Do elephants prevent other African herbivores from using waterholes in the dry season?

In some African protected areas, concerns have arisen about the influence of locally high elephant numbers on other forms of biodiversity. In arid and semi-arid savannas, surface-water resources are scarce and agonistic interactions between elephants and other herbivores have been reported at waterholes, yet surprisingly very little is known about the impact of elephants on the use of waterholes by other herbivores. Here, we test whether when there are elephants at a waterhole, other herbivores (1) do not change their drinking behaviour; (2) spend shorter time around the water because they are disturbed by elephants’ presence and consequently have to leave the waterhole area probably without having met their water requirements, or (3) spend more time around the water probably owing to an increase in vigilance activities or because the presence of elephants may signal safety from predators. Results show that all species spend longer time around water when there are elephants at the waterhole, although the difference is not large. Consequently, this study strongly suggests that elephants do not prevent other herbivores from drinking (time at waterholes is not shortened when elephants are around). Further, if the additional time spent to drink is linked to an increased vigilance, the difference is not large, and hence unlikely to affect the population dynamics of other herbivores.     

The Buzz of Drinking on the Wing in Echolocating Bats

Bats broadcast rapid sequences of echolocation calls, named ‘drinking buzzes’, when they approach water to drink on the wing. So far this phenomenon has received little attention. We recorded echolocation sequences of drinking bats for 12 species, for 11 of which we also recorded feeding buzzes. Based on the different sensorial tasks faced by feeding and drinking bats, we hypothesize that the drinking buzz structure will differ from that of feeding buzzes since unlike the latter drinking buzzes are not designed to detect and track mobile prey. We demonstrated that drinking buzzes are structurally different from feeding buzzes. We show that the buzz‐II phase common in feeding buzzes is absent in drinking buzzes; that is, call frequency is not lowered to broaden sonar beam since the task of drinking does not imply tracking fast‐moving targets. This finding indirectly confirms the role of buzz II in feeding buzzes. Pulse rate in drinking buzzes is also lower than in feeding buzzes, as predicted since the high pulse rate typical of feeding buzzes is important to update rapidly the relative location of moving targets. The most likely function of drinking buzzes is to guide a safe drinking manoeuvre, similar to ‘landing buzzes’ broadcast when bats land on the ground.     

Estimating koala density from incidental koala sightings in South‐East Queensland,Australia (1997–2013), using a self‐exciting spatio‐temporal point process model

The koala, Phascolarctos cinereus, is an iconic Australian wildlife species facing a rapid decline in South‐East Queensland (SEQLD). For conservation planning, the ability to estimate the size of koala populations is crucial. Systematic surveys are the most common approach to estimate koala populations but because of their cost they are often restricted to small geographic areas and are conducted infrequently. Public interest and participation in the collection of koala sighting data is increasing in popularity, but such data are generally not used for population estimation. We modeled monthly sightings of koalas reported by members of the public from 1997 to 2013 in SEQLD by developing a self‐exciting spatio‐temporal point process model. This allowed us to account for characteristics that are associated with koala presence (which vary over both space and time) while accounting for detection bias in the koala sighting process and addressing spatial clustering of observations. The density of koalas varied spatially due to the heterogeneous nature of koala habitat in SEQLD, with a mean density of 0.0019 koalas per km² over the study period. The percentage of land areas with very low densities (0–0.0005 koalas per km²) remained similar throughout the study period representing, on average, 66% of the total study area. The approach described in this paper provides a useful starting point to allow greater use to be made of incidental koala sighting data. We propose that the model presented here could be used to combine systematic koala survey data (which is spatially restricted, but more precise) with koala sighting data (which is incidental and often biased by nature, but often collected over large geographical areas). Our approach could also be adopted for modeling the density of other wildlife species where data is collected in the same manner.     

