GROOMING IN IMPALA - ROLE OF ORAL GROOMING IN REMOVAL OF TICKS AND EFFECTS OF TICKS IN INCREASING GROOMING RATE

In Experiment 1, five adult female impala were fitted with harnesses t hat restrained oral self-grooming of the anterior part of the body. At the same time, six cohoused female impala were fitted with control ha rnesses that allowed normal oral grooming. The impala were allowed to habituate to the harnesses for 10 days, and both groups were then expo sed to larval ticks (Boophilus decoloratus) by herding them into a tic k-seeding corral. During the third week following tick seeding, when f emale ticks were estimated to have developed into engorging adults, th e impala were immobilized, tick numbers on the animals sampled by patc h sampling, and the harnesses removed. Observations continued for 5 da ys following removal of the harnesses. Twenty-minute focal observation s were conducted daily on each impala during the habituation, tick-see ded, and postharness phases. Restrained impala had a median of 20 time s more adult female ticks (both engorged and unengorged) than control impala. Oral grooming, which had been suppressed in the restrained imp ala during habituation and tick-seeded phases, increased 10-fold once the harnesses were removed and occurred 2.5 times more frequently than in control impala during the postharness phase. In Experiment 2, 15 a dult female impala were seeded with larval ticks as in Experiment 1; i n week 3 after tick seeding all ticks were removed from animals by app lication of an acaricide. Grooming was recorded during 3 weeks of base line observations prior to tick seeding, 3 weeks after tick seeding, a nd then for 3 weeks beginning 1 week after acaricide treatment. Oral g rooming and scratch grooming significantly increased from baseline dur ing tick seeding and significantly declined following removal of the t icks with acaracide. Taken together, the two experiments demonstrate t hat oral grooming is very effective and important in removing fitness- compromising ticks in free-ranging impala. Correspondingly, exposure t o, and subsequent infestation by, ticks increases the rate of grooming .