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131.
Hans-Ulrich Schnitzler Elisabeth K. V. Kalko Ingrid Kaipf Alan D. Grinnell 《Behavioral ecology and sociobiology》1994,35(5):327-345
When hunting for fish Noctilio leporinus uses several strategies. In high search flight it flies within 20–50 cm of the water surface and emits groups of two to four echolocation signals, always containing at least one pure constant frequency (CF) pulse and one mixed CF-FM pulse consisting of a CF component which is followed by a frequency-modulated (FM) component. The pure CF signals are the longest, with an average duration of 13.3 ms and a maximum of 17 ms. The CF component of the CF-FM signals averages 8.9 ms, the FM sweeps 3.9 ms. The CF components have frequencies of 52.8–56.2 kHz and the FM components have an average bandwidth of 25.9 kHz. A bat in high search flight reacts to jumping fish with pointed dips at the spot where a fish has broken the surface. As it descends to the water surface the bat shows the typical approach pattern of all bats with decreasing pulse duration and pulse interval. A jumping fish reveals itself by a typical pattern of temporary echo glints, reflected back to the bat from its body and from the water disturbance. In low search flight N. leporinus drops to a height of only 4–10 cm, with body parallel to the water, legs extended straight back and turned slightly downward, and feet cocked somewhat above the line of the legs and poised within 2–4 cm of the water surface. In this situation N. leporinus emits long series of short CF-FM pulses with an average duration of 5.6 ms (CF 3.1 and FM 2.6) and an average pulse interval of 20 ms, indicating that it is looking for targets within a short range. N. leporinus also makes pointed dips during low search flight by rapidly snapping the feet into the water at the spot where it has localized a jumping fish or disturbance. In the random rake mode, N. leporinus drops to the water surface, lowers its feet and drags its claws through the water in relatively straight lines for up to 10m. The echolocation behavior is similar to that of high search flight. This indicates that in this hunting mode N. leporinus is not pursuing specific targets, and that raking is a random or statistical search for surface fishes. When raking, the bat uses two strategies. In directed random rake it rakes through patches of water where fish jumping activity is high. Our interpretation is that the bat detects this activity by echolocation but prefers not to concentrate on a single jumping fish. In the absence of jumping fish, after flying for several minutes without any dips, N. leporinus starts to make very long rakes in areas where it has hunted successfully before (memory-directed random rake). Hunting bats caught a fish approximately once in every 50–200 passes through the hunting area. 相似文献
132.
Allison T. Moody Sabina I. Wilhelm Maureen L. Cameron-MacMillan Carolyn J. Walsh Anne E. Storey 《Behavioral ecology and sociobiology》2005,57(3):224-230
Behavioral precursors of 12 divorces were examined in 30 color-banded pairs of common murres (Uria aalge) over six breeding seasons. Common murres are long-lived seabirds that typically return each year to the same mate and nest site in dense colonies. At least one parent is present continuously from egg lay to chick fledging. Murres, therefore, have considerable opportunities to compare their mates parental behavior with that of several familiar neighbors. Previous reproductive success was lower for divorcing birds than for reuniting pairs. As predicted by the better option hypothesis, there were clear choosers (seven females and five males) that initiated divorce by moving to a new birds site or by courting a new partner at their current site. Choosers improved their reproductive success after the divorce, whereas their previous partners, the victims did not. Yearly divorce rates (average 8.2% per year) were significantly correlated with yearly mortality rates. Divorces appear to be opportunistic: pairs divorced after varying numbers of reproductive failures with the immediate precursor usually being the disappearance (death) of a murre from a successful neighboring site. In contrast to the delays experienced by victims, choosers formed new pairs quickly and laid their eggs no later than reuniting pairs. Prior to the divorce, victims fed their chicks less often than choosers, and some engaged in other behaviors that compromised egg or chick survival. These observations suggest that deficiencies in parental behavior were precursors to the divorce. This report is one of the first cases where reproductive failure of divorcing pairs has been linked to deficits in the parental behavior of the subsequent divorce victim.Communicated by C. Brown 相似文献
133.
