Wednesday, 13 December 2017

The sum of all parts of the quarry (3); thrushes

This December, the two roost counts at Berengrave are going to be rather far apart. My chance to muse on what gets counted. OCD muppet that I am, I try to count everything. Results? All 'normal', but all fascinating, and helping to refine my personal views on the local populations.

This is just one small relatively insignificant, often overlooked, reserve. But look hard enough and there's enough to keep a birder happy.

The Thrushes

Now, same as for everything I count, the number must never be thought to represent the actual number of birds using the pit; it is far higher than these counts. Blackbirds into roosts are like stealth bombers, zipping over the hedge and dropping fast and low into the scrub. Some call, most don't; those silent ones that whizz past me, head height, shout out 'you're missing shedloads'. Thankfully, the trends do hold up to scrutiny; a strong start to the autumn, bolstered by more arrivals, then a steady drop off into the spring; if only all species trends looked like this I could take a few counts off..

Absolutely nowhere near the numbers seen back in the mid-nineties when, as a raw ringing trainee, I would join the Reverend for a roost catch; birds everywhere. I would argue that, like this year, the pit just isn't right- Fieldfares like to roost over water, and levels are low. A couple of these recent winters have seen the pit so full of water paths were closed. I have tried to put it down to more birds using the Motney reedbed since Kent Wildfowlers improved the sluices a few years back and certainly they are now always there in higher numbers, just some 600 metres to the north of the pit. However, stand on the seawall and watch to the south and east and you will appreciate there are not as many birds, full stop; the grubbing-out of orchards for paddocks, combined with the 'upgrading' of those that remain to industrial sites, have cut down the local feeding opportunities. I would love a three-figure count here, but I won't be holding my breath. (Even though my counts 'officially' finish 30 minutes after sun down, I do hang on until pitch black though- from experience I know birds can still drop in up to an hour after sundown. Ever the optimist..)

Song Thrush
Probably my favourite Thrush at roost. Certainly not for the excitement levels; that graph shows a resident dropping away to breeding numbers. But because you can always count on a little call as they scuttle about the pit edge, and you can expect a bit of interaction as they try to keep their personal spaces personal. Which makes this year interesting; has there been a local influx? If overwintering numbers are up, you can expect to find more birds out and about on the marshes, but they usually do not travel far to roost. Are these perhaps a few extra from the cleared scrubland a little to the east, dirt levels awaiting development? If so, will the next count stay low, perhaps showing that influx was too much, that the carrying capacity cannot be extended? Who know?! All something to think about, roll on moth end.. 


Last year, the waters were high. Unlike the previous high years, there were also Redwings about. Perfect combination. Ringing has shown no wintering fidelity- a bird might spend one year here, moving through the season down to Iberia. Next year that same bird might choose the foothills of the Alps before wandering down the spine of Italy. Enjoy them when you can. Last year's mid-winter influx was nerd-birding nirvana, flights of 'wings coming in out of the gloom, screaming as they circled the sallows.
Was it always like that a few decades back. My dullard mind tries to tell me yes, my counts from the time told me no; but there were more peaks, f'sure. End of the month I'll be back in situ, hoping for an influx.

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