TheImprovement ofTropical and Subtropical Rangelands

294 IMPROVEMENT OF TROPIOAL AND SUBTROPIOAL RANGELANDS
of imperfect knowledge of precipitation, labor markets, and political
relations, and only after a great deal of debate. In such a situation,
despite the regularizing limitations of habit and previous experience,
much variation in migratory movement at the camp level from year
to year is to be expected and does in fact occur.22
Coupled with the high degree of flexibility in and variability of
movement at the camp level is an apparently bewildering variety
of movements at the tribal level.2 s During the hot months of summer
there is a general northward shift toward higher elevations that
brings Marri camps out of their tribal territory and into the Pathan
regions around Sanjawi, Loralai, and Mekhtar. A similar movement
north into the northwest Marri area or the southwest Pathan area is
undertaken by Marri groups who winter in the plains around Sibi.
However, at the same time there is a drift southward by camps in
northern Marri areas into the Kohlu valley and surrounding areas;
this meets a contrasting northward drift of camps from the extreme
south. To further complicate the pattern, there is also a summer
movement of scattered camps southward into the surrounding lowlands.
These apparently contradictory movements can best be explained
by a concept of niches. 2fo The Marri, because of their mixed
agricultural and pastoral economy, are able to effectively occupy all
oftheir niche, while they are blocked in any directly southward mov.
ment by the Bugti, who practice an identical mixed economy. To the
north, the sedentary Pathan and nomadic ,otDindw exploit two se~
arate halves of the same niche.2& Either because of an inferior power
position via-a-vis the ,otDindtJu, or because of a desire to establish
a mutually symbiotic relationship with them, or because of lack of
inclination or opportunity, the northern sedentary Pathana keep few
animals. Thus, when the ,otDindw leave on their summer trek to
central Afghanistan, a niche is open for exploitation, and the Marri
move in to fill it. Rent must be paid to the Pathans for use of the
grazing, but, since it is generally the wealthier Marri with an almost
exclusive emphasis on herding (the traditional role of agriculture
being frequently neglected among wealthy Marri with large herds)
who move in, the cost of gruing is not an insufferable burden. Since
they are able to use relatively abundant pasture during the year's
best rainfall in a zone having a cool temperature and a minimum
of competition for pasture, the arrangement is an advantageous one.
With the arrival of winter, the ,otDindw return from the north and
reoccupy their winter quarters. Since the Marri and the ,otoindtJlu