Temporal patterns of domestic and wildlife rabies in central Namibia stock-ranching area, 1986-1996

Eleven years (1986-1996) of wildlife- and domestic-rabies data from the agriculture stock-ranching area of central Namibia were studied using time-series analysis. Nine hundred and sixty three rabies cases were observed in domestic ruminants (5.4 cases/mo), black-backed jackals (Canis mesomelas, 1.3 cases/mo), domestic dogs (0.5 case/mo), and bat-eared foxes (Otocyon megalotis, 0.1 case/mo). The incidence of rabies for all species did not change significantly over the whole study period. However, seasonal variations with an increase in the number of cases between June and November of each year, as well as 34 yr cyclical fluctuations were identified in domestic ruminants and black-backed jackals. The black-backed jackal time-series variable was a significant predictor of the domestic-ruminant and dog time-series variables. The rainfall seasonality combined with the seasonal reproductive pattern of the black-backed jackal appeared to be plausible explanations for the seasonal variations of rabies. However, there was no overall significant correlation between the cyclical weather fluctuations and the 3-4 yr cyclical rabies variations.     

Parental care in a polygynous group of bat-eared foxes,Otocyon megalotis (Carnivora: Canidae)

This study reports the first recorded instance of polygyny and communal nursing in Otocyon m. megalotis. The polygynous group, which was studied in the Kalahari Desert, consisted of a male, two lactating females and a litter of five pups. New aspects of parental care that were observed include the bringing of food items to pups at the den. Although bat-eared foxes in this area seldom capture lizards for their own consumption, lizards were the main food item carried to the den. It is suggested that bat-eared foxes specifically seek out lizards because they are more easily transportable than their normal insect prey. Despite this behavioural adaptation, there is relatively little opportunity for the male to contribute to the nutrition of the pups when compared to the contribution made by the males of large carnivorous canids, which routinely bring large volumes of meat to the den. Instead, young bat-eared foxes depend heavily on milk, so the females have to forage for extended periods to replenish their milk supplies. This study shows that the major duties of males are guarding and grooming the pups while the females are foraging. In this social context there are relatively few disadvantages in sharing a father between two litters and these disadvantages are occasionally outweighed by the benefits of communal care, amongst which are cooperative attacks on predators and alternate nursing.     

Non-invasive measurement of adrenocortical activity in a myrmecophageous mammal,the bat-eared fox

Measuring physiological stress reactions through the quantification of plasma cortisol often involves physical restraint, which acts as a stressor itself. Here, we present the validation of a non-invasive method for assessing adrenocortical activity as an indicator of stress in the bat-eared fox (Otocyon megalotis). By conducting an adrenocorticotropic hormone (ACTH) challenge, we examined the suitability of three enzyme immunoassays (EIAs) detecting 11,17 dioxoandrostanes (11,17-DOA) as well as faecal glucocorticoid metabolites (fGCM) with a 5β-3α-ol-11-one (3α,11oxo-CM), or 11,17,21-trihydroxy-4-ene-20-one structure (cortisol), respectively, for monitoring stress-related physiological responses in male and female bat-eared foxes. Our results suggest that the cortisol EIA seems most suitable for measuring fGCMs in this myrmecophageous mammal. Using the cortisol EIA, we compared fGCM concentrations of three populations of foxes. Only one population experienced a sudden change in social environment and the assay appeared to effectively detect the expected resulting increase in stress hormone levels. Therefore, the identified EIA is effective at detecting intraspecific variation in fGCM levels and hence is a useful tool to evaluate physiological stress responses in this species.     

