Fig 2-9 - uploaded by Philip Bethge
Content may be subject to copyright.
Percentage of resident platypuses using a single and multiple burrow sites at Lake Lea (n=28, determined from trapping locations)
Source publication
In this work, behavioural field studies and metabolic studies in the laboratory were conducted to elucidate the extent of adaptation of the platypus Ornithorhynchus anatinus to its highly specialised semiaquat-ic lifestyle. Energy requirements of platypuses foraging, resting and walking were measured in a swim tank and on a conventional tread-mill...
Similar publications
The metabolic response of fish to exercise is highly dependent on environmental factors such as temperature. In addition to natural challenges that force exercise (foraging, avoiding predators, etc.), sportfish species are also subjected to exercise when they are hooked by anglers, leading to metabolic energy costs that may impact fitness. While se...
Citations
... Platypus interactions at localised scales remain relatively unknown, but are probably influenced by density, competition, habitat characteristics, and river geomorphology (Bethge, 2002;Serena, 1994). Adult males and females generally have overlapping home ranges, reflecting their polygamous mating system (Gardner & Serena, 1995;Gust & Handasyde, 1995;Serena, 1994;Serena, Thomas, Williams, & Officer, 1998). ...
• The platypus is a cryptic mammal that inhabits freshwater streams and rivers of eastern Australia. Tracking the movements of wild platypuses has been notoriously difficult due to the animals' morphology and methodological limitations. Knowledge of fine‐scale movements and interactions among individuals remain particularly poorly understood, as do responses to changes in hydrology.
• We tracked movements of 15 platypuses (six females, nine males) downstream of the Jindabyne Dam on the Snowy River, using externally attached acoustic transmitters (September–November 2017), to assess spatio‐temporal activity patterns among individuals and changes in movement and activity before and after an environmental flushing flow. As the study took place during the breeding season, we expected to observe overlap in area of activity among males and females, but not among males due to increased territoriality during these months. We also anticipated that a large flow event would impact their activity and foraging behaviour, possibly displacing platypuses downstream.
• Overlaps in area of activity and temporal co‐occurrence within a pool varied among individuals, with two resident males exhibiting some spatial overlap of activity and varying temporal co‐occurrence, despite tracking during the breeding season. All six tracked females were captured in the same pool and appeared to be residents, possibly highlighting preferences for certain habitats during the breeding months.
• We found no evidence that the movements of adult platypuses were affected by an environmental flushing flow, with no significant changes to area of activity, number of detections, or daily range of movements. However, foraging duration increased in the week after the flow, possibly associated with increased prey availability.
• These findings suggest that territoriality between males during and after the breeding season may depend on platypus density and resource availability and that pools with high resource availability may support several breeding females.
... The lake system results do not preclude the possibility of selective predation, but do not provide clear evidence for selectivity either. In previous dietary studies in Lake Lea, Bethge 48 showed that Trichoptera make up a major part of the diet of platypuses, and we also found that members of this family contributed to dissimilarity in samples between the + PLATYPUS and − PLATYPUS treatments. However, the lack of treatment effects on the abundance of any invertebrate trophic group and the contribution of three of four of these groups to compositional differences between the + PLATYPUS and − PLATYPUS treatments suggest that platypuses simply ate what they encountered during foraging. ...
... We selected this lake as natural undisturbed freshwater lakes are rare in mainland Australia, and none have been studied with respect to platypus. Lake Lea, by contrast, has a large and well-studied population of platypuses [32][33][34][46][47][48] . Prior to our experiment, 52 individual platypuses were captured 48 . ...
... Lake Lea, by contrast, has a large and well-studied population of platypuses [32][33][34][46][47][48] . Prior to our experiment, 52 individual platypuses were captured 48 . However, as Bethge 48 did not sample the entire lake, the population probably exceeded 52 animals. ...
Predators can have strong impacts on prey populations, with cascading effects on lower trophic levels. Although such effects are well known in aquatic ecosystems, few studies have explored the influence of predatory aquatic mammals, or whether the same predator has similar effects in contrasting systems. We investigated the effects of platypus (Monotremata: Ornithorhynchus anatinus) on its benthic invertebrate prey, and tested predictions that this voracious forager would more strongly affect invertebrates—and indirectly, epilithic algae—in a mesotrophic lake than in a dynamic stream ecosystem. Hypotheses were tested using novel manipulative experiments involving platypus-exclusion cages. Platypuses had strongly suppressive effects on invertebrate prey populations, especially detritivores and omnivores, but weaker or inconsistent effects on invertebrate taxon richness and composition. Contrary to expectation, predation effects were stronger in the stream than the lake; no effects were found on algae in either ecosystem due to weak effects of platypuses on herbivorous invertebrates. Platypuses did not cause redistribution of sediment via their foraging activities. Platypuses can clearly have both strong and subtle effects on aquatic food webs that may vary widely between ecosystems and locations, but further research is needed to replicate our experiments and understand the contextual drivers of this variation.
