Seasonal variation in foraging behaviour of plains zebra (Equus quagga) may alter contact with the anthrax bacterium (Bacillus anthracis)

2014 ◽  
Vol 92 (4) ◽  
pp. 331-337 ◽  
Author(s):  
Zepee Havarua ◽  
Wendy C. Turner ◽  
John K.E. Mfune
Keyword(s):  
Seasonal Variation ◽  
Bacillus Anthracis ◽  
Foraging Behaviour ◽  
Dry Season ◽  
Wet Season ◽  
Contact Rates ◽  
Bacterium Bacillus ◽  
Environmental Pathogens ◽  
Host Foraging ◽  
Plains Zebra

Pathogens transmitted via the environment are often aggregated in space, and seasonal variation in wildlife foraging behaviour may alter contact rates with environmental pathogens. The soil-borne bacterium Bacillus anthracis Cohn, 1872 causes anthrax, and herbivores acquire gastrointestinal anthrax by ingesting spores. Therefore host foraging behaviour could be a fundamental component of anthrax epidemiology. This study investigated seasonal changes in bite density and diet of plains zebras (Equus quagga Boddaert, 1785) in relation to anthrax seasonality in Etosha National Park, Namibia, where most zebra anthrax cases are observed in wet seasons. The diet of zebras shifted from more short grasses during the wet season to more tall grasses in the dry season, suggesting a greater potential for soil ingestion in wet seasons. Zebras also foraged most intensively in the wet season with the number of bites/step declining through the dry season. This higher bite density in wet seasons may lead individuals to ingest greater concentrations of the pathogen if foraging in a localized infectious area. Although sex and reproductive state affected bite density, no sex difference in anthrax occurrence was observed. This study demonstrates how considering variation in host foraging behaviour may enhance our understanding of disease seasonality for pathogens with foraging-dependent transmission.

scholarly journals Seasonal variation in quality of Louhajong river water, Tangail

2016 ◽  
Vol 28 (1) ◽  
pp. 9-16
Author(s):  
Md Rakib Hasan Sarker ◽  
Asadul Islam ◽  
Ariful Islam ◽  
Md Mahbubul Hoque ◽  
Shimul Roy
Keyword(s):  
Seasonal Variation ◽  
River Water ◽  
Water Samples ◽  
Dry Season ◽  
Fish Culture ◽  
Chemical Parameters ◽  
Wet Season ◽  
Physico Chemical ◽  
Standard Level

Water samples were collected from three points of Louhajong river (Dighulia, Kagmari Bridge and Oloa) to see the seasonal variation in physico-chemical parameters. The results revealed that some of the parameters such as TDS, alkalinity and acidity have exceeded the standard level in dry season in all of the points, which are unsuitable for different purposes including fish culture. During dry and wet seasons the highest concentrations of BOD was recorded as 2.0 and 0.8 ppm at Kagmari Bridge (point-2) respectively. DO ranged from 1.4 to 3.1 and 2.4 to 3.8 ppm during dry and wet seasons. Maximum and minimum EC was recorded as 890 and 130 ?s/cm at Dighulia (point-1) during dry and wet seasons. The results suggest that at wet season Louhajong river may be suitable for fish culture and other purposes.Bangladesh J. Sci. Res. 28(1): 9-16, June-2015

scholarly journals THE EFFECT OF SEASONAL VARIATION ON PERFORMANCE OF EGG TYPE POULTRY: A Case Study of Mitchell Farms, Mosogar, Delta State, Nigeria

2021 ◽  
Vol 24 (2) ◽  
pp. 101-105
Author(s):  
E. E. Guobadia
Keyword(s):  
Seasonal Variation ◽  
Feed Intake ◽  
Egg Production ◽  
Management Practices ◽  
Secondary Data ◽  
Dry Season ◽  
Wet Season ◽  
Egg Hatchability ◽  
Significant Difference

The study was designed to find out the effect of seasonal variation on poultry in Delta State of Nigeria. The variables considered were mortality rate, feed intake, egg production and egg hatchability in the wet and dry seasons of the year. Secondary data were also collected from records kept in the farm. Sites 4AHI-BLK,5AKI-BLK, 9H/BF and 10H/BF were used for the study with each having an average of 2,500-3,500 birds of the same breed and sex aged 1-9 weeks and 21-52weeks. The records were grouped into dry season (October-March) and wet season (April-September) covering three years, 1991-1994. The analysis of the result showed that seasonal variation does not have any significant effect (P < 0.05) on mortality and feed intake in the two seasons. However percentage egg production and egg hatchability revealed a significant difference (P < 0.05) between the two seasons, with a mean % egg production and hatchability of 74±.03 and 80.6 in the wet season and 53.67±0.01 and 55.9 respectively in the dry season. Recommendation is therefore made for proper planning which ensures the utilization of wet and dry season management practices to reduce the effect of high humidity and embient temperature on production.

