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Common Mynas Initiated 86% of Aggressive Encounters Recorded in Pretoria

Common myna in grass in South Africa
Research · Behaviour

A study of urban birds in Pretoria, South Africa, found that invasive common mynas (Acridotheres tristis) initiated most of the aggressive encounters with other species in which they were involved. The surveys recorded interactions with ring-necked doves (Streptopelia capicola), laughing doves (Spilopelia senegalensis), house sparrows (Passer domesticus), cape sparrows (Passer diffusus) and cape starlings (Lamprotornis nitens).

A transect is a predefined line or route used to survey an area systematically, with observations, signs or sampling points recorded along it.

Researchers conducted 90 standardised transect surveys at three suburban sites from April to August 2022, outside the main breeding season for many of the birds present.

Mynas initiated 86% of aggressive encounters

The researchers recorded 36 interspecific interactions involving common mynas. Twenty-six, or 72%, were aggressive, and mynas initiated 86% of those incidents.

In most aggressive encounters, the other bird fled. Cape starlings were the larger species reported to retaliate successfully. The observations therefore provide evidence for interference competition, in which mynas directly confronted other birds rather than merely sharing the same urban resources.

Displacement was a possible consequence, not a measured long-term effect

The authors suggest that repeated aggression may help common mynas displace other birds from feeding sites or nesting areas. The transect observations documented the encounters themselves, however, not whether other species were permanently excluded from those resources or declined in abundance.

The study therefore shows a strong asymmetry in the observed interactions: common mynas were usually the aggressors, and their opponents usually retreated. The authors argue that this direct competition should be considered when assessing the ecological effects of the invasive species in South African cities.

Sources and image credit

  1. Nelson, R., & Somers, M. J. (2026). Aggressive interactions by invasive Common Mynas Acridotheres tristis with urban birds in Pretoria, South Africa. Ostrich: Journal of African Ornithology, 97(1), 58–63. https://doi.org/10.2989/00306525.2025.2603263

Image: Bernard DUPONT — common myna photographed at Pilanesberg Game Reserve, South Africa, on 22 February 2023; representative species image. Source: Wikimedia Commons. · CC BY-SA 2.0 — https://creativecommons.org/licenses/by-sa/2.0/ · Source

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