Study finds urban environments may have the edge on woodland

Research carried out by Anglia Ruskin University suggests that birds breeding in British woodland struggle more in cold, wet weather than those in urban environments.

Over a 10-year period, scientists observed the breeding patterns of blue tits and great tits at three sites in Cambridgeshire.

The research team compared 2012 - a year which saw lower than average temperatures and a particularly cold, wet spring - to the previous nine years.

While researchers say that the number of chicks in the brood and their individual weights dropped at all three sites in 2012, the most significant declines were seen in Brampton Wood Nature Reserve - a deciduous woodland of common ash, English oak and field maple.

The other two sites to be surveyed were the Cambridge University Botanical Gardens in Cambridge city centre, and Cow Lane Nature Reserve, a missed riparian zone of reed beds and willows, close to the banks of the Great Ouse.

Researchers say blue tits and great tits usually lay one egg per day until their clutch is complete, and then begin to incubate them.

The birds at Brampton Wood, however, delayed their incubation in response to the cold weather in 2012, leading to delays in chick hatching.

The period between the laying of the first egg and hatching was 32 days for the tits at Brampton Wood, which was almost twice as long as the period of 17 days for birds at the botanical gardens.

According to the team at Anglia Ruskin, the prolonged delay in the nesting cycle during 2012 was unprecedented in the 10-year period of the study.

Scientists believe these delays could be down to the negative effect of the cold on the birds' caterpillar prey. It is thought that the urban birds may have struggled less as they are not so reliant on a single food source to feed their young.

Dr Nancy Harrison, senior lecturer in life sciences at the university, explained: "Over the 10-year period of the study, birds living in the traditional woodland habitat fared significantly better and produced larger and healthier broods than their city cousins.

"However, if these extreme weather events become more commonplace due to the effects of climate change, then birds living in urban environments may have the advantage."

Image courtesy of Anglia Ruskin University