Ecology of the small mammals in the riverine forests of the Jubba Valley, Southern Somalia

1990 ◽  
Vol 6 (2) ◽  
pp. 179-189 ◽  
Author(s):  
Nigel Varty
Keyword(s):  
Small Mammals ◽  
Environmental Conditions ◽  
Stomach Contents ◽  
Dry Season ◽  
Mastomys Natalensis ◽  
Hystrix Cristata ◽  
Pregnant Females ◽  
Riverine Forests ◽  
Degree Of Overlap ◽  
Acomys Dimidiatus

ABSTRACTSeven species of rodent, Paraxerus ochraceus, Tatera robusta, Saccostomus meamsi, Praomys (Mastomys) natalensis, Acomys dimidiatus, Thamnomys (Grammomys) dolichurus and Hystrix cristata were recorded in the riverine forests of the Jubba Valley, southern Somalia, in the dry season of 1986. Acomys dimidiatus was the most common of the five species trapped. Overall trap success was low, but increased over successive days. Saccostomus mearnsi, Praomys natalensis, Acomys dimidiatus and Thamnomys dolichurus all showed signs of breeding, and pregnant females of A. dimidiatus and T. dolichurus were trapped until the end of the dry season. Analysis of stomach contents revealed that all five trapped species relied heavily on seeds and, where comparisons could be made, the degree of overlap in diets was high. The findings are discussed in relation to the environmental conditions in the forest and neighbouring habitats.

scholarly journals Pathogenic Leptospira in Commensal Small Mammals from the Extensively Urbanized Coastal Benin

Urban Science ◽  
2019 ◽  
Vol 3 (3) ◽  
pp. 99 ◽  
Author(s):  
Houéménou ◽  
Gauthier ◽  
Etougbeétché ◽  
Badou ◽  
Dossou ◽  
...  
Keyword(s):  
Small Mammals ◽  
Environmental Conditions ◽  
Rattus Norvegicus ◽  
Mastomys Natalensis ◽  
Pathogenic Leptospira ◽  
The World ◽  
Human Contamination ◽  
Diachronic Analysis ◽  
Standing Waters

Leptospirosis is caused by spirochete bacteria of the genus Leptospira that affect one million and kill 60,000 persons annually in the world, who get infected through environmental mammal-excreted (notably rodent) pathogens. Using qPCR and DNA sequencing approaches, we here examine Leptospira occurrence and diversity in 971 commensal small mammals in urban and peri-urban habitats from south Benin, where socio-environmental conditions are favorable for human contamination. Prevalence reached 12.9% on average, but showed very important variations in both space and time, thus pointing toward a role of local processes in the maintenance and circulation of rodent-borne leptospires in the area. Prevalence peaks may occur during or one month after moderate (100–200 mm) monthly rainfall, suggesting that rodent-borne leptospires may be more prevalent when standing waters are present, but not at their highest levels (i.e., floods). However, this pattern will have to be confirmed through proper diachronic analysis. Finally, an incomplete but significant host-specificity was observed, with L. kirschneri retrieved only in African shrews, and the invasive Rattus norvegicus and the native Mastomys natalensis preferentially infected by L. interrogans and L. borgpeterseni, respectively. Our study highlights the urgent need for investigations on human leptospirosis in the extensively urbanized Abidjan–Lagos corridor.

scholarly journals Distribution of guppies Poecilia reticulata (Peters, 1860) and Phalloceros caudimaculatus (Hensel, 1868) along a polluted stretch of the Paraíba do Sul River, Brazil

2009 ◽  
Vol 69 (1) ◽  
pp. 41-48 ◽  
Author(s):  
FG. Araújo ◽  
MG. Peixoto ◽  
BCT. Pinto ◽  
TP. Teixeira
Keyword(s):  
Environmental Conditions ◽  
Poecilia Reticulata ◽  
Condition Factor ◽  
Spatial Separation ◽  
Fishing Effort ◽  
Seasonal Patterns ◽  
Industrial Complex ◽  
Pregnant Females ◽  
Significant Difference ◽  
Paraíba Do Sul River

