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1.
A study of the associations between three species of rodents in the Atlantic forest and their parasitic arthropods was undertaken at the Juréia-Itatins Ecological Station, located in the State of S?o Paulo, Southeastern Brazil, from March 1989 to February 1990. Individuals of three species, Oryzomys russatus, Proechimys iheringi and Nectomys squamipes were captured and examined for ectoparasites. Eleven species of parasitic arthropods were found, including four species of insects and seven of Acari. Parasitism intensity, phenology, and rainfall were positively correlated with the abundance of the ectoparasites and their hosts. The most abundant host was O. russatus (Muridae: Sigmodontinae), and the most common parasite on it was the laelapid mite Gigantolaelaps oudemansi. The cuterebrid Metacuterebra apicalis caused myiasis in O. russatus. A mutualistic association between the staphylinid beetle Amblyopinus sp. and its host P. iheringi (Echimyidae) was observed. The few N. squamipes captured had small numbers of ectoparasites.  相似文献   

2.
A study on the ecology of rodents and insectivores on Mount Chilalo and the Galama Mountain range was conducted during August, 2007–April, 2008. Study grids were marked in nine randomly selected habitats. Sherman live traps and snap traps were used to capture the small mammals. A total of 2525 (including recaptures) individual rodents and insectivores were captured in 5488 (Sherman) and 1590 (snap) trap‐nights. Among the live‐trapped animals, 2037 (96.2%) and 80 (3.8%) were rodents and insectivores, respectively, that comprised 17 species. These were as follows: Arvicanthis abyssinicus, Arvicanthis blicki, Arvicanthis dembeensis, Lophuromys flavopunctatus, Lophuromys melanonyx, Mastomys natalensis, Mus mahomet, Otomys typus, Rattus rattus, Stenocephalemys albipes, Stenocephalemys albocaudata, Stenocephalemys griseicauda, Crocidura glassi, Crocidura flavescens and Crocidura thalia. Tachyoryctes splendens and Hystrix cristata were sighted but not captured. Endemics to Ethiopia constituted 60% of the trapped small mammals. Lophuromys flavopunctatus was the most abundant and widely distributed rodent species, while M. mahomet was the least. The altitudes between 3301 and 3400 m asl had the highest species composition and abundance although it is second in number of catches per trap‐nights. The majority of rodents and insectivores were associated with montane forest habitat, whereas the least were in the shrubland. Anthropogenic effects were witnessed affecting the distribution of small mammals.  相似文献   

3.
Water vole latrines were studied on four of the principal rivers in the North Yorkshire Moors National Park. Water voles occupied 'core' and 'peripheral' sites on these rivers. Core sites were marked by latrines and held breeding colonies of voles; animals at core sites were readily captured. Peripheral sites were not marked by latrines, but showed erratic water vole activity as measured by activity indices (tracks m-1 of muddy bank month-1). It was never possible to catch voles at these peripheral sites, and there was no evidence of breeding.
Latrines on core sites were not maintained outside the breeding season. The appearance of latrines coincided with the start of the breeding season, and while they were maintained, latrines provided a useful guide to the number of animals in the area. A curvilinear response was obtained between latrine production and date, with production rising steadily from early spring until mid-to-late summer, which suggests that latrines signal sexual activity.
Future studies on the distribution of water voles should use a variety of techniques. Latrine surveys will only be applicable during the breeding season at core sites. Similarly, live-trapping will only detect water voles at core sites. Tracking provides the best evidence that water voles are present at peripheral sites even though they may not be breeding or entering traps.  相似文献   

4.
Observations were made on the breeding of Praomys morio in a lake shore forest in Uganda, during a mark-release-recapture programme whose other aim was to study the role of rodents in the epidemiology of arboviruses. Because of the few numbers of animals captured other means of increasing reproduction data were employed. These included calculating the months of birth of very young animals from their weights.
It was found that pregnancies and births were more numerous in January, April, July, August and November. Recruitment of young animals occurred in three peaks, viz; February, June and September, corresponding to low rainfall months. It was concluded that P. morio shows some form of seasonality in its breeding that may be related to rainfall.  相似文献   

