Thanks to volunteer Phil for his article and photos.
The Shoveler is one of the duck species that frequent Pulborough Brooks in winter and being fairly common at this time of year is not one to which we pay a great deal of attention. However, I have started to think it is the most fascinating of our wintering wildfowl species.
The Shoveler drakes do draw attention to themselves by their bright colours with green head and chestnut flanks.
The females on the other hand are very typically duck coloured.
You wouldn’t say that these are elegant birds, like the wintering Pintails which tend to attract more interest, nor do they gather in very big numbers like the Wigeon and Teal. So, what makes them so interesting? The answer lies in the Shovelers feeding behaviour.
They use their large spatulate bills to ingest water at the tip and then expel this through comb like filters at the side which separate out tiny invertebrates that live in the water. They can also feed on underwater vegetation by upending like all our common wintering ducks, but this is not their preferred diet, just something they do to supplement their food typically during winter when the invertebrates are not so numerous.
You can sometimes see Shovelers filter feeding with their bills dipped into the water as in this photo taken at West Mead a few years ago.
In more recent times I have noticed a rather curious feeding behaviour where a pair of Shovelers, usually male and female, will circle round each other quite quickly in small circles with beaks dipped into the water. I have wondered if this might be courtship behaviour. From reports I’ve read it seems likely to be a form of cooperative feeding, but perhaps with an obvious pair it may help to reinforce their bond.
Having attempted a little online research, some of the articles discuss an interesting extension of the circling behaviour in which many Shovelers huddle together in a sort of circle and then the whole mass spins around. I’ve not seen this at Pulborough Brooks but I did witness this at the London Wetland Centre in January.
I have come across two theories about what is happening in these manoeuvres. One is that the paddling motion of the ducks’ feet helps to stir up the invertebrates in the water and the more feet involved the more food becomes available. Another theory is that the circling motion creates a vortex which helps to suck up the invertebrates to the surface and further notes that circling motion is always in an anticlockwise direction. Not being an expert in fluid dynamics, I cannot really comment on the likelihood of this, but it sounds interesting.
If the pair bonding idea/ cooperative feeding idea is correct, with Spring just round the corner this could be a good time to look for pairs of Shovelers circling round each other. I will certainly be looking out for this, and further will be trying to work out whether they always do it in an anticlockwise direction.