Ranging behaviours across ecological and anthropogenic disturbance gradients: a pan-African perspective of giraffe (Giraffa spp.) space use.

Animal movement behaviours are shaped by diverse factors, including resource availability and human impacts on the landscape. We generated home range estimates and daily movement rate estimates for 149 giraffe (Giraffa spp.) from all four species across Africa to evaluate the effects of environmental productivity and anthropogenic disturbance on space use. Using the continuous time movement modelling framework and a novel application of mixed effects meta-regression, we summarized overall giraffe space use and tested for the effects of resource availability and human impact on 95% autocorrelated kernel density estimate (AKDE) size and daily movement. The mean 95% AKDE was 359.9 km2 and the mean daily movement was 14.2 km, both with marginally significant differences across species. We found significant negative effects of resource availability, and significant positive effects of resource heterogeneity and protected area overlap on 95% AKDE size. There were significant negative effects of overall anthropogenic disturbance and positive effects of the heterogeneity of anthropogenic disturbance on daily movements and 95% AKDE size. Our results provide unique insights into the interactive effects of resource availability and anthropogenic development on the movements of a large-bodied browser and highlight the potential impacts of rapidly changing landscapes on animal space-use patterns.

Semi-automated detection of ungulates using UAV imagery and reflective spectrometry.

In the field of species conservation, the use of unmanned aerial vehicles (UAV) is increasing in popularity as wildlife observation and monitoring tools. With large datasets created by UAV-based species surveying, the need arose to automate the detection process of the species. Although the use of computer learning algorithms for wildlife detection from UAV-derived imagery is an increasing trend, it depends on a large amount of imagery of the species to train the object detector effectively. However, there are alternatives like object-based image analysis (OBIA) software available if a large amount of imagery of the species is not available to develop a computer-learned object detector. The study tested the semi-automated detection of reintroduced Arabian Oryx (O. leucoryx), using the specie's coat sRGB-colour profiles as input for OBIA to identify adult O. leucoryx, applied to UAV acquired imagery. Our method uses lab-measured spectral reflection of hair sample values, collected from captive O. leucoryx as an input for OBIA ruleset to identify adult O. leucoryx from UAV survey imagery using semi-automated supervised classification. The converted mean CIE Lab reflective spectrometry colour values of n = 50 hair samples of adult O. leucoryx to 8-bit sRGB-colour profiles of the species resulted in the red-band value of 157.450, the green-band value of 151.390 and blue-band value of 140.832. The sRGB values and a minimum size permitter were added as the input of the OBIA ruleset identified adult O. leucoryx with a high degree of efficiency when applied to three UAV census datasets. Using species sRGB-colour profiles to identify re-introduced O. leucoryx and extract location data using a non-invasive UAV-based tool is a novel method with enormous application possibilities. Coat refection sRGB-colour profiles can be developed for a range of species and customised to autodetect and classify the species from remote sensing data.

Spatially restricted occurrence and low abundance as key tools for conservation of critically endangered large antelope in West African savannah.

The effective conservation of mammals on the brink of extinction requires an integrated socio-ecological approach, yet the updated ecological knowledge of species remains fundamental. This study brings spatiotemporal behaviour, population structure, age-specific survival rates, and population size estimate of the Western Derby eland (WDE) in the Niokolo Koba National Park (NKNP), Senegal, investigated during dry seasons 2017 and 2018. WDE was strongly localised in the core area of NKNP (< 5%), active throughout the day with the highest peak in the hottest daytime, with a mean group size 7.6 ± SE 8.9. The adult sex ratio was female-biased and showed low annual adult male survival rates. The population consisted of high proportion of juveniles, whilst adults did not exceed 40%. The estimated population density was 0.138 WDE/km2 (± 0.0102) and estimated size 195 WDE in NKNP (CI95 from 54 to 708 individuals). Findings highlighted that the WDE population has potential to expand in the NKNP, due to an underutilized capacity. The age-specific vital rates indicate adult males as the most vulnerable; suggesting either an increase in the large predators' population, livestock encroachment pressure, and/or poaching. Findings imply that targeted monitoring with science-based interpretation may bring forward strong conservation solutions to the protected area management decision-makers.

Blood mineral profile of the critically endangered Western Derby eland (Taurotragus derbianus derbianus) in two conservation breeding reserves in Senegal.