5.
Histopathologic and morphometric (area, perimeter, major and minor diameters) analysis of hepatic granulomas isolated from twelve naturally infected Nectomys squamipes were compared to four experimentally infected ones and six C3H/He mice. Liver paraffin sections were stained for cells and extracellular matrix. Both groups of N. squamipes presented peculiar granulomas consisting predominantly of large macrophages, full of schistosome pigment, characterizing an exudative-macrophage granuloma type, smaller than the equivalent granuloma type in mouse. Naturally infected animals exhibited granulomas in different stages of development, including large number of involutional types. Morphometric analysis showed that all measurements were smaller in naturally infected animals than in other groups. The results demonstrated that both N. squamipes groups reproduced, with small variations, the hepatic granuloma aspects already described in cricetidium (Calomys callosus), showing a genetic tendency to set up strong macrophage responses and small granulomas. Unexpectedly, natural infection did not engender distinguished histopathological characteristics distinct from those derived from experimental single infection, showing changes predominantly secondary to the duration of infection. It appears that the variability of the inocula (and the number of infections?) interfere more with the quantity than with the quality of the pathological changes, denoting some morpho-functional determinism in the response to schistosomal infection dependent on the animal species.  相似文献   

6.
The black-spotted pond frog (Rana nigromacu-lata) is one of the most widely distributed species in China. However, there have been only a few qualitative descrip-tions of their breeding ecology and oviposition site selec-tion. From 2004 to 2006, we investigated the breeding ecology and oviposition site selection of K nigromaculata in Ningbo, China, quantitatively. Analyses of breeding ecology show that: (1) mean frog density in the breeding season was 0.0903 ± 0.0029 individuals per meter (n = 11) (mean ± SE); (2) R. nigromaculata was a sexually dimorphic species, with females significantly larger than males in both body weight and snout-vent length; (3) the clutch size averaged 4643.04± 235.96 eggs (range 1546-7897, n = 50); and (4) the egg size ranged from 1.50 to 1.74 mm in diameter, with an average egg size of 1.6050 ± 0.0046 mm (n = 226). Oviposition sites differed significantly from random sites in percentages of water, bare ground and vegetation cover, water depth (cm), water temperature (°C) and water turbidity. Rana nigro-maculata preferred microhabitats with higher percentages of water and vegetation cover, while it avoided microha-bitats with deeper water. The results suggest that micro-habitats with higher percentages of water and vegetation cover, but not deeper water, should be priorities for pro-tection and conservation of the breeding habitats of R. nigromaculata.  相似文献   

7.
The effect of a well-developed epiphytic vegetation on the interception of rainfall was investigated in an upper montane rain forest at an altitude of 3370 m in the Cordillera Central of the Colombian Andes. Total epiphyte mass was estimated at 12 tonnes dry weight per hectare, most of it being bryophytes and dead organic matter. The hydrological properties of the epiphyte mass were studied using detached branches. Water gain (during rainfall) and water loss (after experimental saturation) were determined gravimetrically in the field.Rain falling on epiphyte-covered branches was efficiently captured. Drainage of water (held temporarily in excess of the retention capacity) was very gradual. Water loss through evaporation was slow. The observations are in accordance with previously reported data for rainfall interception in the forest studied. The potentially large influence of the exceptionally high canopy storage capacity is restricted due to the clumped distribution of epiphytes and associated low turnover rates of water in the epiphyte mass.  相似文献   

