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What the duck is going on?

09 November 2019

Kirstin's paper on duck hybridisation is published

Although many of you are tuned to reading about reptiles and amphibians on this blog, this paper is about one of the large radiation that appeared from within the reptiles many years ago... and they are invasive in large numbers!

Mallard ducks are invasive in many places around the world. They were imported for sport, farming and more recently as pets for large peri-urban gardens. What wasn't well appreciated is that the genus Anas, to which they belong, easily hybridises with the result that the Mallards quickly start forming hybrid populations in many places where they move to. 

The recent rise in many of their populations in urban areas of South Africa caused great concern some years back when a video of Mallard males mating with native Yellow-billed ducks went viral on social media. The matter came up at the CAPE-IAA, a forum of invasive animal workers in the fynbos biome. There was a need for a study as it was clear that hybrids were being produced. And so Kirstin's project was formed to find out exatly what was going on. 

The result that Kirstin found was that in Cape Town there is hybridisation, but that it happens into the Mallard Duck population more than into the native Yellow-billed Ducks. Moreover, the mating seems to be predominantly in the direction of Yellow-billed males mating with Mallard Duck females.

This is not the last word in the story. Colleagues in Kwa-Zulu Natal are sure that Mallard males are the aggressors in that area. It could also be that the situation gets worse over time, with introgression swinging into the native Yellow-billed ducks.

To know more, read Kirstin's paper here:

Stephens, K., Reynolds, C., Measey, J. & le Roux, J.J. (in press) Occurrence and extent of hybridization between the invasive Mallard Duck and native Yellow-billed Duck in South Africa Biological Invasions. pdf

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