scholarly journals Temperature as a constraint on the timing and duration of African elephant foraging trips

2020 ◽  
Author(s):  
David Rozen-Rechels ◽  
Hugo Valls-Fox ◽  
Cheryl Tinashe Mabika ◽  
Simon Chamaillé-Jammes
Keyword(s):  
Dry Season ◽  
Sweat Glands ◽  
Arid Environments ◽  
African Elephants ◽  
Large Herbivores ◽  
Daily Movement ◽  
Thermal Constraints ◽  
Terrestrial Animal ◽  
Hwange National Park ◽  
Hot Environments

Abstract In arid and semiarid environments, water is a key resource that is limited in availability. During the dry season, perennial water sources such as water pans often are far apart and shape the daily movement routines of large herbivores. In hot environments, endotherms face a lethal risk of overheating that can be buffered by evaporative cooling. Behavioral adjustments are an alternative way to reduce thermal constraints on the organism. The trade-off between foraging and reaching water pans has been studied widely in arid environments; however, few studies have looked into how ambient temperature shapes individual trips between two visits to water. In this study, we tracked during the dry season the movement of eight GPS-collared African elephants (Loxodonta africana) cows from different herds in Hwange National Park, Zimbabwe. This species, the largest extant terrestrial animal, is particularly sensitive to heat due to its body size and the absence of sweat glands. We show that most foraging trips depart from water at nightfall, lowering the average temperature experienced during walking. This pattern is conserved across isolated elephant populations in African savannas. We also observed that higher temperatures at the beginning of the trip lead to shorter trips. We conclude that elephants adjust the timing of foraging trips to reduce the thermal constraints, arguing that further considerations of the thermal landscape of endotherms are important to understand their ecology.

scholarly journals Driving factors of temporary and permanent shallow lakes in and around Hwange National Park, Zimbabwe

Water SA ◽  
2018 ◽  
Vol 44 (2 April) ◽  
Author(s):  
Stembile Msiteli-Shumba ◽  
Shakki Kativu ◽  
Beaven Utete ◽  
Edwin Makuwe ◽  
Florence D Hulot
Keyword(s):  
Land Use ◽  
Water Level ◽  
Aquatic Ecosystems ◽  
National Park ◽  
Water Hardness ◽  
Dry Season ◽  
Driving Factors ◽  
Water Level Fluctuations ◽  
Arid Environments ◽  
Hwange National Park

Small aquatic ecosystems in semi-arid environments are characterised by strong seasonal water level fluctuations. In addition, land use as well as artificial pumping of groundwater to maintain water resources throughout the dry season may affect the functioning of aquatic ecosystems. In this study, we investigated pans situated in and around Hwange National Park, Zimbabwe, where certain waterholes are artificially maintained during the dry season for conservation purposes. We monitored 30 temporary and permanent waterholes for 7 months across the wet and dry seasons in 2013, and analysed them for standard parameters to investigate seasonal variations, assess the effects of land use and pumping on lake functioning, and determine the driving factors of these aquatic systems. Results show an increase in conductivity, hardness, and turbidity when temporary pans dry up and permanent ones are filled with groundwater. Prominent parameters explaining the diversity of aquatic ecosystems are water hardness, conductivity, turbidity, and the presence of vegetation. Seasonality differences in certain parameters suggest the influence of water level fluctuations associated with rainfall, evaporation, and pumping activities. Further, the distinction between turbid pans and those with clear water and vegetation suggests the alternative functioning of pans. Land use had no significant effects, while the effects of pumping are discussed. In times of water scarcity, animals gather around artificially maintained waterholes and foul water with faeces and urine, thus inducing water eutrophication.

Home range and space use by African elephants ( Loxodonta africana ) in Hwange National Park, Zimbabwe

2021 ◽  
Author(s):  
Liberty Mlambo ◽  
Munyaradzi Davis Shekede ◽  
Elhadi Adam ◽  
John Odindi ◽  
Amon Murwira
Keyword(s):  
Home Range ◽  
National Park ◽  
Space Use ◽  
Loxodonta Africana ◽  
African Elephants ◽  
Hwange National Park

Spatial relationship between elephant and sodium concentration of water disappears as density increases in Hwange National Park, Zimbabwe

2007 ◽  
Vol 23 (6) ◽  
pp. 725-728 ◽  
Author(s):  
Simon Chamaillé-Jammes ◽  
Hervé Fritz ◽  
Ricardo M. Holdo
Keyword(s):  
National Park ◽  
Spatial Relationship ◽  
Sodium Concentration ◽  
African Elephants ◽  
Mineral Concentration ◽  
Savanna Vegetation ◽  
Selection Processes ◽  
Elephant Population ◽  
Hwange National Park ◽  
Nutrient Selection

