Barbary macaques (Macaca sylvanus, L.) occur at varying densities in a number of different habitat types in Morocco and Algeria. Taub (1977) has argued that ...
International Journal of Primatology, Vol. 5, No. 3, 1984
Habitat Distribution and Habitat Preference in Barbary Macaques (Macaca sylvanus) J. E. Fa ~
Received February 14, 1983; revisedApril 19, 1983
Barbary macaques (Macaca sylvanus, L.) occur at varying densities in a number of different habitat types in Morocco and Algeria. Taub (1977) has argued that the abundance o f the species in cedar forests o f the Moyen Atlas, Morocco, is an indication o f a habitat preference. A reexamination of available data on the distribution and abundance o f Barbary macaques suggests that monkey numbers reflect the distribution of habitat size rather than habitat types. Differences between populations relative to habitat types can be seen only between forest and scrub localities. Human factors are considered more important in determining the present status o f this eclectic feeder. The modern distribution o f the Barbary macaque is inadequate evidence for a habitat preference. KEY WORDS: Macaca sylvanus; geographic distribution; habitat types; habitat preference.
INTRODUCTION A preference for a habitat evolves because organisms leave more descendants than organisms in other habitats (Krebs, 1978). Natural selection will favor development o f sensory systems which can help distinguish key factors that promote increased survival. Habitat selection can be often hastily invoked to explain the distribution of an animal where populations of that species occur at different densities within a set of habitats. Geophysical events and the powers of dispersal o f a species will set the ultimate limits o f
'Department of Zoology, Universityof Oxford, Oxford OXI 3PS, U.K. 273 0164-0291/84/0600.0273503.50/0 9 1984 Plenum Pub|ishins Corporation
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its geographical range. These limits will be modified by the species' competitive interactions with other species, which will also affect local distribution within the geographical range. It is only within these constraints that choice of habitat can operate. It clearly follows that distribution of species in different habitats may not follow directly from habitat preference or choice; inter- and intraspecific competition can exclude animals from preferred habitats and force them into less suitable areas (see Partridge, 1978, for further discussions on this topic). The Barbary macaque (Macaca sylvanus, L.) is a monkey that was widespread throughout Europe and North Africa during prehistoric times (Delson, 1980). Recent records of the species' distribution (Deag, 1977; Taub, 1977) indicate that by the beginning of this century it was found discontinuously in only five regions in Morocco and Algeria: Rif, Moyen Atlas, Haut Atlas, and Petite and Grande Kabylies. The species occurred in habitats within temperate and subtropical regions in Europe (Singer et al., 1982; Delson, 1980) and is at present found in a number of habitats in the Mediterranean climatic zone of North Africa. The animal lives in relatively small habitat isolates created by human incursions into the primeval landscape and ranging from lowland thermophilous scrub (Olea/Ceratonia/Pistacia) through midaltitude mixed deciduous and evergreen oak forests 2 (Portuguese oak Quercusfaginea, Pyrenean oak Q. pyrenaica, Afares oak Q. afares, Holly oak Q. ilex, and Cork oak Q. suber) to high-altitude coniferous forests (Moroccan fir Abies pinsapo, Numidian fir A. numidica, and the Blue Atlantic cedar Cedrus atlantica). Monkey populations contained in these ecological islands differ in size and density, and Taub (1977) believes that high numbers in the Moyen Atlas indicate an affinity for cedar forests maintained by a preference for cedar products. This conclusion is based on three main assumptions: (1) The Barbary macaque has a specific dietetic bias for cedar products. (2) Because of the food preference for cedar, winter survival in cedar forests is enhanced by the evergreen nature of the conifer. It is also assumed that the climatic constraints in the cedar forests are similar in all other habitats. 2In the Mediterranean region, the term forest is applied not only to classical forest landscapes with unbroken tree cover and a thin undergrowth of herbaceous plants commonly found in European forests, but also to open or semiopen forest stands, where the undergowth does not include any herbaceous species directly linked with the forest (Quezel, 1977). It is thus possible to distinguish among (1) dense forests growing on generally mature soils with a fairly dense growth of associated woodland plants, (2) dense forests on generally degraded soils with virtually no floristic associated vegetation, (3) thin forests on degraded soil where trees mingle with the associated vegetation, and (4) scattered forests where tree patches are dissociated completely from the herbaceous vegetation, The latter type, although not properly referred to as forest, corresponds to matorra| vegetation as defined by Tomaselli (1972), For the present thermophilous scrub refers to a formationof category 4 above, but one typically linked with lowland warm variants of semiarid, subhumid, and even arid bioclimatic zones.
Habitat Distribution and Preference in the Barbary Macaque
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Following the above two assumptions, Taub implicitly presents the idea that the actual distribution of the monkey in different habitats represents a primeval availability of environments, which he implies has not changed since prehistoric times. The present study reexamines these assumptions and the available data on the distribution and feeding biology of Barbary macaques to demonstrate that there is inadequate evidence for habitat selection and that monkey populations within each habitat type can be best explained with reference to their past history and in particular with reference to habitat modification by humans.
MATERIALS AND METHODS Population surveys used in this paper are those of Taub (1977) for the Moyen Atlas in Morocco and the Algerian Kabylies, Drucker (personal communication, 1983) for the Haut Atlas, and Fa (1982) for those of the Moroccan Rif Mountains. Habitat characterization followed the classifications employed in the above-mentioned studies. Habitat sizes were calculated from topographic maps given by Taub (1975) and from data published by Fa (1982). All localities have also been arranged according to bioclimate as defined by Emberger (1955). This takes into account a pluviothermic index (Q) and the mean minimum temperature of the coldest month (m) for each.
BARBARY MACAQUE DISTRIBUTION AND HABITAT OCCUPATION The present data available on the Barbary macaque populations found in Morocco and Algeria are summarized in Table I. Population estimates are maximum values and density is calculated as the "ecological density" (Eisenberg, 1980). Maximum figures of population estimates are employed because they are considered to represent a more viable approximation to probable population sizes. For example, Fa's (1982) maximum population sizes for Barbary macaques in the Rif fir forests have been recently substantiated by Mehlman's (in press) longer-term censuses in the area. Similarly, Taub's (1977) maximum population estimates are considered more realistic in view of the bias toward underestimates that is typical of the broad survey technique employed. The largest populations and highest monkey densities are found in cedar forests of the Moyen Atlas (Table I). High densities are also found in Algerian mixed oak forests, but lowest figures are typical of thermophilous
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