scholarly journals Spatially different annual cycles but similar haemosporidian infections in distant populations of collared sand martins

BMC Zoology ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Steffen Hahn ◽  
Martins Briedis ◽  
Christos Barboutis ◽  
Raffaella Schmid ◽  
Martin Schulze ◽  
...  
Keyword(s):  
West Africa ◽  
Chronic Infection ◽  
Blood Parasite ◽  
Spring Migration ◽  
Lake Chad ◽  
Annual Cycles ◽  
Nonbreeding Season ◽  
Breeding Populations ◽  
High Parasitaemia ◽  
Western Palaearctic

Abstract Background Populations of long-distance migratory birds experience different environments and are consequently exposed to different parasites throughout their annual cycles. Though, specific whereabouts and accompanied host-parasite interactions remain unknown for most migratory passerines. Collared sand martins (Riparia riparia) breeding in the western Palaearctic spend the nonbreeding period in Africa, but it is not yet clear whether specific populations differ in overwintering locations and whether these also result in varying infections with vector-transmitted endoparasites. Results Geolocator tracking revealed that collared sand martins from northern-central and central-eastern Europe migrate to distant nonbreeding sites in West Africa and the Lake Chad basin in central Africa, respectively. While the ranges of these populations were clearly separated throughout the year, they consistently spent up to 60% of the annual cycle in Africa. Ambient light recorded by geolocators further indicated unsheltered roosting during the nonbreeding season in Africa compared to the breeding season in Europe. We found 5–26% prevalence of haemosporidian parasites in three breeding populations and one migratory passage population that was only sampled but not tracked. In total, we identified seven Plasmodium and nine Haemoproteus lineages (incl. two and seven new lineages, respectively), the latter presumably typical for swallows (Hirundinae) hosts. 99.5% of infections had a low intensity, typical for chronic infection stages, whereas three individuals (0.5%) showed high parasitaemia typical for acute infections during spring migration and breeding. Conclusions Our study shows that blood parasite infections are common in several western Palaearctic breeding populations of collared sand martins who spent the nonbreeding season in West Africa and the lake Chad region. Due to long residency at the nonbreeding grounds blood parasite transmissions may mainly occur at host population-specific residences sites in Europe and Africa; the latter being likely facilitated by unsheltered roosting and thus high vulnerability to hematophagous insects. The rare cases of high parasitaemia during spring migration and breeding further indicates either relapses of chronic infection or primary infections which occurred shortly before migration and during breeding.

scholarly journals The Intraseasonal Variability of African Easterly Wave Energetics

2014 ◽  
Vol 27 (17) ◽  
pp. 6559-6580 ◽  
Author(s):  
Ghassan J. Alaka ◽  
Eric D. Maloney
Keyword(s):  
West Africa ◽  
Energy Conversion ◽  
East Africa ◽  
Diabatic Heating ◽  
Heating Temperature ◽  
Intraseasonal Variability ◽  
West African ◽  
Boreal Summer ◽  
Lake Chad ◽  
Baroclinic Energy Conversion

Abstract African easterly waves (AEWs) and associated perturbation kinetic energy (PKE) exhibit significant intraseasonal variability in tropical North Africa during boreal summer. Consistent with East Africa (e.g., east of Lake Chad) being an initiation region for AEWs, previous studies have shown that increased East African PKE precedes and leads to increased West African AEW activity on intraseasonal time scales. In this study, reanalysis budgets of PKE and perturbation available potential energy (PAPE) are used to understand this behavior. The variability of PKE and PAPE sources is analyzed as a function of Madden–Julian oscillation (MJO) phase and a local 30–90-day West African PKE index to diagnose when and where eddy energy conversions terms are important to periods of increased or decreased intraseasonal AEW activity. In East Africa, an increased meridional temperature gradient locally enhances baroclinic energy conversion anomalies to initiate periods of increased intraseasonal AEW activity. Downstream barotropic and baroclinic energy conversions associated with strong AEWs are important for the maintenance of intraseasonal AEW activity in West Africa. Barotropic energy conversions dominate south of the African easterly jet (AEJ), while baroclinic energy conversions are most important north of the AEJ. In both East and West Africa, diabatic heating does not appear to aid intraseasonal PKE creation. Instead, negative PAPE tendency anomalies due to the diabatic heating–temperature covariance act as a negative feedback to increased baroclinic energy conversion downstream in the AEJ.

scholarly journals Tropospheric NO<sub>2</sub> concentrations over West Africa are influenced by climate zone and soil moisture variability

