Annual Schedule Adjustment by a Long-Distance Migratory Bird

Area of Science:

• Ecology
• Animal Behavior
• Conservation Biology

Background:

• Annual cycle events in migratory animals must align with resource availability for individual fitness.
• Delays in one annual cycle stage can cascade through subsequent stages, negatively impacting performance.

Purpose of the Study:

• To investigate how migratory birds manage their annual schedules.
• To identify where and when adjustments to the annual schedule occur.
• To understand the consequences of schedule adjustments on breeding success.

Main Methods:

• Tracking of 38 Icelandic whimbrels (Numenius phaeopus islandicus) over 7 years.
• Analysis of full annual cycle data, including migration and breeding periods.
• Assessment of timing of annual cycle events and potential delays.

Main Results:

• Whimbrels used wintering sites to compensate for delays, often stemming from successful previous breeding.
• A domino effect was observed from spring departure to laying date, potentially affecting breeding output.
• Time saved during stationary periods appeared sufficient to prevent interannual carry-over effects between breeding seasons.

Conclusions:

• Nonbreeding sites are critical for migratory birds to adjust their annual schedules.
• Preserving high-quality nonbreeding sites is essential to mitigate adverse effects of late arrival at breeding grounds.
• Understanding schedule flexibility is key to effective conservation of migratory species.