Salt intake and regulation in two passerine nectar drinkers: white-bellied sunbirds and New Holland honeyeaters

Avian nectarivores face the dilemma of having to conserve salts while consuming large volumes of a dilute, electrolyte-deficient diet. This study evaluates the responses to salt solutions and the regulation of salt intake in white-bellied sunbirds (Cinnyris talatala) and New Holland honeyeaters (Phylidonyris novaehollandiae). Birds were first offered a choice of four sucrose diets, containing no salt or 25, 50 or 75 mM NaCl. The experiment was repeated using five sucrose concentrations (0.075-0.63 M) as the base solution. Both species ingested similar amounts of all diets when fed the concentrated base solutions. However, when birds had to increase their intake to obtain enough energy on the dilute sucrose diets, there was a general avoidance of the higher salt concentrations. Through this diet switching, birds maintained constant intakes of both sucrose and sodium; the latter may contribute to absorption of their sugar diets. A second, no-choice experiment was designed to elucidate the renal concentrating abilities of these two nectarivores, by feeding them 0.63 M sucrose containing 5-200 mM NaCl over a 4-h trial. In both species, cloacal fluid osmolalities increased with diet NaCl concentration, but honeyeaters tended to retain ingested Na+, while sunbirds excreted it. Comparison of Na+ and K+ concentrations in ureteral urine and cloacal fluid showed that K+, but not Na+, was reabsorbed in the lower intestine of both species. The kidneys of sunbirds and honeyeaters, like those of hummingbirds, are well suited to diluting urine; however, they also appear to concentrate urine efficiently when necessary

On-line multiobjective automatic control system generation by evolutionary algorithms

Evolutionary algorithms are applied to the on- line generation of servo-motor control systems. In this paper, the evolving population of controllers is evaluated at run-time via hardware in the loop, rather than on a simulated model. Disturbances are also introduced at run-time in order to pro- duce robust performance. Multiobjective optimisation of both PI and Fuzzy Logic controllers is considered. Finally an on-line implementation of Genetic Programming is presented based around the Simulink standard blockset. The on-line designed controllers are shown to be robust to both system noise and ex- ternal disturbances while still demonstrating excellent steady- state and dvnamic characteristics

Foraging activity by the southern brown bandicoot (Isoodon obesulus) as a mechanism for soil turnover

Mammals that forage for food by biopedturbation can alter the biotic and abiotic characteristics of their habitat, influencing ecosystem structure and function. Bandicoots, bilbies, bettongs and potoroos are the primary digging marsupials in Australia, although most of these species have declined throughout their range. This study used a snapshot approach to estimate the soil turnover capacity of the southern brown bandicoot (Isoodon obesulus, Shaw 1797), a persisting digging Australian marsupial, at Yalgorup National Park, Western Australia. The number of southern brown bandicoots was estimated using mark-recapture techniques. To provide an index of digging activity per animal, we quantified the number of new foraging pits and bandicoot nose pokes across 18 plots within the same area. The amount of soil displaced and physical structure of foraging pits were examined from moulds of 47 fresh foraging pits. We estimated that an individual southern brown bandicoot could create ∼45 foraging pits per day, displacing ∼10.74kg of soil, which extrapolates to ∼3.9 tonnes of soil each year. The digging activities of the southern brown bandicoots are likely to be a critical component of soil ecosystem processe

Evidence for citation networks in studies of free-roaming cats: A case study using literature on Trap–Neuter–Return (TNR)

Trap–Neuter–Return and its variants (hereafter TNR) aims to control unowned cat populations. Papers on this topic form a useful case study of how how an area of literature grows, papers become influential, and citation networks form, influencing future study as well as public perceptions of the science. We analysed 145 TNR studies published 2002–2019. Common topics, identified by frequently used language, were population control, interactions with wildlife, disease transmission (including implications for pets, wildlife and humans), free-roaming cats, and feral and domestic cat management. One or more papers on each of these topics was judged influential because of high citations overall, high average citations/year, or frequent mentions in social media. Open Access papers were more influential in social media, raising greater public awareness than studies published in journals that were less accessible. While divergent views exist on a range of topics, the network analysis of the TNR literature indicated potential for forming self-reinforcing groups of authors. While it is encouraging that diverse views are expressed, there is a risk of reduced dialogue interactions between groups, potentially constraining dialogue to refine arguments, share information, or plan research. Journal editors could encourage communication by choosing reviewers from different camps to assess manuscripts and by asking authors to acknowledge alternative views

Changing topography of the RPE resulting from experimentally induced rapid eye growth

