Mikumi National Park Research Articles

Reciprocity and the Trade-Off Between Associate Quality and Relatedness

The inclusive fitness gains that individuals receive from associating with one another depend on their (1) relatedness, and (2) abilities to provide one another with aid which I term their associate qualities, as well as (3) the degree to which they provide aid. I show how these variables trade off to influence choice of social partners. Preferential association between distant kin can be naturally selected when their associate qualities to one another are only slightly greater than that between close kin. I describe conditions under which such associate quality differences are most likely to arise, and summarize results from an empirical investigation of some predictions from this model (Wasser 1981, in press) on female yellow baboons at Mikumi National Park, Tanzania.

Communities of baboon troops (Papio cynocephalus) in Mikumi National Park, Tanzania. A preliminary report.

Daily censuses were collected on a troop of 108-130 yellow baboons (Papio cynocephalus) for 22 months. 12 adult females, 5 subadult males, and 26 adult males either emigrated from or immigrated into the troop. 10 adult females immigrated into the troop over a 4-month period. 2 adult females emigrated from the troop. 1 of the latter probably conceived while absent. This female returned to the troop when pregnant and subsequently bore and successfully raised the offspring. There was a strong negative correlation between the relative size of the subadult males (a correlate of age) and the date on which they emigrated. Only 6 old and past-prime males never emigrated from the troop.

Movement patterns of yellow baboons (Papio cynocephalus): Central positioning of walking infants

AbstractAccording to DeVore and Washburn's protection theory of the spatial organization of moving baboon troops, walking infants, which are among the most vulnerable and least self‐sufficient of all troop members, should tend to occupy the troop's center. The protection theory is an ultimate hypothesis from which persistently recurring behavior is expected. Two troops living in Mikumi National Park, Tanzania, were compared with troops studied at other locations. Walking infants tended to occupy the center of their troop and to be underrepresented primarily in the frontal portion of progressions and secondarily in the rear. The lead position of progressions was analyzed using 82 walking infants, 11 troops, three locations, two species, and three studies involving eight or more observers employing somewhat different procedures at the different study sites. Despite so many opportunities for variation, 1,317 observations from these 11 troops did not produce a single instance in which a walking infant led the troop and very few in which one was in the frontal twelfth.

Some developmental markers in yellow baboon infants of Mikumi National Park, Tanzania

Infants of known birthdates were sampled from a population of yellow baboons (Papio cynocephalus) in Mikumi National Park, Tanzania, to ascertain the reliability of several maturational changes which could be used to age infants whose birthdates are unknown. The transition from the infant's black natal coat to the uniform yellow or tan adult pelage proved extremely variable, with completion varying from 7 to 19 months. The transition from the pink skin of the newborn to the completely grey adult pigmentation was much less variable. Skin on the hands and feet and on the paracallosal area was completely grey in all individuals by 8 months, while skin on the face and ears changed more gradually and was entirely grey by 12 months. These data are in substantial agreement with maturational markers established for yellow baboon infants in Amboseli National Park, Kenya, despite differences in habitat and age-sex structure between the two populations.