Avian Tick Burdens Across an Urban to Forest Land-Use Gradient




Peters, Ryan

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Interactions between Ixodes scapularis, the primary vector of Lyme disease in the Eastern and Midwestern USA, and their hosts determine infection rates in ticks, and influence the human risk of infection. Several factors alter tick burdens over temporal and spatial gradients and determine the role birds play in tick-borne pathogen transmissions cycles. In the research described here, I have determined seasonal patterns of tick burdens on 23 species of birds at 16 sites along an urbanization gradient in the Mid-Atlantic, USA. Landscape and species-specific attributes, as well as questing tick abundance are examined in order to understand variability in tick burdens. Tick burdens on birds were highly seasonal, decreased with increasing urbanization of the capture site, and varied substantially between species of birds. Carolina wrens (Thryothorus ludovicianus) and Northern Cardinals (Cardinalis cardinalis) hosted 28.0% and 25.0% of all ticks obtained from birds while only comprising 4.9% and 11.9% of the avian community. Foraging height, as well as gender and age of the bird also influenced tick burdens, but to a lesser degree. I present models to estimate or predict avian tick burdens using individual, species, and site characteristics, and the density of questing ticks. Identifying causes of variation in tick burdens on avian hosts will increase our understanding of host-parasite interactions and the role birds play in the ecology of Lyme disease.



Ixodes scapularis, Birds, Tick burden, Land-use, Lyme disease, Urbanization