コウノトリは仲間の助けを借りて空を飛ぶ(Storks fly with a little help from their friends)

2024-04-18

2024-04-12 マックス・プランク研究所

ドイツのマックス・プランク動物行動研究所の研究により、ヨーロッパからアフリカへの長距離を飛行するコウノトリが群れで移動する現象の理由が明らかになりました。この研究は158羽のコウノトリの一生にわたる移動データを分析し、特に若い鳥が他のコウノトリが多く飛行するルートを選ぶ傾向があることを示しています。コウノトリは経験を積むにつれて、社会的な影響を無視し、良い飛行条件のルートを選ぶ自立性を得るとされます。この研究は、集団行動がコウノトリの移動決定に及ぼす影響を初めて示したもので、その意思決定に集団がいかに重要であるかを示しています。

<関連情報>

集団で移動するコウノトリは、経験によって仲間のルートを選択することが少なくなる Experience reduces route selection for conspecifics by the collectively migrating white stork

Hester Brønnvik,Elham Nourani,Wolfgang Fiedler,Andrea Flack
Current Biology Published:April 17, 2024
DOI:https://doi.org/10.1016/j.cub.2024.03.052

Highlights

Storks of all ages selected energetically efficient routes
Storks of all ages selected routes with flocks present
Older storks had lower selection strength on the availability of flocks
Experience may replace social information for migratory decision-making

Summary

Migration can be an energetically costly behavior with strong fitness consequences in terms of mortality and reproduction.¹^,²^,³^,⁴^,⁵^,⁶^,⁷^,⁸^,⁹^,¹⁰^,¹¹Migrants should select migratory routes to minimize their costs, but both costs and benefits may change with experience.¹²^,¹³^,¹⁴This raises the question of whether experience changes how individuals select their migratory routes. Here, we investigate the effect of age on route selection criteria in a collectively migrating soaring bird, the white stork (Ciconia ciconia). We perform step-selection analysis on a longitudinal dataset tracking 158 white storks over up to 9 years to quantify how they select their routes based on the social and atmospheric environments and to examine how this selection changes with age. We find clear ontogenetic shifts in route selection criteria. Juveniles choose routes that have good atmospheric conditions and high conspecific densities. Yet, as they gain experience, storks’ selection on the availability of social information reduces—after their fifth migration, experienced birds also choose routes with low conspecific densities. Thus, our results suggest that as individuals age, they gradually replace information gleaned from other individuals with information gained from experience, allowing them to shift their migration timing and increasing the timescale at which they select their routes.