Alex A. S. Weir

Near-Infrared Spectroscopy and Spectral Mapping of Jupiter and the Galilean Satellites: Results from Galileo's Initial Orbit

The Near Infrared Mapping Spectrometer performed spectral studies of Jupiter and the Galilean satellites during the June 1996 perijove pass of the Galileo spacecraft. Spectra for a 5-micrometer hot spot on Jupiter are consistent with the absence of a significant water cloud above 8 bars and with a depletion of water compared to that predicted for solar composition, corroborating results from the Galileo probe. Great Red Spot (GRS) spectral images show that parts of this feature extend upward to 240 millibars, although considerable altitude-dependent structure is found within it. A ring of dense clouds surrounds the GRS and is lower than it by 3 to 7 kilometers. Spectra of Callisto and Ganymede reveal a feature at 4.25 micrometers, attributed to the presence of hydrated minerals or possibly carbon dioxide on their surfaces. Spectra of Europas high latitudes imply that fine-grained water frost overlies larger grains. Several active volcanic regions were found on Io, with temperatures of 420 to 620 kelvin and projected areas of 5 to 70 square kilometers.

Development of tool use in New Caledonian crows: inherited action patterns and social influences

New Caledonian crows, Corvus moneduloides, are the most advanced avian tool makers and tool users. We previously reported that captive-bred isolated New Caledonian crows spontaneously use twig tools and cut tools out of Pandanus spp. tree leaves, an activity possibly under cultural influence in the wild. However, what aspects of these behaviours are inherited and how they interact with individual and social experience remained unknown. To examine the interaction between inherited traits, individual learning and social transmission, we observed the ontogeny of twig tool use in hand-reared juveniles. Successful food retrieval was preceded by stereotyped object manipulation action patterns that resembled components of the mature behaviour, demonstrating that tool-oriented behaviours in this species are an evolved specialization. However, there was also an effect of social learning: juveniles that had received demonstrations of twig tool use by their human foster parent showed higher levels of handling and insertion of twigs than did their naive counterparts; a choice experiment showed that they preferred to handle objects that they had seen being manipulated by their human foster parent. Our observations are consistent with the hypothesis that individual learning, cultural transmission and creative problem solving all contribute to the acquisition of the tool-oriented behaviours in the wild, but inherited species-typical action patterns have a greater role than has been recognized.

Tool use by wild New Caledonian crows Corvus moneduloides at natural foraging sites.

New Caledonian crows Corvus moneduloides use tools made from sticks or leaf stems to ‘fish’ woodboring beetle larvae from their burrows in decaying wood. Previous research on this behaviour has been confined to baited sites, leaving its ecological context and significance virtually unexplored. To obtain detailed observations of natural, undisturbed tool use, we deployed motion-triggered video cameras at seven larva-fishing sites. From 1797 camera hours of surveillance over 111 days, we recorded 317 site visits by at least 14 individual crows. Tool use was observed during 150 site visits. Our video footage revealed notable variation in foraging success among identifiable crows. Two nutritionally independent, immature crows spent considerable time using tools, but were much less successful than local adults, highlighting the potential role of individual and social learning in the acquisition of tool-use proficiency. During systematic surveys of larva-fishing sites, we collected 193 tools that crows had left inserted in larva burrows. Comparing these tools with the holes in which they were found, and with raw materials available around logs, provides evidence for tool selectivity by New Caledonian crows under natural conditions. Taken together, these two complementary lines of investigation provide, to our knowledge, the first quantitative description of larva fishing by wild crows in its full ecological context.

Lateralization of tool use in New Caledonian crows (Corvus moneduloides)

We studied laterality of tool use in 10 captive New Caledonian (NC) crows (Corvus moneduloides). All subjects showed near–exclusive individual laterality, but there was no overall bias in either direction (five were left–lateralized and five were right–lateralized). This is consistent with results in non–human primates, which show strong individual lateralization for tool use (but not for other activities), and also with observations of four wild NC crows by Rutledge & Hunt. Jointly, these results contrast with observations that the crows have a population–level bias for manufacturing tools from the left edges of Pandanus sp. leaves, and suggest that the manufacture and use of tools in this species may have different neural underpinnings.

Using prevalence indices to aid interpretation and comparison of agreement ratings between two or more observers

Veterinary clinical and epidemiological investigations demand observer reliability. Kappa (κ) statistics are often used to adjust the observed percentage agreement according to that expected by chance. In highly homogenous populations, κ ratings can be poor, despite percentage agreements being high, because the probability of chance agreement is also high. Veterinary researchers are often unsure how to interpret these ambiguous results. It is suggested that prevalence indices (PIs), reflecting the homogeneity of the sample, should be reported alongside percentage agreements and κ values. Here, a published PI calculation is extended, permitting extrapolation to situations involving three or more observers. A process is proposed for classifying results into those that do and do not attain clinically useful ratings, and those tested on excessively homogenous populations and which are therefore inconclusive. Pre-selection of balanced populations, or adjustment of scoring thresholds, can help reduce population homogeneity. Reporting PIs in observer reliability studies in veterinary science and other disciplines enables reliability to be interpreted usefully and allows results to be compared between studies.

Jovian atmospheric studies with the Galileo near infrared mapping spectrometer: An update

Abstract In its first two years of operation since arrival at Jupiter in December 1995, the Near Infrared Mapping spectrometer (NIMS) on the Galileo orbiter spacecraft obtained extensive coverage of the planet, including detailed coverage of the north equatorial belt (NEB) ‘hot spot’ region and the Great Red Spot. We will present the current state of data analysis including recent results on the abundances and variability of several minor constituents (H 2 O, CH 4 , NH 3 , GeH 4 , CH 3 D and PH 3 ) and the cloud structure and morphology.

Near-IR Spectroscopy of the Atmosphere of Jupiter

The Galileo Near Infrared Mapping Spectrometer (NIMS) obtains spectral images in the wavelength range 0.7 to 5.2 μm with a spectral resolving power of approximately 200. This spectral range allows NIMS to sense cloud-reflected solar radiation, thermal emission produced in the deep atmosphere, and auroral emission from the thermosphere of Jupiter. Using 5 μm thermal emission spectroscopy, the amount of water vapor in the deep atmosphere, at approximately the 6 to 8 bar level, is found to vary by a factor > 100. Deep atmosphere ammonia was also found to vary, with a spatial behavior different from that of water vapor. No evidence is found for a massive water cloud. Using reflected solar radiation in conjunction with thermal emission, two cloud layers are found, the upper at 0.5 bars and a lower one at 1–1.3 bars. The inferred absorption properties of these clouds are consistent with ammonia crystals (the upper cloud) and ammonium hydrosulfide particles (the lower cloud).