Identification of tick species parasitizing passerine birds around Newark, DE
Migratory birds have been implicated in the spread of ticks and tick-borne pathogens; yet their role in local disease transmission, especially in urbanized landscapes, is not well understood. To identify the primary bird species hosting ticks and to describe the diversity of tick species parasitizing birds in urban forests, we examined birds in ten forest fragments around Newark, Delaware. Based on tick collection records from birds in the region and a 1968 study in one of the same field sites, we hypothesized that we would find several species of ixodid ticks. In 1968 a study in one of the same forest fragments found the predominant tick species on birds in the area to be Haemaphysalis leporispalustris and Ixodes dentatus. During the summers of 2013 and 2014, birds were captured using mist nets and carefully checked for the presence of ticks. We removed ticks from birds with forceps and stored them at -80C until they could be identified. The ticks were identified using a Nikon SMZ1500 microscope and with keys from the Entomological Society of America.
Approximately 450 ticks were collected from 177 birds of different species and age classes. Out of the approximately 450 ticks collected, 323 were identified as Ixodes scapularis (297 larvae, 26 nymphs), the blacklegged tick, which is an important vector of zoonotic pathogens. Some ticks that were in poor condition could not be completely identified. Some ticks that were in poor condition were identified to the genus Ixodes spp. (59 larvae, 17 nymphs) or to the family Ixodidae (44 larvae). We saw a lack of diversity in the tick species found, which contrasts with similar studies performed approximately 50 years ago. The 1968 study in the same area did not find any Ixodes scapularis nymphs or larvae on birds. Our results suggest that there has been a turnover in the dominant tick species parasitizing birds in this area, and that birds are an important host of immature blacklegged ticks.