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In parallel with economic and social changes, mutualism in human-vulture relations has virtually disappeared worldwide. Here, we describe the mutualistic relationship between humans and the globally threatened Egyptian vulture in Socotra, Yemen. By analyzing both the spatial distribution of vultures and the amount of human byproducts they consume, we show that human activities enable the maintenance of the densest population of this rare scavenger, whereas vultures provide a key regulating service by disposing of up to 22.4% of the organic waste annually produced in towns. Globalization is impacting the archipelago, and therefore policies that better integrate societal needs and biodiversity conservation are urgently needed. We propose a win-win solution that relies on the restructuring of the mutualism, shifting from regulating services toward cultural services. Our study highlights the necessity of reconciling trade-offs between biodiversity conservation and economic development in a framework of global change affecting Middle Eastern countries.

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The stability of the ammonium radical (NH4) was determined from measurements of the kinetic energy released in its fragmentation products following formation in a fast electron capture process: NH4++Na → NH4*+Na+. Scattering profiles for heavy (NH3) and light (H) dissociation products were obtained from beam measurements with 5–16 keV NH4+ ions. The existence of a predissociative barrier in the radical is inferred from edge structure and scattering continua in H atom profiles. The radical is bound with respect to a potential minimum but all of the isotopic species NH4, NH3D, NH2D2, and NHD3 undergo rapid loss of H atoms and have ground states lying above their dissociation limits. The radical ND4 has unusual stability with its ground state lying close to or below its dissociation limit. Dissociative lifetimes for stable and unstable states of ND4 differ by at least two orders of magnitude. The possible significance of these observations on the interpretation of optical transitions involving the ground states of NH4 and ND4 are discussed. From these measurements the ionization potential of 4.73±0.06 eV for NH4 is calculated. The stabilities of CH3NH3 and CH3ND3 radicals and their dissociative pathways have also been investigated.

further SCF-LMO and experimental studies on such systems as B3C2H6, B7C2H9, B8C2Hio, Bi0Hh, and the isomers of Bi0C2Hi2. Such investigations are now in progress.Acknowledgments. We thank J. H. Hall, Jr., for helpful discussion and the Office of Naval Research for financial support. D. S. M. and I. R. E. are grateful to the National Science Foundation for predoctoral fellowships. Portions of this study were supported by a grant from the Research Corporation to I. R. E.