Whimbrel populations differ in trans-atlantic pathways and cyclone encounters

Area of Science:

• Ornithology
• Ecology
• Climate Science

Background:

• Millions of birds migrate across the Atlantic Ocean annually, coinciding with peak tropical cyclone season.
• The impact of these storm encounters on migratory bird populations is largely unknown.

Purpose of the Study:

• To investigate the migratory routes of whimbrels from the Mackenzie Delta and Hudson Bay.
• To analyze the overlap between these routes and tropical storm activity.
• To determine the frequency and consequences of storm encounters during trans-Atlantic migration.

Main Methods:

• Tracking of whimbrels from two distinct populations (Mackenzie Delta and Hudson Bay) using GPS technology.
• Analysis of migration routes in relation to historical tropical cyclone data.
• Quantification of storm encounter rates and assessment of post-encounter outcomes, including flight duration and survival.

Main Results:

• Whimbrels from the Mackenzie Delta and Hudson Bay utilize different trans-Atlantic migration strategies.
• Mackenzie Delta whimbrels undertake long, nonstop flights (approx. 5440 km) around storm activity, encountering storms on 3 of 22 crossings.
• Hudson Bay whimbrels take shorter flights (approx. 3643 km) through Hurricane Alley, encountering storms on 13 of 18 crossings, with over half resulting in island landings and increased migration duration.

Conclusions:

• Whimbrel migration strategies involve a trade-off between avoiding storms and utilizing island stopovers.
• Storm encounters, particularly for Hudson Bay whimbrels, can lead to significant delays and increased mortality.
• The demographic impact of storm encounters may influence the future evolution of trans-Atlantic migratory routes, especially with rising global temperatures.