African elephants Loxodonta africana (Blumenbach) may profoundly affect vegetation and associated animal bio-diversity in savannas (Conybeare 2004, Skarpe et al. 2004). Understanding the patterns of habitat use by elephants is crucial to predict their impacts on ecosystems (Ben-Shahar 1993, Nelleman et al. 2002), particularly now that many populations are recovering from past culling events or poaching outbreaks (Blanc et al. 2007). Surface water is one of the major constraints on elephant distribution (Chamaillé-Jammes et al. 2007, Stokke & du Toit 2002), and accordingly, elephant impacts are higher in the vicinity of water (Ben-Shahar 1993, de Beer et al. 2006). However, waterhole selection by elephant remains poorly understood. Weir (1972) showed in Hwange National Park (hereafter Hwange NP), Zimbabwe, that elephant numbers at waterholes over 24 h increased with the sodium concentration of water on nutrient-poor Kalahari sands. His work has become widely cited in elephant studies as it remains the only one, to the best of our knowledge, to have studied elephant use of waterholes in relation to the mineral concentration of water. Weir's work, however, took place when elephant densities in Hwange NP were low, likely below 0.5 elephants km−2 as estimated by aerial censuses (Williamson 1975). Since then, the elephant population has increased dramatically, particularly since the halt to culling operations in 1986 (Chamaillé-Jammes 2006, Cumming 1981). The present elephant density is much higher, estimated to be over 2 elephants km−2 (Chamaillé-Jammes et al. 2007, in press), and is one of the highest in the world (Blanc et al. 2007). Increased density may modify ecological constraints and affect the hierarchy of habitat selection processes (Morris 2003), and the extent to which water-nutrient selection still constrains elephant distribution at high population density – when their impact on savanna vegetation is the highest – remains unknown.

Water Balance in Giraffes

2021 ◽  
pp. 241-260
Author(s):  
Graham Mitchell
Keyword(s):  
Surface Water ◽  
Urine Volume ◽  
Water Soluble ◽  
Sweat Glands ◽  
Arid Environments ◽  
Water Metabolism ◽  
Access To Water ◽  
Fecal Water ◽  
Kidney Anatomy ◽  
And Function

Wild giraffes live in arid environments. Having access to water and minimizing water requirements are critical. The main sources of water are the water in browse and water generated by metabolism. Giraffes rely less on surface water: intermittent use of surface water is a legendary characteristic of giraffes. The volume of water needed depends on body mass. For a giraffe weighing 750 kg, ~25 L of water is needed daily. The water content of browse is ~60%, and as a giraffe of that mass will eat ~35 kg of fresh browse daily, it simultaneously will acquire ~20 L of water. Metabolism of the fat, carbohydrates, and proteins in 35 kg of fresh browse will produce ~10 L of water. These two sources of water exceed daily requirements and reduce the need to drink surface water. Water is lost through feces, evaporation from the skin and respiratory tract, and in urine. Fecal water loss and water lost in exhaled air amount to ~4 L daily (~2 L each). It is not known if giraffes sweat, but their skin contains active sweat glands. The volume of water lost as sweat will vary according to what thermoregulatory mechanisms are activated to minimize sweating, but may be 5 L daily. Obligatory excretion of water-soluble wastes in urine can account for most water lost daily, and that amount is related to kidney anatomy and function. In a 750-kg giraffe, obligatory urine volume is ~10 L daily.

scholarly journals Distribution and density of oxpeckers on giraffes in Hwange National Park, Zimbabwe

2019 ◽  
Author(s):  
Roxanne Gagnon ◽  
Cheryl T. Mabika ◽  
Christophe Bonenfant
Keyword(s):  
Foraging Behaviour ◽  
Food Resource ◽  
Bird Species ◽  
Body Parts ◽  
Large Mammals ◽  
Large Herbivores ◽  
Aggregation Behaviour ◽  
Hwange National Park ◽  
Host Parasite ◽  
Parasite Dynamics

AbstractOxpeckers (Buphagus sp.) are two bird species closely associated to large mammals, including giraffes (Giraffa camelopardalis). We tested whether oxpeckers distributed themselves at random across individuals or aggregated on individual giraffes, and if birds select the host’s body parts with the expected greatest amount of ticks. By counting oxpeckers on giraffe’s body from photographs, we quantified the distribution of birds per hosts and over predefined zones on the giraffe body. Oxpeckers displayed a strong aggregation behaviour with few hosts carrying many birds while many carried a limited number or no birds, a pattern that was most exaggerated for males. Oxpeckers were disproportionately found on the mane and back, where the density of ticks is presumably the highest. This high aggregation level of birds is typical of parasitic species and could suggest that oxpecker distribution may mirror the distribution of ticks, their primary food resource, on giraffes. Abundance of ticks appears as a major driver of the oxpecker foraging behaviour, and the oxpecker–large herbivores system proves to be highly relevant for the study of host–parasite dynamics.

scholarly journals Drone Surveys Revealed Bottom-Up, And Not Top-Down, Effects On The Marsh Deer Local Abundance

2021 ◽  
Author(s):  
Ismael Verrastro Brack ◽  
Andreas Kindel ◽  
Douglas Oliveira Berto ◽  
José Luis Passos Cordeiro ◽  
Igor Pfeifer Coelho ◽  
...  
Keyword(s):  
Mixture Models ◽  
Negative Relationship ◽  
Dry Season ◽  
Relative Influence ◽  
Top Down ◽  
Large Herbivore ◽  
Large Herbivores ◽  
Bottom Up ◽  
Vegetation Greenness ◽  
Local Abundance

