Image by Don McCrady, CC BY-NC-ND 2.0
Friends volunteer, popular guide and bird expert Trevor Gunton introduces the next in this series of informative articles.
Latin name: Anas Strepera
Most literature give Gadwall as a naturalised resident. It is a very special Paxton Pits bird in that we hold, on average during late Autumn and Winter up to 350 of these attractive wild fowl. This exceeds 1% of the entire English wintering population, and our reserve was granted SSSI (Site of Special Scientific Interest) for this, plus the BTO lists Paxton Pits as one of the top ten sites for wintering Gadwall.
In September you can visit Heronry South and spot about 30 Gadwall whose numbers will build up as early autumn turns into winter. We are unsure if these are East Anglian birds, or if they could be near continental birds?
The species may not have been seen in Britain until a pair were released at Narford in Norfolk in the year 1830, from where they quickly spread with the assistance of other introductions, across Norfolk, Suffolk and the Fens.
Locally today Gadwall can be found throughout the year in good numbers on the Nene and Ouse washes. Here at Paxton pits the bird breeds, but only in small numbers, the best year being 2018, with three pairs. Generally throughout Britain however the picture is confused, with the first breeding pair in Yorkshire being near Wakefield as late as 1954.
The Wildfowl Trust released many Gadwall (numbers unspecified) between 1950 and the late 1970’s. In 1962 around 900 were released into the wild by a local wild fowling club, where did they all end up? Were these multi releases augmented by incoming wintering Gadwall from the near continent? We shall never know!
The Gadwall has a strange distribution in that it can be found across Eurasia and North America separated by thousands of miles. How can that be? Did our bird once have a much wider breeding range and today we are looking at a remnant population? Again, we may never know the answer.
Looking back at Europe, where there are around 120,000 pairs, ringing shows that the small Icelandic population of about 300 pairs may mostly winter in Ireland, whilst some Scottish birds winter as far south as Spain. I can only find one record of Gadwall and Mallard interbreeding successfully and that was in Scotland. Locally Rutland Water has hosted up to 900 of these birds during the harsh winter months. In the UK it is not a common breeding species with many areas having no breeding pairs; overall we may have around 1000+ breeding pairs.
Let’s take a look at its breeding requirements in the UK. The bird seems to need low lying fresh water lakes, marsh lands in open country, and it avoids fast flowing rivers and the coast, even in winter. Only the female incubates 7-10 eggs from early May, the male playing no part in the incubation, nor does it assist in caring for the young. The drake enters eclipse plumage in late May/June. On gravel pits like Paxton, many small ducklings of all species may be taken by pike and other predators such as Herons, Otters and Minks.
Quite a dangerous place, gravel pits!
Having led many guided walks over the years I know that the Gadwall can be very challenging to sort out from other species but can usually be found at the far side of Heronry South with Mallard. The male, as you know, is a very attractive bird in close up, but the female can be tricky. So take the easy way out and wait for them to fly! Then you will see the very clear white patch on the wing (called a speculum), you will also notice a clear black rear end of the male.
Watching wildfowl is one of the great joys of Autumn and Winter birdwatching on our very special nature reserve. By the way the Bus Stop hide is now the best place to observe wintering wildfowl on Heronry South. Keep counting those wildfowls, your counts are of real conservation value.