Range extension and new ecoregion records of the Crocodile Monitor Varanus salvadorii (Peters & Doria, 1878) (Reptilia: Varanidae) in Papua New Guinea

: The Crocodile Monitor Varanus salvadorii is one of the longest lizards and an apex predator in New Guinea. Limited information is available on its ecology and distribution, mainly due to its arboreal lifestyle and preference for inaccessible primary forest habitats. Here we provide the first published record, using camera trapping technology in the Torricelli Mountain Range, of V. salvadorii living at a higher elevation than previously recorded in montane rainforest habitat. This range extension implies the occupation of a distinctive ecoregion for the species: the Northern New Guinea Montane Forest, a substantially cooler region from the formerly known distribution area. We present trail camera images of an active animal at an elevation of 1,500 m & at 18 o C temperature and we discuss the implications of this finding for understanding the behaviour & conservation of the Crocodile Monitor.

ISSN 0974-7907 (Online); ISSN 0974-7893 (Print) Abstract: The Crocodile Monitor Varanus salvadorii is one of the longest lizards and an apex predator in New Guinea. Limited information is available on its ecology and distribution, mainly due to its arboreal lifestyle and preference for inaccessible primary forest habitats. Here we provide the first published record, using camera trapping technology in the Torricelli Mountain Range, of V. salvadorii living at a higher elevation than previously recorded in montane rainforest habitat. This range extension implies the occupation of a distinctive ecoregion for the species: the Northern New Guinea Montane Forest, a substantially cooler region from the formerly known distribution area. We present trail camera images of an active animal at an elevation of 1,500 m & at 18 o C temperature and we discuss the implications of this finding for understanding the behaviour & conservation of the Crocodile Monitor.

INTRODUCTION
New Guinea is considered a high-biodiversity wilderness area, an important region for conservation that combines a large percentage of intact habitats with rich endemism, exceptionally diverse biota, and low human population density (Richards 2007;Mittermeier et al. 2011). With the remaining natural forest cover extending over 90% of its land, Papua New Guinea (hereafter PNG) is one of the least explored regions in the world (Mittermeier et al. 2003 The Crocodile Monitor Varanus salvadorii is the largest lizard of New Guinea and an apex predator on this island (Heinsohn & Hope 2006). A handful of studies exist on this elusive species in captivity (Adams 1995; Waterloo & Bayless 2006;Mays 2007;Trout 2007;Camina et al. 2013;Reh et al. 2021) but V. salvadorii has been poorly studied in the wild, mainly because it is restricted to commonly inaccessible forests, strictly avoids contact with humans, and predominantly displays arboreal behaviour (Horn et al. 2007;Pattiselanno 2007;Shea et al. 2016).
The distribution of the species includes lowland and hill forests around most of the coastal lowlands of New Guinea. However, it has not been reported to occur in habitats above 600 m. The species has previously been reported from open woodland habitats within the Trans-Fly region, and lowland and mangrove forests on the islands of Salawati, Warir, and Selat Sagawin (northwest tip of Papua) (Allison 2006;Horn et al. 2007;Borja Reh pers. comm. 1.xii.2009). Crocodile Monitors are excellent swimmers, and individuals have been observed in forests along rivers (Marshall & Beehler 2011).
Here we report the first discovery of Crocodile Monitors in the Torricelli Mountain Range captured with trail camera traps at elevations above 1,000 m. TCA uses Reconyx cameras (models 650 and 850) that are rotated for each survey, and no more than 25 are deployed at any one time. The cameras are attached to a tree 30 cm above the ground, the area is cleared of debris and tested before being set for each survey. Camera traps are left in the field for three months before being collected, and then results are analysed. Further information regarding camera trap setup by the TCA can be found at the link https://tenkile.com/wp-content/ uploads/2022/02/Camera-Trap-Field-Manual.pdf Each camera trap survey consists of a team of 12 people from the villages close to the research site. Each team consists of four research officers and eight rangers.

MATERIALS AND METHODS
The trail cameras provide temperature data, time of capture, and moon phase. When triggered by motion sensors, predefined settings of the trail cameras are to take three photos at three-second intervals and leave a 10-minute delay to prevent repeated photography of the same individual.
The elevation is recorded at each trail camera location with a Garmin GPS and confirmed using the map of global terrain elevations by Yamazaki et al. (2017).
The images collected are reviewed by experts looking at key indicators of species such as colour pattern, size, posture, and the shape of the body. The animals are also compared with sympatric species of the same family.

