25 years of BTO Garden BirdWatch

The last time I saw a yellowhammer in my garden was on 31st December 1994.  It sat in the kitchen garden for an hour or so, the day before the BTO (British Trust for Ornithology) Garden BirdWatch (GBW) was due to go live.  I had high hopes of starting off with a yellowhammer - but I haven't seen one here since.  I didn't get a photo either - this is Thomas Bewick's woodcut.

GBW is a citizen science project whose participants submit weekly records of birds seen in their gardens.  It is funded by contributors' subscriptions.  The number of contributors rose from 2,000 in the first year to a peak of over 12,000 in 2003 but I was surprised to see that it has gradually tailed off to 6,000 last year.  The number of submissions peaked at almost 500,000 per year and now runs at about 250,000.  

In the early years of GBW the data were submitted on A4 cards to be read by a scanner but sometimes the cards were damaged in the post and couldn't be fed into the card reader (once that problem was realised we had to submit them folded in an A5 envelope) so three of my quarters were lost, meaning that I have only 97 of a possible 100, with 1250 weeks in total.

I am not one for lists but I can see from my own GBW data that I have recorded 61 bird species in the last 25 years,

The commonest birds I have recorded are:

It is interesting to see rook and pheasant on the list.  When I first moved here 30 years ago there was a rookery in the copse at the top of the garden.  At its peak there were 44 nests (and a lot of rooks) but it dwindled over time and one year they didn't return.  I can see from the GBW data that the last time I recorded a rook was in 2011 and the last nests were in 2010.  I doubt they will ever return but I would be pleased if they did.

It is also now exactly two years since I saw "my" pheasant here.  He was a daily visitor for five years and so was at least six when he was last here, very old for a pheasant.

The rarest bird sightings, with one each, have been woodcock, sedge warbler, grey heron and buzzard.  Of these, the only one I managed to photograph was the juvenile sedge warbler.

As well as the yellowhammer, other rare sightings in the garden before GBW began were waxwing, red-backed shrike, and cockatiel(!) so the garden list is 65.  (I don't have a life list, or a patch list, or a year list, or a garden year list, etc, etc.)

As well as birds, GBW offers to record mammals, reptiles/amphibians, butterflies, dragonflies and other insects, although from memory these weren't included at the start 25 years ago.  The only one I have completed regularly is mammals, although I have tried to do bumblebees, butterflies and dragonflies.  I am not sure how much use is made of these data.  I know the British Dragonfly Society doesn't use them because there is no way of validating the sightings. I suspect the same is true for bumblebees and butterflies but at least it gives me some sort of record.

I can see that I have had 16 species of mammals in the garden, with red fox the commonest and stoat the rarest.  I have had 15 species of butterfly, with commonest being red admiral, speckled wood and large white and the rarest holly blue, small skipper and small copper, each with one record.  Dragonflies are rare in the garden but I have seen eight species, the commonest, not surprisingly, being common darter.

Garden BirdWatch's main strength is its size.  It has now accumulated a vast amount of data which can be used to examine long term trends and show which species are thriving or in decline in the UK's gardens.  For example, this is the 25 year trend in reporting rate for wood pigeon.  (It looks as though we are approaching peak wood pigeon!)

Goldfinch is another bird doing well in gardens.

As is ring-necked parakeet.  Although some people don't approve of them, I would love to see one of these in my garden.

GBW data can also be used to identify birds doing badly.  These are data for song thrush,

starling,

and house sparrow, all three of which are on the Red List in the UK.

Bullfinch is a bird I see a lot here (in 35% of weeks according to the table above but in 46 of 52 weeks last year) and its numbers have also been increasing in GBW.

The data can also be analysed to show the annual pattern of garden use.  This is a plot of average weekly count (ie numbers seen) whereas the graphs above are of reporting rate (ie the likelihood of at least one bird being seen).

If you would like to join GBW and contribute your observations you can do so here.