Growing pigs’ drinking behaviour: number of visits,duration, water intake and diurnal variation

Individual drinking patterns are a potential tool for disease monitoring in pigs. However, to date, individual pig drinking behaviour has not been described, and effects of external factors have not been examined. The aim of this study was to perform detailed quantification of drinking behaviour of growing pigs and to examine effects of period of day and effects of competition for access to the drinking nipple on the drinking behaviour, amount of water used and water wastage. In all, 52 cross-bred castrated male pigs (live weight 20.5±1.7 kg; mean±s.d.) maintained as either 3 (N3) or 10 (N10) pigs per pen and water nipple (four groups/treatment) were used. All pigs were fitted with a transponder ear tag. A radio frequency identification reader recorded and time stamped visits at the nipple. In each pen, water flow was logged every second. The drinking behaviour was recorded for 4 consecutive days and analysed using a linear mixed model. Overall, the pigs spent 594 s at the nipple during 24 h distributed among 44 visits. During this period, 5 l of water were used, of which >30% was wasted. Social competition did not affect the drinking behaviour over 24 h, except for the proportion of interrupted visits where pigs, kept with recommended nipple availability (N10), showed an increased proportion of interrupted drinking bouts compared with pigs kept at very low level of competition (N3) (0.18±0.01 v. 0.11±0.01; P<0.01). However, splitting data into 8-h periods (P1, P2, P3) starting from 0600 h revealed differences between treatments, showing that in N3, water use per visit was lower in P1 than P2 and P3 (110±10 v. 126±7 and 132±7 ml; P<0.05), whereas in N10, the water used per visit was higher during P3 than during the other periods (P1: 107±14 ml, P2: 112±10 ml v. P3: 151±10 ml; P<0.001). A similar pattern was found for visit duration. In N3, fewer nipple visits were observed in P2 than P1 (15.6±1.2 v. 22.0±1.2; P<0.001), whereas no difference was found between P1 and P2 in N10. The results demonstrate that growing pigs at the two levels of competition maintained a comparable level of 24 h water intake by changing behavioural variables involved in drinking. This dynamic characteristic of drinking behaviour means that if individual drinking patterns are to be used as disease monitoring tools, it is important to consider effects of external factors and include data on period level to allow rapid detection of behavioural changes.     

Factors affecting the drinking behavior of black howler monkeys (Alouatta pigra)

Water is essential for animals, and is particularly critical for thermoregulation. Animals obtain water from three main sources, free water, water contained in food, and water produced in the body during metabolism. Howler monkeys (Alouatta spp.) spend a small proportion of their time drinking water and some populations have not been observed drinking, suggesting they obtain most of their water requirements in food or by metabolism. However, when howler monkeys have been observed drinking there is evidence suggesting the drinking is associated with low precipitation, temperature, and fruit consumption, and high mature leaf consumption, although it remains unclear which factors determine drinking by this genus. In this study we tested the hypothesis that drinking by howler monkeys results from increased hydration requirements in drier climates and from lower consumption of foods rich in water (e.g., new leaves, fruit). We tested this hypothesis by comparative analysis of 14 groups of Yucatán black howler monkeys (A. pigra) living under different climatic conditions. From April 2005 to November 2008 we collected a total of 3,747.2 focal observation hours of the feeding and drinking behavior of 60 individuals, with data on ambient temperature and rainfall. Individuals spent more time drinking when they lived in habitats with higher maximum temperature and when they consumed more mature leaves. For this species, therefore, drinking seems to be linked to heat stress and a low availability of water in ingested food.     

Influences on koala habitat selection across four local government areas on the far north coast of NSW

Conserving habitats crucial for threatened koala (Phascolarctos cinereus) populations requires rating habitat quality from a fine spatial scale to patches, landscapes and then regions. The koala has a specialized diet focused on the leaves of a suite of Eucalyptus species. We asked: what are the key regional influences on habitat selection by koalas in the far north coast of New South Wales? We addressed this question by investigating the multi-scale factors, and within-scale and cross-scale interactions, that influence koala habitat selection and distribution across four local government areas on the far north coast of New South Wales. We assembled and analysed a large data set of tree selection, identified by the presence of scats, in a wide range of randomly selected 5 × 5 km grids across the region. This resulted in more than 9000 trees surveyed for evidence of koala use from 302 field sites, together with associated biophysical site features. The dominant factor influencing habitat use and koala occurrence was the distribution of five Eucalyptus species. Koalas were more likely to use medium-sized trees of these species where they occurred on soils with high levels of Colwell phosphorous. We also identified new interactions among the distribution of preferred tree species and soil phosphorous, and their distribution with the amount of suitable habitat in the surrounding landscape. Our study confirmed that non-preferred species of eucalypts and non-eucalypts are extensively used by koalas and form important components of koala habitat. This finding lends support to restoring a mosaic of koala-preferred tree species and other species recognized for their value as shelter. Our study has provided the ecological foundation for developing a novel regional-scale approach to the conservation of koalas, with adaptability to other wildlife species.     