Differences in diet between two rodent species,Mastomys natalensis and Gerbilliscus vicinus,in fallow land habitats in central Tanzania

Differences in the ecological niche requirements among rodent species competing in the same habitat may result from differences in the use of one to three resources: space, time and food or some combination of these. Alternatively, differences in resource use utilization among animal species may simply reflect availability of food, and when food is limited, different animal species compete. In this study, the diet of two rodent pest species, Mastomys natalensis and Gerbilliscus vicinus, coexisting in fallow land in central Tanzania were studied to assess the degree of diet differentiation among them. Dietary niche breadth of G. vicinus was greater than that of M. natalensis in all stages of the maize cropping seasons. The rodent species studied overlapped considerably in the food items consumed ranging from niche overlap (O_jk) of 0.77–0.89. Grains/seeds featured high in the diet of M. natalensis while plant material occurrence was high in G. vicinus. These two food categories may have contributed to differences in diet partitioning, which may, in turn, facilitate their coexistence in fallow land.     

Anatomical parameters of the body and the digestive tract of Callithrix sp. marmosets under the influence of seasonality

Due to the ecological importance and given the scarcity of studies on the digestive morphology of primates, anatomical aspects of the body and digestive tract, as well as food content were analysed for marmosets Callithrix sp. (hybrids of exotic species) captured in forest fragments in Minas Gerais - Brazil, during the dry and rainy seasons, considering that seasonal variations affect the availability of food and quality of diet. Data such as body weight and length, and thoracic and abdominal perimeters were analysed, and no significant difference was found between dry and rainy seasons. In relation to the digestive tract, length, weight and diameter of the oesophagus, stomach, small intestine and large intestine were measured, in addition to the isolated caecum. There was a significant difference in the diameter of the ascending colon, which was larger in the animals in the dry season than in the rainy season. The difference found may be related to diet, and through analysis of the gastric and caecal contents, it was observed that gum was the main food item for the dry season marmosets, while in the rainy season the animals consumed mainly arthropods. Thus, the characteristic observed in the digestive tract of dry season marmosets is a reflection of an adaptive response to gum intake, since this food item is of low digestibility, necessitating that the food content be retained for a long time in this segment of the large intestine, helping the process of microbial fermentation and better energy utilization for these animals.     

Effect of low protein diets for growing Leghorn pullets upon subsequent laying performance

An experiment was conducted with White Leghorn pullets to study the effect on laying performance of dietary protein content and amino acid supplementation during the growing period. From 0 to 6 weeks of age birds fed on diets containing either 149 g protein/kg supplemented with methionine and lysine or 182 g protein/kg grew faster than those fed on a diet containing 149 g protein/kg alone. However, only those fed on the supplemented diet utilised their food more efficiently. From 7 to 20 weeks of age neither body weight gain nor food utilisation was affected by the dietary protein content. Pullets fed the low protein diet supplemented with 2 g methionine/kg and 2.5 g lysine/kg during the period of 0 to 6 weeks of age had significantly better egg production than birds fed the low protein diet alone. The dietary protein content during 7 to 20 weeks of age did not influence subsequent egg production.     

Seasonal variations in the diet and food selection of the Algerian hedgehog Atelerix algirus

The Algerian hedgehog Atelerix algirus is an insectivorous species. However, the exact composition of its natural diet remains largely undetermined, especially in relation to seasonal variations in food availability. From March to November, we simultaneously analysed the composition of 180 hedgehog faecal samples and food availability in the Soumman Valley, Algeria to assess food selection in this species. The faeces contained 196 different prey species, of which 92% belonged to the class Insecta. The highest prey species diversity was found in the Coleoptera order (100 species recorded) and the highest species occurrence was found in Hymenoptera (65% of the prey items, mainly represented by the harvester ant Messor barbarus, a crop-ravaging species). This study shows that the Algerian hedgehog is mainly a generalist species with a diet that is strongly linked to food availability. However, seasonal variations were observed in prey selection, and a notable shift in food preference was observed during autumn. The exact nature of these changes in feeding behaviour remains to be investigated, notably in relation to changes in energy requirements of this species before hibernation, in terms of quantity and/or quality.     