8.
2010~2011年4~7月,在四川省瓦屋山自然保护区对金色林鸲(Tarsiger chrysaeus)的繁殖生态和巢址选择进行了研究。共发现26巢,金色林鸲2010年和2011年的繁殖成功率分别为43.8%和44.4%,孵化率分别为52.5%和60.0%;育雏成功率分别为85.7%和100.0%。主成分分析表明,影响金色林鸲巢址选择的主要因子包括巢位因素、苔藓盖度因素和乔木郁闭度因素。步道两侧的土坎为金色林鸲巢址选择提供了适宜条件。在瓦屋山,人类活动是影响金色林鸲繁殖、巢址选择、巢的分布和数量的重要因素,并存在两面性;人行步道的修建为金色林鸲提供了更多适宜的巢址,而游客的频繁活动限制了金色林鸲的繁殖活动。  相似文献   

9.
Introduced mammals pose serious threats to native island fauna, and understanding their distribution is fundamental to evaluating their conservation impact. Introduced sugar gliders (Petaurus breviceps) are the main predator of critically endangered swift parrots (Lathamus discolor) on mainland Tasmania. We surveyed sugar glider occurrence over ~800 km2 in an important swift parrot breeding area, the Southern Forests. During 4–5 visits per site, we used call broadcast of predatory owls to elicit sugar glider alarm calls and surveyed 100 sites during February/March 2016. Naïve occupancy by sugar gliders was high (0.79), as was detectability (0.52 ± 0.03 SE), resulting in a cumulative detection probability of effectively 1. Occupancy modelling indicated a positive effect of the proportion of mature forest cover on occupancy. The best model, based on AIC scores, included the proportion of mature forest cover within a 500 m radius with constant detectability. Our study revealed surprisingly high rates of occupancy of available forest habitat throughout the heavily logged study area, such that even when mature forest cover was <10%, sugar glider occupancy was >0.5; where forest cover approached 100% (i.e. in the best quality breeding habitat for swift parrots), occupancy by sugar gliders approached 1. Our results reveal that sugar gliders are widespread across the study area which may be indicative of occupancy rates elsewhere in the breeding range of the critically endangered swift parrot. As a result, the risk of predation by sugar gliders for small birds may be widespread across logged Tasmanian forests. Additional work to identify whether population densities of sugar gliders vary with forest cover (and whether this may impact predation likelihood) is critical to understanding the conservation consequences of deforestation in the breeding range of the swift parrot.  相似文献   

10.
11.
Due to a long running research bias toward the breeding season, there are major gaps in knowledge on the basic nonbreeding ecology of many species, preventing a full‐annual cycle focus in ecology and conservation. Exacerbating this problem is the fact that many species are extremely difficult to detect outside of breeding. Here, we demonstrate a partial solution to this problem by using archival GPS tags to examine the overwintering ecology of a migratory nocturnal bird, the eastern whip‐poor‐will (Antrostomus vociferous). We deployed tags on 21 individuals and were able to recover 11 (52%) one year later. Tags collected high precision (approx. 10 m) points throughout the nonbreeding period. With continuous time movement models, we used these data to estimate overwintering home ranges. All individuals exhibited at least one bounded home range during this phase of the annual cycle, three of eleven had two wintering locations, and home range area ranged from 0.50 to 10.85 ha. All overwintering home ranges contained closed‐canopy forest land cover (42%–100%), and no other land cover type represented >40% of any home range. We found some evidence, with caveats, that total edge within the landscape surrounding the home range was negatively related to home range area. The prevalence of contiguous closed‐canopy forest cover in overwintering home ranges contrasts with apparent breeding habitat preferences, which includes clear‐cuts and other, more open, habitats. This study is the first to reveal key aspects of overwintering space use in this species by using archival GPS to overcome both logistical and methodological limitations. Expanded use of such technology is critical to gathering basic ecological and distributional data, necessary for achieving a more complete understanding of full‐annual cycles of animal populations.  相似文献   

