Carrion use by terrestrial vertebrates is much more prevalent than conventional theory implies, and, rather than a curiosity of animal behavior, is a key ecological process that must be accounted for. Human aversion to rotted substances and difficulties associated with identifying scavenged material in studies of food habits have contributed to the relative lack of information concerning scavenging behavior in vertebrates. Several lines of evidence, however, suggest that carrion resources are more extensively used by vertebrates than has been widely assumed: 1) a substantial number of animals die from causes other than predation and become available to scavengers, 2) a wide variety of vertebrate scavengers, rather than microbes or arthropods, consume most available carcasses, and 3) intense competition exists between vertebrate scavengers and decomposers, especially in warm climates. Although vultures are best adapted to use carrion, nearly all vertebrate predators are also scavengers to some extent. The costs and benefits associated with carrion use influences the evolution of scavenging behavior in vertebrates, resulting in a continuum of facultative scavengers that use carrion to varying degrees. The realized usage of carrion by a vertebrate species is influenced by the speed and efficiency with which it forages, its visual and olfactory abilities, and its capacity for detoxifying products of decomposition. A deeper understanding of carrion use by facultative scavengers will improve our knowledge of community and ecosystem processes, especially the flow of energy through food webs.

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Scavenging by vertebrates: behavioral, ecological, and evolutionary perspectives on an important energy transfer pathway in terrestrial ecosystems

Wingless and fighting males in fig wasps and other insects

Burying beetles conceal small vertebrate carcasses underground and prepare them for consumption by their young. This review places their complex social behavior in an ecological context that focuses on the evolution of biparental care and communal breeding. Both males and females provide extensive parental care, and the major benefit of male assistance is to help defend the brood and carcass from competitors. As intensity and type of competition vary, so do the effectiveness and duration of male care. In many species, a single brood may be reared on large carcasses by more than one male and/or female. Limited reproductive opportunities, the greater effectiveness of groups in preventing the probability of brood failure (especially that caused by competing flies), and the superabundance of food on large carcasses have contributed to the evolution of this cooperative behavior.

The ecology and behavior of burying beetles

This is the first report of an ongoing study of insect succession on carrion in British Columbia. Pig (Sus scrofa L.) carcasses were used as human models to determine insect succession on carrion over time in an open, sunlit, rural area in summer in southwestern British Columbia, in order to begin a database of insect colonization of carrion in this province. Insects colonized the remains in sequence over 271 days postmortem. Some species, in particular, those in the Piophilidae and Dermestidae families, were collected earlier in the decomposition process than usually reported from other regions, probably indicating geographic variation in colonization times. Maggot activity raised internal carcass temperature, but minimum and maximum internal temperatures fluctuated more than ambient temperatures, with diel internal temperature differences of more than 35°C. Soil fauna also showed considerable changes in identity and number of species, and had not returned to pre-carcass levels 271 days postmortem.

Initial studies on insect succession on carrion in Southwestern British Columbia

Recent theoretical insights are helping to clarify how animal mating sys­ tems evolve. An integrated theory is beginning to emerge from the realiza­ tion that males and females have overlapping but nonidentical reproductive interests and that the type of mating system shown by a species results from interactions between the individual interests of each sex. The optimal mat­ ing system for promoting individual reproductive interests often differs for each sex, and when it does, the interests of one sex constrain the reproduc­ tive options open to the other. Thus, mating system theory revolves around two major issues: the factors determining which sex predominates in shap­ ing each mating system, and the factors determining which mating system is optimal for members of the "controlling" sex. The greatest progress has been made in explaining how polygynous mat­ ing systems evolved, particularly among territorial vertebrates, and more recent work is clarifying the specific environmental conditions involved (4, 46, 145, 146, 161, 227, 244, 246, 247). Promiscuous and polyandrous mating systems are less well understood, but several promising avenues toward a general theory have begun to develop (7 1, 9 1 , 126, 240, 245, 246). In contrast, theoretical work on the evolution of monogamy lags far behind, despite an enormous literature on monogamous animals.

The Evolution of Monogamy: Hypotheses and Evidence

The Social Behavior of Burying Beetles

The Audubon Society field guide to North American insects and spiders

PROTECTIVE coloration and habits have interested most biologists. Few of the very many articles on these topics mention a remarkable example among the crustaceans. Certainly the ghost crab is large enough to be noticed easily, and is common from Atlantic City to Rio de Janeiro, on beaches where people vacation every summer and should have time for interesting observations. Yet there is only one good scientific report on the ghost crab of our Atlantic coastline, and this comes not from the American mainland but from the iiow abandoned laboratory of the Carnegie Institution of Washington on Loggerhead Key in the Dry Tortugas, beyond the tip of Florida. It would seem that the ghost crab has succeeded in concealing itself f rom zoologists as well as the general public. The first observations made on this ghost crab were by the French naturalist, L. A. G. Bosc, on the coast of "Carolina" prior to 1802. Although Bosc grouped the fiddler crab (Uca pugilator (Latr.)) with the ghost crab '(Ocypoda quadrata (Fab.)) in the genus Ocypode (the latter as 0. albicans Bosc), his account shows clearly that he watched both of these land forms in the living state. Concerning the ghost crab, Bosc noted that "when they fear some danger, they save themselves by walking sidewise into their burrow with such rapidity that this naturalist was a long time observing them before forming an idea about the species of animal which was fleeing before him; it finally took all the speed of his horse to procure several specimens of them, again after several futile attempts. One knows well that an animal which is so difficult to catch can not serve commonly as nourishment; thus in Carolina no one makes any use of them. These

Margery J. Milne

Papers

The Social Behavior of Burying Beetles

The Audubon Society field guide to North American insects and spiders

Notes on the Behavior of the Ghost Crab

Notes on the Behavior of Burying Beetles (Nicrophorus spp.)

Insects of the Water Surface