... Unlike most aquatic mammals, the platypus swims using alternate strokes of its large webbed front limbs, swimming at 0.7-3.6 km/h (Grant and Fanning 2007). Collecting predominantly small organisms on each short dive, foraging normally lasts for 8-16 h per day (Serena 1994;Gust and Handasyde 1995;Otley et al. 2000;Bethge et al. 2003Bethge et al. , 2009, although, particularly in winter, animals may forage continuously for more than 30 h per bout (Bethge 2002). When walking, the limbs are splayed away from the body, which is not continuously held above the ground surface, and the energy required for walking is 19-27% higher than for most terrestrial mammals of similar size (Bethge et al. 2001;Fish et al. 2001). ...
... Platypuses are predominantly nocturnal McLeod 1993;Gardner and Serena 1995;Francis et al. 1999), although some foraging occurs during daylight, particularly in winter or during lactation Serena 1994;Gardner and Serena 1995;Gust and Handasyde 1995;Bino et al. 2018). Individuals may also sometimes align activity patterns with the lunar cycle, synchronizing with moonrise and moonset (Bethge 2002;Bethge et al. 2009). Activity levels also vary throughout the year. ...
... In a lake in northern Tasmania, platypuses were most active between late winter and early spring, and least active in mid-summer. Peak activity coincided with the breeding season, mate searching, and increased foraging by lactating females in late spring-summer (Bethge 2002). Interactions between platypuses may also affect temporal partitioning of movements (Hawkins 1998;Bethge et al. 2009). ...
The platypus (Ornithorhynchus anatinus) is one of the world's most evolutionarily distinct mammals, one of five extant species of egg-laying mammals, and the only living species within the family Ornithorhynchidae. Modern platypuses are endemic to eastern mainland Australia, Tasmania, and adjacent King Island, with a small introduced population on Kangaroo Island, South Australia, and are widely distributed in permanent river systems from tropical to alpine environments. Accumulating knowledge and technological advancements have provided insights into many aspects of its evolutionary history and biology but have also raised concern about significant knowledge gaps surrounding distribution, population sizes, and trends. The platypus' distribution coincides with many of Australia's major threatening processes, including highly regulated and disrupted rivers, intensive habitat destruction, and fragmentation, and they were extensively hunted for their fur until the early 20th century. Emerging evidence of local population declines and extinctions identifies that ecological thresholds have been crossed in some populations and, if threats are not addressed, the species will continue to decline. In 2016, the IUCN Red Listing for the platypus was elevated to "Near Threatened," but the platypus remains unlisted on threatened species schedules of any Australian state, apart from South Australia, or nationally. In this synthesis, we review the evolutionary history, genetics, biology, and ecology of this extraordinary mammal and highlight prevailing threats. We also outline future research directions and challenges that need to be met to help conserve the species.
... Surprisingly, however, the tail fat stores (indicating body condition) of captive platypuses did not vary between seasons, which is in contrast to the published literature on wild platypuses (Temple-Smith 1973; Grant and Carrick 1978;Handasyde et al. 2003). Bethge (2002) found that wild platypuses spend more time foraging in winter than in summer, increasing their feeding rates by 68% in winter to meet their energy requirements. That study was conducted in Tasmania where the breeding season occurs around three months later than in Victoria (Grant 2007). ...
... This is in contrast to wild males that have been recorded swimming over 1 km in 30 min (Gust and Handasyde 1995). Previous studies have calculated energy expenditure in platypuses to be 341 kJ kg -1 day -1 (Grant and Carrick 1978) and 684 kJ kg -1 day -1 (Bethge 2002), which is much lower than the energy intake that we found of 921 kJ kg -1 day -1 . While energy intake is expected to be higher than expenditure for growth and reproduction (Nagy 2005), the firstlisted estimate of energy expenditure is based on the assumption that the platypus spends 8 h foraging and 16 h resting, which may explain why it is lower. ...
... While energy intake is expected to be higher than expenditure for growth and reproduction (Nagy 2005), the firstlisted estimate of energy expenditure is based on the assumption that the platypus spends 8 h foraging and 16 h resting, which may explain why it is lower. Wild platypuses in Tasmania were found foraging for up to 16 h during the winter (Otley et al. 2000) and have been found to have significant seasonal variation in their activity levels, with these being higher during the breeding season (Bethge 2002). In captivity, platypuses that were housed in breeding pairs were often active in the water for more than 24 h at a time during the breeding season and would therefore be expected to have a higher energy expenditure than at other times of the year (J. ...
