ハヤブサ防衛行動ログ＃6

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

2026/02/07(土)　曇り　2℃　北西2ｍ/ｓ

9:15 観察開始　start

右の崖の上に１羽、中央の崖の上にもう１羽確認

One individual was observed on the right cliff, and another on the central cliff.

9:20 50m～上空　トビが侵入・旋回　中央の崖のハヤブサが警戒鳴きの後、追撃！

A Black Kite intruded and circled approximately 50 m above. The peregrine on the central cliff issued an alarm call and initiated pursuit.

このハヤブサのテリトリーには数か所の「貯蔵庫」がある。なので、子育てシーズン以外でも侵入者への警戒鳴きや威嚇はされる。50ｍ～100ｍの距離で30秒から60秒の間、侵入者が旋回するとハヤブサは追い払う行動に出ている。

This peregrine territory contains several cache sites. Therefore, alarm calls and defensive displays toward intruders occur even outside the breeding season. When an intruder circles within a distance of about 50–100 m for 30–60 seconds, the peregrine typically initiates a chasing behavior to drive it away.

9:45 100ｍ～上空　トビが１羽通過　その後トビが２羽通過

9:50 50m～上空　トビが１羽旋回し通過したが、この間ハヤブサは不在のため反応なし。

Black Kites appeared three times, but no response was observed because both peregrines were absent.

11:00 観察終了

朝から自分が求めているシーン（警戒・威嚇・追い払い・追撃・迎撃）があり興奮した。ハヤブサはテリトリー防衛の活動が活発だと伺えたので今後の子育て期間での防衛行動にも期待が持てる。仮説をいくつか立てるにおいてやはり測量を行いたい。レーザー距離計を調べようと思う。

From early morning, I observed multiple instances of vigilance, threat displays, and pursuit behavior that matched the scenarios I had been hoping to document. These observations suggest that territorial defense activity is currently active, which raises expectations for defensive behavior during the upcoming breeding period. To develop and test several working hypotheses, I consider quantitative distance measurements to be important, and I plan to investigate the use of a laser rangefinder.