凉水自然保护区松鼠巢址选择的特征

2006 年6 月11 日至9 月27 日和2007 年8 月14 日至9 月21 日采用样线法,并结合定位观察的方法在凉水国家级自然保护区对松鼠的巢址选择进行了定量研究,共获取107 个巢样方和230 个对照样方。对每个样方分别测定了12 个巢树参数和7 个环境参数。统计分析结果表明,松鼠仅在针叶树上营巢,59.8 ± 4. 7% 的巢建于红松上,但对枝叶比红松更为浓密的云杉和臭冷杉有显著的选择性,而且显著倾向于在以云杉、臭冷杉为优势树种的生境中营巢。松鼠选择比较高大(树高21.5 ± 0.4 m)、活动通道比较多(3.6 ±0.1)的树营巢,巢树周围的树木密度(169 ± 4 株/ hm² )和多样性(辛普森指数0.51 ± 0.01)显著高于对照样方。巢址生境多位于南向的中、下坡位。巢址高12.4 ± 0.4 m,紧贴树干,多朝南。红松树上的巢多建于树冠的中下部,云杉和臭冷杉树上的巢多建于树冠的上部。松鼠巢对包括道路在内的林隙没有显著的回避。     

Diets of native and introduced tree squirrels in Washington

Competition for food resources can be a primary mechanism for displacement of native species by introduced species. Investigation of dietary partitioning between potential competitors and spatiotemporal variability in food resources can reveal contested food items and intensity of competition. Introduced eastern gray squirrels (Sciurus carolinensis) have been implicated as competitors with western gray squirrels (S. griseus) and Douglas’ squirrels (Tamiasciurus douglasii), but little is known about interactions among these species. We collected foraging observations and fecal pellets of sympatric gray and Douglas’ squirrels trapped and radio-tracked in western Washington, USA, from 2007 to 2012. We compared food resources consumed across species, seasons, and years to evaluate dietary overlap and the potential for competitive interactions. All squirrel species ate hypogeous fungi throughout all seasons; spores of several genera were present in 272 of 275 fecal samples and observed in all months. Rhizopogon, Geopora, and Melanogaster spp. occurred in most fecal pellets for all squirrels, but the diet of the Douglas’ squirrels had slightly lower richness of hypogeous fungi than gray squirrels. Although foraging observations suggest that eastern and western gray squirrels shared important dietary items such as acorns, strong differences in consumption of seeds of a common conifer may facilitate their coexistence. Our results suggest that dietary overlap among arboreal squirrels could lead to competitive interactions during periods of food scarcity, but subtle differences may be sufficient to permit long-term coexistence. Tree squirrels in Washington would likely benefit from forest management practices that promote or sustain robust crops of hypogeous fungi. © 2019 The Wildlife Society.     

Interspecific effects of grey squirrels (Sciurus carolinensis) on the space use and population demography of red squirrels (Sciurus vulgaris) in conifer plantations

Interspecific competition between red squirrels and grey squirrels was investigated by comparing the population demography, spacing behavior and habitat use of red squirrels in two large conifer plantations in northern England: one site had only red squirrels (the red-only site), in the other both red and grey squirrels occurred (the red–grey site). Despite more abundant food at the red–grey site, red squirrel densities (0.26 ha^–1 at the red–grey site, 0.29 ha^–1 at the red-only site), adult survival rates and the breeding rates of females were similar at both study sites. Grey squirrels at the red–grey site occurred at higher densities (0.92–1.1 ha^–1) than did the reds and tended to have higher breeding rates. In the presence of grey squirrels, the recruitment pattern of red squirrels changed and there was little recruitment of subadults. The juvenile recruitment rate in the red–grey site (13%) was much lower than in the red-only site (50%). Grey squirrels, in contrast, had higher juvenile recruitment rates at the red–grey site (41%). The core areas of the home ranges of red squirrels in the red–grey site were more strongly overlapped by grey squirrels than by conspecifics. Red squirrels did not select the habitat with the best tree seed crop (Scots pine) but preferred dense Sitka spruce plantations; they appeared to avoid the Scots pine area with its high grey squirrel density. Data on foot length and body condition indicated decreased body growth in young red squirrels when grey squirrels were present. Our data suggest that adult red squirrels suffered little from interspecific competition with grey squirrels and that the key factor is decreased juvenile recruitment in red squirrels.     

