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1.
Miguel Delibes-Mateos Miguel ángel Farfán Jesús Olivero Ana Luz Márquez Juan Mario Vargas 《Environmental management》2009,43(6):1256-1268
Agricultural change has transformed large areas of traditional farming landscapes, leading to important changes in the species
community assemblages in most European countries. We suspect that the drastic changes in land-use that have occurred in Andalusia
(southern Spain) over recent decades, may have affected the distribution and abundance of game species in this region. This
article compares the distribution of the main game species in Andalusia during the 1960s and 1990s, using data from maps available
from the Mainland Spanish Fish, Game and National Parks Service and from recent datasets on hunting yield distributions, respectively.
Big-game and small-game species were significantly segregated in southern Spain during the 1990s, as two clearly independent
chorotypes (groups of species whose abundances are similarly distributed) were obtained from the classification analysis.
In contrast, big-game and small-game species were not significantly segregated several decades ago, when there was only one
chorotype consisting of small-game species and wild boar. The other three ungulates did not constitute a significant chorotype,
as they showed positive correlations with some species in the group mentioned above. These changes seem to be a consequence
of the transformations that have occurred in the Iberian Mediterranean landscape over the last few decades. The abandoning
of traditional activities, and the consequent formation of dense scrubland and woodland, has led to an expansion of big-game
species, and a decrease of small-game species in mountain areas. Moreover, agricultural intensification has apparently depleted
small-game species populations in some agricultural areas. On the other hand, the increasingly intensive hunting management
could be artificially boosting this segregation between small-game and big-game species. Our results suggest that the conservation
and regeneration of traditional agricultural landscapes (like those predominating in the 1960s) should be a priority for the
conservation of small-game species. 相似文献
2.
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
3.
4.
A common explanation for hunting in groups is that doing so yields a greater per capita caloric benefit than hunting solitarily.
This is logical for social carnivores, which rely exclusively on meat for energy, but arguably not for omnivores, which obtain
calories from either plant or animal matter. The common chimpanzee, Pan troglodytes, is one of the few true omnivores that regularly hunts in groups. Studies to date have yielded conflicting data regarding
the payoffs of group hunting in chimpanzees. Here, we interpret chimpanzee hunting patterns using a new approach. In contrast
to the classical assumption that hunting with others maximizes per capita caloric intake, we propose that group hunting is
favored because it maximizes an individual’s likelihood of obtaining important micronutrients that may be found in small quantities
of meat. We describe a mathematical model demonstrating that group hunting may evolve when individuals can obtain micronutrients
more frequently by hunting in groups than by hunting solitarily, provided that group size is below a certain threshold. Twenty
five years of data from Gombe National Park, Tanzania are consistent with this prediction. We propose that our ‘meat-scrap’
hypothesis is a unifying approach that may explain group hunting by chimpanzees and other social omnivores. 相似文献
5.
The human-driven loss of biodiversity has numerous ecological, social, and economic impacts at the local and global levels, threatening important ecological functions and jeopardizing human well-being. In this perspective, we present an overview of how tropical defaunation—defined as the disappearance of fauna as a result of anthropogenic drivers such as hunting and habitat alteration in tropical forest ecosystems—is interlinked with four selected Sustainable Development Goals (SDGs). We discuss tropical defaunation related to nutrition and zero hunger (SDG 2), good health and well-being (SDG 3), climate action (SDG 13), and life on land (SDG 15). We propose a range of options on how to study defaunation in future research and how to address the ongoing tropical defaunation crisis, including but not limited to recent insights from policy, conservation management, and development practice. 相似文献
6.
Vernon George Thomas 《Ambio》2013,42(6):737-745
Proposals to end the use of lead hunting ammunition because of the established risks of lead exposure to wildlife and humans are impeded by concerns about the availability, price, and effectiveness of substitutes. The product availability and retail prices of different calibers of lead-free bullets and center-fire rifle ammunition were assessed for ammunition sold in the USA and Europe. Lead-free bullets are made in 35 calibers and 51 rifle cartridge designations. Thirty-seven companies distribute internationally ammunition made with lead-free bullets. There is no major difference in the retail price of equivalent lead-free and lead-core ammunition for most popular calibers. Lead-free ammunition has set bench-mark standards for accuracy, lethality, and safety. Given the demonstrated wide product availability, comparable prices, and the effectiveness of high-quality lead-free ammunition, it is possible to phase out the use of lead hunting ammunition world-wide, based on progressive policy and enforceable legislation. 相似文献
7.
