Shortest Day Survey - Results

The BTO Shortest Day Survey took place on 21st December 2004 and was promoted by BBC Radio 4 via the Today Programme. Some 5,460 responses were received from participants and these were used to determine patterns in the arrival of birds at garden feeders.

The pattern of arrival, on average, was:

Species Time after first light
13.0 minutes
16.0 minutes
Blue Tit
19.5 minutes
Song Thrush
21.9 minutes
22.0 minutes
23.2 minutes
23.4 minutes
Great Tit
23.5 minutes
House Sparrow
24.1 minutes
24.7 minutes
Long-Tailed Tit
25.1 minutes
Coal Tit
25.5 minutes
27.0 minutes
Wood Pigeon
27.7 minutes
28.0 minutes
Collared Dove
28.8 minutes
29.0 minutes
30.0 minutes
30.2 minutes
Great Spotted Woodpecker
32.2 minutes

The mean time of arrival after time of local 'first light'

These arrival patterns were then examined in relation to a number of factors, including relative eye size and local habitat, in order to establish whether there was anything that determined when birds first arrived at feeding stations.

We found that there was a negative correlation between eye size and time of arrival at garden feeders across species, and that this relationship remained significant when body mass was taken into account. This suggests that the time at which garden birds begin to forage on winter mornings may be limited by their visual capability at low light intensities.

We also found that birds appeared at garden feeding stations later in the morning in urban areas than in rural areas during winter. This supports the hypothesis that heat pollution may reduce overnight energy costs in small birds in urban areas, thereby reducing the urgency for them to 'refuel' first thing in the morning.

Two papers were published from this work.

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