For many nondomestic species, nutritional requirements and the challenges faced in their current habitats are unknown. This is the case of small semi-captive population of the critically endangered Western Derby eland held in two wildlife reserves (the Bandia and the Fathala) in Senegal. The aim of this study was to determine the mineral profile (Ca, P, Mg, Cu, Fe, Zn, Se, K, S) in blood serum and to identify potential mineral deficiencies. Serum data (11 individuals) were compared to other Tragelaphineae, where it was lower in almost all elements. Considerably low concentrations were recorded for Cu, Fe and Zn. Animals in the Bandia reserve had higher serum levels of Fe and K compared to the Fathala reserve and a higher serum level of S in the Fathala reserve compared to the Bandia reserve. Recorded mineral levels may reflect most likely the limited mineral background in the local environment. The knowledge of adequate nutritional requirements and health status of these animals is relevant for the conservation breeding programme. No other serum mineral reference values exist for Western Derby eland, neither for free-ranging nor captive animals. Therefore, the knowledge of reference intervals for minerals in serum may serve for monitoring of the population's health.

Digesta passage in common eland (Taurotragus oryx) on a monocot or a dicot diet.

The way that fluids and particles move through the forestomach of a ruminant is species-specific, and can be used to classify ruminants according to their digestive physiology into 'moose-types' (with little difference in fluid and small particle passage) and 'cattle-types' (where fluids move through the forestomach much faster than small particles). So far, 'moose-types' appear limited to a dietary niche of browsing, whereas 'cattle-types' are particularly prominent in the intermediate and grazing diet niches. However, some species, including members of the spiral-horned antelopes (the Tragelaphini), have a 'cattle-type' physiology but a browse-dominated diet niche. Eland (Taurotragus oryx), the largest member of the Tragelaphini, are strict browsers in the wild but have been considered intermediate feeders in the past, and can seemingly be maintained on grass diets. We quantified food intake, mean retention time (MRT) in the gastrointestinal tract and the reticulorumen (RR) of a solute, a small and a large particle marker, and diet digestibility in six eland each fed a monocot (grass hay) and a dicot (lucerne silage) forage. Food intake and digestibility was lower on the diet with higher fibre content (grass hay), with corresponding longer MRT. At the higher intakes on lucerne, the difference in MRT between small and large particles was larger, indicating a greater reliance on particle sorting and clearance under this condition of potentially limiting gut capacity. Regardless of diet or intake, the ratio of small particle and solute MRT in the RR was constant and small, at a quotient of 1.54, classifying the eland as a typical 'moose-type' ruminant. This finding is consistent with previous literature reports on low faecal metabolic nitrogen and high apparent protein digestibility in eland. Given the relative ease at which eland can be maintained under farm husbandry conditions, they appear ideal model ruminants to study the effects of differences in rumen physiology compared to cattle.

Minerals in the Blood, Hair, and Faeces of the Critically Endangered Western Derby Eland Under Human Care in Two Wildlife Reserves in Senegal.

The widely used means of investigating animal mineral profiles are blood serum or plasma and internal organ tissues. The acquisition of these types of samples can be invasive and requires much effort. These factors become key obstacles in the case of rare and elusive species such as the Western Derby eland (Taurotragus derbianus derbianus, WDE), which is a critically endangered antelope with a current distribution limited to the Niokolo Koba National Park, and two wildlife reserves in Senegal. One of the solutions to this problem is to collect easily accessible samples, such as faeces or fur, which may provide valid information about animal mineral status. Our study focuses on determining the macroelement and microelement levels in animal blood serum, hair, and faeces, and analysing their correlations to evaluate whether hair and/or faeces can be used as a proxy for blood mineral levels. Samples were collected from 11 individual WDEs (6 males, 5 females) during translocations within two reserves. Correlations of mineral concentrations in the blood, hair, and faeces were not found except for Fe in the faeces, which was positively correlated with Fe in the hair (r = 0.64, P < 0.05) and blood (r = 0.69, P < 0.05). The lack of correlations among the different types of samples may be because of the low number of samples; hence, we recommend conducting further research with a broader dataset. Our findings, however, currently indicate that faeces and fur analyses cannot stand alone for the assessment of the mineral status and the determination of WDEs' potential mineral deficiencies.

Comparison of physiological responses of Arabian striped hyaena (Hyaena hyaena sultana) to effective immobilisations with ketamine-medetomidine and ketamine-xylazine in (semi-) captive conditions.