2017 ◽  
Author(s):  
Ajoke R. Onojeghuo ◽  
Heiko Balzter ◽  
Paul S. Monks
Keyword(s):  
Soil Moisture ◽  
West Africa ◽  
Linear Regression Models ◽  
Climate Zones ◽  
Climate Zone ◽  
Annual Cycles ◽  
Causality Tests ◽  
Arid Desert ◽  
Soil Moisture Variability ◽  
Moisture Variability

Abstract. The annual cycles of soil moisture and NO2 have been analysed across the climate zones of West Africa using two satellite data sets (OMI on AURA and ASCAT on MetOp-A). Exploring the sources and sinks for NO2 it is clear that the densely populated urban cities including Lagos and Abuja had the highest mean NO2 concentrations (> 1.8 × 1015 molecules cm−2) indicative of the anthropogenic urban emissions. The data analysis shows that rising soil moisture levels may influence the sink of NO2 concentrations after the biomass burning. The results also show significant soil moisture changes in areas of high humidity especially in the east equatorial monsoon climate zone where most of the Niger delta is located (4 %/yr.). A decline in NO2 (0.9 %/yr.) was also observed in this climate zone. Beyond seasonal linear regression models, climate based Granger’s causality tests show that tropospheric NO2 concentrations from soil emissions in the arid steppe (Sahel) and arid desert climate zones of West Africa are significantly affected by soil moisture variability (F > 10, p  0.8 %/yr). The results demonstrate the critical sensitivity of the West African emissions of NO2 on soil moisture and climate zone.

Of Man and Cattle: A Reconsideration of the Traditions of Origin of Pastoral Fulani of Nigeria

1991 ◽  
Vol 18 ◽  
pp. 1-21 ◽  
Author(s):  
A. G. Adebayo
Keyword(s):  
Twentieth Century ◽  
West Africa ◽  
Population Growth ◽  
Dominant Factor ◽  
Northern Nigeria ◽  
Lake Chad ◽  
The People ◽  
Southern Nigeria

The fair-skinned people who inhabit the Sudan fringes of west Africa stretching from the Senegal valley to the shores of Lake Chad and who speak the language known as Fulfulde, are known by many names.1 They call themselves Fulbe (singular, Pullo). They are called Fulani by the Hausa of southern Nigeria, and this name has been used for them throughout Nigeria. The British call them Ful, Fulani, or Fula, while the French refer to them as Peul, Peulh, or Poulah. In Senegal the French also inadvertently call them Toucouleur or Tukulor. The Kanuri of northern Nigeria call them Fulata or Felata. In this paper we will adopt the Hausa (or Nigerian) name for the people—Fulani.Accurate censuses are not available on the Fulani in west Africa. A mid-twentieth century estimate puts the total number of Fulani at “over 4 million,” more than half of whom are said to inhabit Nigeria. Another estimate towards the end of 1989 puts the total number of Nigeria's Fulani (nomads only) at over ten million. If both estimates were correct, then the Fulani population in Nigeria alone must have grown 500 per cent in forty years. The dominant factor in this population growth is increased immigration of pastoralists into Nigeria in the wake of the 1968-73 Sahelian drought.

Muslim Brotherhoods in West African History

2021 ◽  
Author(s):  
Mauro Nobili
Keyword(s):  
West Africa ◽  
18Th Century ◽  
West African ◽  
The Novel ◽  
African History ◽  
Lake Chad ◽  
History Of ◽  
Independent States ◽  
European Colonialism ◽  
Colonial Government

Muslim Sufi brotherhoods (ṭuruq, sing. ṭarīqa) are ubiquitous in contemporary Islamic West Africa. However, they are relative latecomers in the history of the region, making their appearance in the mid-18th century. Yet, Sufism has a longer presence in West Africa that predates the consolidation of ṭuruq. Early evidence of Sufi practices dates to the period between the 11th and the 17th centuries. By that time traces of the Shādhiliyya and the lesser-known Maḥmūdiyya are available between the Atlantic Ocean and Lake Chad, but it was the activities of the Kunta of the Qādiriyya and of al-ḥājj ‘Umar of the Tijāniyya that led to the massive spread of Sufi brotherhoods in the region. The authority of leaders of ṭuruq did not disappear with the imposition of European colonialism. In fact, the power of those leaders who adjusted to the novel political situation further consolidated thanks to their role as mediators between their constituencies and the colonial government. Eventually, the end of the colonial period did not signal the decline of ṭuruq in West Africa. Conversely, during the postcolonial years, Sufi brotherhoods continued flourishing despite the secular nature of West African independent states and the increasing tension with a plethora of equally rising Salafi movements.

