Blacklegged tick population synchrony between oak forest and non-oak forest

1. Fluctuations in abundance of blacklegged ticks in space and time are well-documented, but the extent to which populations fluctuate synchronously across habitat types is poorly understood. In oak forests, blacklegged tick density depends on small mammal abundance, which is in turn driven by fluctuations in acorn production. It is currently unknown whether fluctuations in tick abundance in oak forest, long understood to depend largely on masting events, are shared with nearby non-oak forest.

2. In this study, we analyzed 22 years of tick population data from nine forest plots in southeastern New York in order to compare fluctuations of nymphal and larval blacklegged tick populations in oak-dominant forests and non-oak forests.

3. We found that population peak densities of nymphal ticks were strongly synchronous in oak and non-oak forests among years and that larval population dynamics were weakly synchronous between these two forest types.

4. Our results suggest that drivers of immature tick density in oak-dominant forest, including climatic factors and mast-driven host dynamics, may also influence tick population fluctuations in the surrounding landscape.

Tick collection was conducted at all grids from 1995 to 2016. Ticks were collected from each grid by drag sampling using a 1m² white corduroy drag cloth (Ostfeld et al., 1996). Ticks were identified by life stage, counted, and removed from the grid. Due to differences in grid layout, ticks were removed every 30m on the oak-dominant grids (450m² total) and every 20m on the non-oak grids (400m² total). Collection occurred approximately once every three weeks from April to November.