scholarly journals The Cost of Reproduction in a Cooperatively Breeding Mammal: Consequences of Seasonal Variation in Rainfall, Reproduction, and Reproductive Suppression

2021 ◽  
Vol 12 ◽  
Author(s):  
Paul Juan Jacobs ◽  
Daniel William Hart ◽  
Tobias Suess ◽  
Andries Koch Janse van Vuuren ◽  
Nigel Charles Bennett
Keyword(s):  
Oxidative Stress ◽  
Seasonal Variation ◽  
Cost Of Reproduction ◽  
Dry Season ◽  
Breeding Period ◽  
Wet Season ◽  
Reproductive Suppression ◽  
Mole Rat ◽  
Cooperatively Breeding ◽  
The Cost

Biological investments, such as reproduction, are influenced by both biotic and abiotic factors and their interactions. The trade-off between reproduction and survival has been well established. Seasonally breeding species, therefore, may exhibit variations in these trade-offs, but there is a dearth of knowledge concerning this. This study investigated the physiological cost of reproduction (measured through oxidative stress) across seasons in the cooperatively breeding highveld mole-rat (Cryptomys hottentotus pretoriae), one of the few seasonal breeding mole-rats. Oxidative stress indicates elevated reactive oxygen species (ROS) levels, which can overwhelm antioxidant defences resulting in damaged proteins, lipids and DNA, which overall can reduce longevity and compromise reproduction. Oxidative markers such as total oxidant status (TOS-measure of total peroxides present), total antioxidant capacity (TAC), oxidative stress index (OSI), and malondialdehyde (MDA) are utilised to measure oxidative stress. In this study, breeding and non-breeding male (NBM) and female mole-rats were captured during the dry season (breeding period) and wet season (non-breeding period). There was an apparent cost of reproduction in the highveld mole-rat; however, the seasonality pattern to the cost of reproduction varied between the sexes. Breeding females (BFs) had significantly higher MDA during the breeding period/dry season in comparison to the non-breeding period/wet season; this is possibly a consequence of bearing and nursing offspring. Contrastingly, breeding males (BMs) showed increased oxidative damage in the non-breeding/wet season compared to the breeding/dry season, possibly due to increased activities of protecting their mating rights for the next breeding/dry season, but this was not significant. Interestingly, during the non-breeding period/wet season, non-breeding females (NBFs) are released from their reproductive suppression, which resulted in increases in TOS and OSI, which again indicated that just the mere ability to be able to breed results in a cost (oxidative stress). Therefore we can speculate that highveld mole-rats exhibited seasonal variation in redox balance brought about by variation in abiotic variables (e.g., rainfall), physiology and behaviour. We conclude that physiological changes associated with reproduction are sufficient to induce significant acute oxidative stress in the plasma of female highveld mole-rats, which become alleviated following transition to the non-breeding season/wet period suggesting a possible hormetic effect.

scholarly journals Seasonality and pathogen transmission in pastoral cattle contact networks

2017 ◽  
Vol 4 (12) ◽  
pp. 170808 ◽  
Author(s):  
Kimberly VanderWaal ◽  
Marie Gilbertson ◽  
Sharon Okanga ◽  
Brian F. Allan ◽  
Meggan E. Craft
Keyword(s):  
Water Resources ◽  
Disease Outbreaks ◽  
Dry Season ◽  
Pathogen Transmission ◽  
Contact Network ◽  
Wet Season ◽  
Contact Networks ◽  
Contact Rates ◽  
Animal Populations ◽  
The Impact

