Living Reference Work Entry

Encyclopedia of Evolutionary Psychological Science

pp 1-4

Date: Latest Version

Bird Clutch Size

  • Eduardo S. A. SantosAffiliated withBECO do Departamento de Zoologia, Universidade de São Paulo Email author 


Avian clutch size


The number of eggs laid in a single brood (or nest) by one or more female birds.


Variation in the number of eggs laid in a single brood has fascinated researchers, especially ornithologists, since at least the 1940s. The number of eggs laid by a female varies enormously among taxonomic groups. Generally, it is constant and small, as in albatrosses and King Emperor penguins that lay one egg. In other species, clutch size is variable, and sometimes large, as in the partridge, which can lay between 14 and 20 eggs. The factors that are associated with the evolution of clutch size are, perhaps, one of the oldest topics in life history theory. To this end, several processes have been proposed that may influence selection on bird clutch size. Attempts to understand causes of avian clutch size variation range from intra- and interspecific studies, work on intrinsic (e.g., body mass, migratory behavior, nest type, diet) and extrinsic (e.g., latitude ...

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