Chemical immobilisation is an integral component for the conservation of wild animals and can be stressful if proper protocols are not administered. References on the immobilisation of Arabian striped hyaena (Hyaena hyaena sultana) are scarce. The current study was designed to evaluate the physiological and clinical responses of Arabian striped hyaena, immobilised with ketamine-medetomidine (KM) and ketamine-xylazine (KX); and to compare immobilisation effectiveness of the two combinations in a cross-sectional clinical study. A total of 15 (six males, nine females) (semi-) captive and adult Arabian striped hyaena with an average weight of 31.39 ± 0.36 kg were immobilised 50 times for annual vaccination and translocation purposes from January 2014 till March 2018 on Sir Bani Yas Island, United Arab Emirates. A total of 34 immobilisations were executed with (Mean ± SE) 2.27 ± 0.044 mg/kg ketamine and 0.04 ± 0.001 mg/kg medetomidine; while 16 with 4.95 ± 0.115 mg/kg ketamine and 0.99 ± 0.023 mg/kg xylazine. The drugs were remotely delivered intramuscular. The evaluation of physiological and clinical parameters included monitoring of vital signs through pulse oximetry, blood gas analysis of arterial blood through Istat blood gas analyser, and blood biochemistry and haematology. The quality of induction, anaesthesia and recovery was also assessed. Atipamezole (0.21 ± 0.003 mg/kg) was used to antagonise the effects of KM and 0.09 ± 0.003 mg/kg atipamezole or by 0.23 ± 0.006 mg/kg yohimbine for KX. Data were analysed using the general linear model and inferential statistics. KM was more effective in induction (scores; KM = 1.41 ± 0.10; KX = 1.31 ± 0.12), anaesthesia (KM = 1.00 ± 0.00; KX = 2.0 ± 0.0) and recovery (KM = 1.76 ± 0.15; KX = 2.69 ± 0.12) phases as compared to KX. There was a significant difference (P < 0.05) amongst the two combinations for anaesthesia time (KM = 59.5 ± 2.41; KX = 49.25 ± 1.31 min.), time to stand after reversal (KM = 4.91 ± 0.60; KX = 10.38 ± 1.48 min.) and full loss of the signs of anaesthetics (KM = 12.32 ± 1.37; KX = 21.25 ± 2.16 min.) along with rectal temperature (KM = 37.58 ± 0.29; KX = 36.00 ± 0.68 °C), pulse rate (KM = 50.46 ± 1.90; KX = 61.14 ± 2.79 beats/min), respiration rate (KM = 29.44 ± 0.99; KX = 23.80 ± 1.57 breaths/min.) and partial pressure of oxygen (KM = 89.59 ± 1.34; KX = 82.06 ± 3.92%). The blood oxygen saturation by oximeter indicated hypoxaemia in KX (82.06 ± 3.92), supported by the data from blood gas analyser. KM combination was more suitable for the immobilisation of Arabian striped hyaena, providing a better quality of induction, anaesthesia and recovery compared to KX. However, we strongly suggest further investigation to see the effects of oxygen supplementation for the compensation of hypoxaemia.

Drivers of diet selection of critically endangered Western Derby eland during the food shortage period within conservation breeding in Senegal.

Browsers represent a challenge for breeding facilities because of their sensitivity to nutritional management. Western Derby eland (Tautrotragus derbianus derbianus, WDE) is a large browsing antelope with a very diverse diet. Because of its critically endangered status, a small WDE population is kept for conservation purposes in the fenced Fathala reserve (Senegal) and during the critical, hot dry season, the animals are offered supplementary Acacia albida pods. We aimed to identify which woody plant species were preferentially selected/avoided by WDE during the period of food shortage, which plant nutritional properties were drivers of animals' diet selection, and how this selectivity was affected by supplemental feed. The animals were selective for certain plant species, most for Piliostigma thonningi pods. Preferences decreased with a feed supplement, while avoidances remained intact. Diet selection was connected with chemical traits, mostly by negative correlations to N, Mg, Ca and hemicellulose, which disappeared or were weaker when supplemental feed was offered. Our findings indicate that large browsers during periods of food shortage must cope with inappropriate chemical composition in regard to nutrition and seek to alleviate them not only by diversification of plant species in the diet, but also by adjusting chemical diet quality as a whole.

Application of Spatial and Closed Capture-Recapture Models on Known Population of the Western Derby Eland (Taurotragus derbianus derbianus) in Senegal.

Camera trapping with capture-recapture analyses has provided estimates of the abundances of elusive species over the last two decades. Closed capture-recapture models (CR) based on the recognition of individuals and incorporating natural heterogeneity in capture probabilities are considered robust tools; however, closure assumption is often questionable and the use of an Mh jackknife estimator may fail in estimations of real abundance when the heterogeneity is high and data is sparse. A novel, spatially explicit capture-recapture (SECR) approach based on the location-specific capture histories of individuals overcomes the limitations of closed models. We applied both methods on a closed population of 16 critically endangered Western Derby elands in the fenced 1,060-ha Fathala reserve, Senegal. We analyzed the data from 30 cameras operating during a 66-day sampling period deployed in two densities in grid and line arrays. We captured and identified all 16 individuals in 962 trap-days. Abundances were estimated in the programs CAPTURE (models M0, Mh and Mh Chao) and R, package secr (basic Null and Finite mixture models), and compared with the true population size. We specified 66 days as a threshold in which SECR provides an accurate estimate in all trapping designs within the 7-times divergent density from 0.004 to 0.028 camera trap/ha. Both SECR models showed uniform tendency to overestimate abundance when sampling lasted shorter with no major differences between their outputs. Unlike the closed models, SECR performed well in the line patterns, which indicates promising potential for linear sampling of properly defined habitats of non-territorial and identifiable herbivores in dense wooded savanna conditions. The CR models provided reliable estimates in the grid and we confirmed the advantage of Mh Chao estimator over Mh jackknife when data appeared sparse. We also demonstrated the pooling of trapping occasions with an increase in the capture probabilities, avoiding violation of results.