12.
1. In this study we predict stream sensitivity to non‐point source pollution based on the non‐linear responses of hydrological regimes and associated loadings of non‐point source pollutants to catchment properties. We assessed two hydrologically based thresholds of impairment, one for catchment storage (5–10%) and one for mature forest (<50% versus >60% of catchment in mature forest cover) across two different hydrogeomorphic regions within the Northern Lakes and Forest (NLF) ecoregion: the North Shore [predominantly within the North Shore Highlands Ecological Unit] and the South Shore (predominantly within the Lake Superior Clay Plain Ecological Unit). Water quality samples were collected and analysed during peak snowmelt and baseflow conditions from 24 second‐order streams grouped as follows: three in each region × catchment storage × mature forest class. 2. Water quality was affected by a combination of regional influences, catchment storage and mature forest. Regional differences were significant for suspended solids, phosphorus, nitrogen: phosphorus ratios, dissolved organic carbon (DOC) and alkalinity. Catchment storage was significantly correlated with dissolved silica during the early to mid‐growing season, and with DOC, specific conductance and alkalinity during all seasons. Total nitrogen and dissolved nitrogen were consistently less in low mature forest than in high mature forest catchments. Catchment storage interacted with the influence of mature forest for only two metrics: colour and the soluble inorganic nitrogen : phosphorus ratio. 3. Significant interaction terms (region by mature forest or region by storage) suggest differences in regional sensitivity for conductance, alkalinity, total organic carbon, and colour, as well as possible shifts in thresholds of impact across region or mature forest class. 4. Use of the NLF Ecoregion alone as a basis for setting regional water quality criteria would lead to the misinterpretation of reference condition and assessment of condition. There were pronounced differences in background water quality between the North and South Shore streams, particularly for parameters related to differences in soil parent material and glacial history. A stratified random sampling design for baseflow and snowmelt stream water quality based on both hydrogeomorphic region and catchment attributes improves assessments of both reference condition and differences in regional sensitivity.  相似文献   

13.
Eleven small mammal species (nine rodents and two shrews) were recorded in 16 months of trapping in the Karkloof Forest, Natal. Total densities varied seasonally, ranging from 60.7 animals/ha in the dry autumn and winter to 29.1 animals/ha at the onset of the rains in spring and early summer. Peaks in breeding coincided with high body fat and water content in the five common species during summer: in winter, when body fat and water levels were low, there was no breeding. This may be related to poor food quality at this time. Annual changes in density, breeding season and juvenile recruitment of Rhabdomys pumilio, Mastomys natalensis and Myosorex varius are the same as recorded in conspecific populations from other habitat types and do not seem modified by the habitat stability of the forest environment. Of the five common species, only Grammomys dolichurus , one of the few forest-associated small mammals in southern Africa, and Graphiurus murinus demonstrated stable, K-selectéd life-history styles.  相似文献   

14.
The development of commercial forests presents potential threats to large raptors that rely on prey caught in open country. We examined the effect of afforestation of breeding habitat used by a population of Golden Eagles Aquila chrysaetos in Scotland where, over the last 50 years, extensive stands of exotic conifers have been planted. Using data for 31 years on territory occupancy and breeding success, together with spatiotemporally dynamic mapping of forest cover and predicted areas of territory‐use in a Geographical Information System, we examined relationships between forest cover and Eagle ecology at landscape and individual territory scales. Several territories were abandoned during the earliest phases of forest planting, but relatively few were apparently lost to later plantings. Territories with poorer breeding productivity appeared to be more vulnerable to abandonment than territories with better breeding productivity. At the landscape scale, temporal differences in breeding productivity were negatively related to the extent of forest cover, although productivity of individual territories showed no clear relationship with forest cover. Several territories with less than a 5% increase in forest cover experienced reduced productivity; however, territories least constrained by neighbouring pairs of Eagles showed an increase in productivity. Territories experiencing the greatest increases in forest cover showed a greater use of spatially separated nest‐sites by occupying pairs. Hence, pairs that were less constrained by neighbours appeared to compensate for loss of open habitat by shifting their territory‐use, whereas pairs that were more constrained could not compensate for open habitat loss and suffered reduced productivity (and, probably in some cases, abandoned the territory). We suggest that simple guidelines based on the extent and locations of habitat loss are inadequate when predicting effects on large territorial raptors such as Golden Eagles. Consideration should also be given to the ‘quality’ of a territory or occupying pair, as well as the extent to which territory‐use is constrained by neighbouring pairs or other ‘unsuitable habitat’ which may have been affected by previous episodes of open habitat loss.  相似文献   

