The breeding season and diet of Arvicanthis in northern Nigeria

1989 ◽  
Vol 5 (4) ◽  
pp. 375-386 ◽  
Author(s):  
Safianu Rabiu ◽  
Martin Fisher
Keyword(s):  
Breeding Season ◽  
Food Supply ◽  
Rainy Season ◽  
Dry Season ◽  
Northern Nigeria ◽  
East African ◽  
African Savanna ◽  
Seasonal Differences ◽  
Sudan Savanna ◽  
Semi Arid

ABSTRACTThe breeding season and diet of the rat Arvicanthis was monitored from December 1983 to November 1985 in the semi-arid Sudan savanna at Kano, Nigeria, West Africa. Breeding began 1–2 months before the start of the rainy season and ceased at the beginning of the dry season. The diet of Arvicanthis was omnivorous, but with seasonal differences. Monocotyledons and dicotyledons predominated in the diet in the dry season, with seeds and insects increasing in the diet in the rainy season. The major differences between the ecology of Arvicanthis at Kano and on the East African savanna were that in East Africa the breeding season is longer and begins after the start of the rainy season. These and other dissimilarities between the biology of Arvicanthis in the two areas could be due to the effect of climatic differences on food supply and to the possible existence of different taxonomic groupings of Arvicanthis in the two regions.

Second Report of the Tsetse-fly Investigation in the Northern Provinces of Nigeria

1924 ◽  
Vol 15 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Llewellyn Lloyd ◽  
W. B. Johnson ◽  
W. A. Young ◽  
H. Morrison
Keyword(s):  
Breeding Season ◽  
Food Supply ◽  
Close Relation ◽  
Dry Season ◽  
Tsetse Fly ◽  
Trypanosome Infection ◽  
Wet Season

This report contains a record of the trypanosome infections, food and breeding of G. morsitans and G. tachinoides obtained by examining the flies at various foci over a period of fourteen months.It confirms the fact that the breeding of both species is practically confined to the dry season and follows a period of increased food supply. G. tachinoides is well fed through the rains, except in one month of flood, and starts breeding as soon as the rains cease, owing to its habit of feeding on reptiles. G. morsitans starts free breeding about six weeks later, as its increased food supply is due to the ungulates becoming more available.G. morsitans does not feed on reptiles, but in times of hunger draws a proportion of its food from birds, the largest proportion recorded being 17 per cent, in one month at one focus. It draws the bulk of its food in this locality from small antelope, large game being scarce. G. tachinoides is much less specialised in its diet, and in the wet season nearly one-fifth of its food was drawn from a group of animals which included man, monkey and dog.The infection of the flies with T. vivax and T. congolense bears a close relation to the amount of blood obtained from antelope, and consequently morsitans is in general nearly four times as heavily infected as tachinoides. Infections with T. brucei and T. gambiense are scarce in this locality. Trypanosome infection rises just before the main breeding season in morsitans in all localities and in tachinoides in places where the fly is largely a mammal feeder. The proportional infection in general falls in the season of most rapid breeding, owing to masking of the actual rise by the number of young flies examined. It rises rapidly when breeding ceases. The total infection is reduced when fly food is hard to obtain, in the time of long grass and flood, owing to T. vivax infections dying out when the flies are starved.It is shown that in some cases T. grayi may be obtained by tachinoides when it feeds on Varanus, and a somewhat similar infection in the laboratory may be obtained by feeding the flies on toads.It is shown that in some cases T. grayi may be obtained by tachinoides when it feeds on Varanus, and a somewhat similar infection in the laboratory may be obtained by feeding the flies on toads.There is just an indication that postponement of grass burning may interfere with the free breeding of morsitans and in some cases that of tachinoides. This possibility is to be tested.The experiment of excluding game and pig from one of the dry season foci of the flies by means of fencing will be carried out.

scholarly journals Seasonal study of contamination by metal in water and sediment in a sub-basin in the southeast of Brazil

