Woodlands - the forgotten wetlands

A walk around my local Broxbourne Woods was rewarded with a now irregular sighting of a Hawfinch, once a frequent bird in these parts. There has been a steep decline in many woodland birds over recent years – Lesser Spotted Woodpecker, Willow Tit and Hawfinch all come to mind. However, this decline is not ‘across the board', with some of the more generalist species doing well. Some of the declines have been linked to changes in woodland structure, but in the case of the Hawfinch, the reasons for the decline are still unclear. There has been a 78% decline in the breeding distribution of the Hawfinch between 1970 and 2010 (although there have been some gains in winter distribution). A large number of hypotheses have been put forward to explain this decline, and they include the impact of increasing deer populations, woodland management practices, and of course, the impact of predators.   Hawfinches are mainly associated with extensive areas of mixed broad-leaved woodland, with mature trees, and with an open understorey. There are hints that they prefer woodlands with wet features and that they have disappeared from sites with high densities of Grey Squirrels. Jays are also suspected to be a major nest predator yet evidence remains anecdotal.

The link with wet features is interesting as the importance of wetness in woodlands is surely undervalued. Visit many woodlands and you will see a network of ditches alongside the rides. Many of these were put in to drain water off the site and allow easier removal of timber. Take Wolves Wood in Essex as an example. The ‘old boys’ will tell you that visiting in spring was a nightmare; flooded paths and mosquitoes everywhere. Well, times have changed. Everywhere is drier, yet many of these woodland ditches still drain away winter rainfall. Flooded paths and mosquitoes are a thing of the past. With many woodland birds declining, the loss of Nightingales, Song Thrush and Willow Warblers from some areas could well be the result of reduced invertebrate food as a result of drier conditions. At Wolves Wood, recent work has been undertaken to block up all the ditches as they leave the woodland and extra internal bunds have been constructed to hold water back in the ditches and ponds. The aim is to try and retain winter rainfall and make the site wetter again. We wait to see if the birds and mosquitoes respond.