Effect of water trough type on the drinking behaviour of pasture-based beef heifers

The objective of this study was to investigate the effects of different trough types on the water consumption and drinking behaviour of pasture-based beef heifers. Two trials were implemented with 32 beef heifers to test two different types of water troughs, namely a rectangular concrete trough (RC) and a round polyvinyl chloride water tank (PVC). In Trial 1, both troughs were simultaneously available to groups of four animals within eight paddocks. In Trial 2, the animals were distributed in pairs throughout 16 paddocks and, in a crossover design, were exposed to one type of trough at a time. In both trials, estimated water intake was per four animals. Number of drinking bouts, time spent drinking and amount of water intake from the RC and PVC trough were recorded in both trials. Data were statistically analysed by analysis of variance. In Trial 1, group and trough effect were in the model. In Trial 2, stage, pair and trough were tested. In Trial 1, where both types of troughs were available, animals had a higher number of drinking bouts (3.32 v. 0.57 ± 0.09; P < 0.01), longer drinking periods (144.21 v. 22.81 ± 7.3 s; P < 0.01) and greater intake (160.21 v. 23.76 ± 13.06 l; P < 0.01) from the PVC water tank, compared to the RC trough. In Trial 2, all groups drank more often (5.10 v. 3.28 ± 0.32; P < 0.001), for longer periods (167.23 v. 115.23 ± 15.61 s; P < 0.02) and with higher intake (141.36 v. 118.47 ± 5.01 l; P < 0.02) from the PVC than from the RC trough. Thus, heifers not only prefer, but also drink more from a PVC water tank in comparison to a RC trough.     

Deuterium oxide dilution accurately predicts water intake in sheep and goats

The aim of this study was to test whether the deuterium oxide dilution technique accurately predicts water intake in sheep and goats. Two other issues were also studied: (i) a comparison of water intake in sheep and goats and (ii) an assessment of whether observations of drinking behaviour can accurately measure the water intake. In this study, eight dry Boer goats and eight dry German Black Head Mutton ewes were kept under controlled stable conditions. Animals had access to hay and water ad libitum. Diurnal drinking behaviour was recorded by video. Individual daily water intake was measured and estimated for 2 weeks by re-weighing water buckets and from water kinetics using the deuterium oxide dilution technique, respectively. In addition, dry matter intakes were directly measured and were significantly higher in sheep than in goats. The average daily water consumption by drinking differed significantly between the two species, with higher intakes in sheep than in goats. Total body water expressed as a percentage of body mass did not differ between species. Measurement methods of total water intake (TWI) using deuterium oxide dilution and re-weighing water buckets did not differ significantly in both species (P = 0.926). Results obtained for measured and estimated TWI confirm that the isotope dilution technique gives reliable results for estimates of water intake in sheep and goats. The higher amount of water intake in sheep was also reflected by their drinking behaviour. Sheep spent approximately 0.3% per 24-h drinking, while Boer goats spent only 0.1%. However, measured and estimated TWIs were only moderately correlated to the daily time spent drinking. The lower water intake found in Boer goats confirms a superior water management capacity compared with Black Head Mutton sheep even under temperate conditions.     

