Comparing Measures of Immunity and Health Status in the Golden-winged Warbler (Vermivora chrysoptera) X Blue-winged Warbler (V. cyanoptera) Hybridization System

Abstract

I report the results of the first immunological tests in the Golden-winged Warbler (Vermivora chrysoptera) X Blue-winged Warbler (V: cyanoptera) hybridization complex. The study intended to investigate whether the Blue-winged Warbler or hybrids could have superior immunity over the Golden-winged Warbler, contributing to the rapid displacement of the latter. Blood samples were collected from breeding Golden-winged Warblers, Blue-winged Warblers and their hybrids in Central Wisconsin. I found no significant differences in the index to natural antibodies or hematocrit among these species and their hybrids. Unexpectedly, tick prevalence was higher in the Blue-winged Warblers than in the Golden-winged Warblers or their hybrids. It seems unlikely that the difference in immune quality is a factor for the displacement of the Golden-winged Warbler. Still, the comparable performance of hybrids relative to the parent species may provide additional support to the scenario that hybridization could continue where these species co-occur.