Anecdotal observations of captive platypuses (Ornithorhynchus anatinus) suggest that they show a seasonal preference for particular foods, but this has never been rigorously measured. This study aimed to determine seasonal food preferences and energy consumption of captive platypuses so that better protocols for maintaining platypuses in captivity can be developed. Seven platypuses were fed an ad libitum diet with all food items weighed in and out of tanks. Food items were analysed for energy, fats, carbohydrates, proteins, vitamins and minerals. Platypuses preferred less mobile prey (mealworms, earthworms and fly pupae) over highly mobile prey (crayfish). There was no significant seasonal change in preference for different dietary items, which is more likely to be driven by prey behaviour. Crayfish contributed the largest percentage (mass) consumed and was highly nutritious. While the relative percentage of items in the diet did not change seasonally, the quantity eaten did. The mean energy intake of platypuses was 921 kJ kg -1 day -1 and varied seasonally, being lowest during the breeding season (810 kJ kg -1 day -1) and highest in the postbreeding season (1007 kJ kg -1 day -1). These changes were associated with preparation and recovery from the breeding season. We conclude that the platypus diet is influenced by nutrition and seasonal factors as well as by prey behaviour. This knowledge will contribute to improving the husbandry and management of platypuses, which are widely recognised as difficult to maintain in captivity.
... Platypuses are sexually dimorphic in body length and body mass and are generally larger in Tasmania (Grant and Temple-Smith 1983;Connolly and Obendorf 1998;Munks et al. 1998;Bethge 2002;Koch et al. 2006;Gust and Griffiths 2011). Our findings are consistent with these observations. ...
... Our findings are consistent with these observations. Studies of Tasmanian platypuses have shown mean mass in different river systems in the ranges 0.91-1.65 kg and 1.47-2.5 kg for females and males, respectively (Connolly and Obendorf 1998;Stewart 2001;Bethge 2002;Koch et al. 2006;Gust and Griffiths 2011). Mean body masses in our study were near the middle of these ranges and were very close to the mean values of 1.3 kg for females and 2.1 kg for males reported by Macgregor (2008) in the Inglis River Catchment. ...
Changes in the health of individuals within wildlife populations can be a cause or effect of population declines in wildlife species. Aspects of individual platypus ( Ornithorhynchus anatinus ) health have been reported. However, holistic studies investigating potential synergistic effects of both pathogens and environmental factors are needed to expand understanding of platypus individual health. We collected baseline data on the health of platypuses in two Tasmanian river catchments (including evidence of the potentially fatal fungal disease mucormycosis) and on individual, demographic, geographic, and temporal patterns associated with health data results. We examined 130 wild platypuses from the Inglis River Catchment and 24 platypuses from the Seabrook Creek Catchment in northwest Tasmania between 29 August 2011 and 31 August 2013. This study revealed seasonal effects on body condition in female platypuses and habitat effects on body size. More than 90% of captured platypuses were infected with ticks, Theileria spp., and trypanosomes. Evidence of exposure to other infections, including Salmonella spp., Leptospira spp., and intestinal parasites, was low (<10%). Three platypuses had single fungal granulomas in the webbing of a forefoot, but no evidence of mucormycosis was found in any of the study animals. Possible subclinical hepatopathies or cholangiohepatopathies were found in six platypuses. Exposure to infectious agents did not cluster geographically, demographically, or in individuals, and there was minimal evidence of morbidity resulting from infection. This study has provided important baseline data for monitoring the effects of threatening processes, including mucormycosis, on the health of infected populations.
... We also examined the maximum total monthly flows between January and December and maximum total monthly flows between January and April, the period aligning with the platypus' breeding and emergence of young. High stream flows can reduce the availability of macroinvertebrate prey species 24 , increase metabolic demand on foraging platypuses 42 and drown dependent nestlings in burrows during the breeding season 22,24 . ...
... A similar event resulted in poor recruitment in a Victorian population 24 . Such flood levels can drown nestlings in burrows and inflict metabolic stress on foraging platypuses 42 . Also, distribution and numbers of platypuses in peri-urban streams around Melbourne were affected by the area of non-absorbent surfaces in their catchments and subsequent high run-off during rain events 83 . ...
