This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A team led by Vojtěch Brlík from Charles University in Czechia and the University of Guelph in Canada analyzed data from more than 2,300 birds tracked using miniature devices to find out how closely linked individual stages of the migratory birds' annual cycle are. The scientists were also interested in whether these linkages break down at a certain stage and whether late-departing individuals can make up for their delay.
They found that departure and arrival times are closely linked during spring and fall migration, but on wintering grounds, where migratory birds spend nearly 45% of the year, a reset of the entire migration schedule occurs, allowing them to partially make up for delays. Migratory birds cover thousands of kilometers during the year, and the success of their annual journey depends not only on where they go but also on correct timing. They must arrive at the right places at the right time, often traveling across deserts, oceans and entire continents, frequently under conditions that can vary significantly from year to year.
However, information about when a bird departs or arrives captures only part of the story. Events throughout the year can be linked: A late departure from the breeding grounds can lead to a late arrival at the wintering grounds, and the resulting delay can carry over into subsequent phases of the annual cycle. How exactly do migratory birds plan their annual cycle, and what happens when they get delayed somewhere?
A new study by an international team of scientists led by Brlík from the Department of Ecology, Faculty of Science, Charles University, answers these questions. The research published in the journal Nature Ecology & Evolution provides the most comprehensive view of avian migration across continents to date. Until now, scientists have studied bird migration primarily during individual periods of the year or in individual species.
However, the team led by experts from the Faculty of Science, Charles University, built a unique global database of tracking device data and mapped the complete annual schedule of 2,324 individuals belonging to 83 bird species from six continents. The results show that departure timing determines when a bird arrives at its destination. If it sets off late, it tries to make up for lost time.
It likely shortens its travel time by reducing time spent at stopover sites used for resting and refueling. This resembles a driver on a highway who shortens rest breaks when running late. "Our research shows that birds have a certain ability to compensate for delays by speeding up their journey.
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