Disturbance from roads negatively affects Andean condor habitat use     

Karina L. Speziale  Sergio A. Lambertucci 《Biological conservation》2008,141(7):1765-1772

Human disturbance can be a severe problem for some animal species. Behavioural ecology theory predicts that sensitivity to mortality risks, and thereby to disturbance, will be related to life-history characteristics. Long-lived species with low reproductive rates are expected to have a high cost of predation and therefore avoid risks strongly. In this paper we quantify the effect of roads on the Andean condor (Vultur gryphus) using behavioural indicators. We used a pair wise design, offering condors standardized food patches near and far from roads simultaneously. The patches consisted of dead adult sheep. We recorded condors’ behaviour when visiting each patch. This study establishes the versatility of behavioural indicators and their usefulness to study conservation problems. We found that, although near and far patches were discovered after similar times and there were similar numbers of condors in the vicinity of near and far patches, the use of patches differed strongly. In the patches far from roads many more condors came to feed, the average time spent per individual was longer, the proportion of time spent vigilant was lower, and the amount of food left uneaten on the carcasses was lower. These results strongly suggest that Andean condors clearly avoid roads, and behave in a way predicted from theory if they trade off safety for energy. This study shows that roads have stronger influence on the habitat use of Andean condors, than previously thought, and may be a significant problem for the species in populated areas.  相似文献   

The spatial extent of termite influences on herbivore browsing in an African savanna   总被引：1，自引：0，他引：1  

Shaun R. Levick  Gregory P. Asner  Ty Kennedy-Bowdoin  David E. Knapp 《Biological conservation》2010,143(11):2462-2467

Termite mounds form islands of fertility in savanna landscapes and create foraging hotspots for herbivores, but the magnitude and spatial extent of these influences is unknown. We mapped terrain, termite mound and woody vegetation three-dimensional (3-D) structure at 56 cm resolution across a large-scale (254 ha), long-term (34 years) herbivore exclusion experiment in the Kruger National Park, with the Carnegie Airborne Observatory (CAO). We compared vegetation 3-D structure in areas protected from herbivores with those accessible to herbivores, both on termite mounds and in the landscape matrix between termite mounds. Termite mound density was 1.1 ha⁻¹ across the study area and mound size did not differ between protected and accessible areas. Woody vegetation canopy cover was ∼100% greater on protected than accessible mounds, but was only ∼20% greater in the protected inter-mound matrix when compared to the accessible matrix. Woody canopy height class distributions differed significantly between protected and accessible areas, with the tallest vegetation (>10 m) occurring on protected termite mounds. The impacts of herbivore browsing were evident at distances of up to 20 m from termite mound centres. Spatial analysis of mound distribution revealed that the sphere of termite mound influence constitutes ∼20% of the total landscape. Termite influences on herbivore browsing operate at scales much larger than the spatial extent of their mound building activities.  相似文献   

Liver apolipoprotein B₁₀₀ expression and secretion are down-regulated early postpartum in dairy cows     

U. Bernabucci  L. Basiric  D. Pirazzi  F. Rueca  N. Lacetera  E. Lepri  A. Nardone 《Livestock Science》2009,125(2-3):169-176

Acorn weight, size, shape and composition vary a great deal among evergreen oaks (Quercus ilex rotundifolia); however these characteristics remain constant for a tree throughout the fruiting period. The number of consumed acorns under the canopy of a tree could be an indicator of preference for its acorn characteristics. This paper analyses the characteristics of the acorns selected by free-ranging Iberian pigs at the start (November) and end (February) of the montanera or acorn mast-feeding season, when these are sustained fattened. At these two stages, acorn samples were taken from 20 oak trees (Q. ilex rotundifolia) that had been rejected by the pigs (only eating between 2 and 9 acorns from the ground underneath the tree) and from 20 oak trees that were actively sought out by the pigs (eating at least 40 acorns). The differences observed between the sought out and rejected acorns at the start and end of the montanera season are too great to be only a matter of chance, suggesting that Iberian pigs must form associations between variables when choosing to eat or reject the acorns from a specific oak tree. The results show that pigs tend to select heavier acorns at the start of the montanera season, while at the end their selection is based more on the composition of the acorns. The greatest number of significant differences between the groups of acorns were found in the sought out acorns in November and February, owing to all the variables related with the composition of the acorns: crude fat (10.8 ± 0.3 vs. 7.4 ± 0.3), starch (58.3 ± 1.0 vs. 50.3 ± 0.4), sugars (6.8 ± 0.4 vs. 13.2 ±0.3); most of the fatty acids; dimensions: length (38.1 ± 0.8 vs. 31.9 ± 0.7) and diameter (16.6 ± 0.4 vs. 13.9 ± 0.1); acorn weights: fresh whole acorn (6.9 ± 0.3 vs. 3.4 ± 0.1) and kernel DM (2.5 ± 0.2 vs. 1.7 ± 0.1). Pigs prefer acorns with larger kernel. This selective consume goes along with the theory of Optimal Foraging and suggest that pigs learn to use visual stimuli when grazing. In conclusion, this study shows a constant selective acorn consumption and a variation in acorn preferences throughout the montanera period; consequently it is proven that acorn diet is not homogeneous and varies over the fattening period.  相似文献   

Pollen meta-barcoding reveals different community structures of foraged plants by honeybees (Apis mellifera L.) along space-time gradient in Japan     

《Urban Forestry & Urban Greening》2023

The availability of pollen in urban-rural landscapes is an essential factor that influences the population dynamics of insect pollinators. The amount and diversity of pollen play a pivotal role in the foraging ecology of pollinators for their growth and health, but investigations on the spatio-temporal patterns of foraged plants remain rare, especially in cities as neo - ecosystems. Here, we explored the temporal foraging habits of a highly pollinator (Apis mellifera L.) in Tokyo, including different landscape classes from rural to urban areas. Mixed-pollen samples in each month and each location (N = 17) were analysed using DNA meta-barcoding to identify plants visited by honeybees. The results showed that the landscape class (rural, suburban and urban areas) explains spatial variations in pollen source-plant composition foraged by honeybees, but not in taxa richness. Furthermore, pollen diversity and pollen source-plant composition showed a strong seasonal dependence. A higher plant richness and foraged woody taxa was found to occur in spring, which was mainly dominated by the genera Prunus and Acer. In summer and autumn, the genera Trifolium and Plantago of the herbaceous stratum were the most visited plants. The Fabaceae, Rosaceae, Brassicaceae, Plantaginaceae, and Onagraceae plant families were the most frequently observed in all combined samples. The present study contributes to a deeper understanding of the foraging ecology of A. mellifera colonies across urban-rural gradient surrounding mega-cities such as Tokyo.  相似文献