Knowledge of the life-history and population dynamics of Australia's iconic and evolutionarily distinct platypus (Ornithorhynchus anatinus) remains poor. We marked-recaptured 812 unique platypuses (total 1,622 captures), over four decades (1973-2014) in the Shoalhaven River, Australia. Strong sex-age differences were observed in life-history, including morphology and longevity. Apparent survival of adult females (Φ = 0.76) were higher than adult males (Φ = 0.57), as in juveniles: females Φ = 0.27, males Φ = 0.13. Females were highly likely to remain in the same pool (adult: P = 0.85, juvenile: P = 0.88), while residency rates were lower for males (adult: P = 0.74, juvenile: P = 0.46). We combined survival, movement and life-histories to develop population viability models and test the impact of a range of life-history parameters. While using estimated apparent survival produced unviable populations (mean population growth rate r = -0.23, extinction within 20 years), considering residency rates to adjust survival estimates, indicated more stable populations (r = 0.004, p = 0.04 of 100-year extinction). Further sensitivity analyses highlighted adult female survival and overall success of dispersal as most affecting viability. Findings provide robust life-history and viability estimates for a difficult study species. These could support developing large-scale population dynamics models required to underpin a much needed national risk assessment for the platypus, already declining in parts of its current distribution.
... The platypus is found associated with inland water bodies in Eastern Australia and spends its time either feeding in water or resting in a burrow (Grant and Bishop, 1998). Platypuses are generally out of their burrow each day for a single period of 7.3-16 h (Serena, 1994;Gust and Handasyde, 1995;Otley et al., 2000;Bethge, 2002). A platypus must dive to the bottom of the water body to find and collect its food (Grant, 2007), returning to the surface to breathe and masticate the food. ...
... Evans et al. (1994) found that in captive platypuses most dives lasted between 30 s and 4 min, but observed a maximal dive time of 11 min. Bethge (2002) observed a mean dive depth of 1.21 m and a maximal dive depth of 8.77 m in wild platypuses. ...
Health and conservation research on platypuses (Ornithorhynchus anatinus) may require anaesthesia to reduce stress and the risk of injury to both the animal and the researcher, as well as to facilitate
examination and sample collection. Platypus anaesthesia can be difficult to manage, with reports of periods of apnoea and
bradycardia described. This study investigated the conditions around sudden-onset apnoea and bradycardia in 163 field-anaesthetized
platypuses as part of a health study. Anaesthesia was induced and maintained using isoflurane delivered in oxygen by face
mask. Sudden-onset apnoea and bradycardia was observed in 19% of platypuses, occurring either at induction of anaesthesia,
during recovery, or both. At induction, occurrence was more often recorded for adults (P = 0.19) and was correlated with low body temperature (P < 0.001), season (P = 0.06; greater incidence in summer) and longer pre-anaesthetic holding time (P = 0.16). At recovery, sudden-onset apnoea and bradycardia occurred only in platypuses that had been placed in dorsal recumbency
as part of their examination, and correlated with poor body condition (P = 0.002), time in dorsal recumbency (P = 0.005), adults (P = 0.06), number of fieldworkers (P = 0.06) and females (P = 0.11). The sudden-onset apnoea and bradycardia we observed is likely to result from the irritant nature of isoflurane (stimulating
the trigeminal nerve via nasal chemoreceptors). We propose that this mechanism is analogous to that of submersion of the face/nasal
cavity in cold water during a natural dive response, but that the term ‘nasopharyngeal response’ would more appropriately
describe the changes observed under isoflurane anaesthesia. Although we did not record any long-term adverse effects on platypuses
that had undergone this response, the nasopharyngeal response could complicate the diagnosis of anaesthetic dose-dependent
apnoea and bradycardia. Therefore, we suggest that these responses during anaesthesia of platypuses might be avoided by minimizing
the stress around capture and handling, as well as reducing the time in dorsal recumbency.
... Platypus body weight and body length data were collected throughout their geographic distribution (Figure 2.1) from a number of sources incorporating museum records, livetrapping data collected by the authors and previously published data (Grant and Temple-Smith 1983, Gust and Handasyde 1995, Bethge 2002, Gust and Griffiths 2011 (Table 2.1). Only individuals for which information was available on the capture location as well as details of the age, sex and body weight or length of the platypus were included in the current analyses. ...
The semi-aquatic platypus, Ornithorhynchus anatinus, is endemic to Australia. It is widespread throughout waterways along the east coast of Australia with a distribution extending as far north as Cooktown in Queensland to Tasmania in the south. The platypus is one of the last extant monotremes and the only member of its family.
