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1.
In many species, the ability to evade predators is known to be periodically impaired by increased weight loads due to feeding
and reproduction. Not only may extra weight reduce escape speed, but feeding and mating can also make the prey more noticeable
to visually hunting predators. A number of butterfly species mate for hours, and if a mating couple is disturbed, one of the
butterflies is responsible for flying, whereas its partner remains still. This study investigated the ability of male Pieris napi butterflies to fly while mating, with the prediction that mate carrying impairs flight ability compared to single flying
males and that males with relatively high flight muscle ratios (FMR; male thorax mass/male + female body mass) will have better
flight performance in copula. Our results clearly show that whereas single males always take off at steep angles and fly upwards,
couples invariably have a negative take-off angle and rarely gain height. Moreover, landing height of the couples is positively
associated with higher FMR. Hence, male flight ability when in copula is positively associated with a high relative thorax
mass. Butterfly pairs may thus be at greater risk of predation as a consequence of their impaired flight ability, especially
couples with critically low FMRs (<16%). 相似文献
2.
Avian escape strategy is highly dependent on the ability to fly, and the success rate of raptor attacks is reduced if the
prey gets fully airborne. Therefore, when escaping from predator attacks, the initial take-off is crucial and a rapid take-off,
high velocity, and high angle of ascent maximize the chance of survival. However, due to the laws of gravity, birds face a
trade-off between maximizing its linear acceleration and maximizing its rate of climb when taking off. The optimal policy
between velocity and angle of ascent when a bird escapes from an attacking predator might depend on the detailed nature of
the predator’s attack, the proximity to cover, and the presence of conspecifics. Many small birds rely on a quick dash to
protective cover. In this study, we examine how the availability of protective cover affects take-off strategy in birds. Male
great tits (Parus major) were subjected to a surprise attack by a model predator either in the presence or absence of protective cover. When attacked
by the predator, great tits took off and perched in the cover when it was available. Birds subjected to the predator attack
in the absence of cover took off in 10° higher angle of ascent and flew faster in the start of the take-off, compared to birds
that took off in the presence of cover. Thus, this study for the first time shows that a bird do trade off speed with angle
of ascent in an adaptive way, depending on the presence of protective cover. 相似文献
3.
Cecilia Kullberg Thord Fransson Johanna Hedlund Niclas Jonzén Ola Langvall Johan Nilsson Kjell Bolmgren 《Ambio》2015,44(1):69-77
Many migratory bird species have advanced their spring arrival during the latest decades, most probably due to climate change. However, studies on migratory phenology in the period before recent global warming are scarce. We have analyzed a historical dataset (1873–1917) of spring arrival to southern and central Sweden of 14 migratory bird species. In addition, we have used relative differences between historical and present-day observations (1984–2013) to evaluate the effect of latitude and migratory strategy on day of arrival over time. There was a larger change in spring phenology in short-distance migrants than in long-distance migrants. Interestingly, the results further suggest that climate change has affected the phenology of short-distance migrants more in southern than in central Sweden. The results suggest that the much earlier calculated arrival to southern Sweden among short-distance migrants mirrors a change in location of wintering areas, hence, connecting migration phenology and wintering range shifts. 相似文献
4.
Thomas J. Fredette Joseph D. Germano Drew A. Carey Peggy M. Murray Paula G. Kullberg 《Chemistry and Ecology》2013,29(1-4):173-194
Geochemical analysis and visual inspection of cores collected from capped dredged material mounds revealed that in many cores, cap material was clearly distinguishable, both visually and chemically, from mound material. Contaminated dredged sediments were disposed in Long Island Sound eleven and seven years prior to sampling, and capped with uncontaminated dredged sediments. Core data provided no conclusive evidence of physical disturbance of, or chemical migration from, the contaminated mound sediments. Obvious chemical gradients of contaminant concentrations, which we propose are indicators of chemical migration, were not detected in the cores. Heterogeneity of the cap and mound sediments in some cores made the interface less distinct. We postulate that the preservation of spatial variability of sediment texture and associated contaminants observed within dredged material mounds is a result of the dredging process. Preservation of the textural and contaminant history of dredged sediments within finegrained cohesive cap materials provides evidence of the absence of physical or chemical disturbance. 相似文献
5.
Jannika?E.?Bostr?mEmail author Cecilia?Kullberg Susanne??kesson 《Behavioral ecology and sociobiology》2012,66(5):819-821
In a previous study, we found that juvenile northern wheatears (Oenanthe oenanthe) exposed to a magnetic displacement to the west of their natural migration route increased their body mass. The total intensity
and inclination used for the western displacement may also have been interpreted as northern compared to the experimental
site (stronger total field intensity and steeper inclination angle). In order to investigate whether the fuelling response
was a response to an unexpected magnetic field or specific to the northern magnetic field, we conducted a new experiment.