Cyprinodontiformes fishes (guppies) are widely distributed in Neotropical regions and use deteriorated microhabitats in rivers where few species can occur. This study was carried out in a stretch of the Paraíba do Sul River in bracketing a large urban-industrial complex. The aim was to assess eventual effects that the industrial complex could have on distribution of two closely related fish species of guppies, Phalloceros caudimaculatus and Poecilia reticulata. The area was divided into three zones: Z1, 40 km upriver of the major urban-industrial complex of Volta Redonda; Z2, just down river of the complex; and Z3, 30 km down river of the complex. Six sites (two in each zone) were sampled monthly between November 1998 and October 1999, using a standardized fishing effort with cast net throws, trays lifts and seine hauls, covering different microhabitats, that is, riffles, pools and the proximity of the river's margins. Poecilia reticulata was widely distributed, peaking at Z2, the most polluted area, while P. caudimaculatus showed the highest abundance at Z3, being almost absent in Z1. Both species occurred in high numbers throughout the year but they were scarce between April and June. Females outnumbered males for both species in most size classes and at all sites. Juveniles were more abundant than adults, with non-pregnant females outnumbering pregnant ones. Condition factor was always higher in males than females but only males P. reticulata showed significant difference among the three zones, with the highest values at Z2. The higher number of females confirms the expectation that these species can use very polluted areas and that availability of food provided by organic loads allowed their distribution all over the area. Although these two species have shown indication of spatial separation in the study area, their similar seasonal patterns of occurrence suggest that they respond in a similar way to changes in environmental conditions.

scholarly journals Seasonal variation on diet of juvenile Elops saurus Linnaeus, 1766 (Ladyfish) in the Parnaiba River Delta

2020 ◽  
Vol 32 ◽  
Author(s):  
Tatiane Araujo Santos ◽  
Thamires Souza Gonçalves ◽  
Patricia Silva do Nascimento ◽  
Cézar Augusto Freire Fernandes ◽  
Francisca Edna de Andrade Cunha
Keyword(s):  
High Frequency ◽  
Rainy Season ◽  
Stomach Contents ◽  
Dry Season ◽  
River Delta ◽  
Frequency Of Occurrence ◽  
Relative Importance ◽  
Dry Period ◽  
Food Items ◽  
Importance Index

Abstract: Aim Identify seasonal variations in the diet of juvenile living in the estuary of the Parnaíba River Delta. Methods Food items were identified through analysis of stomach contents, and later submitted to analysis by regular methods for Frequency of Occurrence (FO), Frequency Numerical (FN), Gravimetric Frequency (FW) and Relative Importance Index (IRI). Results Juvenile diet of Elops saurus that inhabit the lagoons in the Parnaíba delta was composed in order decreasing of importance by Osteichthyes (Teleostei), Insecta and Crustacea in addition to Polychaeta and Nematoda. It was also observed a high frequency of occurrence of fragments of plastics in the diet. In the rainy season, 17 items were recorded in the diet, whereas in the dry season only 7 items were present. Relative Importance Index showed high presence of the Teleostei fish (69.93%) on diet of E. saurus during the rainy season, whereas during the dry period the insects of the families Corixidae (43.25%) and Dysticidae (39.16%). Conclusions With the study it was possible to identify that juvenile are piscivorous in the rainy season when there is a higher availability of prey in the environment and insectivores in the dry season when it reduces the supply of food, indicating feeding flexibility to environmental alterations.

The Small Mammals of Little Nourlangie Rock, NT. V. The Effects of Fire

1981 ◽  
Vol 8 (3) ◽  
pp. 515 ◽  
Author(s):  
RJ Begg ◽  
KC Martin ◽  
NF Price
Keyword(s):  
Body Weight ◽  
Litter Size ◽  
Small Mammals ◽  
Pregnant Females ◽  
Preferred Habitat ◽  
Closed Forest ◽  
The Mean ◽  
Fuel Characteristics ◽  
Release Program