On the recent Swarming of Locusta migratorioides, R. & F.

1931 ◽  
Vol 22 (3) ◽  
pp. 365-378 ◽  
Author(s):  
Owen B. Lean
Keyword(s):  
West Africa ◽  
East Africa ◽  
Water Regime ◽  
Breeding Ground ◽  
Lake District ◽  
Lake Chad ◽  
Breeding Grounds ◽  
Imperial Institute ◽  
Ultimate Control ◽  
River Niger

The present paper attempts to summarise the information collected by the Imperial Institute of Entomology on the swarming of migratorioides in Africa.It is concluded that the outbreaks in West, Central and East Africa are all interrelated and probably originated in one or at most two permanent breeding-grounds.The area most suspected is the lake district of the middle Niger, where conditions seem suitable for the formation of the swarming phase. Lake Chad is probably a secondary rather than a permanent breeding-ground.It is indicated that the key to the problem of the cause of the original outbreak may be found in the study of recent variations in the water régime of the River Niger.Should these suppositions be substantiated, we are well on the way towards a solution of the problem. The ultimate control of the locusts depends not on control during the swarming periods, but upon preventing the swarming phase from developing in the permanent breeding-grounds.It is therefore important to check and augment the records of the early swarms in West Africa and more important still, to study the behaviour of the locust, its ecology, and the water régime in the suspected areas.In conclusion the author wishes to acknowledge the constant help and advice of Mr. B. P. Uvarov. His thanks are also due to Mr. H. B. Johnston for his permission to make use of his paper in manuscript.

scholarly journals Population specific annual cycles and migration strategies in a leap-frog migrant

2021 ◽  
Vol 76 (1) ◽  
Author(s):  
Linus Hedh ◽  
Juliana Dänhardt ◽  
Anders Hedenström
Keyword(s):  
Annual Cycle ◽  
Light Level ◽  
Complex Interaction ◽  
Breeding Area ◽  
Annual Cycles ◽  
Breeding Populations ◽  
Migration Strategies ◽  
Migratory Population ◽  
Migratory Strategies ◽  
Specific Timing

Abstract A common migratory pattern in birds is that northerly breeding populations migrate to more southerly non-breeding sites compared to southerly breeding populations (leap-frog migration). Not only do populations experience differences in migration distances, but also different environmental conditions, which may vary spatiotemporally within their annual cycles, creating distinctive selective pressures and migratory strategies. Information about such adaptations is important to understand migratory drivers and evolution of migration patterns. We use light-level geolocators and citizen science data on regional spring arrivals to compare two populations of common ringed plover Charadrius hiaticula breeding at different latitudes. We (1) describe and characterize the annual cycles and (2) test predictions regarding speed and timing of migration. The northern breeding population (NBP) wintered in Africa and the southern (SBP) mainly in Europe. The annual cycles were shifted temporally so that the NBP was always later in all stages. The SBP spent more than twice as long time in the breeding area, but there was no difference in winter. The NBP spent more time on migration in general. Spring migration speed was lower in the SBP compared to autumn speed of both populations, and there was no difference in autumn and spring speed in the NBP. We also found a larger variation in spring arrival times across years in the SBP. This suggests that a complex interaction of population specific timing and variation of breeding onset, length of breeding season, and proximity to the breeding area shape the annual cycle and migratory strategies. Significance statement Migration distance, climate, and the resulting composition of the annual cycle are expected to influence migration strategies and timing in birds. Testing theories regarding migration behaviours are challenging, and intraspecific comparisons over the full annual cycle are still rare. Here we compare the spatiotemporal distributions of two latitudinally separated populations of common ringed plovers using light-level geolocators. We found that there was a larger long-term variation in first arrival dates and that migration speed was slower only in spring in a temperate, short-distance migratory population, compared to an Arctic, long-distance migratory population. This suggests that a complex interaction of population specific timing and variation of breeding onset, length of breeding season and proximity to the breeding area shape the annual cycle and migratory behaviours.

scholarly journals Contribution of the triple oxygen isotope composition of precipitation to the identification of surface-atmosphere interactions in the sub-humid part of West Africa

2020 ◽  
Author(s):  
Christine Vallet-Coulomb ◽  
Anne Alexandre ◽  
Christophe Peugeot ◽  
Abdoukarim Alassane ◽  
Vinel Gbewezoun ◽  
...  
Keyword(s):  
Stable Isotope ◽  
West Africa ◽  
Isotope Composition ◽  
Phase Changes ◽  
Water Evaporation ◽  
Stable Isotope Composition ◽  
Initial Water ◽  
Positive Feedbacks ◽  
Lake Chad ◽  
Surface Atmosphere

