2022-07-19 テキサス大学オースチン校(UT Austin)
この研究は、野生の動物の自然な計時能力を調査した初めてのもので、中南米に生息し、笛のような鳴き声で知られる茶色の小鳥、ミソサザイの鳴き声を調査したものです。一
その結果、野生の鳥の歌は、飼育下で訓練された哺乳類や鳥の歌よりも、時間を計る能力が高いことが分かりました。
一部の種は同じ曲を歌い、識別可能なパターンで音を鳴らす。
それぞれの鳴き声の間の休止時間は予測可能な方法で長くなり、毎回約0.5秒ずつ長くなっていく。そして、その間が10秒程度になると、今度は頭から歌い始めるのです。
ミソサザイの場合、43%の歌(評価条件を満たした23曲のうち10曲)が、歌の間、一貫して時間を保ち、休止時間が長くなっても、一定のパターンが維持されていることがわかった。
<関連情報>
- https://news.utexas.edu/2022/07/19/songbird-can-keep-time-with-the-best-of-them/
- https://www.sciencedirect.com/science/article/abs/pii/S0003347222001567
鳥の鳴き声における音程の正確で非スカラーなタイミング Precise and nonscalar timing of intervals in a bird vocalization
Carlos A.Rodríguez-Saltos,Fernanda G.Duque.Julia A.Clarke
Animal Behaviour Available online:16 July 2022
DOI:https://doi.org/10.1016/j.anbehav.2022.06.004
Highlights
- •In Microcerculus marginatus songs, intervals increase from about 1 to 10 s in 0.5 s increments.
- •In many songs, the precision for timing intervals does not follow scalar timing.
- •Singing M. marginatus can be as precise as humans counting to time intervals.
- •Studying birdsong may reveal specialized neural mechanisms for precise timing.
Animals can time their behaviours at predictable intervals. Their precision for doing so, however, may depend on the duration of the intervals. Laboratory experiments with animals show that timing precision decreases in proportion to the duration of the interval, a phenomenon known as scalar timing. In these experiments, animals are trained to wait for arbitrary intervals of time to get rewarded. In nature, animals time intervals as part of many stereotyped behaviours, regardless of whether the intervals are learned. It is unknown whether timing in this context is also scalar. Here, we tested for scalar timing in the song of the scaly-breasted wren, Microcerculus marginatus, which consists of whistles separated by intervals that increase in duration from less than 1 s to more than 10 s. We found that in nearly half of the songs, the timing of whistles was better explained by a model of constant precision rather than one of scalar timing. Moreover, in songs showing support for constant precision, the precision at the longest intervals was higher than that of nonhuman mammals and birds trained in the laboratory for timing presses at an operant device. The precision of the wren is also higher than that of humans, except when the latter count to increase their performance at timing. This study highlights the value of studying natural behaviours to uncover diverse strategies in interval timing among animals.
