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Endocrine disrupting nonyl- and octylphenol in infant food in Germany: considerable daily intake of nonylphenol for babies 总被引:1,自引:0,他引:1
Nonylphenol and octylphenol are persistent endocrine disrupters that are priority substances of the European Union Water Framework Directive. Their presence in the environment has caused increasing concern about their impact to human health. Infants are more sensitive to hormonal impacts of environmental chemicals than adults. The results of the present study indicate that nonylphenol is ubiquitous in foodstuffs for babies and toddlers commercially available in Germany, while octylphenol could only be determined in 80% of all food samples. The daily intakes based on consumption studies in μg nonylphenol kg−1 body weight per day for high consumers in the baby category (0.23-0.65 μg kg−1 bw d−1) were relatively high. This could lead to a higher risk especially for babies. 相似文献
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Roswitha Wiltschko Cordula Haugh Michael Walker Wolfgang Wiltschko 《Behavioral ecology and sociobiology》1998,43(4-5):297-300
Although the sun compass of birds is based on learning the sun's arc during development, it was unclear whether birds can
use the sun when its apparent movement is reversed, in particular, whether northern birds that have been introduced into the
southern hemisphere can use the southern sun. To answer this question, clock-shift experiments were performed with local homing
pigeons in Auckland, New Zealand (37°S). In three fast-shift tests and two slow-shift tests, the experimental birds showed
deflections from the untreated controls that were the mirror images of those observed in the northern hemisphere. These results
clearly show that homing pigeons in New Zealand use a sun compass that is adapted to the situation in the southern hemisphere.
The learning processes establishing the compensation mechanisms thus appear to be free of constraints concerning the direction
of the sun's movement. Differences from recent findings with migratory birds, where the direction of celestial rotation proved
of crucial importance for establishing the migratory direction, are discussed: the differences may arise from the different
orientation tasks, in particular, from the involvement of innate information in establishing the migratory direction.
Received: 13 November 1997 / Accepted after revision: 28 February 1998 相似文献
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Summary A series of clock-shift experiments with young homing pigeons of various ages was performed to determine at what age they normally learn sun compass orientation. The response of untrained pigeons to shifting of their internal clock seems to depend on their age. When the clock-shifted birds were tested at an age of 11 weeks and younger, their departure bearings did not differ significantly from those of controls (Fig. 1, diagrams on the right); in tests with birds 12 weeks and older the characteristic deviation indicating the use of the sun compass was observed (Figs. 2 and 3). Birds that had participated in a short training program, however, used the sun compass at 8 weeks, the earliest age tested (Fig. 1, diagrams on the left). These findings show that the time of development of the sun compass strongly depends on flying experience. Within the first months of a bird's life, it seems to take place after the bird has been confronted with the need to orient, either spontaneously during extended exercise flights around its loft or imposed by training releases.The departure bearings of the very young, inexperienced birds that did not rely on the sun compass, however, were already oriented homeward. This indicates that the ability to navigate develops independently of the sun compass, before the sun compass is learned.Dedicated to Prof. Dr. F.W. Merkel for his 70th birthday 相似文献
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Summary To test the hypothesis that information on the route of the outward journey is involved in the orientation of displaced homing pigeons, we compared the behavior of control pigeons that had been displaced by the most direct route with that of experimental pigeons that had been transported along detours to the same release sites. At distances of 40 km we found no consistent effect. At distances between 75 and 130 km, however, deviations to the left of the direct route induced deflections to the left, while deviations to the right induced deflections to the right, i.e. the deflections of the vanishing bearings tended to compensate for the initial detour of the outward journey. The deflections were smaller than the deviations of the routes; they were not related to the routes themselves or the location of the release sites. A significant correlation emerged with the vector length of the controls, as longer vectors were associated with smaller deflections. This suggests that information on the route of the outward journey is used together with local map information in the navigational process, the significance of the route-specific information apparently depending on quality and reliability of the available local information. The nature of factors controlling the detour effect is still open.Correspondence to: R. Wiltschko 相似文献
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Pigeons released away from their loft usually fly around at the release site for a while before they finally leave. Visual
observations had suggested that the moment when the birds decide to head home is associated with a certain change in flying
style. To see whether this change is also reflected by GPS-recorded tracks, a group of pigeons equipped with flight recorders
was released at two sites about 10 km from their home loft. The initial part of their flight paths was analyzed in order to
find objective criteria indicating the point of decision. We selected the highest increase in steadiness as the best estimate
for the moment of decision. This criterion allows us to divide the pigeons’ paths in two distinct phases, an initial phase
and the homing phase, with the moment of decision, on an average, 2 min after release. The moment of decision marks a change
in behavior, with a significant increase in steadiness and flying speed and headings significantly closer to the home direction.
The behavior of the individual birds at the two sites was not correlated, suggesting no pronounced individual traits for the
length of the initial phase. The behavior during this phase seems to be controlled by flight preparation, exploration, and
non-navigational motivations rather than by navigational necessities alone.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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Avian magnetic compass: fast adjustment to intensities outside the normal functional window 总被引:1,自引:0,他引:1
To determine how fast birds can adapt to magnetic intensities outside the normal functional window of their magnetic compass,
we tested migratory birds in a magnetic field of 92,000 nT, twice the intensity of the local geomagnetic field at the test
site in Frankfurt a.M., Germany. In the local field, robins showed a significant preference of their southerly migratory direction,
whereas in the 92,000-nT field, they were initially disoriented. However, when the birds were preexposed to 92,000 nT for
1 h before being tested, they were able to orient under this intensity, and their behavior did not differ from that in the
geomagnetic field. These data show that birds require only a short time to adjust to magnetic intensities, which they cannot
spontaneously use for orientation. Interpreting these findings in view of the radical pair model (Ritz et al. 2000), this means that they can learn rather quickly to interpret novel activation patterns on their retina. 相似文献