Latitudinal gradients in avian colourfulness

Christopher R. Cooney, Yichen He, Zoë K. Varley, Lara O. Nouri, Christopher J.A. Moody, Michael D. Jardine, András Liker, Tamás Székely, Gavin H. Thomas

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It has long been suggested that tropical species are generally more colourful than temperate species, but whether latitudinal gradients in organismal colourfulness exist remains controversial. Here we quantify global latitudinal trends in colourfulness (within-individual colour diversity) by collating and analysing a photographic dataset of whole-body plumage reflectance information for >4,500 species of passerine birds. We show that male and female birds of tropical passerine species are generally more colourful than their temperate counterparts, both on average and in the extreme. We also show that these geographic gradients can be explained in part by the effects of several latitude-related factors related to classic hypotheses for climatic and ecological determinants of organismal colourfulness. Taken together, our results reveal that species’ colourfulness peaks in the tropics for passerine birds, confirming the existence of a long-suspected yet hitherto elusive trend in the distribution of global biodiversity.

Original languageEnglish
Pages (from-to)622-629
Number of pages8
JournalNature Ecology and Evolution
Issue number5
Early online date4 Apr 2022
Publication statusPublished - 31 May 2022

Bibliographical note

Funding Information:
This work was funded by a Leverhulme Early Career Fellowship (ECF-2018-101) and a Natural Environment Research Council Independent Research Fellowship (NE/T01105X/1) to C.R.C., a Leverhulme Centre for Advanced Biological Modelling PhD studentship to Y.H., a Royal Society Wolfson Merit Award (WM170050, APEX APX\R1\191045) and a National Research, Development and Innovation Office of Hungary grant (ÉLVONAL KKP-126949, K-116310) to T.S., and a European Research Council grant (615709, Project ‘ToLERates’) and a Royal Society University Research Fellowship (UF120016, URF\R\180006) to G.H.T.

Data availability
All analysis data are available in Supplementary Data 1. In addition, the phylogenetic trees were downloaded from, the geographic and ecological data were accessed via BirdLife International’s Data Zone (, and the global climate data were downloaded from WorldClim (

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology


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