GBW Annual Results 2015

Blue Tit by John Harding

The 2015 annual results of the BTO Garden BirdWatch show an interesting story. Thanks to a wet spring, some of our common bird species appeared to have poor breeding season, leading to low average numbers during the second half of the year. Many of the seed-eating and insectivorous species were seen in very high numbers toward the end of the year, possibly due to a poor tree-seed crop and stormy weather. It was also another year with low winter migrant numbers, which could have been driven by relatively mild winters at both ends of the year. Explore the year in more detail by viewing the results for individual species using the drop-down menu below or scroll down to see our seasonal guide.

Select a species from the drop-down list and click on the graph to enlarge.

Black-headed Gull

Black-headed Gulls usually only visit gardens during very unsettled or cold weather, and we did see a small peak at the end of January when a patch of wintry weather hit. After that, however, their numbers followed their normal seasonal pattern.

Seasonal guide to 2015

GBW results 2015

Graphic by Nigel Hawtin. Click to expand.


The first quarter of the year started as it meant to go on – unsettled. This was especially true in northern parts of the UK with major storms and heavy snow showers. Widespread frosts at the end of January saw increased bird numbers move into gardens as temperatures dropped to their lowest of the winter, with small increases in species like Goldcrest and Brambling. There were peaks in the average numbers of many species in February potentially due to ongoing unsettled weather. Robin, for example was seen in its highest average numbers for the month since 2009. Even Siskin numbers, which were notably scarce during the winter of 2014/15, slightly increased. Towards the end of the winter, we saw normal increases in numbers of farmland birds including Reed Bunting which reached the second highest numbers seen in March, lower only than 2013. This reflects the importance of supplementary food during late winter, when surplus food in the wider countryside becomes scarce.


Spring 2015 started off fairly settled with the sunniest April since records started in 1929. Temperatures cooled towards the end of the month and small peaks were seen in the average numbers of a variety of species, including Blackcap and Bullfinch. The weather quickly turned wet, however, with many areas receiving more than double their average rainfall in May. While there were small unexpected peaks in the average numbers of Blackbird and Carrion Crow in mid-May which may have been driven by the adverse weather, the numbers of many species increase in May anyway, as juvenile birds start to join their parents in gardens to feed. The June peak for many species were later than those seen in 2014, possibly due to the rain affecting time of breeding. Goldfinch, Bullfinch and Starling all reached high average numbers in June, but Blue Tit and Great Tit did not do so well.  Preliminary Nest Record Scheme results show that they, along with other resident breeding species such as Blackbird, had particularly poor breeding seasons and this was reflected in the low numbers seen in gardens.

Siskin, by Allan Drewitt

Siskin, by Allan Drewitt


It finally felt like summer had arrived in July with record-breaking temperatures and hot and humid weather. The weather broke by the end of the month, though, with thunderstorms, hail and cooler temperatures. This change in the weather was reflected in the number of birds coming into our gardens. Bullfinch numbers, for example, normally drop at the end of the summer, not rising again until October. At the end of July, however, there was another small peak as they moved back into gardens, with the highest average number ever seen at that time of year that continued until the end of the September. Long-tailed Tit numbers also started to rise quite sharply. We saw the beginning of the autumn trough occur as usual in species such as Blackbirds, and Jays, which were seen in much lower numbers than in 2014 suggesting a good acorn crop. Siskins, on the other hand, were seen in their second highest numbers for September, only less than in 2012 when there was a very poor crop of seeds in the wider countryside. There were also a high number of reports of Siskins on BirdTrack which could mean that we have had a large influx of migrant birds. This may also be the reason for higher numbers of Coal Tits, which matched those seen in 2012.


There was a relatively pleasant start to the autumn with warm temperatures and high pressure dominating. While birds start to return to gardens after the ‘autumn trough’, numbers generally remained low as the mild weather allowed easy access to food in the wider countryside. Some winter migrants, including Brambling, Fieldfare and Redwing, arrived into gardens with the former being seen in higher average numbers than in the previous two years. There was also an influx of migrant Goldcrests with the second highest average numbers for winter, lower only than 2008. November was a very wet month with 200% of the average rainfall, though it was the third warmest since records began in 1910. With Long-tailed Tit numbers increasing in gardens towards the end of the month, it is possible that invertebrates were harder to come by in the wet and windy weather. Although numbers remain low, there was a slight increase in the average numbers of Greenfinches, which crept above the counts for the previous two years at the end of November. The unseasonably mild temperatures continued into December, making it the warmest December ever in the Central England temperature (CET) series that started in 1659. Even the numbers of those birds that were seen in incredibly high numbers throughout earlier parts of the quarter, such as Coal Tit and Goldcrest, dropped in December. Species that we would expect to see increasing in gardens as natural foods dwindle, such as Reed Bunting and Yellowhammer, did not really make an appearance in gardens this year. Some birds, however, remained in high numbers including Nuthatch which reached a new record at the end of December, reflecting the lack of tree seeds in the wider countryside.