Interested in conducting research on this experimentLocation of bird boxes at Silwood Park [JPEG, 766KB]
Dr. Julia Schroeder explains how the blue tit project help us understand the effect of genes and the environment on birds behaviour

Understanding whether natural populations can adapt fast enough to climate change is one of the more challenging question in ecology and environmental sciences.  The timing of key events in organisms' lifetime has evolved to synchronize with abundance patterns of their preys and natural enemies. Consequently, changes in climate and environmental cues can create a mismatch in phenology between interacting species threatening the stability of food chains and ecosystems.

European Blue tits (Cyanistes caeruleus) time reproduction so the period for rearing cheeks is synchronized with the peak of abundance of caterpillars, most of which feed on young leaves of deciduous trees. A long-term study at Silwood Park aims to understand the extent to which a mismatch between breeding phenology and prey availability affects a wild population of these birds. Hundred of nest boxes and thousand of oak trees distributed across the campus' woodlands are monitored annually since 2002 to track the breeding activity of nesting tits, record the time of emergence of new oak leaves, and estimate the amount of caterpillars available for the foraging birds.

The blue tit project is one of the experiments of The Grand Challenges in Ecosystems and the Environment Initiative (GCEE). It was created by Professor Ian Owen in 2002 with the support of a NERC grant, and managed by Dr. Alex Lord until 2015. This project is currently led by Dr. Julia Schroeder and supported by the department of Life Sciences at Imperial College London.

details blue tit projec

Experimental design

There is an array of woodcrete nest boxes (made with a mix of wood and concrete) with a hole suitable for birds of tit's size distributed around the oak and birch woodlands of Silwood Park.  Two third of them where placed on 2002, followed by more added between 2004 and 2010.  From 21st March to 21st June each nest box is monitored every other day to register the breeding activity of tits; from nest building to the date the first egg is laid. Individual broods are then followed through the season to record their size and take physical measures of adults and nestlings.  

In addition, more than 3.500 oaks (Quercus robur) distributed across the 110 ha of Silwood Park are marked and their leaf phenology followed during the season. Oak shoots and new leaves are the food of the winter moth caterpillars (Operophtera brumata), which are a key resource for the growing chicks.  Thus the seasonal collection of information on oaks' budburst timing and caterpillar frass is used to estimate the quality of the breeding territory surrounding nest boxes.  

Data

Data from blue tits breeding in the experimental nest boxes set around Silwood Park grounds has been collected since 2002. Core data includes: 

  • Date of the first egg laid
  • Number of eggs laid (clutch size)
  • Morphological measures of the breeding couple and all offspring
  • Sex ratio of clutch (available for some years)

Adults and fledglings  are marked with individually numbered aluminium leg rings

The leaf-out phenology of a proportion of tagged oak trees is annually monitored from March to June to register the date of four stages from bud burst to fully extended and hardened leaves. 

 

 

Publications

Hadfield JD, Burgess MD, Lord A, Phillimore AB, Clegg SM, Owens IP (2006) Direct versus indirect sexual selection: genetic basis of colour, size and recruitment in a wild bird. Proceedings of the Royal Society B: Biological Sciences 273: 1347–1353. 

Hadfield JD, Owens IPF. 2006. Strong environmental determination of a carotenoid-based plumage trait is not mediated by carotenoid availability. Journal of Evolutionary Biology 19: 1104–1114.

Hadfield JD, Nutall A, Osorio D, Owens IPF. 2007. Testing the phenotypic gambit: Phenotypic, genetic and environmental correlations of colour. Journal of Evolutionary Biology 20: 549–557. 

Bell SC, Owens IPF, Lord AM (2014) Quality of breeding territory mediates the influence of paternal quality on sex ratio bias in a free-living bird population. Behavioral Ecology 25: 352–358. 

Thorley JB, Lord AM (2015) Laying date is a plastic and repeatable trait in a population of blue tits Cyanistes caeruleus. Ardea 103 (1): 69-78 

Requirednest box in Mann's copse

Nest box in Mann's Copse, April 2016

oak tree tag

One of the thousand oak trees tagged at Silwood Park woodlands

veteran oak

Veteran oak tree