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Robinson, Michael H., and Barbara Robinson. Ecology and Behavior of the Giant Wood Spider Nephila maculata (Fabricius) in New Guinea. Smithsonian Contributions to Zoology, number 149, 76 pages, 30 figures, 11 tables, 1973.-Investigations of the seasonal, reproductive, and population ecology of Nephila maculata are reported in detail. In an investigation of feeding ecology over a one-year period, the discarded remains of the prey caught by a sample population of ten adult female spiders were collected daily. These remains were identified (where possible) and the accumulated weekly discards from each spider were dried and weighed. Data from this study are analyzed, tabulated, and compared with the catches from insect traps located in the study area. The study included an investigation of web structure, frequency of web renewal, and the number of kleptoparasites associated with Nephila maculata. Studies of behavior included courtship, mating, predatory behavior, and responses to predators, sunlight, and rainfall. Courtship behavior included a complex pattern of silk deposition by the male on the female, here reported for the first time for the Araneida. The predatory behavior of N. maculaia is analyzed in terms of behavior units and behavior sequences and is compared with that of other Nephila species, related species, and that of other araneids studied by the authors. The phenological aspects of the study are stressed and discussed. OFFICIAL PUBLICATION DATE is handstamged jji a limited .number of initial copies and is recorded in the Institution's annual report, Sm^tnsonian Year. SI PRESS NUMBER 4779. SERIES COVER DESICN: The coral Montastrea cavemosa (Linnaeus). Library of Congress Cataloging in Publication Data Robinson, Michael H. Ecology and behavior of the giant wood spider Nephila maculata (Fabricius) in New Guinea.

The stabilimentum of orb web spiders is a structure for which several functions, both mechanical and defensive, have been suggested. Argiope argentata (Fabricius) builds a stabilimentum in the form of a white diagonal cross. Analysis of over 2500 webs of this species shows that the perfect cross is seldom built and nearly two thirds of the webs contain no stabilimentum at all. Experiments with wild birds as predators show that they can use stabilimentum-like models in prey location. From these data, and a review of the defensive adaptations of orb web spiders, it is argued that the A. argentata stabilimentum is not an anti-predator device. The evidence for a mechanical function is reviewed and discussed. It is suggested that the stabilimentum provides the spider with a means of making a final adjustment to the mechanical state of the web when this is necessary.

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