• Question from:Mike Simpson

The traditional English rhyme about counting magpies, beginning "One for sorrow, two for joy..." only goes up to ten, suggesting that larger magpie groups were uncommon in times past.

This certainly ties in with my memories of growing up in the English countryside in the 1970s when magpies (Pica pica) were common birds but usually encountered singly or in pairs.

It is now very common to see large flocks of magpies - I counted 24 in a single field last week. I never saw large flocks like that when I was young.

Has there been any research into this increased flocking in the species? And if so, what explanation is there?

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  • University of Exeter
  • Posts: 1,011

From a very quick literature search I can't find anything related to flocking behaviour per se. Certainly it is true that the population size of magpies has been growing rapidly and there are many more of these birds than there were when someone came up with that rhyme!

One possibility that comes to mind is that many corvids form breeding pairs that hold a territory and it could be that with the increased numbers there aren't enough territories to go around. In that case it wouldn't surprise me to find that non-territory holding birds flocked together more. This I should say is pure conjecture but it is a phenomenon that occurs in quite a few animals.

There has been a lot in the UK press about the possibility of culling magpies as a way to help songbird populations that are in decline. Although there is logic to this (magpies do predate nests and eggs especially) I think it may be oversimplistic to argue that the increase in magpies is the cause of all problems for our songbirds. in fact a recent study concluded that songbird declines are likely our fault (caused by habitat fragmentation etc). I'm also aware of a couple of studies that have looked at whether songbirds bounced back after culling corvids  - they didn't.

So as far as I can tell a lot of the discussion re reducing magpie numbers is really based on emotional and commercial arguments. More here:

http://www.guardian.co.uk/theguardian/2 … d-survival

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  • Horniman Museum & Gardens, London, UK
  • Posts: 56

Incidentally, there are dozens of versions of that counting rhyme, with many regional and historical variations. Some versions have as few as 4 magpies, and others apparently went up as far as 20!

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  • QMUL, London
  • Posts: 1,218

The rise of various corvids seems to be linked, in part, to the loss of true big predators (like wolves, eagles etc.) meaning pseudo-predators like crows can come to dominate enviornments. Their numbers are starting to fall in areas where big predaotrs (like the red kite) are comeing back through conservation efforts.

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  • University of Glasgow and British Geological Survey, Edinburgh
  • Posts: 238

To follow up on Alastair's post, the British Trust for Ornithology helped carry out a detailed analysis of the effect of a range of predators on songbird numbers.

http://www.bto.org/node/902

An excellent press summary is given at the end of this article, explaining what conclusions the study reached and is very cautious, as the BTO tends to be. I will declare an interest as a BTO Fellow and volunteer fieldworker, but as a research scientist I have great respect for the BTO's integrity.

Despite the best efforts to explain the science to the papers, several papers chose to misrepresent the BTO work, which was funded by Songbird Survival. You can read more about this on Mark Avery's blog.
http://www.rspb.org.uk/community/ourwor … tors.aspx 

Chris Packham's article also identifies the unhappy tendency of many people to view nature as a morality play, rather than a set of interactions among organisms superbly adapted to their respective niches.

"Hope is a duty from which palaeontologists are exempt."
David Quammen