From BBC Earth

Establishing the ratio of male to female common pochard ducks could be the key to understanding why the two European populations of this species are declining. Measuring the ratio of male to female common pochard ducks in a flock is a relatively simple affair for an enthusiastic bird watcher or dedicated bird counter.

And it shouldn’t be too hard for the rest of us either, because the distinctive males have a spectacular reddish brown head with a black breast and tail; females on the other hand are not so colourful. The difference between the sexes is really quite obvious at this time of year.

But why would anyone want to count ducks?

Birds are dying for some reason or fewer young are being produced

The reason, explains Kane Brides, monitoring officer for the Wildfowl and Wetlands Trust (WWT), is that there are two populations of common pochard Aythya ferina in Europe: one in central Europe and the Black Sea area and another in Europe’s northwest and northeast.

“Both populations have been decreasing at a steady rate and that’s why there is quite a lot of interest in the pochard at the moment to try and find out why that happened.”

There is so much concern over the decline that their conservation status has recently been upgraded to Vulnerable in the IUCN red list of threatened species, as well as being moved from the UK’s amber list to the red list of conservation status. In Jersey, although small numbers winter each year, common pochard is Red listed to protect the tiny breeding population (1-2 pairs breed most years). This means pochards are now a priority species requiring urgent action to find out what is happening to the populations.

“Birds are dying for some reason or fewer young are being produced, either survival or productivity is the reason and we’re going to work on that to find out,” Mr Brides told BBC Earth.

Because little is known about their population structure and any differences in survival rates between the sexes, so counting the number of males and females could be instrumental in understanding the decline.

What is well known, explains Mr Brides, is that in wintering duck flocks in the north there are more males in the flock, and further south there are more females. And, with males being dominant over females they are able to occupy more favourable wintering areas, and migrate shorter distances. So the smaller females’ have a longer migration and also stay on breeding grounds for longer, leading to an increased risk of predation.

“The combination of all of that probably has an effect on the females’ chances of survival,” he says.

But the last sex ratio survey in pochards was done nearly 50 years ago. So, across Europe, the new pochard sex ratio survey is open to anyone, whether they are an enthusiastic bird watcher and dedicated counter, or just happen to come across a flock of pochards on a lake or estuary.

“What it will do is give us useful information on the population structure and also give us a very crude estimate of changes to survival rates between the two sexes over those years,” Brides told BBC Earth.

It is happening throughout January with a co-ordinated snapshot of what’s going on at one time planned for the 16 and 17 January during the International Waterbird Census. To take part simply record the number of males, females and the size of the flock and submit your data on the Duck Specialist Group (DSG) website.

In Jersey, we only regularly see common pochard at a couple of well-visited sites. Most birds are at St Ouen’s Pond and the Mont a la Brune Sandpits but there may be others on the Island’s reservoirs. If you see any please send your observations to Tony Paintin cavokjersey@hotmail.com so that they can be forwarded to the DSG.

The only requirement “is to recognise a pochard and how to identify the male and female,” says Mr Brides.