2011 ◽  
Vol 71 (4) ◽  
pp. 833-843 ◽  
Author(s):  
WAC. Chiba ◽  
MD. Passerini ◽  
JAF. Baio ◽  
JC. Torres ◽  
JG. Tundisi
Keyword(s):  
Rainy Season ◽  
Principal Component ◽  
Dry Season ◽  
Seasonal Differences ◽  
Sediment Samples ◽  
Fluorescent Lamps ◽  
Water And Sediment ◽  
Temporal Occurrence ◽  
Bodies Of Water ◽  
Water And Sediment Samples

The spatial and temporal occurrence of heavy metals (Al, Cd, Pb, Zn, Cr, Co, Cu, Fe, Mn and Ni) in water and sediment samples was investigated in a sub-basin in the southeast of Brazil (São Carlos, SP). All samples were analysed using the USEPA adapted metal method and processed in an atomic absorption spectrophotometer. The discriminant analysis demonstrated that there are significant seasonal differences of metal distribution in the water data, but there are no differences to sediment. The basin studied has high levels of contamination by toxic metals in superficial water and sediment. The superficial water, in the rainy season, presented high levels of Cr, Ni, Pb and Cd, while in the dry season it presented high levels of Zn and Ni. The Principal Component Analysis demonstrated that the season has a huge influence on the levels, types and distribution of metals found in water. The source of contamination was probably diffuse, due to products such as batteries and fluorescent lamps, whose dump discharge can contaminate the bodies of water in the region in the rainy season. Due to fires from the harvest of sugar cane, high levels of Zn were found into the environment, in the dry season.

Investigations into the chemical composition and nutritive value of certain forage plants at medium altitudes in the tropics I. Seasonal variation in the chemical composition of the grasses Bothriochloa insculpta, Chloris gayana and Brachiaria dictyoneura, under rotational light grazing, with a note on the persistence of the grasses

1956 ◽  
Vol 47 (1) ◽  
pp. 29-34 ◽  
Author(s):  
J. R. Todd
Keyword(s):  
Chemical Composition ◽  
Protein Content ◽  
Rainy Season ◽  
Nutritive Value ◽  
Dry Season ◽  
East African ◽  
African Grasses ◽  
Chloris Gayana ◽  
Inorganic Constituents ◽  
The Tropics

Seasonal variations in the contents of organic and inorganic constituents of three East African grasses, Bothriochloa insculpta, Chloris gayana and Brachiaria dictyoneura are reported.Protein content is closely associated with rainfall and the stage of growth of the grasses. Protein content of from 15 to 20% is maintained for a short time only, at the beginning of the rainy season. During the dry season the values fall to 4–5%.Even in the vegetative phase the fibre contents are relatively high, 23% being the lowest figure recorded.A common feature of the grasses is a high content of silica, which may amount to more than 10% of the dry matter.The phosphorus content of the grasses is low, ranging from 0·65% P2O5 in young grass during the rainy season to 0·13% during the dry season.

scholarly journals Wing morphometrics reveals the migration patterns of Africanized honey bees in Northeast Brazil

Sociobiology ◽  
2018 ◽  
Vol 65 (4) ◽  
pp. 679
Author(s):  
Caroline Julio Moretti ◽  
Claudineia Pereira Costa ◽  
Tiago Maurício Francoy
Keyword(s):  
Geometric Morphometrics ◽  
Morphological Variation ◽  
Honey Bees ◽  
Rainy Season ◽  
Dry Season ◽  
Dispersion Pattern ◽  
Northeast Brazil ◽  
Africanized Honey Bees ◽  
Wing Morphometrics ◽  
Semi Arid

Climatic differences can directly affect the population structure of organisms. The Northeastern Brazilian covers an area of about 1.5 million square kilometres, in which the semi-arid part corresponds to approximately 60%. It is probably the most vulnerable region to climatic variations in Brazil. Here, we investigated the variability of Africanized honey bees in different localities from Northeast Brazil during the dry season and the influence of drought periods in morphological variation among populations. Analyses were carried out with data collected by traditional and geometric morphometrics of bees sampled during the dry season and showed a subtle morphological variation in agreement to the climatic pattern. Furthermore, once we added samples collected during the rainy season, we observed a change in its pattern, with a very different result from the same population sampled during drought periods. The geometric morphometrics results emphasized that samples collected during the rainy season in Mossoró would be more similar to bees from humid coastal areas. These results probably reflect the probable dispersion pattern of these bees between humid coastal and semi-arid areas.