Abstract Context: Spatial variation in large herbivore populations can be highly affected by the availability of resources (bottom-up) but modulated by the presence of predators (top-down). Studying the relative influence of these forces has been a major topic of interest in ecological and conservation research, while it has also been challenging to sample large herbivores. Objective: i) Explore the use of spatiotemporally replicated drone-based counts analysed with N-mixture models to estimate abundance of large herbivores. ii) Evaluate the relative influence of bottom-up (forage and water) and top-down (jaguars) processes on the local abundance of the threatened marsh deer.Methods: We conducted spatiotemporally replicated drone flights in the dry season of Pantanal wetland (Brazil) and imagery was reviewed by either one or two observers. We fitted counts using N-mixture models (for single and double observer protocols) and modelled local abundance in relation to vegetation greenness, distance to water bodies, and jaguar density.Results: We found a positive relationship of marsh deer local abundance with vegetation greenness, a negative relationship with distance to water, but no relation with jaguar density. Individuals were concentrated in the lower and wetter region, even though it is the area expected to be more lethal from jaguar predation.Conclusions: Bottom-up processes are shaping the distribution of marsh deer in the dry season; the benefits of accessing high-quality areas outweigh predation risk from jaguars. Spatiotemporally replicated drone-based counts may serve as an accessible and cost-effective protocol for large herbivores abundance estimation and monitoring while accounting for imperfect detection.

scholarly journals Seasonal density estimates of common large herbivores in Hwange National Park, Zimbabwe

2009 ◽  
Vol 47 (4) ◽  
pp. 804-808 ◽  
Author(s):  
Simon Chamaillé-Jammes ◽  
Marion Valeix ◽  
Mathieu Bourgarel ◽  
Felix Murindagomo ◽  
Hervé Fritz
Keyword(s):  
National Park ◽  
Large Herbivores ◽  
Density Estimates ◽  
Hwange National Park

scholarly journals Normalized difference vegetation index, temperature and age affect faecal thyroid hormone concentrations in free-ranging African elephants

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Isabelle D Szott ◽  
Yolanda Pretorius ◽  
Andre Ganswindt ◽  
Nicola F Koyama
Keyword(s):  
Energy Expenditure ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Large Population ◽  
African Elephants ◽  
Large Herbivores ◽  
Factors Affecting ◽  
Animal Populations ◽  
Faecal Samples ◽  
Free Ranging

Abstract Conservation biologists can use hormone measurements to assess animals’ welfare, reproductive state, susceptibility to stressors, as well as energy expenditure. Quantifying hormone concentrations from faecal samples is particularly advantageous as samples can be collected without disturbing animals’ behaviour. In order for an endocrine marker to be useful for wildlife managers, we need to understand how extrinsic and intrinsic factors affect hormone concentrations in free-ranging animal populations. Thyroid hormones are linked to basal metabolic rate and energy expenditure. Previous research demonstrated that triiodothyronine (T3) can be measured successfully in faecal matter of African elephants, Loxodonta africana. However, to our knowledge, research into factors affecting changes in elephant T3 levels has only been carried out in captive elephants so far. Thus, we present the first study of faecal T3 metabolite (mT3) concentrations of a large population of free-ranging African elephants. Over 15 months, we collected faecal samples from identified (n = 43 samples) and unidentified (n = 145 samples) individuals in Madikwe Game Reserve, South Africa. We investigated whether vegetative productivity [normalized difference vegetation index (NDVI)] in interaction with mean monthly temperature, age and sex affected mT3 concentrations. We found a significant negative interaction effect of NDVI and temperature. Increasing NDVI was related to higher concentrations of mT3, but increasing temperature was related to a decrease in mT3 concentrations in individually identified and unidentified elephants. In unidentified individuals, juvenile elephants had significantly higher mT3 concentrations compared to adult elephants. Faecal T3 can successfully be quantified in samples from free-ranging elephant populations and thus provides insight into energy expenditure in large herbivores.

The function of cattle sweat glands.

1955 ◽  
Vol 6 (4) ◽  
pp. 640 ◽  
Author(s):  
KA Ferguson ◽  
DF Dowling
Keyword(s):  
Heat Loss ◽  
Sweat Gland ◽  
Skin Surface ◽  
Bromothymol Blue ◽  
Sweat Glands ◽  
Quantitative Measurements ◽  
Stereo Microscope ◽  
Hot Environments

Evidence is presented that the apocrine sweat glands of cattle have a temperature-regulating function. Under the stereo microscope, sweat droplets could be observed forming at the openings of the sweat gland ducts in response to intradermal injections of adrenaline, and during exposure to hot conditions. The sweat spots could be stained macroscopically, and prints showing the location of the spots were obtained with bromothymol blue papers pressed onto the skin surface. Quantitative measurements indicate that the evaporation of this sweat is the main source of heat loss in hot environments.

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