Poor old Gilbert is getting restless. Despite the fact that there is more interest in wildlife than ever before, it seems that most of the so-called conservation organisations are losing interest in species. Instead they prefer to babble on about landscape scale conservation and ecosystem services (whatever they are). Could this be because most of their staff don't have any knowledge about species if they don't have four legs?
This is my attempt to encourage an interest in good old-fashioned natural history.

Monday, 15 July 2013

That end of season feeling

On Sunday I ringed the chicks at Fallen Cedar nest, which were thankfully still ok. The remainder of the day was spent checking round all the places where I have seen or heard a Wood Warbler in the last couple of weeks. Given the date, I would expect any remaining nests to have young and therefore the adults to be fairly conspicuous. The fact that I didn't find a single Wood Warbler anywhere suggested that it really is the end of the season. Even birds that I know had a mate could easily have been predated, given the widespread losses of nests that I'd already found.

I had to rethink this towards the end of the day when I checked on Double Back nest which still had five eggs. I then went to look at the male from Goshawk wood nest, who certainly had a mate the previous weekend. Sure enough she was there and alarming at me, while he alarmed some distance away. After some difficulty I found the nest and she has 4 eggs. If there are two nests still with eggs, you can bet that there are others but it is unlikely that I will be able to find them now. I was mulling over whether to call this nest 'the married couple' (as they were spending all their time a long way apart) or the Magician (as the female was adept at vanishing right in front of you) but have plumped for the latter as it turned out that the male was alarming at a Buzzard and hence already occupied when I arrived.

This evening I checked on Nursie nest and it has lost the last remaining chick. This time the camera worked.

Another bloody Badger. I was thinking that I hoped no-one sent me another one of the 'please sign the anti- badger cull petitions' and what do I get on Facebook? When I first showed that predation was having a significant effect on Wood Warbler productivity and that it might be the cause of the decline in this species, the response was 'What predator has increased enough to be making a difference to Wood Warbler populations?' Well the nest camera results from myself and the RSPB are showing that there are three primary predators; Jay, Buzzard and Badger. The population trend for Jays is stable whilst that for Buzzard is rapidly increasing (although it is hard to determine what the changes have been within areas occupied by Wood Warblers). There is no national monitoring of mammal population trends as there is for birds but some work has been done on Badgers and surveys in the mid-1980's and mid-1990's showed a 24% increase in the number of Badger social groups and a 43% increase in the total number of all types of sett.

What does this tell us? I certainly wouldn't claim that an increase in Badgers or Buzzards is responsible for the decline in Wood Warblers but, evidence is now emerging of a possible mechanism by which predation may be changing and having a negative impact. A great deal more data will be needed and there are plenty of people and organisations that will oppose any suggestion that predators are doing harm but the advantage of my position is that no-one funds me so no-one can take away my funding if they don't like my results!

No comments:

Post a Comment