Agronomy of Linseed Oil Cultivars (Linum usitatissimum) in Northern Nigeria

1977 ◽  
Vol 13 (1) ◽  
pp. 93-100 ◽  
Author(s):  
J. Y. Yayock ◽  
J. G. Quinn
Keyword(s):  
Seed Yield ◽  
Linum Usitatissimum ◽  
Linear Relation ◽  
Oil Content ◽  
Linseed Oil ◽  
Dry Season ◽  
Row Spacing ◽  
Northern Nigeria ◽  
Sowing Dates ◽  
Sudan Savanna

SUMMARYForty-six cultivars of linseed oil (Linum usitatissimum L.) were grown under wet and dry season conditions in the Sudan Savanna of Nigeria. Only during the dry season was production good and cv Dunes consistently outyielded all other cultivars in terms of seed and oil content. Trials of sowing dates gave maximum seed yield and oil content from plots sown during late October. In row spacing trials, rows 15–22 cm apart and seed rates of 58–78 kg/ha were found to be the most practicable. There was a linear relation between increasing rates of nitrogen and seed yield, maximum production being obtained at 55–88 kg N/ha, but oil content was slightly depressed at levels above 33 kg N/ha.

scholarly journals Vegetation indices as proxies for spatio-temporal variations in water availability in the Rio Santa valley (Peruvian Andes)

2021 ◽  
Author(s):  
Lorenz Hänchen ◽  
Cornelia Klein ◽  
Fabien Maussion ◽  
Wolfgang Gurgiser ◽  
Pierluigi Calanca ◽  
...  
Keyword(s):  
Water Availability ◽  
Rainy Season ◽  
Vegetation Indices ◽  
Growing Season ◽  
Dry Season ◽  
Season Length ◽  
Wet Season ◽  
Peruvian Andes ◽  
Spatio Temporal ◽  
Semi Arid

Abstract. In the semi-arid Peruvian Andes, the growing season is mostly determined by the timing of the onset and retreat of the wet season, to which annual crop yields are highly sensitive. Recently, local farmers in the Rio Santa basin (RSB) reported decreasing predictability of the onset of the rainy season and further challenges related to changes in rainfall characteristics. Previous studies based on time series of local rain gauges however, did not find any significant changes in either the timing or intensity of the wet season. Both in-situ and satellite rainfall data for the region lack the necessary spatial resolution to capture the highly variable rainfall distribution typical for complex terrain, and are often questionable in terms of quality and temporal consistency. To date, there remains considerable uncertainty in the RSB regarding hydrological changes over the last decades. In this study, we overcome this limitation by exploiting satellite-derived information on vegetation greenness to reveal a robust and highly resolved picture of recent changes in rainfall and vegetation phenology across the region: As the semi-arid climate causes water availability (i.e. precipitation) to be the key limiting factor for plant growth, patterns of precipitation occurrence and the seasonality of vegetation indices (VIs) are tightly coupled. Therefore, VIs can serve as an integrated proxy of rainfall. By combining MODIS Aqua and Terra VIs for 2000–2020 and several datasets of precipitation, we explore recent spatio-temporal changes in vegetation and water availability. Furthermore, we examine their links to El Niño Southern Oscillation (ENSO). While different rainfall datasets tend to be incoherent in the period of observation, we find significant greening over the majority of the RSB domain in VI data, particularly pronounced during the dry season (Austral winter). This indicates an overall increase of plant available water over time. The rainy season onset and consequently the start of the growing season (SOS) exhibits high inter-annual variability and dominates the growing season length (LOS). The end of the growing season (EOS) is significantly delayed in the analysis which matches the observed dry-season greening. By partitioning the results into periods of three stages of ENSO (neutral, Niño, Niña), we find an earlier SOS and an overall increased season length in years associated with El Niño. However, the appearance of Niño/Niña events during the analysed period cannot explain the observed greening and delayed EOS. While our study could not corroborate anecdotal evidence for recent changes in the SOS, we confirm that the SOS is highly variable and conclude that rainfed farming in the RSB would profit from future efforts being directed towards improving medium-range forecasts of the rainy season onset.