15.
ABSTRACT.   Although many studies have revealed intraspecific variation in the number of broods raised per breeding season, less is known about the causes of variation between species. We monitored the breeding behavior of congeners traditionally thought to raise one brood per breeding season, Orchard Orioles ( Icterus spurius ) and Baltimore Orioles ( I. galbula ). Both species have similar habitat and nesting requirements. We captured and banded orioles at three study sites in Maryland in 2004 and 2005. No pairs of Baltimore Orioles ( N = 26) were double brooded, whereas 8 of 24 pairs (33%) of Orchard Orioles had a second brood and 7 of 16 pairs (44%) of Orchard Orioles that successfully raised a first brood also successfully raised a second brood during the same breeding season. Our findings provide the first documentation of double brooding by Orchard Orioles. The timing of molt and the amount of time and energy devoted to postfledgling parental care may contribute to this difference between species in terms of the number of broods per breeding season.  相似文献   

16.
Between December 2007 and March 2009, small mammals were captured in 6 Atlantic Forest patches in Brazil. We assessed tick-host associations and whether they differ among forest strata, sites, seasons, and host age classes or between sexes. Moreover, we assessed the exposure of animals to Rickettsia spp. In total, 432 animals were captured and 808 ticks were found on 32·9% of them. Significant differences were found among host species, collection sites, and forest strata; microhabitat preference was a strong risk factor for tick infestation. The highest tick density rates were recorded in forest fragments settled in rural areas; 91·3% of the ticks were collected from animals trapped in these forest fragments. A high prevalence (68·8%) of antibodies to Rickettsia spp. was detected among animals. This study suggests that disturbed Atlantic Forest fragments provide an environment for ticks and small mammals, which are highly exposed to rickettsiae. It also indicates that forest patches settled in rural areas are usually associated with higher small mammal diversity as well as with higher tick density rates.  相似文献   

17.
Jani Heino 《Hydrobiologia》2000,418(1):229-242
Littoral zones of small water bodies are spatially heterogeneous habitats, harbouring diverse biotic communities. Despite this apparent heterogeneity, many studies have stressed the importance of water chemistry in determining the structure of littoral macroinvertebrate assemblages. The purpose of this study was to consider the relative importance of several spatial and water chemistry variables in explaining the patterns in the structure of macroinvertebrate assemblages in 21 lentic water bodies in northeastern Finland. Water bodies were selected to represent various habitat conditions ranging from small permanent bog ponds to small forest lakes. According to canonical correspondence analysis (CCA), the most important environmental factors related to assemblage composition were water body area, moss cover, total nitrogen and water hardness. In general, species composition in small bog ponds tended to differ from that in larger lakes with forested shoreline. Total species richness was best explained by a composite variable (PCA) describing physical habitat heterogeneity, species richness being lowest in small bog lakes with simple bottom structure and low amount of aquatic plants. Species numbers in dominant functional feeding groups were related to different environmental factors. Shredder species richness was best explained by a regression model incorporating total nitrogen and the amount of organic matter, both of which were negatively related to the number of shredder species. The number of gatherer species increased with mean substratum particle size. Scraper species richness was negatively affected by the abundance of detritus and positively affected by depth, and a model including both variables explained most of the variation. Variation in the number of predatory species was best explained by a regression model including moss cover and lake area.  相似文献   