Many predators hunt using the social and waste odors of their prey. It is unknown, however, whether potential prey modify
their behavior in response to the risks of predation associated with accumulations of conspecific odor. We examined this question
by measuring foraging trade-offs of wild house mice (Mus domesticus) in the field where we increased both predation risk and conspecific odor at artificial food patches in a two-factor design.
Mouse giving-up densities (GUDs) were significantly higher in open habitats than in closed habitats but did not differ with
the addition of mouse odors. Fine-scale behavioral observations of captive mice confirmed their attraction to the conspecific
odor in an enclosure experiment, without any change to the GUD. These results indicate that house mice continue to visit and
forage at food patches despite accumulations of predator-attracting odors. This most likely occurs for the social benefits
obtained from conspecific odor exploration; however, such behavior may cause mice to become vulnerable to considerable olfactory
exploitation by their predators. Future work must therefore focus on how mice trade off the social benefits of investigating
odors that also attract their enemies. 相似文献
134.
John Winnie Jr. David Christianson Scott Creel Bruce Maxwell 《Behavioral ecology and sociobiology》2006,61(2):277-289
The risk of predation drives many behavioral responses in prey. However, few studies have directly tested whether predation risk alters the way other variables influence prey behavior. Here we use information theory (Akaike’s Information Criterion, AICc) in a novel way to test the hypothesis that the decision-making rules governing elk behavior are simplified by the presence of wolves. With elk habitat use as the dependent variable, we test whether the number of independent variables (i.e., the size of the models) that best predict this behavior differ when wolves are present vs absent. Thus, we use AICc scores simply to determine the number of variables to which elk respond when making decisions. We measured habitat use using 2,288 locations from GPS collars on 14 elk, over two winters (14 elk winters), in the Gallatin Canyon portion of the Greater Yellowstone Ecosystem. We found that the use of three major habitat components (grass, conifer, sage) was sensitive to many variables on days that wolves were locally absent, with the best models (ΔAICc≤2) averaging 7.4 parameters. In contrast, habitat use was sensitive to few variables on days when wolves were present: the best models averaged only 2.5 parameters. Because fewer variables affect elk behavior in the presence of wolves, we conclude that elk use simpler decision-making rules in the presence of wolves. This simplification of decision-making rules implies that predation risk imposes selection pressures that do not allow prey to respond to other pressures in ways that they otherwise would. If the affected processes are important, then this indirect effect of predation is likely to be important. 相似文献
135.
136.
Bats produce echolocation signals that reflect the sensory tasks they perform. In open air or over water, bats encounter few
or no background echoes (clutter). Echolocation of such bats is the primary cue for prey perception and varies with the stage
of approach to prey, typically comprising search, approach, and terminal group calls. In contrast, bats that glean stationary
food from rough surfaces emit more uniform calls without a distinct terminal group. They use echolocation primarily for orientation
in space and mostly need additional sensory cues for finding food because clutter echoes overlap strongly with food echoes.
Macrophyllum macrophyllum is the only Neotropical leaf-nosed bat (Phyllostomidae) that hunts in clutter-poor habitat over water. As such, we hypothesized
that, unlike all other members of its family, but similar to other trawling and aerial insectivorous bats, M. macrophyllum can hunt successfully by using only echolocation for prey perception. In controlled behavioral experiments on Barro Colorado
Island, Panamá, we confirmed that echolocation alone is sufficient for finding prey in M. macrophyllum. Furthermore, we showed that pattern and structure of echolocation signals in M. macrophyllum are more similar to aerial and other trawling insectivorous bats than to close phylogenetic relatives. Particularly unique
among phyllostomid bats, we found distinct search, approach, and terminal group calls in foraging M. macrophyllum. Call structure, however, consisting of short, multiharmonic, and steep frequency-modulated signals, closely resembled those
of other phyllostomid bats. Thus, echolocation behavior in M. macrophyllum is shaped by ecological niche as well as by phylogeny. 相似文献
137.
