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Many species exhibit fission-fusion dynamics, yet the factors that influence the frequent changes in group size and membership in these species have not been widely studied. Social ties may be influenced by kinship but animals may also form preferred associations because of social attraction or may only associate because they have similar habitat preferences. We investigated the association patterns of 535 wild giraffes, Giraffa camelopardalis, in Etosha National Park, Namibia using behavioural and genetic data from individually identified giraffes. We collected 726 records of group composition over a 14-month period and calculated pairwise association indices, which were tested against a null model. We found that female-female pairs, but not male-male pairs, showed both preferred and avoided relationships. We tested whether females' relationships could be explained by the degree of relatedness between pairs and whether pairs overlapped spatially. Correlations between matrices of pairwise associations, spatial overlap and relatedness showed that female-female associations were strongly correlated with amounts of spatial overlap and pairs that exhibited preferred relationships were more closely related than would be expected by chance. However, only about one-quarter of the variation in observed associations could be explained by spatial overlap and relatedness and therefore much of this variation may have been related to individual social preferences.

A calibration procedure of differential reflectivity on the Weather Surveillance Radar-1988 Doppler (WSR-88D) is described. It has been tested on NOAA's modified WSR-88D research and development polarimetric radar and is directly applicable to radars that simultaneously transmit and receive waves having horizontal and vertical polarization.

Many wild giraffe populations are declining across Africa, with two subspecies listed by the IUCN as Endangered in the past 4 years. We developed 11 microsatellite markers from Giraffa camelopardalis angolensis in Etosha National Park, Namibia using 454 sequencing. In 70 individuals, the loci showed 2-4 alleles per locus and expected heterozygosities of 0. 082-0. 711. There were no significant deviations from Hardy-Weinberg equilibrium for any of the loci. Null allele frequencies were low (

Some results of the first 10 cm dual-Doppler radar measurements in a tornadic storm are presented. A mesoscale, cyclonic circulation confirms proposed single Doppler vortex signature and indicates that the curved reflectivity hook echo is around the periphery of the circulation. The interpolated tornado position is within the mesocyclone where high-variance Doppler velocity spectra suggest strong velocity gradients.