LNHS Talks – Bird Census Methods for Gardens – A Thirty Year Study by Dave Dawson

Dear Readers, those of us who have dipped our toes into the world of citizen science, by participating in the The Great Garden Birdwatch or Butterfly Conservation’s Butterfly Count often wonder what else we should be doing. There are national bird counts, to be sure, but can we sensibly do anything in our own back gardens? Dave Dawson has recorded the birds that he’s seen in his South London garden for the past thirty years, and he would reply with a resounding yes.

Dawson gave a number of reasons for recording the birds in your garden. Firstly there’s the delight of discovery, like the the time that he saw a raven flying over, being mobbed by crows. Then there’s the fact that quantitative information can be extremely useful, both at the time and for posterity. He posited the case of kangaroo numbers in Australia – there are many diary entries that say useful things like ‘we saw lots of kangaroos today but not as many as yesterday’. If only someone had thought to jot down some numbers! Then there’s the importance of documenting things as they actually change – Dawson could never have anticipated that there would be quite so many ring-necked parakeets in London, but neither could he have foreseen that house martin numbers would drop to zero.

Furthermore, counting birds is easily and conveniently done – Dawson remarks that he can do his count in the time that it takes him to brew up his Turkish coffee in the morning. Everyone now agrees that getting out into nature is good for you. And finally, Dawson’s method works – it will enable the user to actually record trends and to gather useful information.

Dawson agrees that to actually record a bird, you need three things – acuity, concentration and knowledge. However, all three can be accumulated by regular observation! He notes that, for himself, he wasn’t sure if the presence of cataracts and his gradual hearing loss impacted on his recording, though on balance I think he concluded that, although without his hearing aids in he ‘lost’ some species, like goldfinches, it didn’t impact on his figures overall. Because, as we’ll see, the recording sessions are so short it shouldn’t be difficult to concentrate. And knowledge of how the different species look and sound can be developed with the aid of field guides and mentors.

So, how does Dawson recommend going about observing and recording the birds in your garden?

  1. Choose a point in your garden to use for observation. Anything within a 25 metre radius of this point counts as a ‘near’ bird, anything further than this (including birds flying over) count as ‘far’. (You can count birds that you see and those that you hear, if you are reasonably confident about bird song (Bug Woman))
  2. Choose a routine that is easy and not too punishing. Most birds can be seen and heard between 8 and 10 a.m. so you won’t gain much by springing up at the crack of dawn.
  3. Choose a point which is ‘sensible’ i.e. with a good view of the garden.
  4. Choose a convenient counting frequency (i.e. a couple of times a week rather than every single day)
  5. Use binoculars
  6. Avoid winds of more than Force 4 or heavy rain
  7. Use a clipboard and a form – you will definitely want to record the date, time and how many birds of each species you saw, but Dawson also records temperature, wind speed, precipitation, cloud cover, and who actually did the count. Much depends on what you are personally interested in.
  8. Count all species – don’t go missing out the feral pigeons, for example,  because chances are you’ll suddenly want to find out something about them.
  9. Count any birds that scatter on your arrival
  10. Count for five minutes
  11. Record the birds that you see within your 25 metres and the ‘far’ birds separately.

So, what sort of information can be produced, and why do this instead of (or as well as) some of the national recording schemes? Dawson found that his results for some species mapped very nicely onto the British Trust for Ornithology’s Breeding Bird survey, but for some his personal records were very different. Although there has been a precipitous decline in house sparrow numbers, for example, the species has disappeared from Dawson’s garden altogether, probably the result of his particular colony dying out. He has also recorded a dramatic fall in the number of blue tits, although they’ve stayed more or less stable in the country as a whole.

Dawson also mentioned another survey that was done in the London Borough of Sutton in 1989. There was a push locally for more high density housing, and Dawson was asked to survey the birds in low, medium and high density areas of the borough to see what the possible impact might be. The study was conducted in a similar way to Dawson’s garden survey, with different areas of similar sizes being compared for their species richness. The only species that favoured the close-packed terraced houses were house sparrows and starlings, but thirteen species were found much less often in such sites, and overall, twenty species were disadvantaged by high-density developments. So, bird counts can reveal a lot of information that can’t be extracted from anecdotal accounts alone. We need quantitative data to make sense of the world sometimes, and Dawson has an infectious love of statistics, honed over nearly sixty years of working in the field. I thoroughly enjoyed his talk, and if you want to watch the whole thing, you can find it here.

1 thought on “LNHS Talks – Bird Census Methods for Gardens – A Thirty Year Study by Dave Dawson

  1. Anne

    This is fascinating. I keep a record of the birds I see every morning whilst breakfasting outside and add to my list those seen if I happen to have tea outside – in the same spot. I have never thought of counting them though! In this way I have noticed the increase in the variation of species seen over the past thirty years as our garden has changed, along with the disappearance of others. I have come to know when to expect the arrival of some and the departure of others. All of this has helped me to increase my knowledge of birds and gain a better understanding of their behaviour.


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