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  • Drought  (1)
  • Meteorology and Climatology  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 109 (1996), S. 88-97 
    ISSN: 1432-1939
    Keywords: Key words Moles ; Activity ; Radio-tracking ; Interaction ; Drought
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Using ratio-tracking data obtained at three sites, we assessed the effects of season and of neighbour avoidance on the activity and patterns of home range use by European moles (Talpa europaea). The home ranges of non-breeding male and female moles did not differ significantly in size, and averaged 2324 m2 (minimum convex polygon). Although overlap between ranges was small (an average of 12.8% of each range being shared with neighbours and an average of only 3.3% of 2×2 m grid cells were shared with an individual neighbour, ranges were not oriented to avoid neighbours. Non-breeding male/female neighbours tended to share more of their grid cells (3.9±5.7%) mean ±SD than did neighbours of the same sex (male:male 1.2±0.95%; female:female 1.1±1.3%), but there was no significant difference in overlap between any combination of sex pairings. On average, each mole spent only 0.9% of its time within 6 m of another mole, and only 3 out of 46 dyads showed evidence of being attracted to each other; there was no evidence from the simultaneous movement patterns of neighbouring moles that they avoided each other. Although moles tended to return to the same part of their range at the same time on successive days, there was also some indication of gradual changes in the spatial pattern of daily home range use. Moles had a triphasic pattern of activity, but this became tetraphasic under drought conditions. There were significant differences between sites, but not between sexes, in sleeping behaviour and activity patterns. These differences could be related to seasonal differences in soil moisture and thus probably to prey renewal rates. We conclude that in our sites, the activity patterns and movements of moles depend on the temporal and spatial dispersion of food, rather than on short-term interactions between the movements of neighbours.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-07-17
    Description: Substorms are often observed to occur at the end of intervals of Southward interplanetary magnetic field (IMF), i.e. following the northward turning. Despite the significant correlation between northward turning and substorms, no direct causal relationship between northward turnings and substorms has been demonstrated. Assuming such a causal relationship, we predict that substorms will occur within a particular interval following the observation of a northward turning in the IMF. We observe 16 northward turnings following steady, southward IMF in data taken by the WIND spacecraft magnetic field instrument (MFI). To ensure that the northward turning was observed at the magnetosphere, we require that the northward turning also be observed by instruments on either one of Geotail or IMP-8 while the separation of the second spacecraft from WIND was more that 10 R(sub E). These two-spacecraft observations also allow us to predict more accurately the arrival time of the northward turning at the Earth. Of the predictions substorms, 10 predictions were clearly successful to within +/- 12 min. Five predictions failed, but the failures reveal clear shortcomings in the criteria for a northward turning that we correct. The failures were caused by an increase in the absolute value of B(sub YGSM) simultaneous with the northward turning in 3 cases, and a weak southward IMF preceding the northward turning in 2 cases. The final northward turning arrived in the recovery phase of an ongoing substorm, and resulted in unusual auroral activity. The implication of the predictability of substorms following sharp northward turnings is that the postulated causal relationship between northward turnings and substorm onset exists. The effect of increases in the absolute value of B(sub YGSM) to negate the triggering ability of northward turnings suggests that the triggering mechanism involves sharp reductions in the magnetospheric convection electric field.
    Keywords: Meteorology and Climatology
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