Dental microwear of sympatric rodent species sampled across habitats in southern Africa: Implications for environmental influence

Dental microwear textures have proven to be a valuable tool for reconstructing the diets of a wide assortment of fossil vertebrates. Nevertheless, some studies have recently questioned the efficacy of this approach, suggesting that aspects of habitat unrelated to food preference, especially environmental grit load, might have a confounding effect on microwear patterning that obscures the diet signal. Here we evaluate this hypothesis by examining microwear textures of 3 extant sympatric rodent species that vary in diet breadth and are found in a variety of habitat types: Mastomys coucha, Micaelamys namaquensis and Rhabdomys pumilio. We sample each of these species from 3 distinct environmental settings in southern Africa that differ in rainfall and vegetative cover: Nama‐Karoo shrublands (semi‐desert) and Dry Highveld grasslands in the Free State Province of South Africa, and Afromontane (wet) grasslands in the highlands of Lesotho. While differences between habitat types are evident for some of the species, inconsistency in the pattern suggests that the microwear signal is driven by variation in foods eaten rather than grit‐level per se. It is clear that, at least for species and habitats sampled in the current study, environmental grit load does not swamp diet‐related microwear signatures.     

Climate and the evolution of group-living behaviour in the armadillo lizard (Ouroborus cataphractus)

We evaluated the hypothesis that the regular use of the southern harvester termite, Microhodotermes viator, as food source by the armadillo lizard, Ouroborus cataphractus, originated as an adaptation to survive the summer dry season in a climatic regime where rainfall is highly seasonal. To do so, we determined the most important climatic predictors of the geographical range of this species. Climatic data were obtained for 130 localities where O. cataphractus is known to occur and 168 adjacent localities where it is known to be absent. For each locality, data for 10 climatic variables were extracted from the South African Atlas of Agrohydrology and Climatology database. We constructed a forward stepwise logistic regression model of the probability of O. cataphractus occurrence, based on the set of 10 climatic variables. The best model included, in order of importance, average monthly summer rainfall, mean annual precipitation, average monthly solar radiation, and the ratio of winter rainfall over summer rainfall as most significant predictors. The selected model predicted 88.80% of the presences correctly and 85.52% of the absences. In essence, O. cataphractus is restricted to the winter rainfall zone of South Africa, excluding the high-rainfall southwestern section. We postulate that the highly predictable seasonal rainfall and the ameliorating effect of the Atlantic Ocean on climates in the Namaqualand region, in particular, have provided a unique selective regime for the origin of group-living in O. cataphractus. Dependence on M. viator as food source developed to survive the summer-autumn period of low food availability and resulted in the evolution of heavy armour and group-living behaviour. The moderate winters and early spring temperatures allowed full capitalization on high arthropod abundance during winter–spring, thereby overriding the negative impacts of armour and group-living on foraging efficiency at the home crevice.     

A longitudinal survey of anti-Ostertagia ostertagi antibody levels in individual and bulk tank milk in two dairy herds in Normandy

The Ostertagia-specific antibody levels in milk were monitored in 2 dairy herds to investigate seasonal variations and the relationship between individual and bulk tank milk antibody levels. Bulk tank and individual milk samples from all lactating animals were collected over a 1-year period at weekly and monthly intervals, respectively. The Ostertagia-specific antibody levels were measured with an indirect ELISA and the test results were expressed as optical density ratios (ODR). A clear seasonal pattern that followed the expected intake of infectious larvae was observed in the individual and bulk tank milk antibody levels of both herds. Within each herd, there was a large variation in the individual ODRs. This variation remained large when the distribution of individual ODRs was plotted according to high and low bulk tank milk ODR categories. The results suggest that the effect of seasonal variations on cut-off levels that predict production responses after anthelmintic control, needs to be assessed.     