Plant trait assembly affects superiority of grazer's foraging strategies in species-rich grasslands.

BACKGROUND: Current plant--herbivore interaction models and experiments with mammalian herbivores grazing plant monocultures show the superiority of a maximizing forage quality strategy (MFQ) over a maximizing intake strategy (MI). However, there is a lack of evidence whether grazers comply with the model predictions under field conditions. METHODOLOGY/FINDINGS: We assessed diet selection of sheep (Ovis aries) using plant functional traits in productive mesic vs. low-productivity dry species-rich grasslands dominated by resource-exploitative vs. resource-conservative species respectively. Each grassland type was studied in two replicates for two years. We investigated the first grazing cycle in a set of 288 plots with a diameter of 30 cm, i.e. the size of sheep feeding station. In mesic grasslands, high plot defoliation was associated with community weighted means of leaf traits referring to high forage quality, i.e. low leaf dry matter content (LDMC) and high specific leaf area (SLA), with a high proportion of legumes and the most with high community weighted mean of forage indicator value. In contrast in dry grasslands, high community weighted mean of canopy height, an estimate of forage quantity, was the best predictor of plot defoliation. Similar differences in selection on forage quality vs. quantity were detected within plots. Sheep selected plants with higher forage indicator values than the plot specific community weighted mean of forage indicator value in mesic grasslands whereas taller plants were selected in dry grasslands. However, at this scale sheep avoided legumes and plants with higher SLA, preferred plants with higher LDMC while grazing plants with higher forage indicator values in mesic grasslands. CONCLUSIONS: Our findings indicate that MFQ appears superior over MI only in habitats with a predominance of resource-exploitative species. Furthermore, plant functional traits (LDMC, SLA, nitrogen fixer) seem to be helpful correlates of forage quality only at the community level.

Effect of phosphorus availability on the selection of species with different ploidy levels and genome sizes in a long-term grassland fertilization experiment.

Polyploidy and increased genome size are hypothesized to increase organismal nutrient demands, namely of phosphorus (P), which is an essential and abundant component of nucleic acids. Therefore, polyploids and plants with larger genomes are expected to be selectively disadvantaged in P-limited environments. However, this hypothesis has yet to be experimentally tested. We measured the somatic DNA content and ploidy level in 74 vascular plant species in a long-term fertilization experiment. The differences between the fertilizer treatments regarding the DNA content and ploidy level of the established species were tested using phylogeny-based statistics. The percentage and biomass of polyploid species clearly increased with soil P in particular fertilizer treatments, and a similar but weaker trend was observed for the DNA content. These increases were associated with the dominance of competitive life strategy (particularly advantageous in the P-treated plots) in polyploids and the enhanced competitive ability of dominant polyploid grasses at high soil P concentrations, indicating their increased P limitation. Our results verify the hypothesized effect of P availability on the selection of polyploids and plants with increased genome sizes, although the relative contribution of increased P demands vs increased competitiveness as causes of the observed pattern requires further evaluation.

Grazing behavior and performance of beef cattle as a function of sward structure and herbage quality under rotational and continuous stocking on species-rich upland pasture.

An experiment to reveal functional response and heifers' performance to sward characteristics and forage chemical composition was conducted for 5 years in rotational (RSS) and continuous (CSS) stocking systems on native species-rich upland grassland. We measured sward characteristics, forage chemical composition, heifers' grazing behavior and live-weight gains from July to September. Mean sward surface height was lower on CSS than on RSS; grass and forb density, and white clover stolon length, were similar. Herbage on CSS had higher crude protein content and lower crude fiber content than on RSS. No difference existed in time budgets of grazing, ruminating and resting between stocking systems and season, while grazing rates were higher on CSS. Stocking rate was 1671 and 1332 kg per ha on CSS and RSS, individual daily live-weight gain 683 and 652 g on CSS and RSS. Gain per ha was 20 kg higher on CSS. Results suggested stocking systems on native species-rich grassland had no effect on activity time budgets or animal performance. Both RSS and CSS allow similar outputs for stocking rates in terms of individual daily live-weight gain. Key parameters determining heifers' behavior and performance were sward height, grass and forb density in the sward, and content of crude fiber and protein in forage.