NBC 2013 season report

After the washout summer of 2012, with record-breaking rainfall in April and June, I’m sure everyone was hoping for a brighter summer in 2013, and we were fortunate in having some lovely warm days, however short the season may have felt. If we think back to the start of the 2013 nesting season, however, the weather was cold, with fluctuating temperatures and some late snow showers. It was actually the coldest spring since 1962, with high pressures blocking milder Atlantic air currents, although, the summer that followed was warmer and drier than average.

The impact of the climate on humans dominated the news, but how did it affect our breeding garden birds? Anecdotal reports seemed to show that breeding attempts in early spring did not prove to be as successful as in previous years, but what did your data have to say?


Five-day old Nuthatch chicks huddled in their distinctive nest.

Photograph by Charlie Howe

Species coverage in 2013

We’re happy to report a further increase in participation last year, with 1,529 of you monitoring a total of 4,180 nest sites. The majority of the boxes registered for NBC were of the 'small hole' variety most frequently used by Blue and Great Tit, but plenty of 'open-fronted' nest boxes were monitored for NBC too, as were a smaller number of larger nest boxes suitable for raptors and owls.

In total, data were collected for 43 species in a variety of artificial and natural nest sites, the top five being Blue Tit, Great Tit, House Sparrow, Blackbird and Robin; Blue and Great Tit nests were reported from a fantastic 1,854 sites (Table 1).

Table 1. Number of nests of top five NBC species monitored

over the past five years.






Blue Tit 1787 1658 1347 1283 1339
Great Tit 717 665 488 499 515
House Sparrow 235 309 289 251 232
Blackbird 162 274 202 224 228
Robin 107 173 122 173 174

Mandarin Duck by Neil Calbrade

For the first time since 2010, a Green Woodpecker was recorded for NBC, building a nest in Buckinghamshire. Dipper also returned to the NBC dataset after a two-year absence, as did Mallard, with three records received; unfortunately, however, it was the first year since NBC began that we received no records of Mandarin Duck.

Figure 1. Average first egg dates (Click to enlarge)

A late start to 2013

As NBC is an online survey, we are able to follow the progress of the breeding season via the live maps and graphs available here. However, the most important outputs are the results of the analyses we run at the end of the season.

In 2013, four of the top recorded species; Blue Tit, Great Tit, Blackbird and Robin, all significantly delayed egg production. The magnitude of the delay was similar across species; Blackbirds laid about 10 days later than average, while the equivalent figure for Robin was 11 days and that for Great Tit and Blue Tit was 12 days (Figure 1). Nest Box Challenge results were very much in line with those recorded across a wider range of habitats and species by BTO Nest Record Scheme participants.


Figure 2. Mean number of chicks fledged per nest (Click to enlarge)

The mean number of Blue Tit and Great Tits raised to fledging was a slight improvement on 2012, but still fell below the average for the previous five years (Figure 2).  The data suggest that small clutch sizes were the cause, indicating that females were in poor condition at the start of the season, possibly due to the low temperatures experienced during laying. Food supplies may also have been limiting. As the weather in 2012 was very wet,  invertebrate numbers in 2013 may have been reduced; insectivorous species such as tits may therefore have struggled to find enough food for their chicks.

You looking at me? Blue Tit chicks watch us watching them.

Photograph by Helena Goodger

Nest box cameras and images

Almost a third (32%) of participants are now using cameras to look inside their boxes, continuing the steady increase observed over recent years. This technology enables us to observe bird behaviour as well as breeding success and it has been fascinating to see how many of you have recorded incidences of Blue Tits roosting over winter and multiple pairs of birds breeding in the same box. All the photos used in this report were taken by participants in 2013.

Successful season – Swallow fledglings waiting to be fed.

Photograph by Pete Stacey.

Taking Part in 2014

Thank you to all Nest Box Challenge supporters for erecting boxes and recording their contents in 2013. The information that you are collecting is helping to advance our understanding of the way that birds use gardens and green spaces in the UK and research at a national scale would not be possible without your help. If you have enjoyed collecting data for NBC then please consider getting involved in the Nest Record Scheme, which allows you to submit information on nests found in sites other than your garden.

Hazel Evans, NBC Organiser

April 2014


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