Plasticity in echolocation signals of European pipistrelle bats in search flight: implications for habitat use and prey detection 总被引:1,自引:1,他引:0
We studied the echolocation and hunting behavior of three aerial insectivorous species of bats (Vespertilionidae: Pipistrellus) in the field in order to characterize the signals used by the bats and to determine how call structure varies in relation to habitat structure (uncluttered versus cluttered space). We documented free-flying, naturally foraging wild pipistrelles in various habitats using multiflash stereophotography combined with simultaneous sound recordings. Then we reconstructed the bat's flight position in three-dimensional space and correlated it with the corresponding echolocation sequences. In all three species of pipistrelles, signal structure varied substantially. In echolocation sequences of the search phase we found a consistent association of signal types with habitat types. In uncluttered habitats (obstacles more than 5 m from the bat) pipistrelles emitted almost exclusively narrowband signals with bandwidths less than 15 kHz. In cluttered habitats (obstacles less than 5 m from the bat) they switched to signals with bandwidths of more than 15 kHz. Wideband signals were also used when the bats were turning in cluttered and uncluttered spaces and for an instant after turning away from obstacles. Prey detection occured only when the outgoing signal did not overlap with the returning echo from potential prey. The bats also avoided overlap of echoes from potential prey and obstacles. Based on the results of this study, we propose an overlap-free window within which pipistrelles may detect potential prey and which allows predictions of minimum distances to prey and clutter-producing objects.
Correspondence to: E.K.V. Kalko 相似文献
8.
Most studies suggest that during times of nutritional stress, an animal faced with two foraging choices should follow a risk-prone
strategy, choosing the option with highest payoff variance. This “scarcity/risk” hypothesis was developed to account for the
foraging patterns of small animals with high metabolic rates susceptible to the threat of starvation. In this paper, we propose
that animals should also be risk-prone when their diet quality is particularly high, far exceeding that which is needed to
survive. Under these circumstances, the costs of experiencing a low or negative payoff can easily be recouped. We suggest
that large-bodied omnivores are most likely to adopt this “abundance/risk” strategy. We investigate this question among wild
chimpanzees (Pan troglodytes) that choose between a risk-averse strategy of feeding on plant material and a risk-prone strategy of hunting red colobus
monkeys. Using 14 years of data on the Kanyawara chimpanzees of Kibale National Park, Uganda, we find strong evidence that
chimpanzees follow the “abundance/risk” strategy. Both hunting rate (hunts/100 observation hours) and the probability of hunting
upon encountering red colobus monkeys were positively correlated with seasonal consumption of ripe drupe fruits, a class of
preferred food associated with elevated reproductive performance by females. Critically, these results remained statistically
significant after controlling for the potentially confounding effects of male chimpanzee party size and the presence of sexually
receptive females. These findings suggest that the relationship between risk-sensitive foraging and diet quality depends upon
the daily probability of starvation, the number of alternative foraging strategies, and the degree to which diet quality satisfies
an animal’s nutritional requirements. 相似文献
9.
A test of male mating and hunting success in the kestrel: the advantages of smallness? 总被引:2,自引:0,他引:2
H. Hakkarainen E. Huhta Katriina Lahti Päivi Lundvall Tapio Mappes Pasi Tolonen Jürgen Wiehn 《Behavioral ecology and sociobiology》1996,39(6):375-380
We tested female choice for male wing and tarsus length and body mass in the kestrel (Falco tinnunculus), a species in which males average about 10% smaller than females. We also studied how male characters are related to their
hunting success. In the laboratory, females preferred lighter males with shorter tarsi as mates, if the difference in those
characters between competing males was larger than average. Lighter and shorter-winged males seemed to be better hunters than
heavier and longer-winged males. Field observations in a year in which voles were scarce suggested that shorter-winged males
were also better food providers in courtship feeding than longer-winged males,although in good vole years such a relationship
was not found. We argue that females may prefer to pair with smaller males, because they have higher flight performance and
better hunting success than heavier males. By doing so, females may gain direct breeding advantages. We conclude that both
female choosiness and the hunting efficiency of males well contribute to reversed sexual size dimorphism (RSD, females larger
than males) in the kestrel.
Received: 18 July 1995/Accepted after revision: 17 August 1996 相似文献
10.
货物列车空车直线地段脱轨机理分析与预防 总被引:1,自引:1,他引:0
对货物列车空车直线地段脱轨机理进行探讨 ,笔者认为脱轨是由于车辆蛇形运动波长与线路横向不平顺波长比例不合适或车辆蛇形运动频率与车辆轮对或转向架横向固有频率相等而产生横向共振导致。因此 ,提出提高线路横向不平顺标准 ,尤其是要消除连续性、周期性的反向波 ,对转 8A转向架结构上的缺陷进行改进 ,减小两钢轨间距以及从车辆部门获得轮对与转向架的横向固有频率等预防措施 ,设法避开根据上述机理所算得的列车共振临界速度 ,以尽量减少或消除货物列车脱轨事故。 相似文献