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A Hard Breeding Season Bought Chicks and Cost Survival

An Alaska field experiment linked raised flight costs to earlier, longer migration, better next-year breeding and lower return rates.

Published Updated Story ID: mp-2026-07-27-010
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Summary

An Alaska field experiment linked raised flight costs to earlier, longer migration, better next-year breeding and lower return rates.

Researchers altered the breeding-season energy burden of black-legged kittiwakes by supplementing food, clipping selected feathers or leaving birds as controls, then tracked them across years. High-cost birds fledged fewer chicks immediately, departed earlier and migrated farther; those longer migrations predicted greater breeding success the next year, but only 67% returned, compared with 83% of controls and 90% of fed birds. The experiment supports an energetic trade-off in one colony rather than a universal seabird rule.

Why it matters

An Alaska field experiment linked raised flight costs to earlier, longer migration, better next-year breeding and lower return rates.

Limits and context

  • High-cost birds fledged fewer chicks immediately, departed earlier and migrated farther; those longer migrations predicted greater breeding success the next year, but only 67% returned, compared with 83% of controls and 90% of fed birds.

Key claims

  1. An Alaska field experiment linked raised flight costs to earlier, longer migration, better next-year breeding and lower return rates.

    Qualification: High-cost birds fledged fewer chicks immediately, departed earlier and migrated farther; those longer migrations predicted greater breeding success the next year, but only 67% returned, compared with 83% of controls and 90% of fed birds.

    Evidence: source-2026-07-27-010

Sources

  1. Nagoya University via EurekAlert: Kittiwake energetic flexibilityNagoya University via EurekAlert · official announcement

Corrections

No corrections have been recorded for this story.

A Hard Breeding Season Bought Chicks and Cost Survival · The Machine Press