A study by Japanese researchers found a surprising discovery of seabirds observing a regular time of returning back to their nests. The seabirds regardless of the distance traveled to wherever their feeding ground is arrived within three hours after sunset.
The research team led by Katsufumi Sato of the University of Tokyo’s Atmosphere and Ocean Research Institute conducted a research among 21 shearwaters nestled in the Kamaishi and Yamadamachi islands in Iwate Prefecture to study the seabirds’ behavior. They put a device installed with Global Positioning System to record behavior in all 21 shearwaters in 2008 and 2009.
The study showed that while shearwaters vary in the distances they have traveled, they all reached their nests at around the same time after sunset. The researchers related that a seabird which traveled 100 kilometers from its nest started its journey back three hours before sunset while another seabird at 400 kilometers away from its nest took off about 14 hours before sunset.
The team said about 70% of the shearwaters they studied returned to their nests within three hours after sunset which results seemed to suggest that these birds follow a certain “curfew” time. Considering that these birds travel at a constant speed of 35 kph, researchers added that it is of surprising precision how these birds could estimate the distance they have traveled and the time it takes for them to get to their nests.
The research team intends to publish the results of the study in an academic journal on animal behavior.
Shearwaters are medium-sized long-winged seabirds commonly found in temperate and cold waters. They feed on squid, fish, and other oceanic food by diving through them. Some seabirds dive as deep as 70 m underwater.