Swirling flight of a seabird caught in a huge typhoon high over mainland Japan

Abstract

Catastrophic weather events influence the movement of wild animals. In particular, airborne animals such as birds and insects are expected to occasionally face challenging flights because of unfavorable atmospheric currents such as hurricanes, cyclones, and typhoons. The frequency of intense storms has increased and is predicted to further increase due to climate change (e.g., Mei & Xie, 2016). Consequently, it is essential to understand how volant animals survive and navigate under such unusual conditions and evaluate how the increasing frequency of severe storms affects wildlife. However, information on the behavioral reactions of animals to extreme weather is still limited given the unpredictability of its occurrence. Bio-logging studies on seabirds have provided some insights: adult red-footed boobies and great frigatebirds avoid cyclones by staying in the breeding colony or circumventing the moving cyclones while climbing to higher altitudes (Weimerskirch & Prudor, 2019), and Eastern brown pelicans tend to be inactive during the passage of a cyclone (Wilkinson et al., 2019). Additionally, some seabird species move toward and stay within the eye of the storms rather than circumventing them probably to avoid being blown by strong winds (Lempidakis et al., 2022; Nourani et al., 2023). Here, I report on a rare case that implies the upper limit of the seabird capacity to tolerate a storm. A GPS-equipped streaked shearwater (Calonectris leucomelas) was apparently caught in a huge typhoon (Figure 1), showing swirling flight high over the mainland of Japan. It finally came through without landfalls when the typhoon returned to the sea.

In summer, especially from August to September, typhoons frequently occur in the Pacific Ocean and pass through Japan. Breeding activities and foraging movements of seabirds around Japan are expected to be physically influenced by the occurrence of typhoons, which may exert selective pressure. In the present study, adult streaked shearwaters (N = 14 birds) were captured on a breeding island in Japan (Mikurajima; 33°52′ N, 139°38′ E) from 25 August to 29 August 2019. GPS loggers (13–14 g, 2%–3% of body mass; PinPoint VHF-GPS, LOTEK) were attached to the back feathers using waterproof tape (Tesa). The loggers were set to record the geographic position every 15 min and send data via radio communication to the receiver placed within the breeding colony when birds returned from the sea. The tracking duration of the birds ranged from 8.9 to 34.2 days (mean ± SD: 24.8 ± 6.8 days).

A typhoon formed in the western Pacific (19°36′ N, 155°24′ E) on 5 September 2019 (JST), which was named “FAXAI.” It originated from a tropical depression occurring on 30 August. The typhoon moved northward, passing about 60 km west of Mikurajima between 18:00 and 21:00 on 8 September, and reached mainland Japan around 03:00 on 9 September (Figure 2, Video S1). After crossing the land, it exited the ocean between 06:00 and 09:00. FAXAI was one of the largest typhoons to hit this area of Japan, with a maximum wind speed of 213 km h⁻¹ (International Best Track Archive for Climate Stewardship; Knapp et al., 2010).

During this period, one GPS-deployed shearwater (male, body mass: 585 g) left the sea near the breeding island at approximately 17:00, flying northward. It started a circling movement in the northeast of the eye of the typhoon around 20:30 and stopped at the water surface for 1 h between 22:00 and 23:00. After restarting flight, the overall direction of the bird's movement overlapped the path of the typhoon, with a sequence of five anticlockwise circles  50–80 km in diameter (Figure 2, Video S1). While swirling, the movement speed of the bird was between 80 and 170 km h⁻¹, with a GPS-based altitude record of up to 4700 m (Figure 3). These speeds and altitudes were much higher than those recorded during regular flights (flight speed: 10–60 km h⁻¹, altitude: <100 m; Figure 4), even though the accuracy of altitude estimation based on GPS is generally low compared with that of horizontal positioning (possible estimation errors: up to 50 m; personal communication with LOTEK). The bird finally returned to sea at the same time as the typhoon and landed on the water around 08:00. The straight-line distance from the start to the end of the circling was 222 km, and the total distance traveled during the 11-h period was 1146 km. After escaping the typhoon, the bird stayed at the water surface for 5 h to rest and/or wait for the typhoon to leave and then departed for its usual foraging area in the north (Figures 2 and 5a). The other GPS-equipped birds that were tracked during the same typhoon period (N = 12 birds), behaved in different ways. Nine birds were located far from the typhoon track (Figure 5b) and were probably little affected by it. The remaining three birds were relatively close to the typhoon track but appeared to have successfully circumvented it (Figure 5b).

As adult streaked shearwaters usually fly only at sea relatively close to the water surface, the observed overland flight with swirling movements at high altitudes was quite unusual, and such an event has not been reported before. Trajectory estimation using NOAA's HYSPLIT Trajectory Model, which is based on archived atmospheric data (see Appendix S1 for details), demonstrated that the simulated air parcel would have moved along a path similar to the shearwater track, but it was estimated to rapidly increase its altitude up to >10,000 m, unlike that observed for the shearwater (Figure 6). Thus, the horizontal movement directions and high speeds of the shearwater were likely to be passively determined, whereas the altitude might have been partially self-controlled. It remains unknown whether the bird could not or chose not to escape from the typhoon; once caught in the storm and displaced toward land, it might have been safer to stay within the storm rather than to resist it until it returned to the ocean with reduced wind speeds. This speculation was supported by the fact that the bird landed on the water as soon as it returned to the sea.

The early evening departure of the bird from the breeding area was also unusual for this species, which usually departs for foraging for several hours before sunrise (Shiomi et al., 2012). This might indicate that the bird attempted to circumnavigate the harsh conditions in advance but failed. Lempidakis et al. (2022) suggested that to avoid landfall due to the strong winds of the storms, the bird would require navigational ability for the recognition of its positional relationship with the landmasses. The bird in the present study might have had a relatively low navigational ability because it tended to fly close to the coast and not offshore during its northward foraging trips (N = 2 trips; Figure 5a). Although the coastline could function as a navigational guide for long-distance travel (Shiomi et al., 2019), a lack of spatial cognitive ability would lead to a higher risk of failure in avoiding landfalls due to irregular strong winds.

While this particular bird survived the unfavorable weather event, streaked shearwaters, especially juveniles, are often found to fall inland and weaken after the occurrence of typhoons or disturbed weather with stronger winds (e.g., Kuroda, 1966). The present study appears to demonstrate an example of the behavior of seabirds at the extreme edge between failure and success of survival during a storm. Further accumulation of such data would contribute toward an understanding of whether and how seabirds manage to survive frequent but irregular weather events.

Kozue Shiomi: Conceptualization, Formal Analysis, Investigation, Writing—Original Draft, Review and Editing, Project Administration, Funding Acquisition.

The author declares no conflicts of interest.

All procedures in the field study were conducted with permission from the Tokyo Metropolitan Government and Mikurajima Village Office and were approved by the Animal Care and Use Committee, National Institute of Polar Research (R1-3).