Ecology 



"It woTild appear that R. praviis shows a preference for bush- 

 veld or dry parklands (in South Africa, and) avoids open grasslands 

 or more htunid parklands. It occvirs in areas with seasonal rainfall 

 alternating vfith fairly long dry periods, and with a rainfall above 

 ten inches and below 25 inches. It appears to be relatively frost- 

 resistant, being established in areas with over 90 days of frost 

 per annum." ^Theiler and Robinson (1953B) f . 



These conditions are generally also true for the Sudan, except 

 that R. pravus is not uncommon in the open grasslands and sparsely 

 treed^savannah of Torit District, where the annual rainfall varies 

 between ^0 and 50 inches. However, it is much more common in the 

 more arid grasslands and savannahs of Eastern District. It is rare 

 or absent in Juba and other districts to the west of Torit, which 

 have higher rainfall, denser savannahs, and forests. Torit and 

 Eastern Districts both have long dry seasons. The apparent absence 

 of R. pravus north of Torit and of Eastern Districts may be due to 

 paucity of collections or lack of popvilation pressure on the north- 

 ern periphery of its range. 



Highland records from goats at Katire and Nagichot may rep- 

 resent introduced individuals, if not, they are difficult to ex- 

 plain from these humid, forested areas. 



In Central Africa and Western Province of Nigeria, R. pravus 

 may invade high rainfall areas (average over 60 inches per annum} 

 as sxoggested by Walker (1956). Rosevear (1953) indicates that in 

 areas with high average rainfall but long dry seasons, vegetation 

 may be of a more xeric type than in areas with a lower rainfall 

 but higher dry season hximidity. Such factors may explain the 

 rather implausible range of a xerophilic tick like R. pravus 

 into certain outlying high-rainfall average areas. ""Cattle brought 

 into these areas for slaughter may also influence the picture. 



Lewis, Piercy, and Wiley (19/+6) found that in Kenya, R. 

 append i c ill at us and R. pravus occur together in some areas 

 pres\imably marginai~for both species (i.e.: Karati Forest, 



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