Following a capture-mark-release program (February 1977-June 1979) on Dasyurus hallucatus, Antechinus bilarni, Zyzomys argurus and Zyzomys woodwardi, the study area was burnt to determine the effects of fire on these species. The area was described in terms of fuel characteristics and details of the fire were recorded. Post-fire trapping began July 1979 and continued until July 1980 (15,600 trap-nights). A. bilarni was the only species to suffer an increased mortality immediately after the fire, but the number of animals known to be alive declined over the year following the fire, for all species except D. hallucatus. The fire affected reproduction in all four species, but in different ways. Breeding in D. hallucatus was delayed by 1 month, and the mean number of young leaving the pouch per female was lower than before the fire. A higher number of resident females kept recruitment up. Litter size in A. bilarni was not affected, but a reduced number of resident females meant that recruitment was halved. Zyzomys argurus and Z. woodwardi showed few lactating and pregnant females in July-August following the fire, and the numbers of juveniles were lower than in the previous two years. Following the fire, no detectable differences in body weight were recorded, but all species except D. hallucatus changed their preferred habitat, moving to the Scree Slope. Z. woodwardi was most affected, and moved from the Closed Forest.

Environmental conditions of the Suape estuarine-port complex area (Pernambuco, Brazil): phytoplankton biomass and hydrological parameters

2018 ◽  
Vol 99 (2) ◽  
pp. 291-301
Author(s):  
Isis Amália Cordeiro ◽  
Fernando Antônio Do Nascimento Feitosa ◽  
Manuel De Jesus Flores Montes ◽  
Amanda Yumi Otsuka ◽  
Alex Costa Silva
Keyword(s):  
Dissolved Oxygen ◽  
Environmental Conditions ◽  
Rainy Season ◽  
High Tide ◽  
Dry Season ◽  
Water Transparency ◽  
Industrial Complex ◽  
Productive Capacity ◽  
Chl A ◽  
Anthropogenic Action

The Suape coastal zone has suffered since the 1980s the effects of anthropogenic action due to the construction of the industrial complex of Suape. This work aimed to evaluate the environmental conditions and possible eutrophication processes of the area. Six campaigns were carried out, three in the dry season (November 2015, January and April 2016) and three in the rainy season (July 2015, July and August 2016). Water samples were collected at the surface during low tide and high tide, in neap tides. Salinity ranged from 19.75 to 37.20, the dissolved oxygen rate ranged from 61.75 to 125.90% and chlorophyll-a from 0.02 to 3.48 mg m−3. Water transparency, temperature, nitrate and silicate presented significant seasonal variation, the concentrations of nutrients being higher in the rainy season and the others in the dry season. Water transparency, salinity, dissolved oxygen saturation and chl-a <20 µm showed significant differences for tide, being higher at high tide, and at low tide for chl-a of <20 µm. The low content of dissolved inorganic nutrient salts and chl-a were indicative of an area still free of eutrophication. Anthropogenic changes in the environment have led to greater marine interference and consequently to a reduction of the productive capacity of the system.

scholarly journals Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

2018 ◽  
Vol 18 (9) ◽  
pp. 6461-6482 ◽  
Author(s):  
Luiz A. T. Machado ◽  
Alan J. P. Calheiros ◽  
Thiago Biscaro ◽  
Scott Giangrande ◽  
Maria A. F. Silva Dias ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Land Surface ◽  
Rain Rate ◽  
Vertical Motion ◽  
Cloud Droplet ◽  
Dry Season ◽  
Wet Season ◽  
Aerosol Loading ◽  
Dry Seasons ◽  
Wet And Dry Seasons

