This is an important post I am sharing from Paul Wildlifewriter in the UK...about water quality in Europe. Given the high failure rate in our Osprey population this year, and the fact that the failures are clustered in specific areas, this raises questions. I wish we had more money to be able to do blood tests and banding. 

INFOGRAPHIC: Europe's heavy metal band

Ospreys are an “indicator species”. What does that mean? It means that creatures such as ospreys, otters, water voles and many others, have a lifestyle that directly and measurably reflects the health (or otherwise) of the environment in which they live. 

In recent years, there's been a worrying discrepancy in the statistics on survival rates of juvenile ospreys in different regions of Europe. Studies in western zones (such as the UK) suggest that about 50-60% of fledged ospreys are still alive after their first year. BUT... researchers in Scandinavia insist that the comparable survival rate in THEIR study areas is lower – around 40%.

Are some of these results right, and others just wrong? Maybe not...

Comparing like-for-like is difficult and there are many factors to consider:- Swedish ospreys (for example) undertake generally longer migrations end to end, and have a wider expanse of the Sahara desert to cross before they can reach their wintering grounds. But would that make such a large difference? In theory, it shouldn't.

Over in the USA, the excellent Dr Erik Greene has established a causal link between mercury and other metallic compounds in the environment, and osprey population figures. [1] Greene's work is now widely cited in other surveys and the results cannot be doubted.

So what if the local variations in European osprey survival have nothing to do with migration? Is the “indicator species” giving us an indication that there might be a problem here, too? The graphic above shows the water quality status (mercury) from the last survey carried out by the European Environment Agency. It's a result that startled me – and it might surprise you as well.

-WLW