Adenovirus: an emerging factor in red squirrel Sciurus vulgaris conservation

相似文献   

Importance of scale in nest-site selection by Arizona gray squirrels

Nests provide a place for individuals to rest, raise young, avoid predators, and escape inclement weather; consequently, knowledge of habitat characteristics important to nest placement is critical for managing species of conservation concern. Arizona gray squirrels (Sciurus arizonensis) are endemic to mountains of southwestern United States and northwestern Mexico. We investigated factors influencing nest-site selection at 4 spatial scales (forest-type, nest-site, nest-tree, and within-canopy placement) to provide ecological information and management recommendations for this sensitive species. Nest densities were 2.6 times higher in riparian than pine-oak woodlands. Nest sites had more large trees, snags, logs, and canopy cover and had lower slope. Arizona gray squirrels selected tall trees with more interlocking trees and tended to place nests adjacent to the main trunk. Regardless of scale, Arizona gray squirrels seemed to select nesting areas for their ability to provide protection from predators and the elements as well as access to food. Consequently, maintaining large trees with closed canopies and downed logs should be considered when determining land management plans. © 2011 The Wildlife Society.     

Post-breeding dispersal by female red squirrels (Tamiasciurus hudsonicus): the effect of local vacancies

Red squirrels (Tamiasciurus hudsonicus) defend food-based territoriesyear round, and juveniles must acquire a territory before winterto survive. We experimentally removed territory owners duringthe time that juveniles were becoming independent to examinethe effect of local vacancies on dispersal patterns. Juvenilesattempted to take over removal territories most frequently.However, females with offspring still on the natal territoryactually took over twice as many territories as juveniles. Thesefemales did not appear to move because of low reproductive potentialor to increase territory quality. Instead, moving to a removalterritory allowed more of their offspring to remain on the natalterritory, which appeared to increase juvenile survival.     

Direct and indirect cues of predatory risk and patch use by fox squirrels and thirteen-lined ground squirrels

We used giving-up densities in food patches to measure the effectsof several direct (left by the predator) and indirect (environmentalcorrelates of risk) cues of predatory risk on the foraging behaviorof free-living fox squirrels (Sciurus niger) and thirteen-linedground squirrels (Spermophihis tridtctmlineatus). Increasesin giving-up density in response to stimuli allow quantitativecomparisons of the effects of different types of cues. We usedolfactory (urine of red fox) and visual (plastic models of owls)direct cues. As indirect cues, we used mkrohabitat (near orfar from a refuge), background coloration (white, green, andbrown tarpaulins), and escape substrate (canvas tarpaulins versusnatural surrounding substrates). Both squirrel species respondedmost strongly to microhabitat Fox squirrels increased theirgiving-up density by 97% when feeding 4–6 m from a treecompared to feeding at the tree base. Thirteen-lined groundsquirrels increased giving-up densities 84% when feeding 2 mfrom their burrows compared to feeding at the burrow entry.In response to an unfavorable escape substrate (canvas versusgrass), fox squirrel giving-up densities increased 61%. Foxsquirrels and ground squirrels increased giving-up densities26% and 35%, respectively, in response to a plastic owL Backgroundcoloration had no demonstrable effect on the giving-up densitiesof fox squirrels. In contrast to other work on nocturnal mammalianherbivores and granivores, the diurnal fox squirrels did notrespond to olfactory cues.     

Multimodal alarm behavior in urban and rural gray squirrels studied by means of observation and a mechanical robot

Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is un-known how urbanization has affected these behaviors. Multimodal communication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be pre-sented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Parian et al. (2009) by providing data on sig-naling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifies are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats.     