Abstract. This study provides an overview of precipitation processes and their sensitivities to environmental conditions in the Central Amazon Basin near Manaus during the GoAmazon2014/5 and ACRIDICON-CHUVA experiments. This study takes advantage of the numerous measurement platforms and instrument systems operating during both campaigns to sample cloud structure and environmental conditions during 2014 and 2015; the rainfall variability among seasons, aerosol loading, land surface type, and topography has been carefully characterized using these data. Differences between the wet and dry seasons were examined from a variety of perspectives. The rainfall rates distribution, total amount of rainfall, and raindrop size distribution (the mass-weighted mean diameter) were quantified over both seasons. The dry season generally exhibited higher rainfall rates than the wet season and included more intense rainfall periods. However, the cumulative rainfall during the wet season was 4 times greater than that during the total dry season rainfall, as shown in the total rainfall accumulation data. The typical size and life cycle of Amazon cloud clusters (observed by satellite) and rain cells (observed by radar) were examined, as were differences in these systems between the seasons. Moreover, monthly mean thermodynamic and dynamic variables were analysed using radiosondes to elucidate the differences in rainfall characteristics during the wet and dry seasons. The sensitivity of rainfall to atmospheric aerosol loading was discussed with regard to mass-weighted mean diameter and rain rate. This topic was evaluated only during the wet season due to the insignificant statistics of rainfall events for different aerosol loading ranges and the low frequency of precipitation events during the dry season. The impacts of aerosols on cloud droplet diameter varied based on droplet size. For the wet season, we observed no dependence between land surface type and rain rate. However, during the dry season, urban areas exhibited the largest rainfall rate tail distribution, and deforested regions exhibited the lowest mean rainfall rate. Airplane measurements were taken to characterize and contrast cloud microphysical properties and processes over forested and deforested regions. Vertical motion was not correlated with cloud droplet sizes, but cloud droplet concentration correlated linearly with vertical motion. Clouds over forested areas contained larger droplets than clouds over pastures at all altitudes. Finally, the connections between topography and rain rate were evaluated, with higher rainfall rates identified at higher elevations during the dry season.

The influence of sex and reproductive state on diet preference in four terrestrial mammals of the French Guianan rain forest

1997 ◽  
Vol 75 (6) ◽  
pp. 929-935 ◽  
Author(s):  
O. Henry
Keyword(s):  
Stomach Contents ◽  
Reproductive Activity ◽  
Relative Energy ◽  
Feeding Strategies ◽  
Mammal Species ◽  
Protein Requirements ◽  
Terrestrial Mammals ◽  
Pregnant Females ◽  
Diet Preference ◽  
Gravid Females

The diets of males and pregnant and nonpregnant females were studied in four French Guianan mammal species, three rodents and one artiodactyl, illustrating a gradient of size, mass, and gestation, and thus of energy and protein requirements. In the rodents (Oryzomys capito, Proechimys cuvieri, Dasyprocta leporina), males were more frugivorous than females, whereas the reverse was the case in the artiodactyl (Tayassu tajacu). For all species, males ate the most pulp, while pregnant females focused on seeds or animal matter. Nevertheless, males and females appeared to be opportunistic foragers, with similar feeding strategies throughout the year. A comparative analysis of stomach contents showed that the diets of males and nonpregnant females were quite comparable, while significant differences occurred in gravid females (especially of the two smallest species). Intra-individual differences gradually decreased from O. capito to T. tajacu, possibly as a result of closer male and female cohabitation as well as lower relative energy and protein requirements for pregnant females of the larger species. Finally, for the two smallest species, reproductive activity was correlated with seed and (or) animal matter intake.

scholarly journals Major Regularities of Transformation of the Small Mammal Ovaries in Unfavourable Environmental Conditions: Ecological and Morphological Aspects

2021 ◽  
Vol 10 (4) ◽  
pp. 28-35
Author(s):  
E. V. Blinova ◽  
N. N. Shevlyuk
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Environmental Conditions ◽  
Functional Organization ◽  
Common Shrew ◽  
Mammal Species ◽  
Wood Mice ◽  
Wide Range ◽  
Mole Vole ◽  
Cortical Substance

