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RESEARCH ARTICLE
Contents Vol 30(4)

Cultural divergence and morphological variation of isolated remnant populations of the endangered Floreana mockingbird

Enzo M. R. Reyes https://orcid.org/0000-0003-2120-4224 A * , Michelle M. Roper https://orcid.org/0000-0002-4878-2203 A E , Christian Sevilla B , Danny Rueda B , Dianne H. Brunton https://orcid.org/0000-0002-1741-1960 A E , Adam N. H. Smith https://orcid.org/0000-0003-0059-6206 C and Luis Ortiz-Catedral https://orcid.org/0000-0001-5707-5140 D
+ Author Affiliations
- Author Affiliations

A School of Natural Sciences, Massey University, North Shore Mail Centre, Private Bag 102904, Auckland, New Zealand.

B Dirección de Ecosistemas, Dirección del Parque Nacional Galápagos, Av. Charles Darwin, S/N Puerto Ayora, Santa Cruz, Islas Galápagos, Ecuador.

C School of Mathematical and Computational Sciences, Massey University, North Shore Mail Centre, Private Bag 102904, Auckland, New Zealand.

D World Parrot Trust, Oceania Conservation Program, Hayle TR27 4HB, UK.

E Present Address: School of Biological Sciences, University of Auckland, Auckland 1010, New Zealand.

* Correspondence to: enzorreyesb@gmail.com

Handling Editor: Rob Davis

Pacific Conservation Biology 30, PC23055 https://doi.org/10.1071/PC23055
Submitted: 24 November 2023  Accepted: 20 June 2024  Published: 22 July 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

Context

Cultural divergence refers to changes over time in behavioural traits. These cultural changes could have important implications for conservation planning, and impact the success of conservation efforts such as translocations.

Aims

Here, we investigate the extent, and potential impacts, of cultural divergence in two isolated populations of the Floreana mockingbird (Mimus trifasciatus) on the Galápagos Islands.

Methods

Using contemporary recordings of vocalisations we test for spatial vocal differentiation between mockingbird populations. Furthermore, we explore the potential drivers of change using morphological measurements and historical recordings of the species.

Key results

We found evidence of spatial and temporal differentiation in vocalisations between the two populations of the Floreana mockingbird. We accurately classified over 75% of the birds to the correct populations based on multivariate measures of audio recordings using canonical analysis of principal coordinates (CAP). We also found significant differences in morphometrics between populations; specifically, beak depth was associated with frequency modulation, an acoustic measure that is significantly different between populations. Furthermore, we found evidence of change in the complexity of the vocalisations over a period of 57 years.

Conclusions

Cultural divergence was found in the two remaining populations of this endangered species. Factors such as changes in morphology and cultural drift might have been influenced the change in vocalisation across time and populations.

Implications

We highlight the importance of considering behavioural factors when planning reintroductions of endangered species where there is a need to minimise the risk of assortative mating so as to maximise genetic diversity.

Keywords: conservation, cultural divergence, cultural drift, Floreana mockingbird, Galapagos, morphology, reintroduction, vocalisations.

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