Capturing heterogeneity in contact patterns in animal populations is essential for understanding the spread of infectious diseases. In contrast to other regions of the world in which livestock movement networks are integral to pathogen prevention and control policies, contact networks are understudied in pastoral regions of Africa due to the challenge of measuring contact among mobile herds of cattle whose movements are driven by access to resources. Furthermore, the extent to which seasonal changes in the distribution of water and resources impacts the structure of contact networks in cattle is uncertain. Contact networks may be more conducive to pathogen spread in the dry season due to congregation at limited water sources. Alternatively, less abundant forage may result in decreased pathogen transmission due to competitive avoidance among herds, as measured by reduced contact rates. Here, we use GPS technology to concurrently track 49 free-roaming cattle herds within a semi-arid region of Kenya, and use these data to characterize seasonal contact networks and model the spread of a highly infectious pathogen. This work provides the first empirical data on the local contact network structure of mobile herds based on quantifiable contact events. The contact network demonstrated high levels of interconnectivity. An increase in contacts near to water resources in the dry season resulted in networks with both higher contact rates and higher potential for pathogen spread than in the wet season. Simulated disease outbreaks were also larger in the dry season. Results support the hypothesis that limited water resources enhance connectivity and transmission within contact networks, as opposed to reducing connectivity as a result of competitive avoidance. These results cast light on the impact of seasonal heterogeneity in resource availability on predicting pathogen transmission dynamics, which has implications for other free-ranging wild and domestic populations.

scholarly journals Seasonal Variation and Ecological Risk Assessment of Heavy Metal in an Estuarine Mangrove Wetland

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2064
Author(s):  
Hualong Hong ◽  
Binghuang Zhang ◽  
Haoliang Lu
Keyword(s):  
Risk Assessment ◽  
Seasonal Variation ◽  
Metal Pollution ◽  
Toxic Metal ◽  
Dry Season ◽  
Wet Season ◽  
Mangrove Wetland ◽  
Mangrove Wetlands ◽  
Zn And Cu In ◽  
Potential Toxic Metals

Potential toxic metal pollution in mangroves has attracted extensive attention globally; however, the seasonal variation of potential toxic metals in mangrove wetlands is still poorly understood. Herein, we investigated the variation of content as well as chemical speciation of typical metals (Pb, Cr, Zn and Cu) in the sediments from the Zhangjiang Estuary mangrove wetland, China. The potential risk of metal contamination was also investigated. Compared to the wet season, we found that sediment metal content was higher in the dry season. Mangrove sites show accumulated significant metals than does the mudflat both in wet and dry seasons. Geo-accumulation (Igeo) shows moderate pollution, probably because of the dilution as result of runoff and tidal hydrodynamics in the wet season. Increased concentrations of all metals in the acid-soluble fraction and decreased metal contents in the residue fraction were found in the dry season. Risk assessment indicated that the concentrations of Pb poses a higher environmental risk in the dry season. These results can increase awareness of metal pollution in the dry season and provide information for potential toxic metal management in mangrove wetlands.

Seasonal Distribution and Diversity of Termite Taxa in Different Habitats in the Middle Montane Ecozone of Northwestern Ethiopia

2019 ◽  
Author(s):  
Melaku Wale ◽  
Desalegn Nega
Keyword(s):  
Foraging Behaviour ◽  
Diversity Index ◽  
Dry Season ◽  
Remedial Action ◽  
Wet Season ◽  
Weather Variables ◽  
Number Of Individuals ◽  
Maize Stalks ◽  
Shannon’S Diversity Index ◽  
Index Of Diversity

Abstract Background: Knowledge of the diversity and occurrence of termites is important for environmental management, but this is unknown in the Bahir Dar Zuria area of northwestern Ethiopia, which represents tepid to cool sub-moist mid-highlands or also known as the middle montane ecozone. The objective of this study was to identify termite taxa and determine the diversity and distribution of termites in different habitats in the middle montane ecozone. Data were collected for eight months starting from December 2016 to July 2017. Termites were collected from different habitats using maize stalks as baits. Results: A total of over 16,000 termite individuals representing one family (Termitidae), two subfamilies, i.e., Macrotermitinae and Termitinae, and five genera (Macrotermes, Odontotermes, Microtermes, Amitermes and Microcerotermes) were found. More Microtermes and Macrotermes termite individuals were found than on other genera. Microtermes and Macrotermes were more abundant. Shannon’s diversity index and Simpson's index of diversity values appeared to be higher in the protected vegetation. The distribution of termites in the different habitats showed that protected vegetation had more genera (five genera), followed by grass and cultivated lands (four genera each). Termite populations were significantly higher during the rainy season. The genus Odontotermes occurred more during the dry season than the wet season, indicating its foraging behaviour on dry ground. Season, habitat and weather variables were the main factors dictating the type of taxa, distribution and abundance of termites in the study area. Generally, number of individuals increased in the wet and declined in the dry season. Microcerotermes was not found in grasslands and Amitermes in cultivated fields, indicating distinct difference in habitat preference. Conclusions: Some taxa could be used as indicators of different habitats and seasons because they specialize in these attributes. They also show the degree of environmental degradation and the need for remedial action. Keywords: Biodiversity, Isoptera, Termites, Abundance, Microtermes, Macrotermes, Odontotermes, Habitat, northwestern Ethiopia

scholarly journals Manakins (Pipridae) in Second-Growth and Old-Growth Forests: Patterns of Habitat Use, Movement, and Survival