The retinal pigment epithelium (RPE) of the quokka wallaby, Setonix brachyurus, grows and changes throughout life. To investigate factors that determine changes in the quokka RPE, we have examined topography of this tissue in experimentally enlarged eyes. Unilateral eyelid suture was conducted at the time of normal eye opening, postnatal day (P) 110, and animals were examined at 1 or 1 1/4 years of age. The numbers and densities of RPE cells and the extent of multinucleation were compared with those in normal animals. Eyelid suture resulted in a 9.8% and 17.4% increase in retinal area at 1 and 1 1/4 years, respectively; a significant degree of myopia was associated with this enlargement. Cell density topography in experimental eyes was not the same as in controls. Cells from central retina were disproportionately larger in the experimental than control eyes. However, the RPE cell topography in sutured eyes was not the same as that of aged retinae of a similar size. Notably, in sutured eyes there was no development of the high or highest cell densities seen in equatorial and temporal central RPE in aged retinae, respectively. Furthermore, the degree of cell enlargement in peripheral regions was slight compared with that observed in similar-sized, aged retinae. There was no increase in RPE cell number; rather, average cell area increased accompanied by no change or a slight decrease in RPE thickness. Consequently, overall volume of cells did not change significantly. The large number of multinucleate cells normally seen n aged animals was not observed in experimentally enlarged eyes, implying that an increase in cell volume may be the trigger for multinucleation

The plant pathogen Phytophthora cinnamomi influences habitat use by the obligate nectarivore honey possum (Tarsipes rostratus)

Introduced plant pathogens can devastate susceptible plant communities, and consequently impact on animal communities reliant on plants for food and habitat. Specifically, plant pathogens change the floristic diversity of vegetation communities, thereby reducing availability of food sources for fauna (e.g. pollen and nectar) and result in major changes to habitat structure when canopy and understorey plant species succumb to disease. Phytophthora cinnamomi poses a threat to flowering plant species (e.g. Banksia species) which are important food sources for nectarivorous fauna. The honey possum (Tarsipes rostratus) is the only obligate nectarivorous non-flying mammal living on a restrictive diet of nectar and pollen; consequently, these tiny mammals are likely to be particularly vulnerable to the landscape-wide devastation caused by P. cinnamomi. We investigated habitat selection by honey possums in a vegetation community infested with P. cinnamomi to determine how these mammals respond to habitat affected by this pathogen. Over four seasons, 18 honey possums were fitted with radio-transmitters and tracked to identify habitat preferences. Vegetation surveys were compared for locations selected by honey possums (as determined from tracking) and randomly selected sites. Radio-tracking revealed that sites selected by honey possums were significantly taller, denser, and more floristically diverse than their paired random locations. The presence of P. cinnamomi influences habitat use by honey possums, but animals show resilience in terms of using the best of what is available in both P. cinnamomi-affected and unaffected locations. Habitat patches comprising less susceptible species, or plants that have yet to succumb to infection, provide refuge and food resources for honey possums. Management to reduce the spread of existing P. cinnamomi infestations and prevent contamination of new locations will benefit vegetation communities and associated faunal communities, while identifying honey possum food plant species that are resilient to the pathogen may support revegetation attempts

Are observer ratings influenced by prescription? A comparison of Free Choice Profiling and Fixed List methods of Qualitative Behavioural Assessment

Qualitative methods of behavioural assessment use observer rating scales to score the overall demeanour or body language of animals. Establishing the reliability of such holistic approaches requires test and validation of the methods used. Here, we compare two methodologies used in Qualitative Behavioural Assessment (QBA): Fixed-Lists (FL) and Free-Choice Profiling (FCP). A laboratory class of 27 students was separated into two groups of 17 and 10 students (FL and FCP respectively). The FL group were given a list of 20 descriptive terms (used by the European Union's Welfare Quality ® program), shown videos of group-housed sows, and as a group discussed how they would apply the descriptive terms in an assessment. The FCP group were shown the same footage but individually generated their own descriptive terms to describe body language of the animals. Both groups were then shown 18 video clips of group-housed sows and scored each clip using a visual analogue scale (VAS) system. We analysed the VAS scores using Generalised Procrustes Analysis (GPA) for each observer group separately, which indicated high inter-observer reliability for both groups (FL: 71.1% of scoring variation explained, and FCP: 63.5%). There were significant correlations between FL and FCP scores (GPA dimension 1: r 16 =0.946, P 0.7 is usually accepted to show strong agreement). This study demonstrates that, regardless of whether they are given their terms or are allowed to generate their own, observers score sow body language in a similar way. Strengths and weaknesses within the two methods were identified, which highlight the importance of providing thorough and consistent training of observers, including providing good quality training footage so that the full repertoire of demeanours can be identifie

Does urbanization influence the diet of a large snake?

