Use of implanted acoustic tags to assess platypus movement behaviour across spatial and temporal scales

Abstract

The platypus (Ornithorhynchus anatinus) is an evolutionarily distinct mammal, endemic to Australian freshwaters. Many aspects of its ecology and life-history, including detailed understanding of movements, are poorly known, hampered by its cryptic and mainly nocturnal habits and small numbers. We effectively trialled intraperitoneal implanted acoustic transmitters in nine platypuses in the Severn River (NSW), Australia, as a potential approach for studying movements in this challenging species. We tracked platypus movements over six months, at fine and broad spatial scales, using an array of acoustic sensors. Over six months (March-August 2016), four of five adult platypuses (two females\three males) maintained localized movements (average monthly maximums 0.37 km ± 0.03 sd), while one adult, one sub-adult, and one juvenile (males) moved further: average monthly maxima 1.2 km ± 2.0 sd, 0.9 km ± 0.6 sd, 4.5 km ± 5.9 sd, respectively. The longest recorded movement was by a male adult, covering 11.1 km in three days and travelling a maximum distance of about 13 km between records. Only one implanted animal was not detected immediately after release, indicative of transmission failure rather than an adverse event. High cumulative daily movements (daily 1.9 km ± 0.8 sd) indicated high metabolic requirements, with implications for previous estimates of platypus abundances and carrying capacities, essential for effective conservation. This novel approach offers new avenues to investigate relating to mating, nesting, and intraspecific competition behaviours and their temporal and spatial variation.

Biofluorescence in the platypus (Ornithorhynchus anatinus)

“…This new observation of biofluorescence in the platypus under UV light strengthens the hypothesis that the trait is adaptive in low-light environments (Kohler et al 2019). Platypuses, like biofluorescent flying squirrels and opossums, are active at twilight and overnight (Bethge et al 2009;Bino et al 2018), when UV absorbance and fluorescence may be particularly important to mammals. Many nocturnal-crepuscular mammals appear to have UV-sensitive vision, further suggesting that UV light is ecologically important in low-light environments (Douglas and Jeffrey 2014).…”

“…Platypuses are semi-aquatic monotremes that inhabit streams, lakes, and lagoons across eastern Australia, ranging from Queensland to Victoria and Tasmania (Pasitschniak-Arts and Marinelli 1998). Platypuses are typically nocturnal-crepuscular and use a suite of unique phenotypic traits to exploit low-light aquatic environments at dawn, dusk, overnight, and in murky water (Pasitschniak-Arts and Marinelli 1998;Pettigrew et al 1998;Bethge et al 2009;Bino et al 2018). Swimming with their eyes closed, they rely on mechanoreception and electroreception to locate prey underwater (Pettigrew et al 1998).…”

The platypus: evolutionary history, biology, and an uncertain future

“…Platypus movements have been investigated using capture-recapture studies (Serena and Williams 2012a), radiotracking (Grant et al 1992; McLeod 1993; Serena 1994; Gardner and Serena 1995; Gust and Handasyde 1995; Serena et al 1998, 2001; Otley et al 2000), microchip implantation (Macgregor et al 2015), and externally attached (Griffiths et al 2013) or implanted (Grant et al 1992; Bino et al 2018) acoustic tags. Unlike other freshwater mammals, the use of collars or harnesses for fine-scale telemetry (GPS, radio, or acoustic) is impractical, given the high risk of strangulation or drowning as platypuses forage between submerged roots and branches and dig their burrows between tree roots (Grant and Fanning 2007).…”

“…Mid and lower river reaches in Australia’s eastern flowing rivers are generally more favored than upper reaches of rivers (Serena et al 1998, 2001; Turnbull 1998; Rohweder and Baverstock 1999; Koch et al 2006; Olsson Herrin 2009; Macgregor et al 2015). Home ranges vary spatially and temporally with breeding season, age, and sex (Grant et al 1992; McLeod 1993; Serena 1994; Gust and Handasyde 1995; Serena et al 1998; Otley et al 2000; Serena and Williams 2012a; Bino et al 2018). Preferred habitat tends to include consolidated earth banks with large trees in the riparian zone, vegetation overhanging the stream channel, wide streams with in-stream organic matter, shallow pools, coarse woody debris, and coarse channel substrates, but platypuses still occur in habitats without some of these features, often in quite degraded agricultural settings (Rohweder 1992; Bryant 1993; Ellem et al 1998; Serena et al 2001; Milione and Harding 2009).…”

High detectability with low impact: Optimizing large PIT tracking systems for cave‐dwelling bats

“…Applying these techniques can be challenging due to low recapture rates, technological constraints, welfare considerations, and the need to minimize disturbance to threatened populations (Cooke et al, ; Schorr, Ellison, & Lukacs, ). A wide range of marking and tagging techniques are available to monitor wildlife, including mutilation (e.g., toe clipping or ear notching), banding, radio‐transmitters, acoustic tags, and bio‐loggers (Bino, Kingsford, Grant, Taylor, & Vogelnest, ; Murray & Fuller, ; O'Mara, Wikelski, & Dechmann, ; Perry, Wallace, Perry, Curzer, & Muhlberger, ; Walker, Trites, Haulena, & Weary, ; Wilmers et al, ). Marking can, however, have potential negative effects on wildlife, including injury, reduced survival and reproduction rates, and changes to behavior and movement (Baker et al, ; Bodey et al, ; Griesser et al, ; Murray & Fuller, ; Rosen, Gerlinsky, & Trites, ).…”