Where have all the grouse ticks gone? Apparent decline in collections of Haemaphysalis chordeilis Packard during the 20th century

Authors: EGIZA, A. - Rutgers University; Maestas, Lauren

Submitted to: International Journal for Parasitology: Parasites and Wildlife
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2022
Publication Date: 11/24/2022
Citation: Egiza, A., Maestas, L.P. 2022. Where have all the grouse ticks gone? Apparent decline in collections of Haemaphysalis chordeilis Packard during the 20th century. International Journal for Parasitology: Parasites and Wildlife. https://doi.org/10.1016/j.ijppaw.2022.11.007.
DOI: https://doi.org/10.1016/j.ijppaw.2022.11.007

Interpretive Summary: The grouse or bird tick, is a three-host tick native to North America. Literature from the early 20th century reported a widespread distribution of this tick across the US and Canada. As its name implies, ground-dwelling birds such as grouse, turkey and quail were frequent hosts, and occasionally large infestations were reported in domestic flocks making it a pest of economic importance. However, after the mid-1900’s records of this species appear scarce, and a number of more recent studies of ticks on birds (including on ostensibly favored host species) did not detect it. To confirm this perception with data, we conducted a literature search for collection records of this species and compared the records across two eras (pre-1965 and post-1965), finding very few records of grouse ticks in recent years, despite increased attention brought to this genus by the detection of exotic long-horned tick populations in the eastern US. We also compiled a list of studies after 1965 that examined appropriate hosts for ectoparasites but failed to find grouse ticks. We interpret this apparent decline in the context of documented population declines in several major host species over the same time frame and discuss whether ectoparasite populations should be subject to the same conservation consideration as their hosts.

Technical Abstract: Haemaphysalis chordeilis, also known as the grouse or bird tick, is a three-host tick native to North America. Literature from the early 20th century reported a widespread distribution of this tick across the US and Canada. As its name implies, ground-dwelling birds such as grouse, turkey and quail were frequent hosts, and occasionally large infestations were reported in domestic flocks making it a pest of economic importance. However, after the mid-1900’s records of this species appear scarce, and a number of more recent studies of ticks on birds (including on ostensibly favored host species) did not detect it. To confirm this perception with data, we conducted a literature search for collection records of this species and compared the records across two eras (pre-1965 and post-1965), finding very few records of H. chordeilis in recent years, despite increased attention brought to this genus by the detection of exotic Haemaphysalis longicornis populations in the eastern US. We also compiled a list of studies after 1965 that examined appropriate hosts for ectoparasites but failed to find H. chordeilis. We interpret this apparent decline in the context of documented population declines in several major host species over the same time frame and discuss whether ectoparasite populations should be subject to the same conservation consideration as their hosts.