Regulation of bone mineral density in the grey squirrel,Sciurus carolinensis: Bioavailability of calcium oxalate,and implications for bark stripping

The damage caused when grey squirrels strip the outer bark off trees and ingest the underlying phloem can result in reduced timber quality or tree death. This is extremely costly to the UK forestry industry and can alter woodland composition, hampering conservation efforts. The calcium hypothesis proposes that grey squirrels ingest phloem to ameliorate a seasonal calcium deficiency. Calcium in the phloem predominantly takes the form of calcium oxalate (CaOx), however not all mammals can utilise CaOx as a source of calcium. Here, we present the results of a small‐scale study to determine the extent to which grey squirrels can utilise CaOx. One of three custom‐made diets containing calcium in varying forms and quantities (CaOx diet, Low‐calcium carbonate (CaCO₃) diet and Control diet) were fed to three treatment groups of six squirrels for 8 weeks. Bone densitometric properties were measured at the end of this time using peripheral quantitative computed tomography and micro‐computed tomography. Pyridinoline—a serum marker of bone resorption—was measured regularly throughout the study. Bone mineral density and cortical mineralisation were lower in squirrels fed the CaOx diet compared to the Control group but similar to that of those on the Low‐calcium diet, suggesting that calcium from calcium oxalate was not effectively utilised to maintain bone mineralisation. Whilst no differences were observed in serum pyridinoline levels between individuals on different diets, females had on average higher levels than males throughout the study. Future work should seek to determine if this apparent lack of ability to utilise CaOx is common to a large sample of grey squirrels and if so, whether it is consistent across all areas and seasons.     

Seasonal changes in digestibility, passage rate and rumen fermentation of alfalfa hay in sika deer (Cervus nippon) under restricted feeding

To investigate seasonal variations in the digestive functions of sika deer, five female sika deer were provided with an amount of alfalfa hay cubes equivalent to voluntary food intake during winter. We measured the rate at which the food passed through the digestive tract, digestibility and rumen fermentation during the summer (August), autumn (November), winter (February) and spring (May). Total mean retention time in the digestive tract during summer and autumn was numerically longer than that in winter and spring, but the difference did not reach significance. Organic matter and fiber were less digestible in summer and autumn than in winter and spring (P < 0.05), whereas the digestibility of the dry matter tended to vary with the seasons (P < 0.1). Ruminal pH values seasonally changed (P < 0.01), and were the lowest in autumn. The concentration of ruminal ammonia‐nitrogen differed significantly among the seasons (P < 0.05), increasing in winter and decreasing during spring and summer. The numbers of protozoa changed significantly among the seasons (P < 0.05), being higher in autumn than in winter and spring, and intermediate in summer. The concentration of total volatile fatty acids was not seasonally affected, but the molar percentages of propionic acid and butyric acid significantly changed according to season (P < 0.05 and P < 0.01, respectively), and the ratio of acetic to propionic acid tended to change with the seasons (P < 0.1). The results of this study suggested that the digestive functions in sika deer, fed a commercial diet at a restricted level, differed notably among the seasons and these variations might partially be due to environmental effects.     

Faecal analysis suggests generalist diets in three species of Western Cape cordylids

Climate has been proposed as an explanation for the present-day distribution of closely-related melanistic and non-melanistic cordylid species in the southwestern Cape of South Africa. However, diet may also contribute towards shaping geographic distributions. We present preliminary data on diet composition based on analyses of faecal pellets of Cordylus cordylus (non-melanistic), C. niger (melanistic) and C. oelofseni (melanistic). Coleoptera were the most common prey ingested both in summer and early spring for all species, followed by Hymenoptera for all species in summer. The overlap in other arthropod taxa ingested was low across species and seasons, suggesting an opportunistic component to their foraging behaviour.We distinguished plant matter in faecal samples of all species in all seasons, reflecting either voluntary or accidental ingestion. The results of this study suggest that the generalist diets of these cordylid species should not constrain their distributions despite the common preference for coleopterans.     