A systematic review into the suitability of urban refugia for the Eurasian red squirrel Sciurus vulgaris

1. Urban growth and intensification are projected to increase as the global human population increases. Historically, urban areas have been disregarded as suitable wildlife habitat, but it is now known that these areas can be biodiverse and that wildlife species can adapt to the environmental conditions. One such urban-dwelling species is the Eurasian red squirrel Sciurus vulgaris, which has suffered population declines in several countries throughout its range in recent decades.
2. The current published literature was systematically reviewed to determine whether or not urban habitats are suitable refugia for red squirrels, through identifying and discussing key topics regarding the urban ecology of red squirrels.
3. Urban environments can support higher population densities of red squirrels than rural areas, probably due to the widespread and reliable provision of anthropogenic supplemental food alongside natural food sources. The availability and quality of urban greenspaces are important determinants of the suitability of urban habitats for red squirrels, as they provide natural food sources and nesting sites. Despite the barriers present in urban landscapes (e.g. roads), red squirrels can still disperse and maintain gene flow at the population level.
4. Road traffic accidents appear to be a significant cause of mortality in some urban red squirrel populations, and seasonal peaks of mortality occur during the autumn months. Diseases (e.g. squirrelpox virus) can also be a significant cause of mortality, although effects differ between populations and depend on whether grey squirrels Sciurus carolinensis are present. Many of the predation events that affect red squirrels appear to be due to free-ranging domestic and feral cats Felis catus, although there is currently little evidence to suggest that predation is a limiting factor for urban red squirrel populations.
5. We conclude that urban areas can be suitable refugia for red squirrels, provided that high-quality greenspaces are maintained. Mitigation measures may also be necessary to reduce population mortality and to prevent disease outbreaks.

     

Geographical distance and physical barriers shape the genetic structure of Eurasian red squirrels (Sciurus vulgaris) in the Italian Alps

Red squirrels (Sciurus vulgaris) are widely distributed throughout Eurasia, occurring in many types of coniferous and mixed-deciduous forests. In fragmented landscapes, small and partly isolated populations with low immigration rates show reduced genetic diversity, but reforestation can increase gene flow and restore levels of genetic variation in a few decades. No studies have so far investigated the genetic structure of red squirrel in large, continuous forests. The Italian Alps are presently characterized by almost continuous, recently reconnected forest habitats, that were affected by deep landscape changes during last glaciations but remained mostly unchanged between 10 000 and 200 years bp, when forest cover was heavily reduced. In this study we analyse patterns of genetic variability of red squirrels in and between seven sites distributed over 250 km of Alpine habitat, using mitochondrial DNA (mtDNA) and microsatellites. We use isolation-by-distance (IBD) models to investigate the relative importance that past (Pleistocene glaciations) and recent (fragmentation, bottlenecks) events had on the present genetic situation. Both nuclear and mtDNA data indicate a significant differentiation among study sites and a significant correlation between genetic and geographical distance only over a large scale. No recent bottlenecks are recorded through microsatellites and demographic models strongly support equilibrium between gene flow and drift; however, mtDNA suggests that there may have been local demographic crashes, probably in correspondence with the 19th-century forest fragmentation. These findings indicate that local landscape factors other than geographical distance per se, such as barriers of unsuitable habitat, affect gene flow and determine differentiation.     

The effects of hoarding habitat selection of Eurasian red squirrels (Sciurus vulgaris) on natural regeneration of the Korean pines

Cone-cores discarded by Eurasian red squirrels were used to study the habitat selection of Korean pine-seeds hoarding, in forest patch Nos. 16 and 19 in Liangshui Nature Reserve, China. Ten transects with a total length of 15 km were uniformly set, and data from 343 valid samples were collected in a 369 hm² area. One hundred and eighty four were hoarding samples which were determined according to the cluster analysis based on the number of the cone-cores, while the other 159 were control samples. The principal component analysis, using 11 habitat factors, suggested that the distance from Korean pine forest, forest type, number of Korean pine seedlings, density and type of bush significantly influenced the habitat selection of hoarding by Eurasian red squirrels. The results of Bailey’s method indicated that the squirrels showed (1) preference for natural coniferous forest, natural fir and spruce forest and planted spruce forest; (2) avoidance of planted Korean pine forest and planted larch forest; and (3) random use of natural Korean pine forest. Moreover the distance from the Korean pines in the range of 150–600 m showed no effect on the habitat selection of hoarding by the Eurasian red squirrels. More than 50% of the cone-cores were discarded in either fringe or gap of the Korean pine forest with more cone-cores found at <300 m than at 300 m away (One-Way ANOVA; df = 3, 183, F = 5.76, p = 0.0009). This demonstrated that the Eurasian red squirrels could take the cone-cores out of the Korean pine forest. The density of bushes in samples of hoarding area was significantly lower than that in control samples (Kruskal–Wallis test; df = 1, χ² = 83.99, p < 0.0001). The number of the Korean pine seedlings in samples of hoarding area was significantly higher than that in the control samples (Kruskal–Wallis test; df = 1, χ² = 104.13, p < 0.0001). This illustrated that the hoarding habitat favoured the germination of the Korean pine seedlings. In conclusion the behavior of hoarding Korean pine seeds by the Eurasian red squirrels can promote the regeneration and dispersal of the Korean pines.     