&lt;p&gt;This study aims at evaluating the information carried by the &lt;sup&gt;17&lt;/sup&gt;O-excess composition of precipitation in the sub-humid part of West Africa. Located at the southern border of the Sahelian band, the so-called &amp;#8220;Sudanian Climatic Zone&amp;#8221;, characterized by annual precipitation of 1200-1400mm, plays a crucial role in providing water to large African watersheds such as the Niger river&amp;#8217;s one, and the Lake Chad catchment. Surface-atmosphere interactions were shown to influence convective processes in the semi-arid Sahelian band, with positive feedbacks between vegetation land cover and rainfall. Less focus has been put on the more humid Sudanian Zone, although surface-atmosphere interactions may have an important influence on the control of rainfall variations, and therefore on water resource availability in these watersheds.&lt;/p&gt;&lt;p&gt;The stable isotope composition of precipitation reflects the combination of different processes associated with phase changes over the atmospheric water cycle, from the initial water vapor formation above the ocean to the raindrop on the ground surface. Classical tracers (&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O, &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H, and d-excess) are affected by multiple factors (i.e. Rayleigh process, temperature, humidity) changing during these successive steps. In contrast, &lt;sup&gt;17&lt;/sup&gt;O-excess variations mainly records evaporation processes controlled by the humidity conditions that prevail during phase change. There are few available &lt;sup&gt;17&lt;/sup&gt;O-excess studies focusing on precipitation in tropical and sub-tropical areas. They show that the &lt;sup&gt;17&lt;/sup&gt;O-excess in precipitation provides information on 1) relative humidity at oceanic moisture sources, and 2) secondary processes, such as raindrop re-evaporation. The contribution of vapor of continental origin, produced either by plant transpiration or soil water evaporation, should additionally affect the &lt;sup&gt;17&lt;/sup&gt;O-excess signature of precipitation, although no data are available so far to evaluate the magnitude of this process.&lt;/p&gt;&lt;p&gt;For the study presented here, we collected precipitation from two sampling stations, both located in Benin and affected by a similar oceanic moisture source in the Gulf of Guinea. The first station (lat. 6&amp;#176;26&amp;#8217; N; long. 2&amp;#176;21&amp;#8217; E) is located along the coast and is essentially subject to oceanic influence. The second station (lat. 9&amp;#176;44&amp;#8217; N; long. 1&amp;#176;34&amp;#8217; E) is located 400 km inland and may be additionally affected by continental vapor recycling. The stable isotope composition of rainfall samples (&amp;#948;&lt;sup&gt;2&lt;/sup&gt;H, &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;&lt;sup&gt;17&lt;/sup&gt;O) are measured on a WS-CRDS Picarro L2140-i, using three replicates per sample. Comparison between those two records allow to investigate how humidity at the oceanic source, raindrop re-evaporation and continental vapor&amp;#173; contribute to the &lt;sup&gt;17&lt;/sup&gt;O-excess signature of precipitation.&lt;/p&gt;

Interregional Monetary Flows in the Precolonial Trade of Nigeria

1974 ◽  
Vol 15 (4) ◽  
pp. 563-585 ◽  
Author(s):  
Paul E. Lovejoy
Keyword(s):  
Economic Theory ◽  
West Africa ◽  
Niger Delta ◽  
African History ◽  
Common Currency ◽  
The West ◽  
Lake Chad ◽  
Cross River ◽  
The North ◽  
Volta Basin

Only recently have historians devoted much attention to monetary developments in African history, primarily because the substantivist school of economic anthropology, which has argued that so-called western economic theory does not apply to African situations, has dominated the field. This view has been increasingly under attack in recent years, particularly by a new group of economic historians who have found many aspects of formal economic theory useful in the reconstruction of Africa's past. Marion Johnson's pioneering work on the gold mithqal and cowrie shell, for example, has documented the spread of a common currency over much of West Africa, throughout an area encompassed by Lake Chad in the east, the upper reaches of the Senegambia in the west, the southern Sahara in the north, and the region between the Volta basin and the Niger Delta in the south. The study of other currencies, including the copper rod standard of the Cross River basin in Nigeria and Cameroons, and the cloth money of the Senegambia, has demonstrated the importance of other standards besides cowries and gold, so that it is now known that virtually all of precolonial West Africa had economies sufficiently developed to require the use of circulating mediums of exchange and units of account. This breakthrough raises a number of important questions which seriously challenge, if not completely undermine, the predominant view that Africa's past, down to very recent times, has been subsistence oriented, non-market directed, and basically static.

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