Modelling Chlamydia–koala interactions: coexistence, population dynamics and conservation implications

1. Considerable research has been conducted on koala Phascolarctos cinereus population dynamics and the epidemiology of Chlamydia psittaci infection in koalas, but the impact of Chlamydia on koala populations has been difficult to assess.
2. I developed a model of koala and Chlamydia population dynamics to examine interactions between Chlamydia transmission and pathogenicity, koala mating behaviour and demography, and koala population persistence.
3. Simulations based on sexual and parent–offspring parasite transmission demonstrate that stable Chlamydia–koala coexistence is possible in a small population for a broad range of demographic, behavioural, pathogenicity and transmission parameter estimations. Koala population persistence was most sensitive to reduced annual survivorship of adults (4–10-year-old males and 2–12-year-old females), highlighting the need for accurate field estimates of adult survivorship in order to assess Chlamydia 's impact on specific populations.
4. If koalas become less resistant to disease in fragmented, high-stress habitats (i.e. experience increased Chlamydia -induced mortality and sterility rates), Chlamydia is not predicted to cause koala extinctions under most conditions. Extinctions are only predicted if Chlamydia transmission rates also increase (e.g. due to new transmission pathways or increased mating frequency), or other non-disease factors change birth and mortality rates to reduce the koala population's intrinsic rate of increase below 0·1.
5. The most important predicted effect of habitat fragmentation and other forms of human disturbance on this unique host–parasite relationship is the extinction of Chlamydia in populations where koala resistance to disease decreases.     

Difficulties of assessing the impacts of the 2019–2020 bushfires on koalas

The 2019–2020 Australian bushfires were unprecedented both in extent and severity, impacting wildlife through direct mortality as well as habitat damage. More than 10% of koala habitat is estimated to have been affected by fires. Estimating the number of koalas lost is crucial to assess koala conservation status and to determine the appropriate management actions required. However, this is not a trivial task, as accurate data on koala distribution and population density before the fires is patchy. Acknowledging this weakness, we sought to estimate fire impact on koalas at specific sites, by comparing habitat areas affected by the fire with habitat areas that were unaffected by the fire, pairing closely related study sites (based on geography and vegetation). To compare koala density, we deployed two koala detection methods; drone-acquired thermal imagery and detection dogs coupled with genetic fingerprinting, in four fire-affected sites paired with four control sites in New South Wales and Queensland. Through drone surveys, we detected 140 koalas in 5,240 ha in New South Wales. The detection dogs found 144 scat samples corresponding to 79 unique koalas in 77 ha of transects in Queensland. Our preliminary results show many koalas were still present in fire-affected areas after the 2019–2020 bushfire season. Koala density was 24 to 71% lower in fire-affected sites compared with control sites in three of the habitat pairs, whereas unexpectedly, in the fourth pair, we observed a 317% higher koala density in the fire-affected site. This underlined that koalas can be present in fire-affected areas and that monitoring their health could be critical for months after the fires.     

The koala-forest-management interactive game: are there lessons in modelling a complex system?

[First paragraph]Koalas are considered to be overabundant in some areas of their natural range. This is the case at Mount Eccles National Park, Victoria, Australia. The concern at Mount Eccles National Park is that an overabundant koala population will have deleterious impacts on the unique forest community as well as leading to a koala population collapse. Due to social and political constraints, the only available management technique is to sterilise adult female koalas. Two questions of interest to management are: (1) Can sterilisation reduce the likelihood of both a decline in the forest community and a severe collapse in the koala population? (2) Can management sterilise enough koalas such that the likelihood is sufficiently reduced?     

Successful artificial insemination in the koala (Phascolarctos cinereus) using extended and extended-chilled semen collected by electroejaculation