Consequently, it is of great evolutionary significance. In addition, its status as an Australian icon and a flagship species make the platypus worthy of conservation attention. This study aims to increase our knowledge of the population ecology and genetics of the species. I investigate the variation that exists among platypus populations, both morphologically and genetically. Large variation in body size is detected throughout the species’ entire geographic range and even across a relatively small geographic scale. Bergmann’s cline is shown to exist in the species with larger body size evident in the cooler regions to the south. Variability inconsistent with this latitudinal cline was shown to exist, however, with significant variation in platypus body size detected either side of the Great Dividing Range on the mainland. Associations with rainfall variables revealed larger-sized individuals were typically found in lower rainfall environments. This variation in body size reveals some clear associations with environmental variables worthy of further investigation.
Following the isolation of thirteen microsatellite loci and sequencing of two partial mitochondrial DNA (mtDNA) genes, significant genetic differentiation was detected among platypus populations of southeastern Australia. Tasmanian individuals revealed clear genetic divergence from mainland individuals displaying a high frequency
of unique microsatellite alleles and a minimum of 2.9% sequence divergence at mtDNA sequences. On the mainland, western Victoria was shown to be genetically divergent from the rest of the state with further genetic partitioning evident among regions of New South Wales. While mainland and Tasmanian populations revealed expected heterozygosities > 0.59 and allelic richness of > 4.8, the genetic diversity of two small island populations was comparatively low, exposing them to an increased risk of extinction. The findings of this study are likely to be useful for the conservation and management of this unique Australian mammal.
... A female-biased sex ratio (0.71M : 1F) was reported from the Shoalhaven River on mainland Australia (Grant 2004a). Malebiased sex ratios have been reported in Tasmania by Stewart (2001) (1.83M : 1F), Bethge (2002) (1.63M : 1F) and in the current study (1.50M : 1F). Pooled data from seven Tasmanian platypus studies suggest Tasmanian platypus populations are significantly male-biased with an overall sex ratio of 1.39M : 1F (Table 10). ...
Context:
Despite widespread interest in platypus (Ornithorhynchus anatinus) conservation, it is unclear how their fundamental morphometric and demographic characteristics differ over a range of scales. This hampers impact assessments and understanding of platypus ecology. Although the ulcerative fungal disease mucormycosis has infected platypuses in Tasmania for three decades, its population level impacts and conservation significance remain unknown.
... An association between low temperature and larger body size is commonly observed among mammals (Rosenzweig 1968;Yom-Tov and Nix 1986;Wigginton and Dobson 1999;Yom-Tov and Geffen 2006). In platypuses, a latitudinal pattern for size has previously been suggested (Grant 2007), which may reflect increased energetic demands associated with exposure to cold air or water conditions (Grant and Dawson 1978;Bethge 2002). It is anticipated that platypuses in cooler environments (typically at the southern extent of their geographic distribution or higher elevations) are likely to be larger to minimise the energy required for thermoregulation. ...
... Platypus body weight and body length data were collected throughout the species' geographic distribution ( Fig. 1) from several sources including museum records, live-trapping data collected by the authors and previously published data (Grant and Temple-Smith 1983;Gust and Handasyde 1995;Akiyama 1998;Bethge 2002;Gust et al. 2009;Gust and Griffiths 2011) (Appendix 1). Only individuals for which information was available on the capture location as well as details of the age, sex and body weight or length of the platypus were included in the current analyses. ...
... The number of individuals (N) from each source is indicated along with the time span over which data were collected. The number of sampling locations (S) is given in parentheses where data have been averaged over several individuals Gust et al. (2009) and Gust and Griffiths (2011) Published data (4) 1997-2000Bethge (2002 ...
The body size of the platypus (Ornithorhynchus anatinus) is known to vary across both its latitudinal range and relatively short geographic distances. Here we consider how variation in platypus length and weight associates with environmental variables throughout the species’ range. Based on data from over 800 individuals, a Bergmann’s cline (increased body size in regions of lower temperature) was detected across the species latitudinal range. The opposite association, however, was present at smaller scales when comparing platypus body size and temperature within southern mainland Australia, or within an individual river basin. Temperature regimes alone clearly did not dictate body size in platypuses, although disentangling the effects of different climatic variables on body size variation was difficult because of correlations amongst variables. Nevertheless, within suitable platypus habitat in south-eastern Australia, areas of relatively lower rainfall and higher temperatures were typically associated with larger-bodied platypuses. The potential benefits to larger-bodied animals living under these conditions are explored, including consideration of variation in energy expenditure and food availability. Assuming these associations with environmental variables are biologically significant, a shift in platypus body size is anticipated in the future with predicted changes in climate.
