Continuing our series of collective nouns blogs, I'm taking a look at another bird that is synonymous with Minsmere, and which owes its continued existence in the UK to the amazing work of RSPB wardens and researchers.

This isn't the place to tell for story of the bittern's recovery, but suffice to say that without the research work undertaken here in the late 1980s, and subsequent pioneering reedbed management work in the mid 1990s, it is highly likely that bitterns would have disappeared from the UK's breeding bird list. Instead, the population has recovered from a low of just 11 booming males in the UK in 1997, to more than 200 males last year. Suffolk remains a stronghold, but the recolonisation of areas like the Fens and Somerset Levels, as well as return to sites in Wales and northern England have also been important in this recovery.

But what do you call a group of bitterns? It would not be a surprise if there wasn't a recognised collective noun, given how shy and elusive they are. Most people are excited enough to see one bittern, so two together would be a major bonus, and as for a flock...

Bittern by Steve Everett

However, flocks do occur, and especially in the spring, when one or more males can often be seen chasing a hapless female around the reedbed. I will always remember the first time I witnessed this behaviour when, whilst leading a dawn chorus guided walk, I watched an incredible courtship chase involving six bitterns! Even more incredibly, one of our regular visitors watched a chase this morning that resulted in the male mating the female on the edge of the Scrape - and he was able to video it and share it with us on Twitter.

Two bitterns in flight by Ian Clarke

The other time that you sometimes see a flock is when one or two bitterns feed in ditches in front of Bittern or Island Mere Hides during the winter, although you still have to be in the right place at the right time to see two or more bitterns together.

So, what do you actually call a flock of bitterns? Of the three terms that I have found, the best one is definitely a pretence of bitterns. Afterall, bitterns are very good at pretending to be reeds as they stand stock still, superbly camouflaged.

The other two terms are both also used generically for herons - not surprisingly as bitterns are a type of heron - as well as for the similar looking cranes. Both terms are likely to be derived from each other, too - probably reflecting regional differences in pronunciation. So we have both a sedge of bitterns (herons/cranes) and a siege of bitterns.

I don't the origins of either term, but as herons, bitterns and cranes all live in wetlands with tall vegetation, it's easy to see where the association with sedges comes from. A siege is harder to explain if you use the recognised meaning of siege, which is why I suspect that it is a derivation of sedge. 

As with many species that were extensively hunted in the past, the true origins of these collective nouns are likely to date back to the days when bittern was a key component of Mediaeval banquets. 

Bittern by Jon Evans

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