随着农村社会经济的发展,农户的生存方式开始逐步由传统的生存方式逐步转变为现代的生存方式。在具体的案例研究过程中,我们既可以看到传统生存方式的环境友好的一面,也可以看到传统生存方式变迁过程中农户经济行为变化对于农村环境的不利影响。与此同时,社会经济发展过程中,新的现代生产生活要素的介入,在不断使农户的生活逐步走向现代化的同时,也带来了种种环境问题。总之,农村环境问题的产生既有传统生存方式本身存在的问题,也来自于生存方式变迁过程中新的外部物质的介入,因此,对于农村环境的改善需要同时从这两方面着手,在改善农户生存方式的同时,更要从根本上控制外部的污染物质的介入。 相似文献
138.
Jessica L. Adams Kari W. Camelio Matthew J. Orique Daniel T. Blumstein 《Behavioral ecology and sociobiology》2006,60(5):742-747
Antipredator behavior includes several qualitatively distinct activities, but few studies have determined the degree to which these activities are independent. If behaviors are not independent, then the nature of the relationship would illustrate potential performance constraints. We studied crimson rosellas (Platycercus elegans) and first focused on acoustic predator discrimination. We measured time allocation before and after playback of one of three experimental treatments (peregrine falcons—Falco peregrinus, wedge-tailed eagles—Aquila audax, and crimson rosellas) to determine whether or not rosellas discriminated predators from non-predators, and specifically whether or not they discriminated large from small predators. We then focused on the decision to flee. We experimentally approached subjects and measured the distance at which they oriented to us (alert distance) and the distance at which they fled (flight initiation distance; FID). We found that rosellas could distinguish among predators; however, there was no effect on general wariness as measured by FID. These two processes of antipredator behavior may, thus, be independent. 相似文献
139.
Shinnosuke Nakayama Reiji Masuda Masaru Tanaka 《Behavioral ecology and sociobiology》2007,61(9):1383-1390
Grouping behavior has various types of antipredator functions. Some of these functions require social transmission of information,
such as the many-eyes effect, whereas others do not, such as the dilution and confusion effects. Functions of grouping behavior
would enhance with social transmission among group members. We investigated and compared the onsets of schooling behavior
and social transmission of information in chub mackerel Scomber japonicus. Onset of schooling behavior was observed in rearing tanks by calculating the degree of parallel swimming. Onset of social
transmission was examined by using visual cues from conspecifics. A group of five individuals was put in each of three experimental
chambers from which they could see a group of conspecifics in the neighboring chamber. A weak electric stimulus was given
to one of these chambers, and information transfer among individuals was observed. We found that social transmission by visual
cues started on 30 days posthatching (25.1 mm in standard length), which was 2 weeks after the onset of schooling behavior.
The late onset of social transmission relative to schooling behavior might be attributed to different predation pressure with
development, or by underdevelopment of optic tectum, as the volume of the optic tectum did not increase just after the onset
of schooling behavior. 相似文献
140.
Effects of Climate and Land-Use Change on Species Abundance in a Central European Bird Community 总被引:2,自引:0,他引:2
NICOLE LEMOINE† HANS-GÜNTHER BAUER‡§ MARKUS PEINTINGER KATRIN BÖHNING-GAESE†‡‡ 《Conservation biology》2007,21(2):495-503
Abstract: Although it is known that changes in land use and climate have an impact on ecological communities, it is unclear which of these factors is currently most important. We sought to determine the influence of land-use and climate alteration on changes in the abundance of Central European birds. We examined the impact of these factors by contrasting abundance changes of birds of different breeding habitat, latitudinal distribution, and migratory behavior. We examined data from the semiquantitative Breeding Bird Atlas of Lake Constance, which borders Germany, Switzerland, and Austria. Changes in the regional abundance of the 159 coexisting bird species from 1980–1981 to 2000–2002 were influenced by all three factors. Farmland birds, species with northerly ranges, and long-distance migrants declined, and wetland birds and species with southerly ranges increased in abundance. A separate analysis of the two decades between 1980–1981 and 1990–1992 and between 1990–1992 and 2000–2002 showed that the impact of climate change increased significantly over time. Latitudinal distribution was not significant in the first decade and became the most significant predictor of abundance changes in the second decade. Although the spatial scale and temporal resolution of our study is limited, this is the first study that suggests that climate change has overtaken land-use modification in determining population trends of Central European birds. 相似文献