The aim of the study was to determine the patterns of structural and functional organization of the ovaries of female small mammals inhabiting technogenically altered ecosystems.Material and methods. We studied the ovaries of small mammal species belonging to the insectivore and rodent families (common shrew, field and pygmy wood mice, common and bank voles, mole vole, steppe pied) that live in anthropogenically altered ecosystems (zones of influence of ferrous and nonferrous metallurgy, as well as gas processing factory). The resulting material was processed using observational histological, histochemical, immunohistochemical and morphometric tests.Results. The results obtained demonstrated that in technogenically altered ecosystems the intensified reproduction results in a complex of morphofunctional reactive and adaptive changes in the ovaries of females of the studied species. The size of the ovaries was reduced; the area of the cortical substance was reduced. In the cortex, there was revealed a decrease in the number of follicles varying over a wide range - from a moderate decrease to their almost complete absence. There was found a decrease in the area of the vessels of the microvasculature; this was one of the major reasons for the increased follicular atresia. In follicles of various types, there was an increase in the proportion of cells expressing the proapoptotic protein P53. A decrease in the number of follicles resulted in the connective tissue overgrowth. The presence of cysts lined with epithelium of various heights was revealed in the cortex and medulla. Conclusion. The results obtained evidence that in technogenically altered ecosystems a decreased ovarian reserve is observed in the ovaries of female small mammals; it is associated with a more rapid depletion of the follicle reserve in the cortex due to both - intensification of reproduction and more rapid death of follicles in unfavourable environmental conditions.

The ecology of small mammals in Ogba Forest Reserve, Nigeria

1989 ◽  
Vol 5 (1) ◽  
pp. 51-64 ◽  
Author(s):  
John Giobaguan Iyawe
Keyword(s):  
Small Mammals ◽  
Seasonal Changes ◽  
Common Species ◽  
Dry Season ◽  
Small Rodents ◽  
Wet Season ◽  
Forest Reserve ◽  
Percentage Composition ◽  
Monthly Variations ◽  
Arvicanthis Niloticus

ABSTRACTA total of 392 small mammals belonging to five species of small rodents and four species of shrews were caught. The small mammals and their percentage composition were Crocidura nigeriae (20.9%), Crocidura grandiceps (11.7%), Crocidura crossei (9.7%), Crocidura flavescens manni (20.4%), Mus musculoides (39.0%), Praomys tullbergi (11.5%), Lophuromys sikapusi (3.6%), Lemniscomys striatus (1.3%), and Arvicanthis niloticus (0.3%).There were monthly variations in the number of Mus musculoides and Crocidura nigeriae.In Mus musculoides breeding was at a maximum at the beginning and towards the end of the wet season and early dry season. In Crocidura nigeriae breeding was maximal during the wet season and low in the dry season.The seasonal changes in the age structure of the two most common species: Mus musculoides and Crocidura nigeriae, are described.

scholarly journals Canopy phenology of a dry forest in western Brazil

2007 ◽  
Vol 67 (3) ◽  
pp. 569-575 ◽  
Author(s):  
J. Ragusa-Netto ◽  
RR. Silva
Keyword(s):  
Environmental Conditions ◽  
Dry Season ◽  
Dry Forest ◽  
Abiotic Factor ◽  
Deciduous Species ◽  
Ecological Processes ◽  
Canopy Trees ◽  
Dry Conditions ◽  
Leaf Shedding ◽  
Mountain Chain

Dry forests are common, although highly threatened in the Neotropics. Their ecological processes are mostly influenced by rainfall pattern, hence their cycles exhibit contrasting phases. We studied the phenology of canopy trees in a primary dry forest in Western Brazil in the foothills of the Urucum mountain chain, in order to improve our knowledge on the functioning of these poorly-known forests. Leaf shedding started in the early dry season and was massive in the latter part of this period. Most leaf loss occurred in dry hills, while wet valleys remained evergreen. Anemochorich and autochorich species predominated in dry hills, presumably due to their tolerance to dry conditions and enhanced exposition to winds, which favour diaspores removal and dispersal. Conversely, zoochorich species dominated the wet valleys. Flowering was intense in the late dry season, the driest period of the year, while fruiting was massive just after the onset of rains, as well as flushing. Therefore, most flowering was unrelated to wet conditions, although such an abiotic factor, potentially, triggered the major fruiting episode, widely comprised by zoochorich species. Anemochorich and autochorich species flowered and fruited in the course of the long dry season. The contrasting environmental conditions present in the hills and valleys determine the arrangement of a mosaic in which patches of zoochorich and evergreen trees alternate with patches of non zoochorich and highly deciduous species. Consequently, species with such syndromes exhibited marked flowering and fruiting patterns, accordingly to the pronounced seasonality.

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