Will mallards hybridize their cousins out of existence?

September 6, 2017

Mallards—the familiar green-headed ducks of city parks—are one of a group of closely related waterfowl species, many of which are far less common. Interbreeding with Mallards can threaten the genetic distinctiveness of those other species and cause concern for their conservation. A new study from The Condor: Ornithological Applications investigates hybridization between Mallards and Mottled Ducks, a species specially adapted for life in Gulf Coast marshes, and finds that while hybridization rates are currently low, human activity could cause them to rise in the future.

In Florida, hybridization between domesticated Mallards and Mottled Ducks is a cause for concern, but the degree of hybridization in the western Gulf Coast region is less well known. Louisiana State University's Robert Ford and his colleagues took blood samples from Mottled Ducks captured on the coast of Louisiana in 2011-2014, supplementing them with samples from Mottled Ducks and Mallards from Texas, Alabama, and Mississippi. Analyzing the birds' DNA, they found that the hybridization rate in the western Gulf Coast region is currently only 5-8%, a level lower than what's been documented in Florida. However, that doesn't mean the western Gulf population is completely in the clear.

Currently, the two species have little opportunity to interact in the region during the breeding season; Mottled Ducks nest in coastal marshes, while most Mallards are migratory and breed outside the region. However, the ongoing loss of marsh habitat could cause Mottled Ducks to move into urban and suburban areas, where they will be more likely to encounter resident Mallards. To prevent future problems, Ford and his colleagues recommend ongoing monitoring of hybridization in the region and better protection of coastal marsh habitat.

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Wild ducks caught on camera snacking on small birds - via Mike Playfair

By Helen Briggs BBC News

30 June 2017

This has never been documented before and is probably a new behaviour, say scientists.

Zoologists at the University of Cambridge filmed a group of mallard ducks hunting other birds on a reservoir in Romania.

Two fledglings - a grey wagtail and a black redstart - were chased and swallowed when they landed in the water.

Mallards are one of the most abundant types of wild duck, and a common sight in parks and on lakes.

The duck normally snacks on seeds, acorns, berries, plants and insects.

It has, on occasions, been seen to eat small fish, but bigger vertebrates are normally strictly off the menu.

Dr Silviu Petrovan noticed the unusual behaviour of a group of mallards while he was out bird watching with friends near a national park in southwest Romania.

He saw the adult female duck grab the grey wagtail in her beak, and repeatedly submerge it in the water, before eventually eating it.

A second bird - a fledgling black redstart - then landed in the water, where it was chased by juvenile mallard ducks.

"The poor bird landed on the water and was screaming and trying to navigate itself out of danger," said Dr Petrovan. "Then it was almost instantaneously attacked by the mallards."

The bird eventually disappeared - assumed to be drowned or consumed.

The scientists could find no record of mallard bird predation in the scientific literature, which suggests such behaviour is both "very rare" and newly-learned.

Continued