Urbanization facilitates synanthropic species such as rodents, which benefit the diets of many predators in cities. We investigated how urbanization affects the feeding ecology of dugites Pseudonaja affinis, a common elapid snake in south-west Western Australia. We predicted that urban snakes: 1) more frequently contain prey and eat larger meals, 2) eat proportionally more non-native prey, 3) eat a lower diversity of prey species, and 4) are relatively heavier, than non-urban dugites. We analyzed the diet of 453 specimens obtained from the Western Australian Museum and opportunistic road-kill collections. Correcting for size, sex, season, and temporal biases, we tested whether location influenced diet for our 4 predictions. Body size was a strong predictor of diet (larger snakes had larger prey present, a greater number of prey items, and a greater diversity of prey). We identified potential collection biases: urban dugites were relatively smaller (snout-vent length) than non-urban specimens, and females were relatively lighter than males. Accounting for these effects, urban snakes were less likely to have prey present in their stomachs and were relatively lighter than non-urban snakes. Other urban-adapted carnivores appear to benefit from urbanization through increased food supplementation, but we found the opposite of this: urban dugites were less likely to contain a meal, and their meals were smaller, indicating they did not make greater use of synanthropic species than was evident for non-urban snakes. In contrast to other carnivores, snakes do not appear to fit a consistent directional pattern for size differences between urban and non-urban populations

Set free: an evaluation of two break-away mechanisms for tracking collars

Context: One of the welfare and ethical challenges with tracking animals is ensuring that the tracking device is removed from the animal at the conclusion of the study. However, for animals that are not readily re-trapped, the impact of devices and alternatives for their retrieval are rarely examined. Aims: We compared the retention time of two types of break-away mechanisms for tracking collars deployed on mainland quokkas (Setonix brachyurus). Methods: We tested a cotton thread (CT) weak-link, where the collar was cut and then a looping stitch was made to link the cut ends of the collar. We compared collar retention time of this simple mechanism with a lightweight automatic micro timed-release device (mTRD, Sirtrack). Key results: Of the 17 radio collars with CT, the fates of 15 collars contributed to retention time data. Seven collars released: six fell off and were recovered 148 ± 64 (s.d.) days after deployment and another collar fell off 136 days after deployment but could not be recovered. Eight quokkas were recaptured (161 ± 109 days after deployment) and collars removed. Two quokkas were each tracked for over a year but then disappeared. Of the 11 GPS collars fitted with a mTRD, the fates of nine collars contributed to retention time data. Two released early at 16 and 29 days and were recovered. Seven fell off around the scheduled release date. There were two unknown fates. Re-trapped collared quokkas did not show evidence of injuries from wearing collars or any significant change in body mass (P = 0.442). Conclusions: The timing of release for the CT weak-link was unpredictable, with a third of the collars releasing within 1 year and 7/15 lasting only about 6 months. Over two-thirds (7/9) of the GPS collars fitted with timed-release device released on schedule while 2/9 released early. Implications: Tracking devices equipped with break-away mechanisms are essential for safeguarding animal welfare outcomes for species where the chance of recapture is not certain. For both break-away types examined in this study, the release timing was unpredictable and poor collar recovery rates show the importance of adding camera traps to monitor the outcomes for collared animals

Subsidised by junk foods: factors influencing body condition in stray cats (Felis catus)

Domestic cats (Felis catus) are one of the most widely distributed and successful carnivores globally. While cats are popular pets, many unowned, ‘stray’ cats live freely in anthropogenic environments at high densities where they make use of anthropogenic resources. These stray cats present a management challenge due to concerns about wildlife predation, pathogen transmission, public nuisance and threats to cat welfare (e.g. vehicle collisions). In Australia, there are few studies of strays compared with pet cats or feral cats (free-roaming cats in rural areas that are independent of resources provided by humans). To contribute original data about stray cat biology, the carcasses of 188 euthanised stray cats were collected from Perth, Western Australia. Cats were assessed for general health, age, reproduction, diet and gastrointestinal parasite biomass. The influence of cat demographics, collection location, season, parasite biomass, diet and history of supplemental feeding by people were tested against body condition. Overall, strays were physically healthy and reproductive, with few life-threatening injuries or macroscopic evidence of disease; however, helminths were extremely common (95% of cats) and pose a threat. Nearly 40% of strays consumed wildlife, including two species of endemic marsupial. Alarmingly, 57.5% of strays were scavenging vast amounts of refuse, including life-threatening items in volumes that blocked their gastrointestinal tracts. These findings illustrate that strays need to be removed from anthropogenic environments for their own health and welfare and to prevent continued breeding. Targeted control programmes should prioritise removal of cats from areas where refuse is common and where valued native fauna exist