Date of this Version
The Prairie Naturalist 40(1/2): March/June 2008, pp 43-46
Exotic infectious diseases can have devastating effects on the distribution and abundance ofnaYve wildlife species (Friend et al. 2001). West Nile Virus (WNV) is an exotic disease that was introduced into North America in 1999 and has resulted in the deaths of tens of thousands of birds (Marra et al. 2004). The natural cycle of WNV involves Culex spp. mosquitoes as principle vectors and birds as principle hosts, although humans, horses, and other mammals can become incidental hosts (Lanciotti et al. 2000). Because the virus can be fatal, outbreaks have become a national health concern for the human population, an economic concern for domestic animal losses, and a conservation concern for the status of free-living wildlife populations (Campbell et al. 2002). For birds, WNV infection can be lethal, but the degree to which birds are adversely affected varies among species and even between individuals within species (Komar et al. 2003). In light of concerns regarding the status of North American bird populations, we captured adult, juvenile, and nestling icterids in central North Dakota and tested them for WNV -specific antibodies. Specifically, we wanted to determine if antibody positive blackbirds were present during the early summer breeding season prior to the peak of mosq~ito populations that typically occurs later in the summer. Sampling during the icterid breeding season also allowed us to test the hypothesis that nestling blackbirds are particularly vulnerable to the virus because they are confined to the nest, lack protective feathers, and have naive immune systems. We also trapped mosquitoes to determine if Culex tarsalis, a known WNV vector in North Dakota (Bell et al. 2005), was present in our study area.