The Influence of Life History Milestones and Association Networks on Crop-Raiding Behavior in Male African Elephants

Factors that influence learning and the spread of behavior in wild animal populations are important for understanding species responses to changing environments and for species conservation. In populations of wildlife species that come into conflict with humans by raiding cultivated crops, simple models of exposure of individual animals to crops do not entirely explain the prevalence of crop raiding behavior. We investigated the influence of life history milestones using age and association patterns on the probability of being a crop raider among wild free ranging male African elephants; we focused on males because female elephants are not known to raid crops in our study population. We examined several features of an elephant association network; network density, community structure and association based on age similarity since they are known to influence the spread of behaviors in a population. We found that older males were more likely to be raiders than younger males, that males were more likely to be raiders when their closest associates were also raiders, and that males were more likely to be raiders when their second closest associates were raiders older than them. The male association network had sparse associations, a tendency for individuals similar in age and raiding status to associate, and a strong community structure. However, raiders were randomly distributed between communities. These features of the elephant association network may limit the spread of raiding behavior and likely determine the prevalence of raiding behavior in elephant populations. Our results suggest that social learning has a major influence on the acquisition of raiding behavior in younger males whereas life history factors are important drivers of raiding behavior in older males. Further, both life-history and network patterns may influence the acquisition and spread of complex behaviors in animal populations and provide insight on managing human-wildlife conflict

Optimal foraging and community structure: implications for a guild of generalist grassland herbivores

A particular linear programming model is constructed to predict the diets of each of 14 species of generalist herbivores at the National Bison Range, Montana. The herbivores have body masses ranging over seven orders of magnitude and belonging to two major taxa: insects and mammals. The linear programming model has three feeding constraints: digestive capacity, feeding time and energy requirements. A foraging strategy that maximizes daily energy intake agrees very well with the observed diets. Body size appears to be an underlying determinant of the foraging parameters leading to diet selection. Species that possess digestive capacity and feeding time constraints which approach each other in magnitude have the most generalized diets. The degree that the linear programming models change their diet predictions with a given percent change in parameter values (sensitivity) may reflect the observed ability of the species to vary their diets. In particular, the species which show the most diet variability are those whose diets tend to be balanced between monocots and dicots. The community-ecological parameters of herbivore body-size ranges and species number can possibly be related to foraging behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47765/1/442_2004_Article_BF00377109.pd

Anterior Cruciate Ligament Reconstruction Associated with Extra-articular Tenodesis

none5Background: This study was undertaken to prospectively analyze, at a mean 11-year follow-up, the clinical and radiographic outcomes in patients undergoing the authors’ intra-articular anterior cruciate ligament reconstructive procedure with extraarticular augmentation, and to compare these data with those at 5-year follow-up. Purpose: The clinical and radiographic outcomes in patients undergoing anterior cruciate ligament reconstruction were analyzed at a mean 11-year follow-up. Study Design: Case series; Level of evidence, 4. Methods: The authors studied 54 of 60 consecutive high-level sports patients who underwent their anterior cruciate ligament reconstruction technique between 1993 and 1995. The surgical technique uses the hamstring tendons with intact tibial insertions for intra-articular double-stranded reconstruction plus an extra-articular plasty (augmentation) performed with the remnant part of the tendons. Clinical and radiographic evaluations were performed. Results: After 11 years, the International Knee Documentation Committee score demonstrated good or excellent results (A and B) in 90.7% of patients. Ligament arthrometry using the KT-2000 arthrometer demonstrated that only 2 patients had >5 mm manual maximum side-to-side difference in laxity. The mean Tegner activity score was 4.5, while the mean Lysholm score was 97.3 and the mean subjective score was 90.0%. Radiographic evaluation demonstrated progressive joint narrowing only for the 20 patients having concomitant medial meniscal surgery. Conclusion: The original technique demonstrates highly satisfactory results. Factors negatively affecting the outcomes are meniscectomy and laxity. In this series, anterior cruciate ligament reconstruction with lateral plasty shows maintenance of knee stability at long-term follow-up. Knee osteoarthritis after anterior cruciate ligament reconstruction with extra-articular tenodesis does not appear to be greater than after anterior cruciate ligament reconstructions without extra-articular augmentation as reported in historical controls.noneM. Marcacci; S. Zaffagnini; G. Giordano; F. Iacono; M. Lo PrestiM. Marcacci; S. Zaffagnini; G. Giordano; F. Iacono; M. Lo Prest