30 years of BTO GardenBirdWatch

The end of 2024 saw the completion of 30 years of data collection and analysis by the British Trust for Ornithology (BTO) Garden BirdWatch (GBW).  It has up to 13,000 people submitting up to half million records each year and once a data set gets that big it starts to produce really interesting and valuable results.  I have been fortunate to be a member and to have been submitting data from my garden from the start in January 1995.  On the GBW website I can look back at my own data but perhaps it is more interesting to examine long-term trends in the North East or the whole country.  Two examples, chosen because of observations in my garden, are Rook and Ring-necked Parakeet which show contrasting fortunes.  When I moved here in 1989 there was a rookery in the small copse in my garden.  The rooks were great fun to have as neighbours but their numbers gradually dwindled from a peak of 44 nests to six nests in 2010.  A few birds turned up for a look round but didn't nest in 2011 and there have been none since.  The GBW data for gardens in the North East show a steady decline but some people are still fortunate to see them.

I can see from my GBW data that the first time I saw a ring-necked parakeet here was in week 12 (March) 2022.  I saw one or two birds until week 17 and then they disappeared.  The next record was in week 46 (November) 2022 and they have been here in numbers ever since, up to 15 at a time.  Here is the graph for gardens in the North East so this is a bird that is obviously here to stay.

Here they are seen through the kitchen window with the iPhone.  Note the three non-native mammals as well.  They are even more regular visitors than the parakeets.

Two finches, both very common here, also show contrasting fortunes.  Greenfinches have long been in decline nationally, probably mainly because of infection with trichomonosis.  In recent weeks here I have been seeing up to nine at a time but this is the national picture, first for presence, then abundance.

.

In contrast, goldfinches, which commonly feed alongside greenfinches, are doing well.  They seem not to be affected by trichomonosis.

The BTO GBW data shows lots of other winners and losers over the past 30 years.  Birds in decline include spotted flycatchers, starlings and collared doves.  Those increasing in numbers include wood pigeons, great spotted woodpeckers and magpies.  One final comparison I have chosen is between our two sparrows.  First house sparrow (a very rare bird in my garden, only two sightings in 30 years),

and tree sparrow (a new arrival here about 13 years ago but scarce for the last two years).

The BTO Garden BirdWatch is one of the largest and most valuable citizen science projects in this country, providing important and fascinating insight into changes and trends in the fortunes of our garden birds.  As someone too lazy to keep lists I find it a great way to check on what has been happening in my own garden as well.

A siskin spring

After a waxwing winter this is a siskin spring.  I usually see a few of these beautiful finches each year but the last few weeks have been exceptional.  My BTO GardenBirdWatch (GBW) records show the first arrived in the first week of January and numbers built up to 22 by the end of March.  The bird in the photo above had the misfortune to bang his head on the kitchen window but he seemed to make a full recovery.

I have two six port seed feeders, amongst others, but never quite managed a photo with six siskins in one go - there's always a hungry goldfinch spoiling the show.  

I am not the only one to have seen a lot of siskins this year.  The BTO GBW website shows records for the North East.  This is the number of gardens seeing siskins - twice as many as average.

And this is the number per garden, four times higher than average.

My impression that this is a particularly good year for siskins is backed up by this graph showing data from the last 25 years.

I read that the probable explanation for the influx is the persistent wet weather.  Sitka spruce pine cones open in dry weather but remain closed when it is wet so the siskins run short of food and turn to gardens instead.  They mostly live and breed in the conifer forests in Northumberland so I expect they will disappear shortly.

WeBS

I signed up to count waterbirds for the Wetland Bird Survey (WeBS) on Banks' Pond at Dinnington last year and I have just completed the first 12 months observations.  WeBS is a partnership funded by the BTO, the RSPB and the JNCC.  It has been collecting data on wetland birds since 1947.  Synchronised counts take place every month with 3000 volunteer counters making 40,000 visits each year to 2800 sites.  "Waterbirds" includes wildfowl (ducks, geese and swans), waders, rails, divers, grebes cormorants and herons and counts of gulls and terns are optional.  Many sites are coastal or estuarine or on large inland water bodies so my site is one of the smallest.

