Cumulative cultural evolution, the accumulation of sequential changes within a single socially learned behaviour that results in improved function, is prominent in humans and has been documented in experimental studies of captive animals and managed wild populations. Here, we provide evidence that cumulative cultural evolution has occurred in the learned songs of Savannah sparrows. In a first step, “click trains” replaced “high note clusters” over a period of three decades. We use mathematical modeling to show that this replacement is consistent with the action of selection, rather than drift or frequency-dependent learning biases. Generations later, young birds elaborated the “click train” song form by adding more clicks. We show that the new songs with more clicks elicit stronger behavioural responses from both males and females. Therefore, we suggest that a combination of social learning, innovation, and sexual selection favoring a specific discrete trait was followed by directional sexual selection that resulted in naturally occurring cumulative cultural evolution in the songs of this wild animal population.

See the README file for more details.

Two data files are associated with Williams et al., 2022: “Cumulative Cultural Evolution and Mechanisms for Cultural Selection in Wild Bird Songs”:

- Williams et al NCOMMS 2022 data.xls

- Song recordings.zip

The corresponding author’s email is hwilliams@williams.edu

Data were collected between 1980 and 2013, on Kent Island, New Brunswick, Canada, the site of the Bowdoin College Scientific Station. Demographic data were collected by Nat Wheelwright of Bowdoin College and Ryan Norris of the University of Guelph and their associates.

Kent Island Savannah sparrow (Passerculus sandwichensis) songs were recorded by several researchers:  Clara Dixon in 1980 and 1982; Nat Wheelwright and his associates in 1988-9 and 1993-5; Iris Levin in 2003; Heather Williams in 2004-2010; Heather Williams and Daniel Mennill in 2010-2013. Most of these recordings (and nearly all of them from 1993 onwards) were of birds identified by unique color band combinations, and demographic data for these birds is known.

Some additional data derive from recordings of birds singing on nearby islands and along the coast of the Bay of Fundy by Clara Dixon in 1980.

Songs were visualized using sound spectrograms and introductory note types scored by H.W.

For additional information, see the README file associated with this data set.

Williams et al NCOMMS 2022 data.xlsx is a standard excel file.

Song recordings.zip is a compressed file that will, when decompressed, yield a folder with 21 .WAV sound files. Any standard sound visualization program can read these files; for example, Audacity (www.audacity.com) is a free, open-source program that is available for both the PC and the Mac OS environments.