Saturday, 17 September 2016

State of Nature report

On Wednesday the latest 'State of Nature' report was published. It got good press on the Radio that morning - I listened as I prepared to leave for a Workshop in Germany. The message is hardly surprising - some species are expanding their range/recovering, but rather more are declining. The biggest declines, inevitably, are amongst invertebrates and plants, whilst the most prominent gains seem to be amongst vertebrates. Why should anybody be surprised?

The positive message?

On the plus side, we are still seeing the bounce-back from the effects of DDT on predatory birds. Coupled with a decline in persecution of raptors in some areas, this change in land management has to be welcomed. It is noteworthy, however, that the agricultural sector is highlighting the improvement as a significant reason for a decline in other species! And, of course there are lobbies to reverse the improvements - badger culls and buzzard culls are just two initiatives; calls for a cull of sparrowhawks is another! So, I guess as part of the new Conservative administration's programme we might well see measures to reverse the trend in wildlife recovery!

The other gains are not necessarily positive. In my experience, gains are happening amongst introduced species, some of which are pests and others are simply establishing as part of the background mesh of wildlife. Other gains are happening where species at the edge of range are improving their foothold as clime change affects the landscape. Whilst such improvements are to be welcomed, we should perhaps treat them with some caution.

there is always a 'but' ....

So, I will be accused of having a glass half empty! Well let that be so. I recall parts of the 'leadership' of my erstwhile employers saying 'I don't want to hear about problems I simply want the good news'. The same holds with the NFU response - the NGOs should have been crowing about successes and brushing the declines under the table.

Well, I for one hope that the NGOs will continue to highlight the problems. In my experience they lie primarily amongst the specialist species and paint a very worrying picture of wildlife's future. The State of Nature  report particularly highlights problems with invertebrates, which on the basis of my field experience I think is correct.

A balanced view of why?

The State of Nature report is actually reasonably balanced. It does highlight changing agricultural practice, but then it also highlights the role a changing climate can play. As always, there will be gains and losses, and different people will lay the blame primarily on one factor. Placing emphasis on a particular cause is an easy way out but it won't solve the problem.

Using the NFU argument, if raptor numbers are increasing we should expect to see a diminution of prey items. That is a good theory, but it starts to fall apart as one travels down the food chain. Perhaps a case could be developed to link declines in smaller birds and mammals to increased raptor numbers? But, I don't think the data are telling us this. The loss of a favourite blackbird from the bird table is a visible expression of nature red in tooth and claw, but it does not mean that there is a problem with raptors. Large-scale losses in farmland birds have not been accompanied by vast increases in sparrowhawk numbers. The scale of sparrowhawk increases would have had to have been much greater to have resulted in the scale of declines in farmland birds. Moreover, the declines in farmland birds started well before a significant increase in sparrowhawks was detectable.

It is invertebrates that are perhaps the best indicators. If the NFU argument was correct, then by rights we should be seen huge increases in invertebrate populations as bird predation diminishes with the decline in their numbers. Sadly, that is not the case. When did you last have to clear your windscreen of splatted insects? When did you last drive through clouds of moths on a balmy summer's evening? I don't remember the last time I saw large numbers of ghost swift moths over a grassland, yet there are plenty of grasslands and the site where I used to see them still exists.

So, I am sorry NFU, you cannot deflect the blame onto 'predators'. nor can you duck the issue by asking that we accentuate the positives and brush the bad news under the carpet.

But who is to blame?

I must depart from the accepted mantra is that the problem primarily lies with changing agriculture. I agree that this is a significant issue, but my instincts and experience suggest that other factors are at work too.

Extreme weather, especially major droughts and exceptionally warm winters, is possibly a far more important influence on our NATIVE wildlife. I would put to one side those at the extreme of range, whose fortune wax and wane with the climate. My feeling is that it is far more important to focus on species that are primarily associated with the equable Atlantic climate. Chilly winters and warm wet summers.

Short warm winters such as that of 2015/16 mean that species adapted to longer cold conditions will not be able to survive and will shift to their favoured climate envelope (more northerly and western). Meanwhile, those species that rely on wet conditions will fail if there are prolonged droughts. There have been several major droughts in the past 30 years, starting with 1976/77, followed by a similar event in the early 1990s and again in the mid-1990s, and then again in the early 2000s. Each time, the wetland assemblage took a hammering and as far as I can see parts of it have never recovered. Good indicators might be the craneflies and snail-killing flies, but the data just are not robust enough to work from. Hoverfly data certainly point to drought as an important factor.

My feeling is that climate change is a very significant factor, but that we should not lose sight of the other big concern: loss of the fabric of the countryside as hedgerows and ditches are cleared and field sizes have been vastly increased. Loss of mixed farms and concentration on bigger areas of just a few crops cannot be positive. Landscape heterogeneity is a major factor in the overall abundance of wildlife, but the loss of unusual habitats such as seepages, log jams, wet soils and semi-permanent water bodies is equally significant.

So, NFU, I cannot let you off the hook, but the problems are much broader and these were properly discussed in the State of Nature report.

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