I have seen 12 species in the first 12 months, many predictable but one or two surprises.  I haven't been trying to photograph them as many are shy and I have to do much of the observation from the bridle path before entering the site.  The list of birds is: 

Canada goose

Coot

Grey heron

Little grebe

Mallard

Moorhen

Mute swan

Shelduck

Teal

Tufted duck

Wigeon

Woodcock

All except grey heron, shelduck, teal, wigeon and woodcock breed at the site.  Woodcock is the only "wader", although it doesn't do much wading, and I didn't see any gulls or terns.  The only other bird I can remember seeing in the past while looking for other things (especially dragonflies and bumblebees) is greylag goose.  Previously I have only been to the pond regularly in summer so it will be interesting to see what else turns up with regular winter visits.

The mute swans have been very successful this year with eight cygnets.  Here they are in May

and in September.

The adult swans can't leave until the cygnets can fly, later in the year.  The male swan has been very aggressive towards the Canada geese this year and in the end they managed to raise only one gosling.  I don't know whether the swan had anything to do with the demise of the other goslings but I have my suspicions.  Young geese learn to fly much more quickly than swans so I expect they were pleased to be able to escape a few weeks ago.  I wonder if they will try again next year or find somewhere quieter.

Counting the birds

Like many of you, I expect, I took part in the RSPB* Big Garden Birdwatch (BGB) last weekend. It involved recording the largest number of each species seen at one time during one hour of birdwatching.  Although it has limitations the BGB gets a lot of publicity and encourages many people to take note of the birds in their gardens.  Despite its size, I have reservations about the way this survey analyses its results.  It prioritises abundance so it is biased in favour of birds that go around in groups and sit around on feeders long enough to be counted, such as finches, rather than birds that dash in, grab a seed, and take it off to eat in cover, such as tits.  In my garden I expect there are more coal tits than greenfinches, yet I rarely see more than two coal tits at one time whereas it is easy to see six greenfinches sitting on the feeder together.

I wrote previously about the differences between the RSPB BGB and other surveys such as the BTO* Garden BirdWatch, which is a weekly survey which has been running since 1995.  The main difference is that while the RSPB BGB prioritises abundance, the BTO GBW prioritises presence, so they reach different conclusions about which is the "commonest" garden bird.  For example, if in ten gardens a robin was seen in eight and six starlings were seen in each of two the RSPB BGB would decide that starlings are the commonest garden birds whereas the BTO GBW would choose robins.

In the RSPB BGB in 2020 nearly half a million people recorded almost eight million birds and the "top ten" were

1. House sparrow
2. Starling
3. Blue tit
4. Wood pigeon
5. Blackbird
6. Goldfinch
7. Great tit
8. Robin
9. Long-tailed tit
10. Magpie

This is despite the fact that house sparrows have declined by 53% since the survey began in 1979 and starling numbers have fallen by 80%.  Both are on the Red List of birds of conservation concern.

This chart shows the BTO GBW results for 2019 (green), the latest available, compared with 1995 (yellow), the first year of the survey.  It shows that the birds you are most likely to see in the garden are blue tit and wood pigeon, with house sparrow in 7th place and starling 13th.

This chart shows the winners and losers over 25 years.  House sparrows, starlings, greenfinches and song thrushes have fared badly for various reasons whereas goldfinches and wood pigeons have done well.

I suppose it doesn't matter all that much whether presence or abundance is given priority so long as it is clear what people are talking about.  However, the 2021 results in a few weeks' time will also get a lot of publicity and it will be a pity if it isn't made clear how much trouble these birds are in.

Last weekend I managed a few photos through the kitchen window when there was a brief break in the cold, wet, sleety, windy weather we are having.  These are biased in favour of birds that sit on my "woodpecker" feeder, a dead branch with suet in a hole.  If the weather improves I'll also take some of the birds on the seed feeders and post them later.

*For readers not from the UK RSPB = the Royal Society for the Protection of Birds and BTO = the British Trust for Ornithology.

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.