Plant DNA‐barcode library and community phylogeny for a semi‐arid East African savanna

2019 ◽  
Vol 19 (4) ◽  
pp. 838-846 ◽  
Author(s):  
Brian A. Gill ◽  
Paul M. Musili ◽  
Samson Kurukura ◽  
Abidikadir A. Hassan ◽  
Jacob R. Goheen ◽  
...  
Keyword(s):  
Dna Barcode ◽  
East African ◽  
African Savanna ◽  
Plant Dna ◽  
Semi Arid

The Effect of Climate on the Migrations and Breeding of Locusta migratorioides in Nigeria

1931 ◽  
Vol 22 (4) ◽  
pp. 551-569 ◽  
Author(s):  
Owen B. Lean
Keyword(s):  
Relative Humidity ◽  
Breeding Season ◽  
Rainy Season ◽  
Dry Season ◽  
High Humidity ◽  
Prevailing Wind ◽  
Breeding Ground ◽  
Local Conditions ◽  
The Mean ◽  
Climatic Elements

The locust infestation in Nigeria, from December 1929 to April 1931, is studied in relation to the climate and the following preliminary conclusions are made.1. Humidity, precipitation and wind are the relevant climatic elements. Temperature does not seem of importance.2. It is considered that the area of dispersal is limited by the humidity factor. With very few exceptions swarms remain where the mean relative humidity (9 a.m., L.M.T.) is not more than 85 per cent. and not less than 40 per cent., while most swarms are found where the humidity is from 60 per cent. to 80 per cent.3. This humidity belt is similar to the area covered by three main types of vegetation and the swarms move across the belt according to the humidity changes.4. Movement along the belt is largely caused by the prevailing wind.5. Breeding does not commence after the dry season until the humidity rises to 60 per cent. and the degree of wetness, calculated from the monthly rainfall, reaches 2. Breeding does not occur if the humidity is above 80 per cent.6. Through the dry season the adults seem unable to live much more than 22 weeks, and if optimum breeding conditions are not reached within that period death may occur.7. Breeding towards the end of the rainy season follows some 11 to 15 weeks after the locusts become adult, so long as the humidity is not more than 80 per cent., and high humidity may cause a diapause.8. Suitable local conditions during the dry season may allow a third breeding season.These conclusions may be utilised in the following ways :—1. To delimit the total area likely to be infested.2. To forecast when the different zones will be infested by flying swarms.3. To forecast whether and when breeding is likely to occur in each locality.4. To check whether unidentified swarms were of this species of locust.5. To test the possibility of one suspected breeding ground having been infested from another.

STUDI BIONOMIK VEKTOR MALARIA DI KECAMATAN KALIBAWANG, KULONPROGO

2018 ◽  
Vol 4 (2) ◽  
Author(s):  
Sardjito Eko Windarso dkk
Keyword(s):  
Land Use ◽  
Malaria Vector ◽  
Rainy Season ◽  
Dry Season ◽  
Physical Factors ◽  
Mosquito Vector ◽  
Anopheles Species ◽  
Commercial Farming ◽  
Study Results ◽  
Dry And Rainy Seasons

The increasing of malaria cases in recent years at Kecamatan Kalibawang has been suspected correspond with the conversion of farming land-use which initiated in 1993. Four years after the natural vegetation in this area were changed become cocoa and coffee commercial farming estates, the number of malaria cases in 1997 rose more than six times, and in 2000 it reached 6085. This study were aimed to observe whether there were any differences in density and diversity of Anopheles as malaria vector between the cocoa and mix farming during dry and rainy seasons. The results of the study are useful for considering the appropriate methods, times and places for mosquito vector controlling. The study activities comprised of collecting Anopheles as well as identifying the species to determine the density and diversity of the malaria vector. Both activities were held four weeks in dry season and four weeks in rainy season. The mea-surement of physical factors such as temperature, humidity and rainfall were also conducted to support the study results. Four dusuns which meet the criteria and had the highest malaria cases were selected as study location. Descriptively, the results shows that the number of collected Anopheles in cocoa farming were higher compared with those in mix horticultural farming; and the number of Anopheles species identifi ed in cocoa farming were also more varied than those in the mix horticultural farming.Key words: bionomik vektor malaria, anopheles,

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