Continent-Wide Drivers of Spatial Synchrony in Breeding Demographic Structure Across Wild Great Tit Populations

Area of Science:

• Ecology
• Population Biology
• Ornithology

Background:

• Age structure variation significantly impacts population dynamics.
• Understanding the spatial scales of demographic synchrony is crucial for conservation.
• Great tits (Parus major) are a well-studied model species for ecological research.

Purpose of the Study:

• To quantify the spatial synchrony of breeding demographic structure (subadult vs. adult breeders) in great tit populations.
• To identify the drivers of demographic structure synchrony across large spatial scales.
• To investigate the influence of environmental variables and local dynamics on the scale of synchrony.

Main Methods:

• Analysis of >130,000 great tit individuals across 32 populations spanning 67 years.
• Quantification of spatial synchrony in breeding age structure.
• Statistical modeling to identify drivers of synchrony and its spatial scale.

Main Results:

• Demographic structure synchrony was maintained up to approximately 650 km.
• Younger populations were associated with larger clutch sizes, colder winters, and larger beech crops.
• Environmental variables, except for beech masting, did not significantly influence the scale of synchrony.

Conclusions:

• Spatial synchrony in demographic structure operates over large scales (hundreds of kilometers) in great tits.
• Local ecological and density-dependent factors mediate the impact of environmental variation on synchrony.
• Findings have implications for understanding age-dependent demography and population persistence.