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Preliminary Evidence Shows Harris’s Hawks Can Prey on Invasive Red-bellied Squirrels in Buenos Aires

Adult-plumaged Harris's hawk perched in coastal grassland in Tamaulipas, Mexico
Research · Ecology

Researchers in Buenos Aires found preliminary evidence that Harris’s hawks (Parabuteo unicinctus) can capture and eat invasive red-bellied squirrels (Callosciurus erythraeus). The work was presented at the XXI Reunión Argentina de Ornitología in 2026 and combined prey remains, pellets, direct observations and interviews with local residents.

From June 2024 to March 2026, the researchers collected material beneath seven Harris’s hawk nests and two perches. They analysed 108 pellets and 38 prey remains. Birds made up more than half of the prey items, while mammals accounted for more than 35%.

Evidence linked specifically to red-bellied squirrels included one skull, one skin and hairs in seven pellets whose internal and surface patterns matched the species. During 38.2 hours of direct observation, the researchers also recorded two occasions when Harris’s hawks pursued squirrels. Five of 21 interviewed residents reported having seen similar pursuits.

The authors describe the study as preliminary. Their results show that red-bellied squirrels can form part of the hawk’s diet in Buenos Aires, but do not establish how often predation occurs or whether it measurably reduces the invasive squirrel population.

Sources and image credit

  1. Lorenzi, J., Gozzi, C., & Borgnia, M. (2026). Evidencia de depredación de la ardilla de vientre rojo por el Gavilán Mixto (Parabuteo unicinctus) en Buenos Aires.Primary conference abstract. The RAO page gives a suggested citation date of 2 September 2026; the meeting itself was held 4–7 August 2026. Researchers analysed 108 pellets and 38 prey remains from seven nests and two perches, found a squirrel skull, a skin and hairs matching Callosciurus erythraeus in seven pellets, and recorded two pursuits during 38.2 hours of observation. The authors describe the work as preliminary.

Image: Adult-plumaged Harris's hawk (Parabuteo unicinctus) in Gulf coastal grassland beside Tamaulipas State Highway 175, Municipality of Matamoros, Tamaulipas, Mexico, 18 March 2009. Photo: William L. Farr / Wikimedia Commons. CC BY-SA 4.0. Representative wild species image; not a bird from the Buenos Aires study. · CC BY-SA 4.0 · Source

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