The Auk ◽  
2002 ◽  
Vol 119 (1) ◽  
pp. 132-148 ◽  
Author(s):  
John G. Blake ◽  
Bette A. Loiselle
Keyword(s):  
Seasonal Variation ◽  
Habitat Use ◽  
Survival Rates ◽  
Dry Season ◽  
Wet Season ◽  
Old Growth ◽  
Old Growth Forest ◽  
Second Growth ◽  
Old Growth Forests ◽  
Capture Rates

AbstractWe used capture and recapture data (1985 to 1994) to examine seasonal variation in habitat use, movements within and among habitats, and survival rates of manakins (Manacus candei, Corapipo altera, Pipra mentalis, P. pipra) in northeastern Costa Rica. Manakins were captured in young and old second-growth woodlands in the lowlands and in old-growth forest at approximately 50, 500, and 1,000 m. Manakin species differed in their use of habitats, with old-growth forest species showing large and predictable seasonal variation in capture rates. Corapipo capture rates in lowland (nonbreeding) habitats were greater during the wet season than during the dry season and were greater in old-growth forest than in second growth. Capture rates at 500 m were higher in the dry season. Pipra mentalis capture rates were high in second growth and old growth. Capture rates were higher in the wet season and were correlated with capture rates of Corapipo, indicating that at least some individual P. mentalis migrate along the elevational gradient. P. pipra capture rates were highest at 1,000 m; few individuals descended to lowlands in the wet season. Manacus capture rates were highest in young second growth and did not vary between wet and dry seasons. Use of second-growth habitats by species typically associated with old-growth forests illustrates the value of maintaining a mosaic of habitats to accommodate seasonal changes in use of habitats. Contrary to expectations based on lek mating systems, there was little evidence that movements within habitats (i.e. recapture distances) varied between sexes. Yet, recapture percentages were higher in all species for adult females than males. Adult survival rates were ∼0.75 for Manacus in young second growth, 0.62 for Corapipo in old-growth forest at 50 m and 0.66 at 500 m, and 0.70 for Pipra mentalis in lowland old-growth forest. Results support the suggestion that geographic variation in survival rates may be common in the tropics and illustrate the need for examining survival rates separately by age and sex.

Diet and habitat-niche relationships within an assemblage of large herbivores in a seasonal tropical forest

2012 ◽  
Vol 28 (4) ◽  
pp. 385-394 ◽  
Author(s):  
Farshid S. Ahrestani ◽  
Ignas M. A. Heitkönig ◽  
Herbert H. T. Prins
Keyword(s):  
Seasonal Variation ◽  
Habitat Selection ◽  
South India ◽  
Niche Breadth ◽  
Niche Overlap ◽  
Dry Season ◽  
Wet Season ◽  
Large Herbivores ◽  
Axis Axis ◽  
Habitat Niche

Abstract:There is little understanding of how large mammalian herbivores in Asia partition habitat and forage resources, and vary their diet and habitat selection seasonally in order to coexist. We studied an assemblage of four large herbivores, chital (Axis axis), sambar (Cervus unicolor), gaur (Bos gaurus) and Asian elephant (Elephas maximus), in the seasonal tropical forests of Bandipur and Mudumalai, South India, and tested predictions regarding the species’ seasonal diet browse : graze ratios, habitat selection and habitat-niche preference and overlap. Field data collected for the study included the seasonal variation in grass quality, the seasonal variation in δ13C in the species’ faeces and the seasonal variation in the species’ habitat selection and overlap using a grid-based survey. Results of the δ13C analyses showed that the chital was more of a grazer in the wet season (−17.9‰ to −21.6‰), but that it increased the proportion of browse in its diet in the dry season (−25.6‰ to −27.7‰); the gaur was a grazer for most of the year (−15.3‰ to −18.6‰); the sambar preferred to browse throughout the year (−21.1‰ to −30.4‰); and that the elephant was a mixed feeder (−14.2‰ to −21.4‰). Elephant habitat-niche breadth was high (0.53 in wet and 0.54 in dry) and overlapped equally with that of the other species in both seasons (0.39–0.94). The gaur had the most restricted habitat-niche breadth in both seasons (0.25 in wet and 0.28 in dry), and it switched from the moist deciduous habitat in the dry season to the dry deciduous habitat in the wet season. These results offer the first insights into the seasonal variation in browse : graze diet ratios and the habitat-niche overlap amongst the common largest-bodied mammalian herbivore species found in South India.

