On the validity of Bergmann's rule

Shai Meiri*, Tamar Dayan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Aim: We reviewed the occurrence of Bergmann's rule in birds (ninety-four species) and mammals (149 species), using only studies where statistical significance of the results was tested. We also tested whether studies using different characters as surrogates of body size have a different tendency to conform to Bergmann's rule, whether body size and nest type (in birds) have an influence on the tendency to conform to the rule, and whether sedentary birds conform to the rule more than migratory birds. Location: Worldwide. Methods: We reviewed published data on geographic and temporal variation in body size, using only studies where the statistical significance of the results was tested. We asked how many species conform to the rule out of all species studied in each order and family. Results: Over 72% of the birds and 65% of the mammal species follow Bergmann's rule. An overall tendency to follow the rule occurs also within orders and families. Studies using body mass in mammals show the greatest tendency to adhere to Bergmann's rule (linear measurements and dental measurements show a weaker tendency); while in birds, studies using body mass and other surrogates (linear measurements and egg size) show a similar tendency. Birds of different body mass categories exhibit a similar tendency to follow Bergmann's rule, while in mammals the lower body size categories (4-50 and 50-500 g) show a significantly lower tendency to conform to the rule. Sedentary birds tend to conform to Bergmann's rule more than migratory species. Nest type does not affect the tendency to conform to Bergmann's rule. Main conclusions: Bergmann's rule is a valid ecological generalization for birds and mammals.

Original languageEnglish
Pages (from-to)331-351
Number of pages21
JournalJournal of Biogeography
Issue number3
StatePublished - 1 Mar 2003


  • Aves
  • Bergmann's rule
  • Body size
  • Geographic variation
  • Latitude
  • Mammalia
  • Size clines
  • Temperature


Dive into the research topics of 'On the validity of Bergmann's rule'. Together they form a unique fingerprint.

Cite this