Wednesday, October 03, 2007
I walk around Cromwell Bottom LNR every weekday morning and obviously with such a regular patch I get to watch many birds and other wildlife on a daily basis throughout the year. Just outside the reserve on the river Calder there is a weir between the old North bank loop and Tag loop. Most days throughout the year I watch a heron fishing here. Its interesting to watch its behaviour and choice of fishing spot change due to river level, vegetation growth and fish movement. In summer the heron tends to be near the far bank fishing in a slow backwater shallow which catches the sun and thus presumably draws in the small fish to the warmer water. In winter they tend to move about more actively fishing as opposed to waiting for the fish to come to them. At the moment the heron(s) are standing in ambush by one of the two main channels that flow downstream from the weir lip. I suspect the reason for this is that its now close season for fishermen for trout as they are spawning. To do so trout will invariable move upstream to find their traditional gravel beds to spawn. The trout are now moving up these two channels whilst waiting for enough water to flow over the weir lip for them to leap it (a spectactular sight to watch over the next few weeks). The herons have obviously cottoned on to this new source of food and have shifted their fishing spots to take advantage of this short lived chance of decent sized meal.