RESULTS
Over the study period, TCA could collect data from 140 GPS camera monitoring sites ranging at elevations 700-1,600 m, corresponding to the Northern New Guinea Montane Forest ecoregion (Wikramanayake et al. 2002) (Image 2). More than 10,000 images have been collected from the camera traps. Birds and mammals account for the majority of animal photos. Only two reptile species (V. salvadorii and V. doreanus) were recorded by camera traps.
Two Crocodile Monitors were photographed, with camera traps in the Torricelli Mountain Range. The first was at the 'Waliapilk' research site in 2012, and at the second at the 'Birr' research site in 2015. Both sites are outside the previously known elevation distribution range for the species (Image 3).
Individual 1, a suspected adult of unknown gender was captured at 1032 h on 12 August 2012, at ground level and 1,522 m elevation with an air temperature of 18 °C. GPS location 3.4075 °S & 142.1819 °E. Although a series of three images were taken, only the first image shows enough of the animal to identify the species (Image 4).
Individual 2, a suspected adult of unknown gender was captured at 1114 h on 8 August 2015, at ground level and 1,200 m elevation when the air temperature was 20°C. GPS location 3.4038 °S & 142.2205 °E. The animal was walking at a normal pace (Image 5). Although principally deployed to capture images of tree kangaroos, camera traps set by TCA in the Torricelli Mountain Range have successfully recorded species of all terrestrial vertebrates (Thomas 2014). The Tenkile and Weimang tree kangaroos are the flagship species for TCA; however, unexpected results, such as those for V. salvadorii, are welcomed and emphasise the importance of protected areas and biodiversity monitoring.

DISCUSSION
The present findings also shed some light on the possibility of V. salvadorii occurring in the North Coastal Ranges of PNG (Bewani-Torricelli-Prince Alexander Mountain Ranges) after several reports of 'kundu drums' made with Crocodile Monitor skin in villages in that region (Horn et al. 2007). The species has been ever-present in the area, being revered, feared and respected. Traditional stories by the Tambuna tribe people suggest the animal can attain great lengths and consume village hunting dogs.

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This species is known to inhabit a range of habitats, including rainforest vegetation such as mixed alluvial and mixed hill forest types, as well as lowland and riparian forests (Horn 2004;Horn et al. 2007). Additionally, the present data indicate that the Crocodile Monitors also inhabit the Northern New Guinea Montane Forest.
Our new reported localities also call into question the minimum preferred temperature range of V. salvadorii. Under captive conditions the species is known to significantly reduce activity levels at temperatures below 24 ºC (Reh et al. 2021). However, images from the trail cameras show active individuals at 18 °C and 20 ºC. Furthermore, the mean annual maximum and minimum temperatures at an elevation of 1,500 m range is between 24.9 ºC and 14 ºC, according to the PNG Resource Information System (Bryan & Shearman 2008).
There are several possible explanations for activity at higher and cooler environment; (1) individuals can elevate their body temperatures by basking on a tree or in patches of sunlight on the forest floor to permit activity, and (2) individuals may move along the ground to escape inter or intraspecific confrontations even at cooler temperatures (Borja Reh pers. comm. 21.xii.2021). Crocodile Monitors have keen senses that allow them to perceive and avoid threats. Using the ground is an excellent way to remain undetected, especially by conspecifics.
Crocodile Monitors are assessed as Least Concern (LC) by the IUCN Red List (Shea et al. 2016). However, their ecological role within habitats is not clear, and they should be considered a focal species for monitoring ecosystem health given their status as apex predators (Simberloff 1998;Sergio et al. 2008;Ray 2015).
New Guinea is experiencing one of the fastest deforestation rates in the world (Curtis et al. 2018; Amindoni & Henschke 2020). The increasing trend of habitat loss due to logging concessions is affecting the primary forest habitat of Crocodile Monitors and other under-researched species, including those that remain undescribed (Allison 1996;Kraus 2010;Miettinen et al. 2011;Letsoin et al. 2020;PNG Data Portal, 2021). Habitat loss is an increasing concern for the conservation of Crocodile Monitors. However, the impact of this threat has not been studied.
Despite its remoteness and inaccessibility, the Torricelli Mountain Range is suffering one of the highest deforestation rates on the island due to clearing and logging (Bryan et al. 2015). Industrial logging persists and is increasing in the area, with new roads being proposed across the range.
Therefore, habitat loss must be considered an increasing concern for the conservation of Crocodile Monitors. The effect of this threat on the viability of V. salvadorii populations remains unexplored. It is thus critical that significant records and information of unknown species, such as the Crocodile Monitor, are published to trigger conservation measures and help protect their area.
Camera traps have proven to be effective in capturing large monitor lizards (Ariefiandy et al. 2013;Jessop et al. 2013) and may offer a suitable solution to more effectively describing the distribution range and behaviour of Crocodile Monitors and many other species that remain understudied in New Guinea (Thomas 2014). However, modifications to existing protocols -such as including meat-based baits or lures or deployment of arboreal camera traps might increase the number of monitors recorded as well as other wildlife unlikely to be detected at ground level (Gregory et al. 2014;Moore et al. 2021).

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