Sibling competition in common tern Sterna hirundo chicks: underlying hormonal and behavioural patterns and mechanisms ...

• Main Author: Schmidt, Luis
• Format: Text
• Language: English
• Published: Friedrich-Schiller-Universität Jena 2008
• Subjects: Flussseeschwalbe; Hormonstoffwechsel; Konkurrenz; 590; Common tern; Sterna hirundo
• Online Access: https://dx.doi.org/10.22032/dbt.14078; https://www.db-thueringen.de/receive/dbt_mods_00014078

In avian young that are dependent on parental food provisioning, brood size and corresponding sibling competition are key environmental factors affecting present performance, future developmental trajectories, and ultimately fitness. I studied the effect of sibling competition on chick condition and possibly underlying behavioural and hormonal patterns and mechanisms in the common tern Sterna hirundo, a semiprecocial bird species exhibiting hatching asynchrony, slight sexual size dimorphism, and profound effects of chicks' mass growth on their fitness. First, I conducted an observational study on sex-, hatching rank-, and brood size-specific patterns in chick condition, success in competitive behaviour, and testosterone (T) and corticosterone (CORT) levels; second, to investigate the effect of sibling competition on chick condition, feeding rates, and T and CORT levels, I experimentally varied the extent of within-brood competition by a one-day removal of the senior siblings from two-chick broods. Overall, ...