Bittern behaviour (1 Viewer)

I saw 6 Bittern yesterday - yes, SIX - at Stodmarsh. Over the past 6 or more years others (not me!) have regularly seen 8 or more Bitterns (with a maximum of 16 birds!). The trick is to be there between late February and the end of March on a clear, calm evening from c15 and 35 minutes after sunset (currently c18.05). Some birds fly up singly, others in 'pairs' (with one bird being larger than the other suggesting male/female). They fly to some height (40m+) often two birds following one another. As they do so they give a gull-like 'unk' croak.

These birds clearly do not breed at the site (such numbers peak in mid-March, quickly diminish and the 4-8 pairs that the figures suggest would have been noticed). There seem to be fewer birds throughout the winter than the numbers seen in this late winter period. So, what's going on? Are they passing migrant birds moving on to the continent. Do the figures actually represent the true wintering population and lack of records merely reflect the secretive nature of the species? If it is some sort of pre-nuptial flight it also appears to suggest that "pair bonds" are made prior to migration.

Equally interesting is the thought that should others visit reedbed sites that are known to hold wintering Bittern will they find a similar situation where numbers are much higher than they would have expected? Also it is probably the easiest way to see this elusive species (albeit in silhouette), John

It must be a Heron thing, I was at Cors Caron one day last week and saw 15 Herons stacked up in the air shortly before sunset.

John,

At Potteric Carr in South Yorkshire we've had up to 5 during the last few winters. The peak numbers can be at any time from late December through to February. This winter only 2 were present until numbers increased in Feb up to 5. They normally depart around the 3rd week of March. The curious habits you noticed haven't been seen at Potteric as far as I know. Are they going off somewhere else to roost or do they drop back down into Stodmarsh?

Rich.

It is usual for Bitterns (even if few people know it). I saw such evening flights in September-October in Poland. If you imitate their call, they will turn and fly over you.

Because they do it in autumn, I don't think it is pairing. If somebody makes a trawl through bird books and finds explanation, I am quite curious.

There doesn't seem to be much in the books - including the BWP. With regard to Potterick Carr I wonder whether many folk are out looking 10-15 minutes after dusk. It may be worth doing so since the numbers recorded at such evening vigils are far in excess of the numbers expected from casual observation. It was clear & blowy tonight and only two birds appeared, John