The mammalian order Carnivora is characterized by a great range of behavior al, ecological, and morphological adaptations, as well as substantial intraspe cific variability ( i .e. behavioral scaling; see 324) . For example, in wolves (see Table 1 for scientific names), body size ranges from 31 to 78 kg, litter size varies from 1 to 11, home-range size differs 50--100 fold, populations are found in every vegetational zone except tropical forests and arid deserts, and indi viduals may live alone, in pairs, or in large packs (124, 204, 332). Despite such widespread variation, comparative analyses indicate that there also is remarkable consistency (86, 105) in the ways many diverse carnivores adapt to their habitats . Therefore , it is possible to highlight trends in the phylogeny of behavior and life history characteristics by drawing on data from numerous disciplines, including anatomy, physiology, taxonomy, behavior, and ecology (16,54,83,84,92,93,97,128,191,196,199,242,243,313, 331). Due to space limitations, we will primarily review field studies focusing on the variation in behavior, body size, and life histories and emphasize data collected on identified individuals that have been observed directly (sometimes supplemented by radio-tracking) over long periods of time. Such studies are