Population dynamics of three lizard species from the genus Sceloporus: short‐term changes in demographic parameters

Most demographic studies focus on numerical changes that occur within populations across years. However, typically studies at an interannual scale do not provide information on the particular times of the year (particular months or seasons) when rates of survival, recruitment, or migration increase or decrease due to physiological, behavioral or ecological processes. These monthly or seasonal changes in demographic parameters may lead to substantial variations in population abundance. In this study, we collected capture–mark–recapture data on 3 species of lizards of the genus Sceloporus (Sceloporus torquatus, Sceloporus grammicus and Sceloporus megalepidurus) found in ecologically similar habitats to examine potential changes in demographic rates among 3 different climatic seasons: rainy, cold‐dry and warm‐dry seasons. We tested different hypotheses about the effect of these seasons on survival, recruitment of new adults, and temporary emigration. We found that during the season with severe thermal constraints, the cold‐dry season, survival of S. torquatus decreased markedly. We also detected a considerable increase in the recruitment rate of S. grammicus during the rainy season, when these lizards are establishing territories and finding mates. In contrast, we found no evidence of intra‐annual changes in the rate of temporary emigration. In addition, we calculated abundance and population growth rates for each species and for each season. Our study represents a significant contribution to the understanding of intra‐annual demographic variation in lizards.     

Effects of body weight and season on serum lipid concentrations in sloth bears (Melursus ursinus ursinus)

Serum lipid levels were measured in 66 healthy sloth bears (Melursus ursinus ursinus) living under semicaptive conditions with access to natural food resources in the Bannerghatta Biological Park (Karnataka, India), a portion of their native habitat range in the Indian peninsula. Total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein cholesterol levels were analyzed. The effects of age, body weight, and season on these lipid parameters were statistically evaluated. There were no correlations between age and any of the serum lipid parameters analyzed. Positive correlations of body weight to both triglyceride and HDL cholesterol levels in these bears were identified. In addition, seasonal trends in physiological serum lipid values, potentially due to variations in the sloth bear diet, were identified. Serum triglyceride levels were higher during postmonsoon season and cholesterol levels were higher during winter compared to other seasons. Serum lipid values obtained from sloth bears in this study were also compared to previously published data on other members of the family Ursidae. This is the first report of serum lipid values as a reference for sloth bears. These values can be used as sensitive predictors of overall health and nutritional status to aid in the captive management and feeding of these bears.     

Habitat use and home range of black-backed jackals (Canis mesomelas) on farmlands in the Midlands of KwaZulu-Natal,South Africa

Black-backed jackals (Canis mesomelas) are an abundant mesopredator on farmlands (croplands and rangelands) across South Africa. Given their adaptability in a changing anthropogenic landscape, knowledge of spatial movements can provide important ecological information on the species. We captured, collared and monitored five black-backed jackals in the Midlands of KwaZulu-Natal to determine their home range and habitat use in farmlands. The 95% fixed kernel (95% FK) home range sizes were large, showing a marked seasonal variation in movement. One adult male dispersed 150?km over two seasons (winter and spring) and thereafter settled into a home range that it maintained. Transient home ranges of males and juveniles were larger than resident home ranges. The mean resident home ranges (95% FK) across seasons for adult males, adult female and juvenile males were 11.4 ± 4.3 km², 5.6 ± 0.36?km² and 2.15 ± 0.45?km², respectively. The mean transient home ranges (95% FK) of all the seasons for adult and juvenile males were 1 181.93 ± 575.81 km² and 104.27 ± 35.64?km², respectively. Adult jackal preferred croplands in spring, summer and autumn but avoided croplands in winter. Variable habitat use and large home ranges in our study confirmed the species’ ability to adapt to agricultural areas.     

Bulk tank milk urea nitrogen: Seasonal patterns and relationship to individual cow milk urea nitrogen values

The objectives of this study were: 1) to determine if bulk tank milk urea nitrogen (BTMUN) and whole herd weighted average of the individual cow MUN levels (WHMUN) were equivalent measurements of herd MUN status; and 2) to determine the seasonal variation in BTMUN concentrations in Prince Edward Island (PEI) dairy herds. For BTMUN-WHMUN correlation testing, bulk tank milk samples from 176 herds were tested for MUN once every 1 to 2 wk between September 1999 and August 2002, as part of routine BTM testing for milk components. During this 3-year period, all herds had all milking cows tested for MUN once a month at the same lab. The WHMUN levels (weighted for milk production) were calculated for each month, and were compared to BTMUN levels using a concordance correlation coefficient (CCC) and a graphic procedure. Tests were only compared if they occurred on the same date, producing a final dataset of 669 comparisons. The BTMUN had good (but not perfect) correlation with WHMUN (CCC = 0.91). This high reliability extended to both the pasture and non-pasture seasons, various milk sampling protocols, and all herd sizes seen in PEI. For evaluating the seasonal variation of BTMUN, the 3 y worth of data (24 803 observations) were divided into 15 seasonal categories, 5 seasons per year (early, mid, and late pasture, and early and late stable). Using linear mixed modelling, significantly (P < 0.05) higher BTMUN values were found during the mid and late pasture seasons of 2000, likely because the precipitation was unusually high during this period, enhancing pasture growth.     

