Energy intake for maintenance in a mammal with a low basal metabolism, the giant anteater (Myrmecophaga tridactyla)

Larger Than Life? Body Mass Records of Zoo-Managed Giant Anteaters (Myrmecophaga tridactyla)

It has been suggested repeatedly that zoo-kept giant anteaters (Myrmecophaga tridactyla) have higher body masses than their free-ranging conspecifics. Here, we assess this hypothesis by comparing body mass data of 184 female and 173 male individuals kept in zoos to published and unpublished data of free-ranging animals (n = 215). In zoos, the average adult body mass of all individuals was 45.9 ± 9.6 kg (range 19.2-72.6 kg), whereas body mass for free-ranging specimens was 33.0 ± 2.3 kg (21-45.5 kg). Among those zoo animals in which a sufficient number of subsequent intra-annual measures had been taken, we assessed visually whether regular, annual fluctuations in body mass were evident. We observed regular, likely seasonal, cycles in body mass, which (i) may be plausibly attributed to ambient temperature changes that affect the body temperature of anteaters, and (ii) would likely not have occurred if the animals were affected by obesity. Additionally, we explain our hypothesis that in the case of giant anteaters, the discrepancy in body mass between natural habitats and zoos most likely is not indicative of a generally obese population in zoos, as is typically concluded in the case of similar comparisons in primates, but represents an unleashing of the full growth potential of the species by conditions of optimal energy and nutrient provision. Future recording of not only body mass but also body dimensions is recommended to better compare the body condition of free-ranging and zoo-managed individuals.

Survey of the feeding management of giant anteaters (Myrmecophaga tridactyla) and tamanduas (Tamandua tetradactyla) in the EAZA ex-situ programme

Feeding giant anteaters and tamanduas as insectivorous species provides a lot of challenges for zoological institutions. In the last decades an in-house mixture, called 'Dortmund mixture', was the most common feed used in giant anteaters and tamanduas in many countries within the European Association of Zoos and Aquaria ex-situ Programme (EEP). Some nutritional problems occurred due to imbalances in the diets. The more recent nutritional recommendations for both species advise an adapted and balanced complete feed formulated for insectivorous species due to different problems arising with an in-house mixed feed as Dortmund mixture. To objectify the present situation a questionnaire was designed and sent out to 78 institutions of the EEPs for giant anteater(s) and tamandua(s). The questionnaire was divided into different sections and asked for data on husbandry, health status, feeding, especially feed composition, feed supplementation and faecal consistency. It was completed by 45 institutions with data for 130 animals, 89 giant anteaters and 41 tamanduas. The data thus represent 54% and 59% of the EEP populations. For both species, a complete feed is mainly utilised. Especially institutions that have integrated anteaters and tamanduas into their facilities during the last 10 and 20 years, use a complete feed. Regarding the in-house mixtures, there are distinct differences, both in composition and amount of each ingredient used. The evaluation of the feeds used for enrichment, for example, shows a clear species difference. While in tamanduas mainly insects are used for this purpose, in giant anteaters it is mainly fruits and avocado. In contrast to the past, many anteaters today are fed an adapted complete feed. Surprisingly, concerning feeding supplements the use of fat-soluble vitamins and combined vitamin-mineral preparations is still common in both species. More effort needs to be put into enforcing current feeding recommendations, especially for the giant anteaters.

Energy budgets of captive Chinese pangolins (Manis pentadactyla)

The Chinese pangolin is an endangered species, and ex situ conservation and captive rescue are important conservation measures. This requires reliable information on nutritional energy requirements and expenditure characteristics. However, we lack sufficient knowledge of their energy physiology to determine their energy requirements for maintenance and growth. An open-flow respirometry system was used to measure the resting metabolic rate (RMR) and the daily energy expenditure (DEE) of Chinese pangolins (Manis pentadactyla), and the dietary digestive energy was measured. The average RMR in Chinese pangolins was 3.23 ml O₂ kg^-1 min^-1 at an ambient temperature (T_a) of 24.5-30°C, which was only 73.0% of the expected value based on body mass (BM). The average DEE values were 744.9 kJ day^-1 in animals with BM >3 kg and 597.3 kJ day^-1 in those with BM <3 kg, which were only 52.4% and 60.6% of the predicted values, respectively. The RMR and DEE levels of the Chinese pangolin were lower than those of similar-sized eutherian mammals and close to those of anteaters. These characteristics suggest that the Chinese pangolin has a low demand for energy in its diet. Although metabolic level data alone cannot be used to calculate the energy requirements of each Chinese pangolin, we believe they can provide a tangible reference for the relocation of Chinese pangolins. These results provide a scientific basis for future research on the physiology and ecology of endangered wildlife such as the Chinese pangolin.

