A new survey has revealed that urban birds are lazy, going to feed at bird tables later in the morning than rural birds.

Researchers behind the British Trust for Ornithology’s (BTO) Shortest Day Survey was carried out with the help of listeners to BBC Radio 4’s Today programme, blamed the waste heat that escapes from buildings and factories, warming up urban birds.

Mike Toms, head of the Garden Ecology Team at the BTO, said: ‘Small birds can used up a large proportion of their energy keeping warm on cold winter nights, and tend to fill up with food as soon as they can after first light to replace these losses.

‘That urban populations of species such as the robin and the blackbird are not under such pressure to get to a food source and fill up suggests that they use of fewer energy resources overnight.

‘The waste heat that escapes from our towns and cities can elevate temperatures by up to 8°C, something that is known as the “urban heat island effect”.’ This extra warmth helps small birds get through the long winter nights.’

Researchers also discovered that birds with larger eyes are able to start feeding earlier in the morning, because their bigger eyes allow them to cope with lower light levels.

The survey was aided by the 6,000 people who contributed their early-morning observations through the BTO’s Online System.

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