Effects of dietary dilution with fibre on the food intake and gut dimensions of Japanese quail.

Japanese quail (Coturnix coturnix japonica) were fed on either a conventional diet (low-fibre) or the same diet diluted with 200 g oak sawdust/kg (high-fibre). The lengths of the colo-rectum, small intestine, two caeca combined and empty gizzard weight were measured at 10 and 20 weeks of age. Food intake and rate of passage were measured and an approximate measure of digestibility was also made. 2. There were separate effects of dietary fibre, sex and age on gut size. It was larger in birds fed on high-fibre diet, in females and in older birds. 3. Increased dietary fibre caused increased food intake, but had no obvious effect on the rate of passage. 4. When quail were fed on the low-fibre diet or the same diet diluted with 200 or 400 g cellulose powder/kg gut size at 20 weeks of age was greatest when the most fibrous diet was fed and decreased concomitantly with dietary fibre concentration. 5. It appeared that differences in gut size between dietary treatments were more a reflection of variations in food intake than of fibre per se, and that the effects of sex and age on gut size were probably similarly explained.     

Food sensitivity in cats with chronic idiopathic gastrointestinal problems

The objectives of this study were to investigate the prevalence of food sensitivity in cats with chronic idiopathic gastrointestinal problems, to identify the food ingredients responsible, and to characterize the clinical features. Seventy cats that presented for chronic gastrointestinal signs underwent diagnostic investigation. Fifty-five cats had idiopathic problems and were entered into the study. Diagnosis of food sensitivity was made by dietary elimination-challenge studies by using commercial selected-protein diets as the elimination diet. Sixteen (29%) of the 55 cats with chronic idiopathic gastrointestinal problems were diagnosed as food sensitive. The clinical signs of another 11 cats (20%) resolved on the elimination diet but did not recur after challenge with their previous diet. The foods or food ingredients responsible for the clinical signs were dietary staples. Fifty percent of affected cats were sensitive to more than 1 food ingredient. The clinical feature most suggestive of food sensitivity was concurrent occurrence of gastrointestinal and dermatological signs. Weight loss occurred in 11 of the affected cats, and large-bowel diarrhea was more common than small-bowel diarrhea. Assay of serum antigen-specific immunoglobulin E (IgE) had limited value as a screening test, and gastroscopic food sensitivity testing was not helpful. In conclusion, adverse reactions to dietary staples were common in this population of cats, and they responded well to selected-protein diets. Diagnosis requires dietary elimination-challenge trials and cannot be made on the basis of clinical signs, routine clinicopathological data, serum antigen-specific IgE assay, gastroscopic food sensitivity testing, or gastrointestinal biopsy.     

气候和植被变化对黄土高原蒸散发的影响

基于全球涡度相关站点观测的蒸散发数据(FLUXNET ET),第三代GIMMS NDVI以及相应的气候数据,运用广义线性模型量化了1982~2011年气候和植被生长对黄土高原蒸散发的贡献程度,并探究贡献程度的季节性差异以及在植被类型之间的差异。结果表明:(1)降水和NDVI是影响黄土高原蒸散发季节性差异的重要因素,而温度对蒸散发的影响较小;(2)随着降水量的增多,降水对蒸散发的贡献程度逐渐减小,夏季和秋季表现得更为明显;(3)秋季林地、灌木、草地NDVI对整个黄土高原蒸散发的贡献普遍较高。