Seasonal Patterns in Soil Moisture, Vapour Pressure Deficit, Tree Canopy Cover and Pre-dawn Water Potential in a Northern Australian Savanna

1997 ◽  
Vol 45 (2) ◽  
pp. 211 ◽  
Author(s):  
G. A. Duff ◽  
B. A. Myers ◽  
R. J. Williams ◽  
D. Eamus ◽  
A. O'Grady ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Seasonal Variation ◽  
Water Potential ◽  
Vapour Pressure ◽  
Canopy Cover ◽  
Vapour Pressure Deficit ◽  
Dry Season ◽  
Tree Canopy ◽  
Wet Season ◽  
Tree Canopy Cover

The wet–dry tropics of northern Australia are characterised by extreme seasonal variation in rainfall and atmospheric vapour pressure deficit, although temperatures are relatively constant throughout the year.This seasonal variation is associated with marked changes in tree canopy cover, although the exact determinants of these changes are complex. This paper reports variation in microclimate (temperature, vapour pressure deficit (VPD)), rainfall, soil moisture, understorey light environment (total daily irradiance), and pre-dawn leaf water potential of eight dominant tree species in an area of savanna near Darwin, Northern Territory, Australia. Patterns of canopy cover are strongly influenced by both soil moisture and VPD. Increases in canopy cover coincide with decreases in VPD, and occur prior to increases in soil moisture that occur with the onset of wet season rains. Decreases in canopy cover coincide with decreases in soil moisture following the cessation of wet season rains and associated increases in VPD. Patterns of pre-dawn water potential vary significantly between species and between leaf phenological guilds. Pre-dawn water potential increases with decreasing VPD towards the end of the dry season prior to any increases in soil moisture. Decline in pre-dawn water potential coincides with both decreasing soil moisture and increasing VPD at the end of the dry season. This study emphasises the importance of the annual transition between the dry season and the wet season, a period of 1–2 months of relatively low VPD but little or no effective rainfall, preceded by a 4–6 month dry season of no rainfall and high VPD. This period is accompanied by markedly increased canopy cover, and significant increases in pre-dawn water potential, which are demonstrably independent of rainfall. This finding emphasises the importance of VPD as a determinant of physiological and phenological processes in Australian savannas.

Ecology of the Northern Bettong, Bettongia tropica, a Tropical Mycophagist

1997 ◽  
Vol 24 (5) ◽  
pp. 549 ◽  
Author(s):  
C. N. Johnson ◽  
A. P. McIlwee
Keyword(s):  
Seasonal Variation ◽  
Body Condition ◽  
Forest Type ◽  
Dry Season ◽  
Wet Season ◽  
Hypogeous Fungi ◽  
Eucalyptus Forest ◽  
Seasonal Ecology ◽  
North Eastern ◽  
Open Woodland

The diet and seasonal ecology of the northern bettong, Bettongia tropica, was studied at three sites along a moisture gradient from closed Allocasuarina-Eucalyptus forest to dry open woodland in north-eastern Queensland. At each site, fungi (sporocarps of hypogeous ectomycorrhizal species) were the major food, and most of the remainder of the diet consisted of grass leaf and stem, roots and tubers, and lilies. Forbs and invertebrates were also eaten, but in small quantities. Fungus consumption was greatest at the wettest forest type and least at the driest site. Seasonal variation was insignificant except at the driest site, where fungus consumption peaked in the late wet season and dropped during the dry season; this seasonal fall in fungus consumption was associated with an increase in consumption of grass and roots and tubers. There was little seasonal variation in body condition, except at the driest site, where the dry-season decline in the proportional representation of fungus in the diet was associated with a decline in body condition. Breeding was continuous and aseasonal. B. tropica is found only in a narrow zone of sclerophyll forest along the western edge of wet tropical rainforest in north-eastern Queensland. We suggest that this species (like bettongs and potoroos in southern Australia) depends on hypogeous fungi, and that expansion of its geographical range into drier forest types is prevented by shortages of fungus during the dry season.

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