Common Bluebottle
  • 日本語: アオスジアゲハ
  • Scientific name: Graphium sarpedon
  • A striking butterfly frequently observed drinking mineral-rich water from moist ground.
• Slender Plant Bug
  • 日本語: ホソヒョウタンカスミカメ
  • Scientific name: Apolygus sp. (identification tentative)
  • A small true bug commonly associated with grasses and herbaceous vegetation.

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Field Observation

This day's survey covered a wide variety of wildlife inhabiting the same urban river corridor. One of the advantages of continuous field observation is that entirely different species often reveal how they share the same environment during the breeding season.

The most significant observation involved a nest of Japanese Sparrowhawks. An adult returned carrying a freshly captured bird and proceeded to feed the white nestlings. Rather than offering the prey whole, the adult repeatedly tore it into smaller pieces suitable for chicks that had not yet developed the ability to swallow larger food items. This sequence illustrates the considerable parental investment required during early nest development.

Because Sparrowhawks mainly prey on small birds, such feeding events provide valuable insight into predator-prey relationships occurring within urban ecosystems. Although predation can appear harsh, it represents an essential ecological process supporting the growth of young raptors.

Throughout the survey, several Eastern Spot-billed Duck families of different ages were also encountered. Some broods were only a few weeks old, while others had already reached later developmental stages. Recording multiple families on the same day allows comparisons of growth, habitat use, and family behavior across different breeding periods.

A particularly meaningful part of the observation occurred at a concrete block section of the river that had become well known among viewers of my long-term recordings. In previous years, numerous ducklings became separated from their mothers or even lost their lives while attempting to cross this artificial structure during family movements.

During this survey, the block arrangement had been modified, creating a noticeably safer passage for duck families. The improvement had previously been featured on Japanese television, and documenting its condition on-site provides useful chronological evidence showing how relatively small engineering changes may reduce risks for wildlife. Whether the modification will continue to improve duckling survival can only be evaluated through continued long-term observation during future breeding seasons.

Other species observed throughout the day included Brown-eared Bulbuls, Azure-winged Magpies with growing chicks, Japanese Wagtails, Rock Pigeons bathing and foraging, Common Kingfishers, Eurasian Tree Sparrows, Chinese Softshell Turtles, Common Bluebottle butterflies, and various insects and plants characteristic of early summer along the river.

Although each observation may appear ordinary when viewed independently, daily documentation across multiple years gradually forms a much larger record. Seasonal timing, breeding success, habitat changes, and interactions among species become easier to recognize when individual field records are preserved in chronological order rather than as isolated events.

Rather than presenting definitive scientific conclusions, this project aims to document real wildlife behavior through continuous visual evidence. By publishing recordings according to their actual filming dates, it becomes possible to compare observations across years and recognize long-term environmental changes that might otherwise go unnoticed.

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Understanding the Observation Codes

Throughout this article and the accompanying videos, you will notice unique observation codes attached to filming dates and duck families.

These codes are part of my long-term wildlife documentation system, allowing individual duck families, breeding seasons, and recording dates to be tracked consistently across many years of daily field observations. They also help connect events recorded on different dates into a continuous chronological record.

A detailed explanation of the observation date codes, duck family identification codes, and the purpose of this long-term documentation project can be found here:

https://okasinaikimono.blogspot.com/p/welcome-to-wild-duck-diaries.html