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First-hatched Common Tern Chicks Were Over 11 Times More Likely to Reach Fledging Age Than Third-hatched Chicks

Adult common tern with two chicks
Research · Reproduction & development

A study following 4,647 common tern (Sterna hirundo) chicks over 32 breeding seasons found that hatch date and hatching order were the strongest factors associated with survival to fledging age. The study followed chicks at a North American breeding colony from 1989 to 2022.

Early-hatched chicks survived best

Survival was highest among chicks that hatched early in the season and declined as hatch dates became later. Hatching order within the brood was equally important: first-hatched chicks were more than twice as likely to survive as second-hatched chicks and over 11 times more likely to reach fledging age than third-hatched chicks.

Starvation was the main recorded cause of chick mortality, and mean productivity at the study colony was lower than at other coastal North American common tern colonies.

Brood size mattered differently in good and poor years

Brood size had a smaller effect than hatch date and hatching order. In relatively good years, chicks in larger broods had higher survival, whereas in poor years the pattern reversed and survival was lower in larger broods.

The authors note that hatch date can partly reflect parental quality. Their results therefore show why comparisons of chick survival and reproductive productivity need to account for when chicks hatch as well as their position in the hatching sequence.

Survival of second-hatched (B-) chicks varied most among years, leading the authors to suggest that this measure could serve as a single index of reproductive performance. Annual colony-wide productivity was also correlated with mean clutch size earlier in the same year.

Sources and image credit

  1. Determinants of Survival for Common Tern Chicks Sterna hirundo: The Importance of Hatch Order, Hatch Date and Other Factors across Three DecadesPrimary journal abstract. The study followed 4,647 common tern chicks over 32 years (1989–2022). Hatch date and hatching order were the strongest factors associated with survival: first-hatched chicks were more than twice as likely to survive as second-hatched chicks and over 11 times as likely as third-hatched chicks; starvation was the main recorded cause of mortality. Ardea cites the article within volume 113(2) as 2025.
  2. Determinants of Survival for Common Tern Chicks Sterna hirundo: The Importance of Hatch Order, Hatch Date and Other Factors across Three DecadesInstitutional publication record explicitly gives the publication state and date as 14 January 2026 and cites the article as Ardea 2026, documenting that the actual publication occurred in 2026 despite the 2025 year used on the journal issue page and in the DOI string.

Image: U.S. Fish and Wildlife Service Headquarters / Wikimedia Commons / Flickr. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY 2.0 · Source

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