Artificial insemination in the koala using chilled, electroejaculated semen provides for a marked improvement in the reproductive and genetic management of captive koala colonies in Australia and internationally, and makes available the option of using semen collected from wild populations to expand restricted gene pools. Dilution of koala semen for artificial insemination is complicated because koalas are induced ovulators, and it is thought that ovulating factors are present in the semen, so that semen extension for preservation purposes might be anticipated to result in a failure to induce ovulation. The first two experiments of this study were designed to determine whether artificial insemination using undiluted, extended, and extended-chilled semen collected by electroejaculation was capable of inducing a luteal phase and/or the production of pouch young. In Experiment 1, 1 ml undiluted electroejaculated semen, 2 ml diluted (1:1) semen, and 1 ml diluted (1:1) semen resulted in seven of nine, six of nine, and six of nine koalas showing a luteal phase, respectively; four pouch young were produced in each treatment. A second artificial insemination experiment was conducted in which 2 ml diluted (1:1) semen was administered in three groups of nine koalas. The first group received semen that had been collected and diluted immediately without chilling, the second group was deposited with semen stored chilled for 24 h, and the final group received semen that had been chilled for 72 h. In the first group, five females had a luteal phase, but none became pregnant. In group 2, two of the five females that had a luteal phase gave birth, whereas in group 3, four of the six females that had a luteal phase produced pouch young. In addition, experiment 3 was conducted to determine whether it was possible to produce pouch young by naturally mating koalas that were in the latter stages of their behavioral estrus; this information is important to the logistics of transporting koala semen for artificial insemination by establishing the maximum time frame in which females might be expected to shed a fertile oocyte. Of the 12 females mated on Day 8 of estrus, 6 gave birth, whereas only 3 of the 10 females naturally mated on Day 10 of estrus produced pouch young. The majority of females (21 of 22) in experiment 3 showed evidence of a luteal phase. Together, these experiments have shown that it is possible to use undiluted, extended, or extended-chilled semen to produce koala offspring up to Day 8 of estrus at conception rates similar to those achieved following natural mating. These findings represent a significant advancement in the use of reproductive technology in marsupials and provide the basis for the shipment of koala semen over long distances. The pouch young produced in this study represent the first marsupials born following artificial insemination of extended-chilled semen and bring the total number of koalas produced by artificial insemination to 31.     

Comparison of funding and demand for the conservation of the charismatic koala with those for the critically endangered wombat <Emphasis Type="Italic">Lasiorhinus krefftii</Emphasis>

This study contrasts the actual conservation spending and the Australian public’s demand for conservation funding for two Australian mammal species, the koala and the northern hairy-nosed wombat. It involves a survey of 204 members of the Australian public. Willingness to fund conservation action to protect the northern hairy-nosed wombat was found to be higher than that for the koala despite the koala’s immense popularity. The critically endangered status of the northern-hairy nosed wombat and the more secure conservation status of the koala is a factor likely to have influenced the comparative willingness-to-pay decisions. Actual annual conservation expenditure for both species is lower than the estimated aggregate willingness-to-pay for their conservation. Furthermore, conservation funding for the koala is much more than that for the northern hairy-nosed wombat even though the estimated public willingness-to-pay (demand) for funding koala conservation was less than for this wombat species. Reasons for this are suggested. They may also help to explain misalignment between demand for conservation funding of other species involving differences in charisma and endangerment.     

Comparative analysis reveals the species-specific genetic determinants of ACE2 required for SARS-CoV-2 entry

Coronavirus interaction with its viral receptor is a primary genetic determinant of host range and tissue tropism. SARS-CoV-2 utilizes ACE2 as the receptor to enter host cell in a species-specific manner. We and others have previously shown that ACE2 orthologs from New World monkey, koala and mouse cannot interact with SARS-CoV-2 to mediate viral entry, and this defect can be restored by humanization of the restrictive residues in New World monkey ACE2. To better understand the genetic determinants behind the ability of ACE2 orthologs to support viral entry, we compared koala and mouse ACE2 sequences with that of human and identified the key residues in koala and mouse ACE2 that restrict viral receptor activity. Humanization of these critical residues rendered both koala and mouse ACE2 capable of binding the spike protein and facilitating viral entry. Our study shed more lights into the genetic determinants of ACE2 as the functional receptor of SARS-CoV-2, which facilitates our understanding of viral entry.     

Drinking tools of wild chimpanzees at Bossou

Use of drinking tools by wild chimpanzees (Pan troglodytes) and the context in which the tools were used were studied at Bossou, Republic of Guinea, West Africa. During the middle to late dry season and early wet season liquids are available occasionally in the holes of trees. Chimpanzees drank water or sap using a leaf (or fiber) as a sponge or spoon. When the chimpanzees were on the ground, they tended to use one of a few kinds of soft, hairless leaves, if they were available nearby. Females, particularly juveniles and adolescents, were thought to be the main users of the drinking tool. In a few episodes, a tool set was used to procure liquid. Once a chimpanzee used a stick to push a leaf sponge into a water hole and to pull it out from the hole. In addition, three chimpanzees used a pestle to squeeze sap from an oil-palm tree before using a fiber sponge. © 1995 Wiley-Liss, Inc.