18.
The existence of wild rodents naturally infected by Schistosoma mansoni is a drawback for schistosomiasis control programs. As a consequence, it is necessary to have a precise diagnosis of S. mansoni infection in wild rodents (water rats; Nectomys squamipes), the species seemingly involved in the transmission of schistosomiasis at Sumindouro, Rio de Janeiro, Brazil. A total of 78 specimens of N. squamipes was captured in an endemic area at Vale do Pamparr?o and Porteira Verde, Sumidouro, Brazil; 5 more were born in captivity and experimentally infected. The sensitivity and specificity of the coprological method of Kato-Katz and serological methods, i.e., enzyme-linked immunosorbent assay (ELISA) and western blot (WB), were compared. The rodents were subsequently killed and necropsied to confirm infection. The prevalences observed using ELISA (48%) and WB (41%) were equivalent to those found at necropsy (41%). The ELISA showed a sensitivity of 97% and a specificity of 87%, whereas the WB showed a sensitivity of 87% and a specificity of 89%. The Kato-Katz method exhibited 50% sensitivity and 100% specificity. The differences found among the ELISA, WB, and necropsy, when compared with Kato-Katz, may be related to the low sensitivity of the coprological method. Serological methods should be used for more reliable epidemiological information.  相似文献   

19.
Adults of Tabanidae may become serious pests wherever they occur due to their attack to humans and others animals. Tabanids were captured near ground, water surface and at 25 m high on primary forests and forest gaps of anthropogenic origin, to understand their abundance, seasonality, diversity and similarity on such environments. Collections were carried out in the Base II of the War Instruction Center in the Jungle (CIGS) located at 54 km from Manaus municipality, Amazonas state. Two Malaise flight interception traps and four attraction traps (two suspended at 25 m high and two above the water surface of igarapé) were installed in forest gap and primary forest, areas for 10 consecutive days, during 15 months. A total of 2,643 specimens of 66 species were captured. Diachlorini (35 species /11 genera) was the most abundant tribe, followed by Tabanini (19 species /three genera), Chrysopsini (seven species /one genus) and Scionini (five species /two genera). Seventeen species were captured only in the primary forest, 11 in the anthropic clearing, and 38 species were common to both environments. The most abundant species were Phorcotabanus cinereus (Wiedemann), Tabanus occidentalis L, Chrysops laetus Fabricius and Tabanus angustifrons Macquart. The greatest richness was found in drier months (September/October) in both areas. Theforest gap showed higher abundance of specimens (1,827) than the primary forest (816). Traps suspended above the water surface were the most efficient (1,723 specimens) probably due to the dispersion of horseflies over small streams.  相似文献   

20.
Studies were made on the Bush rat, Aethomys hindei in Lunyo forest (0° 5', 32° E) on the Northern shores of Lake Victoria. Rats were trapped daily (Monday-Saturday) for 47 weeks during November 1970 to November 1972 from 20–49 live traps set in a 40 by 100 m grid. In the laboratory they were examined for the condition of the external genitalia and for signs of pregnancy. Some pregnant rats were kept in the laboratory and their progeny measured at weekly intervals. The rate of growth (weight gain in g per day) was determined for both laboratory and field rats. Growth curves of laboratory rats were used to calculate the ages of young (<100 g) field rats, even though the results showed that at between 50 to 100 g field rats grew faster than laboratory rats and between 100 to 150 g, laboratory rats grew faster than field rats.
The weight distribution of rats in the field showed a clear weight difference between males and females; with some males weighing as much as 171 g while the maximum weight recorded for females was only 146 g. The weights obtained extend the weight range of these rats beyond that previously published.
Breeding (pregnancies) in the field occurred mostly in the wetter months of November- December and April whereas young animals occurred more in the drier months of December and January. Births obtained by calculation from laboratory growth curves occurred more in November.
Seasonality in the intensity of breeding was indicated although monthly breeding throughout the year was observed. The months of highest population densities were December, January and April.  相似文献   

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