ハヤブサ防衛行動ログ＃9

We are investigating territorial defense behavior against intruders at the nesting
site of a breeding pair of Peregrine Falcons.

2026/02/27(金)　曇り　10℃　北東2ｍ/ｓ

8:45 観察開始　start

手前左崖上に１羽確認、もう１羽は左の餌場で食事中。２羽確認できた。

One individual perched on the upper ledge of the front-left cliff; the second individual was feeding at the left feeding site. Two individuals confirmed.

8:57 50-100m上空にトビが侵入・旋回する。明らかに食事中のハヤブサの餌を意識している様子。崖上のハヤブサが警戒鳴きして飛び出し威嚇するようにさらに上の崖に移動。トビはいなくなる。

A Black Kite intruded at 50–100 m altitude and circled, apparently targeting the feeding peregrine’s prey. The cliff-perched peregrine gave alarm calls, took flight, and shifted to a higher ledge in a defensive display. The kite left the area shortly thereafter.

9:09 餌を食べた１羽が巣に入った。今季初確認

The individual that had been feeding entered the nest. First confirmed nest entry of the season.

9:46 ２羽ともに穏やかに休んでいる。

10:50 崖からオスが飛び出し100ｍほど先の小鳥を捕まえようとするも失敗。その後メスのところへ行き、交尾をする。今季初確認

The male launched from the cliff and attempted to capture a small bird approximately 100 m away but was unsuccessful. He then moved to the female’s location, and copulation occurred. First confirmed copulation of the season.

10:23 100m上空をカラスが６羽通過するも通り過ぎたのでハヤブサは２羽とも反応なし

Six crows passed approximately 100 m overhead; as they continued without circling, neither peregrine showed any response.

11:00 観察終了

今日は今季初確認が２つ。巣に入ったのと交尾を確認することができた。産卵間近だと思う。抱卵が始まるとテリトリー侵入に対しての警戒度が格段に引き上げられるだろう。外敵との距離関係を計測するためにレーザー距離計を購入することに決めた。正確な情報を残していきたい。

Today, two first confirmations of the season were recorded: nest entry and copulation. Egg-laying is likely imminent. Once incubation begins, the level of vigilance toward territorial intrusions is expected to increase substantially. In order to quantify distance relationships between the peregrines and potential intruders, I have decided to purchase a laser rangefinder. I aim to document precise and reliable data.