Molecular replacement studies on crystal structure of allophycocyanin from red algae Porphyra yezoensis

Using the crystal structure of allophycocyanin from cyanobacterium Spirulina platensis (APC-SP) as a search model,the crystal structure of allophycocyanin from red algae Porphyra yezoensis (APC-PY) has been studied by molecular replacement methods.The APC-PY crystals (Form 3) belong to the space group of R32,cell dimensions a=b= 10.53 nm,c=18.94 nm,α= β= 90°,γ=120°;there is one αβ monomer in each crystallographic asymmetric unit in the cell.The translation function search gave a unique peak with a correlation coefficient (Cc) of 67.0% and an R-factor of 36.1% for reflection data from 1.0 to 0.4 nm.Using the results by molecular replacement,the initial model of APC-PY was built,and the coincidence of the chromophore in APC-PY initial model with its 2Fo-Fc OMIT map further confirms the results by molecular replacement.     

Molecular replacement studies on crystal structure of allophycocyanin from red algaePorphyra yezoensis

Using the crystal structure of allophycocyanin from cyanobacterium Spirulina platensis (APC-SP) as a search model, the crystal structure of allophycocyanin from red algae Porphyra yezoensis (APC-PY) has been studied by molecular replacement methods. The APC-PY crystals (Form 3) belong to the space group of R32, cell dimensions a = b = 10.53 nm, c = 18.94 nm, α =β = 90°, γ= 120°; there is one αβ monomer in each crystallographic asymmetric unit in the cell. The translation function search gave a unique peak with a correlation coefficient (Cc) of 67.0% and an R-factor of 36.1 % for reflection data from 1.0 to 0.4 nm. Using the results by molecular replacement, the initial model of APC-PY was built, and the coincidence of the chromophore in APC-PY initial model with its 2Fo-FC OMIT map further confirms the results by molecular replacement.     

Cohort effects in red squirrels: the influence of density, food abundance and temperature on future survival and reproductive success

1. Environmental conditions experienced early in life may have long-lasting effects on individual performance, thereby creating 'silver-spoon effects'. 2. We used 15 years of data from a North American red squirrel (Tamiasciurus hudsonicus Erxleben) population to investigate influences of food availability, density and spring temperature experienced early in life on reproduction and survival of female squirrels during adulthood. 3. We found that spring temperature and food availability did not affect female survival after 1 year of age, whereas higher squirrel densities led to lower survival, thereby affecting longevity and lifetime fitness. 4. In addition, both food availability experienced between birth and weaning, and spring temperature in the year of birth, had long-lasting positive effects on female reproductive success. These results emphasize the critical effect environmental conditions during the early life stages can have on the lifetime performance of small mammals. 5. These long-term effects of early food and temperature were apparent only once we controlled for conditions experienced during adulthood. This suggests that silver-spoon effects can be masked when conditions experienced early in life are correlated to some environmental conditions experienced later in life. 6. The general importance of silver-spoon effects for adult demographic performance might therefore be underestimated, and taking adult environment into account appears to be necessary when studying long-term cohort effects.     

