21.08.2025 - Indoor Meeting : Susan Jones BTO Garden Birdwatch

Report: Cath Robinson

The BTO seems to have an endless supply of excellent, enthusiastic (and often young) speakers who have entertained us over the years, and Susan is another. She recently joined the Garden Birdwatch team and gave us a review of the history and the science of the survey.

Apparently there are an estimated 22 million gardens in the UK with an area of 433,000 hectares which, prior to Garden Birdwatch, was not being monitored for wildlife. It started in 1995 (so 30th anniversary this year) with aims of monitoring the long-term trends in garden birds and engaging the public in meaningful conservation action. Numbers wise by the end of the first year they had 3,481 subscribers; by 2025 they have 10,399! Over the years they have extended the ambit of data collection and now include mammals, bees, butterflies, reptiles, amphibians, dragonflies and work with other organisations to share and study the data.
Susan gave some examples of what the data has shown: the decline in Greenfinches which seemed to coincide with an increase in Wood pigeon reporting. Supplementary feeding was suspected to be the cause and postmortem studies showed that trichomonosis (a protozoan parasite) had transmitted from the pigeons to the finches. This led to updated guidance about cleaning bird feeders regularly (weekly!) and rotating them around the garden. There is also a move away from ground feeders and bird tables, to try to reduce contact with contaminated food. Susan said that there is currently a multi-organisation review into using garden feeders
with a view to updating the guidance. It’s a tricky area as feeding and enjoying birds in the garden gives great pleasure, and also benefits mental health – but, of course, we need to try and do it safely. It seems that there may be a drive towards feeders which are more easily cleaned (How do I dismantle my squirrel buster??)!
The BTO is currently running a Blackbird survey: this was prompted by the drop in numbers reported over the last 5 years due to Usutu, a mosquito borne virus. Interestingly reported Blackbird numbers have always been lower in London but there has been a 50% drop there over the last 5 years. They are currently looking to see if this is perhaps common to other large
urban areas. And as they ask questions about bird health, they have been able to track the spread of Avian pox from Garden birdwatch reports.
Overwintering Blackcaps are a feature of climate change which survey results have highlighted.
Reports showed that more were being recorded in gardens in the winter and also that there is a SW/NE divide, with more in the SW with a milder winter climate. Over time, the winter visitors have been found to have evolved narrower beaks and shorter wing length, a function of differing diet and shorter migration distances, an interesting example of morphology changing with different migration patterns.
She encouraged us to join Garden Birdwatch if we weren’t already (hands raised showed quite a few of us were but quite a few weren’t....). You can do it all online or download paper forms and it is quite self-explanatory. Most of it is tick boxes. You just need to devote a consistent amount of time observing the birds in your garden every week. I have never used the
comments box but it transpires that many people put comments there or send queries or comments or photos to the team who sound amazingly receptive and friendly.
Keen Garden Birdwatchers were encouraged to volunteer as Ambassadors.
Top Norfolk birds are Blackbird, Blue tit, Robin and Wood Pigeon. They currently have 341 reporters in the county and 99 in Norwich. She thought these were good numbers but I was surprised that in a county renowned for its birds and birdwatchers that it was so low. 
​Why not give it a go?
With many thanks to Susan for her stimulating and interesting presentation.