Displaced Nesting

 This week, heavy rain has resulted in a good deal of flooding, this time I did not lose any of my cameras to the rising floodwater. One effect of the raging torrent was that the efforts of the Swans to nest on the sandbank in the middle of the mill pond came to nothing.

Last years successful nest on the sandbank

 The old experienced pair VGY and ZNY used to nest in a secluded part of the river bank, since their demise and the inheritance of their territory by young swans they have each year attempted to nest on the sandbank. On the face of it, this sounds like good sense. Swan clutches can be as high as 7 or 8 individuals with the norm around here being 6, however, mortality is high with up to 50% of cygnets lost in the first few weeks. The island protects from the predation of Foxes which are common down the mill. The flaw is the water level. Flooding is a regular occurrence and often occurs during April when the nest is in full use and results in the nest being washed away eggs and all. Since 2006 when ZNY and VGY left Swans have nested on the site 9 times of which 6 times the nest was washed away and only 1 was successful.

The drive to make a nest is innate, it is hardwired into swans and you will often observe individuals start dragging out reeds and twigs to build a nest. Sometimes the urge is so strong that they will start to build in the most unfeasible sites. I have observed swans build a couple of nests abandoning each before deciding on another.

Over the last week, the pair of swans that are now resident on the site have been beginning to pull together a nest on the sandbank. Their progress was washed away on Friday in the rising waters. Today I watched the pair swim up into the backwater where the water was calmer. Here whilst the male fed the female couldn't help but try and build a nest.

What she was experiencing was displaced behaviour. In this case, although the location was unsuitable, it wasn't even on solid ground the urge to build was so strong that she was trying. More sadly I have seen the same occur late in the season by lone Swans, swans who have failed to find a mate or lost them prior to mating still building a nest, an exercise in futility courtesy of the hard-wired biological imperative to reproduce.