Juvenile wheatears from the same study population were magnetically displaced to southwestern magnetic fields, exposing the
birds to unexpected magnetic combinations, but eliminating the possible effect of a northern magnetic field. A control group
was kept in the local geomagnetic field in Sweden for comparison. There was no difference in body mass increase between treatments,
suggesting that the fuelling response previously found was not a simple response to an unexpected magnetic field, but rather
a specific response to the northern magnetic field. Juvenile wheatears may have developed a fuelling response to northern
magnetic fields in order to enable a successful flight towards the migration goal. 相似文献
6.
Thomas J. Fredette Joseph D. Germano Drew A. Carey Peggy M. Murray Paula G. Kullberg 《Chemistry and Ecology》1992,7(1):173-194
Geochemical analysis and visual inspection of cores collected from capped dredged material mounds revealed that in many cores, cap material was clearly distinguishable, both visually and chemically, from mound material. Contaminated dredged sediments were disposed in Long Island Sound eleven and seven years prior to sampling, and capped with uncontaminated dredged sediments. Core data provided no conclusive evidence of physical disturbance of, or chemical migration from, the contaminated mound sediments. Obvious chemical gradients of contaminant concentrations, which we propose are indicators of chemical migration, were not detected in the cores. Heterogeneity of the cap and mound sediments in some cores made the interface less distinct. We postulate that the preservation of spatial variability of sediment texture and associated contaminants observed within dredged material mounds is a result of the dredging process. Preservation of the textural and contaminant history of dredged sediments within finegrained cohesive cap materials provides evidence of the absence of physical or chemical disturbance. 相似文献
7.
Ian Henshaw Thord Fransson Sven Jakobsson Cecilia Kullberg 《Behavioral ecology and sociobiology》2010,64(8):1317-1323
Night-migrating song birds travel to and from their wintering and breeding areas often separated thousands of kilometers apart
and are clearly capable of finding intended goal areas from a distant location. Displacement experiments provide a useful
way to highlight orientation and navigational skills in migrants. To investigate which cues birds actually use to compensate
for displacement and the exact mechanism of each cue, experiments with manipulation of single cues are required. We conducted
a simulated displacement of lesser whitethroats Sylvia curruca on spring migration. Birds were displaced not geographically but in geomagnetic space only, north and south of their breeding
area to test whether they incorporate information from the geomagnetic field to find their breeding area. Lesser whitethroats
held in southeast Sweden but experiencing a simulated displacement north of their breeding area (Norway) failed to show a
consistent direction of orientation, whereas birds displaced south of their breeding area (Czech Republic) exhibited consistent
northerly orientation, close to the expected seasonally appropriate direction, after displacement toward the trapping location.
The absence of a clear compensatory direction in birds displaced north might be due to unfamiliar magnetic information or
lack of sufficient information such as a magnetic gradient when moving around. By isolating one orientation cue, the geomagnetic
field, we have been able to show that lesser whitethroats might incorporate geomagnetic field information to determine latitude
during spring migration. 相似文献
8.
Kullberg A 《Environmental pollution (Barking, Essex : 1987)》1992,78(1-3):103-106
The structure of stream benthic macroinvertebrate communities in relation to pH and humic content was studied in 20 second and third-order forest streams in southern Sweden. Streams varied in pH from 4.2 to 8.0, and in humic content from a colour of 5 to 1200 mg Pt litre(-1). There was a positive relationship between pH and species richness, with a discontinuity occurring at pH approximately 5.7. At pH > 5.7, species richness decreased with increasing colour. At pH < 5.7 there was a positive correlation between species richness and humic concentration up to a colour of about 200-300 mg Pt litre(-1). this may be explained by high concentrations, 0.4-0.9 mg litre(-1), of labile monomeric Al occurring in the low coloured acid streams. In streams with a colour > 200 mg Pt litre(-1) labile monomeric Al was less than 0.2 mg litre(-1). There was no significant change in species richness above this threshold, but a shift in species composition towards a dominance of Plecoptera and Chironomidae. This threshold model seems to explain the observed differences in stream benthic community structure better than a simple linear relationship with pH or humic content. 相似文献
9.
10.
Robert Axelsson Per Angelstam Lennart Myhrman Stefan Sädbom Milis Ivarsson Marine Elbakidze Kenneth Andersson Petr Cupa Christian Diry Frederic Doyon Marcus K. Drotz Arne Hjorth Jan Olof Hermansson Thomas Kullberg F. Henry Lickers Johanna McTaggart Anders Olsson Yurij Pautov Lennart Svensson Johan Törnblom 《Ambio》2013,42(2):241-253
To implement policies about sustainable landscapes and rural development necessitates social learning about states and trends of sustainability indicators, norms that define sustainability, and adaptive multi-level governance. We evaluate the extent to which social learning at multiple governance levels for sustainable landscapes occur in 18 local development initiatives in the network of Sustainable Bergslagen in Sweden. We mapped activities over time, and interviewed key actors in the network about social learning. While activities resulted in exchange of experiences and some local solutions, a major challenge was to secure systematic social learning and make new knowledge explicit at multiple levels. None of the development initiatives used a systematic approach to secure social learning, and sustainability assessments were not made systematically. We discuss how social learning can be improved, and how a learning network of development initiatives could be realized. 相似文献