Low functional diversity and no redundancy in British avian assemblages


O. L. Petchey, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 1SA, UK. Tel.: 44(0)114 2220029. Fax: +44(0)114 2220002. E-mail: o.petchey@shef.ac.uk


  • 1Spatial and temporal patterns in functional diversity can reveal the patterns and processes behind community assembly and whether ecological redundancy exists. Here, we analyse functional diversity in British avian assemblages over a period of about 20 years.
  • 2Functional diversity is generally lower than expected by chance, indicating that assemblages contain species with relatively similar functional traits. One potential explanation is filtering for traits suitable to particular habitats, though other explanations exist.
  • 3There was no evidence of ecological redundancy over the 20 years. In fact, changes in functional diversity were almost exactly proportional to changes in species richness.
  • 4The absence of functional redundancy results from little redundancy intrinsic to the species’ functional relationships and also because compositional change was nonrandom. Observed extinction and colonization events caused greater changes in functional diversity than if these events were random.
  • 5Our findings suggest that community assembly is influenced by the traits of species and that observed changes in functional diversity provide no reason to believe that the functioning of natural systems is buffered against change by ecological redundancy.