Effects of sphingolipids overload on red blood cell properties in Gaucher disease

Gaucher disease (GD) is a genetic disease with mutations in the GBA gene that encodes glucocerebrosidase causing complications such as anaemia and bone disease. GD is characterized by accumulation of the sphingolipids (SL) glucosylceramide (GL1), glucosylsphingosine (Lyso‐GL1), sphingosine (Sph) and sphingosine‐1‐phosphate (S1P). These SL are increased in the plasma of GD patients and the associated complications have been attributed to the accumulation of lipids in macrophages. Our recent findings indicated that red blood cells (RBCs) and erythroid progenitors may play an important role in GD pathophysiology. RBCs abnormalities and dyserythropoiesis have been observed in GD patients. Moreover, we showed higher SL levels in the plasma and in RBCs from untreated GD patients compared with controls. In this study, we quantified SL in 16 untreated GD patients and 15 patients treated with enzyme replacement therapy. Our results showed that the treatment significantly decreases SL levels in the plasma and RBCs. The increased SL content in RBCs correlates with abnormal RBC properties and with markers of disease activity. Because RBCs lack glucocerebrosidase activity, we investigated how lipid overload could occur in these cells. Our results suggested that SL overload in RBCs occurs both during erythropoiesis and during its circulation in the plasma.     

The effects of hoarding habitat selection of Eurasian red squirrels (Sciurus vulgaris) on natural regeneration of the Korean pines

Cone-cores discarded by Eurasian red squirrels were used to study the habitat selection of Korean pine-seeds hoarding, in forest patch Nos. 16 and 19 in Liangshui Nature Reserve, China. Ten transects with a total length of 15 km were uniformly set, and data from 343 valid samples were collected in a 369 hm² area. One hundred and eighty four were hoarding samples which were determined according to the cluster analysis based on the number of the cone-cores, while the other 159 were control samples. The principal component analysis, using 11 habitat factors, suggested that the distance from Korean pine forest, forest type, number of Korean pine seedlings, density and type of bush significantly influenced the habitat selection of hoarding by Eurasian red squirrels. The results of Bailey’s method indicated that the squirrels showed (1) preference for natural coniferous forest, natural fir and spruce forest and planted spruce forest; (2) avoidance of planted Korean pine forest and planted larch forest; and (3) random use of natural Korean pine forest. Moreover the distance from the Korean pines in the range of 150–600 m showed no effect on the habitat selection of hoarding by the Eurasian red squirrels. More than 50% of the cone-cores were discarded in either fringe or gap of the Korean pine forest with more cone-cores found at <300 m than at 300 m away (One-Way ANOVA; df = 3, 183, F = 5.76, p = 0.0009). This demonstrated that the Eurasian red squirrels could take the cone-cores out of the Korean pine forest. The density of bushes in samples of hoarding area was significantly lower than that in control samples (Kruskal–Wallis test; df = 1, χ² = 83.99, p < 0.0001). The number of the Korean pine seedlings in samples of hoarding area was significantly higher than that in the control samples (Kruskal–Wallis test; df = 1, χ² = 104.13, p < 0.0001). This illustrated that the hoarding habitat favoured the germination of the Korean pine seedlings. In conclusion the behavior of hoarding Korean pine seeds by the Eurasian red squirrels can promote the regeneration and dispersal of the Korean pines.     

红壤旱地不同复种方式的生态功能评价

为了充分发挥红壤旱地的生态功能,筛选出适于红壤旱地的优化复种方式,依据3年的田间定位试验资料,从农田生态系统的生产功能、物质循环特征、能量流动特征、价值流动特征以及养地效果等方面对红壤旱地4种复种方式[处理A(CK): 小麦/大豆-芝麻;处理B: 混播绿肥(油菜×紫云英×肥田萝卜)-大豆‖玉米-绿豆‖芝麻;处理C: 黑麦草-花生‖玉米-粟‖荞麦;处理D: 油菜-绿豆‖甘薯,“/”表示套作,“‖”表示间作,“-”表示接茬,“×”表示混作]的功能和效益进行了分析,并采用灰色关联度法从经济效益、生态效益和社会效益3个层次的13个指标对各复种方式进行了综合评价.结果表明: 混播绿肥(油菜×紫云英×肥田萝卜)-大豆‖玉米-绿豆‖芝麻复种模式的经济效益、生态效益和社会效益的关联度值均居第一位,经灰色关联度分析,得出其综合效益关联度值也最高,为0.847,是比较适宜在红壤旱地推广应用的高效复种方式,对今后红壤旱作区种植业结构布局和优化具有积极意义.