Migrating Birds at Ottenby Sweden as Carriers of Ticks and Possible Transmitters of Tick-Borne Encephalitis Virus

Investigations of birds trapped at the Ottenby Bird Station on the island of eland in the Baltic Sea demonstrated that ticks are carried by numerous bird species, particularly Passeriformes. The resident bird population as well as birds undertaking migration were found to be infested. So far among birds undertaking long-range migration infestation was made probable only for individuals coming in from the south in spring. The tick species most commonly encountered was Ixodes ricinus, while I. arboricola and Hyalomma marginarum were occasionally represented, the last mentioned in but a single case. Infestation rates during autumn migration were: in early August, 0 % (62 birds of 7 species examined), in September 8.8% (136 birds of 14 species), and in October 5.4% (93 birds of 11 species). In most cases only one or a few ticks were taken off each bird. The maximum numbers were as follows: