Seabirds Trade Survival for More Chicks After Energy-Intensive Breeding

A team of international researchers led by Nagoya University has shown that wild seabirds that expend more energy during the breeding season tend to travel farther and produce more offspring the following year, yet this comes at a higher cost to their own survival. The study, which followed individual birds through an entire annual cycle, found a clear trade‑off between reproductive effort and longevity.

Using a controlled increase in flight energy expenditure—achieved by adding lightweight devices to a subset of birds—the scientists monitored the animals during breeding, migration, and the subsequent breeding season. Those with the higher flight cost migrated longer distances, reached more productive feeding grounds, and raised a greater number of chicks. However, the same birds exhibited a statistically significant rise in mortality rates during the following year, indicating that the extra energy spent on flight and reproduction compromises their own survival prospects.

The results underscore the delicate balance seabirds must maintain between energy allocation for reproduction and self‑preservation. Understanding these trade‑offs is crucial for predicting how changes in environmental conditions and resource availability may affect seabird populations and for informing conservation strategies aimed at sustaining both their reproductive success and long‑term viability.