Biomonitoring mercury contamination using fur from roadkilled giant anteaters

The giant anteater (Myrmecophaga tridactyla) can occur in both preserved and anthropogenic environments in Brazilian biomes. The Cerrado biome, where the samples were collected, is considered one of the world's biodiversity hotspots; however, a large part of it has been converted to pasture and agricultural land. In this environment, animals may be exposed to contaminants, such as mercury (Hg). Despite its immense biodiversity, there are few studies investigating Hg contamination in terrestrial mammals in Brazil. This study aimed to create a baseline for Hg levels in giant anteater fur and establish which biotic and abiotic variables can influence its concentration. Total Hg (THg) concentrations were determined by cold vapor atomic absorption spectrometry in 141 individuals sampled on highways between January and October 2017, in the state of Mato Grosso do Sul, Brazil. THg concentrations in fur ranged from 0.27 to 4.77 μg g ^-1. The decomposition stage of the carcasses and vehicular traffic volume on highways did not influence the THg concentrations. Juveniles presented lower THg concentrations than adults. A spatial pattern of higher concentrations in the eastern-southeastern region of the state was found, which could be related to anthropogenic impacts; however, no clear links have been established. The THg concentrations in giant anteaters' fur seems higher than expected considering the trophic position of the species. Despite this, the range was in accordance with studies of other Brazilian terrestrial mammals and within safe threshold levels. This study indicates the potential of utilizing roadkilled fauna to monitor large-scale contamination in wildlife.

The addition of soil and chitin into Sunda pangolin (Manis javanica) diets affect digestibility, faecal scoring, mean retention time and body weight

Pangolins (Manis spp.) are myrmecophagous mammals with a wild diet of termites and ants. Diets are not yet readily acceptable by all pangolins and lack soil and chitin compared to their wild diet. This study aimed to assess the usefulness of including soil and chitin in pangolin diets by measuring changes in digestibility, food mean retention time, faecal scoring and body weight changes. Two male and two female Sunda pangolins (Manis javanica) from Night Safari (Singapore) were fed their typical gruel-type diets, with soil and chitin added in various amounts throughout 10 different treatments. Diet intake was calculated daily and faecal boluses were collected for digestibility analysis. Chromium oxide was added to the diet to measure mean retention time four times per animal per treatment. Faecal consistency scores were recorded daily where 1 is firm and 5 is liquid. Every animal was weighed weekly. Adding soil or chitin to the diet had various effects on the apparent digestibility of organic matter, crude protein and fiber with little effects on crude fat or calcium. Soil had a general positive influence on organic matter and fiber digestion. The addition of chitin and soil together had the stronger effects. Only at 25% inclusion of soil did the faecal score begin to improve. The overall maintenance energy requirements for adult M. javanica was 79.28 Kcal/kg BW^0.75 /day, similar to other myrmecophagous mammals. The usage of soil and chitin in pangolin diets may be helpful in controlling weights while preventing behaviours associated with hunger.

Spatial patterns of road mortality of medium–large mammals in Mato Grosso do Sul, Brazil

Context Brazil has one of the richest biodiversity and one of the most extensive road networks in the world. Several negative impacts emerge from this interaction, including wildlife–vehicle collisions (WVC), which may represent a significant source of non-natural mortality in several species. The understanding of the main drivers of WVC is, therefore, crucial to improve the safe coexistence between human needs (transportation of goods and people) and animal populations. Aims We aimed to (1) evaluate the relative influence of land-cover patterns on the distribution of WVC, (2) assess whether WVCs are clustered forming hotspots of mortality, and, if so, (3) evaluate the benefits of mitigating only hotspot sections. Methods We collected WVC data involving medium–large mammals (4–260kg) along three road transects (920km), fortnightly over 1 year (n=1006 records). We used boosted regression trees to relate the WVC locations with a set of environmental variables including a roadkill index, reflecting overall habitat suitability and landscape connectivity, while accounting for spatial autocorrelation effects. We identified hotspots of mortality using Ripley’s K statistic and testing whether data follow a random Poisson distribution correcting for Type I error. Key results We found a strong association between WVC probability and roadkill index for all focal species. Distance to riparian areas, tree cover, terrain ruggedness and distance to urban areas were also important predictors, although to a lesser extent. We detected 21 hotspots of mortality, yet with little spatial overlapping as only four road sections (2%) were classified as hotspot for more than one species. Conclusions Our results supported that WVC mainly occur in road sections traversing areas with more abundant and diverse mammal communities. Hotspots of mortality may provide important information to prioritise road sections for mitigation, but this should be used in complement with roadkill indexes accounting for overall mortality. Implications The results support focusing on hotspots and habitat quality and landscape connectivity for a better assessment of road mortality. At the local scale, a larger number and improved road passages with exclusionary fencing of appropriate mesh size in riparian areas may provide safe crossings for many species and constitute a promising mitigation measure.

Geometric factors influencing the diet of vertebrate predators in marine and terrestrial environments

Predator–prey relationships are vital to ecosystem function and there is a need for greater predictive understanding of these interactions. We develop a geometric foraging model predicting minimum prey size scaling in marine and terrestrial vertebrate predators taking into account habitat dimensionality and biological traits. Our model predicts positive predator–prey size relationships on land but negative relationships in the sea. To test the model, we compiled data on diets of 794 predators (mammals, snakes, sharks and rays). Consistent with predictions, both terrestrial endotherm and ectotherm predators have significantly positive predator–prey size relationships. Marine predators, however, exhibit greater variation. Some of the largest predators specialise on small invertebrates while others are large vertebrate specialists. Prey–predator mass ratios were generally higher for ectothermic than endothermic predators, although dietary patterns were similar. Model-based simulations of predator–prey relationships were consistent with observed relationships, suggesting that our approach provides insights into both trends and diversity in predator–prey interactions.