Cairncross Rhys J, Spencer Emma E, Meisuria Niraj, Crowther Mathew S, Newsome Thomas M
School of Life and Environmental Science The University of Sydney Sydney New South Wales Australia.
Ecol Evol. 2024 Aug 28;14(8):e70211. doi: 10.1002/ece3.70211. eCollection 2024 Aug.
Scavenging on carrion is critical and often fiercely competitive for a range of vertebrate species, from native apex predators to invasive species and even reptiles. Within Australia, a notable reptilian scavenger is the lace monitor (). In this study, we quantified lace monitor activity at carcasses and compared their use of the resource to common co-occurring predators that also scavenge; the invasive red fox () and a native apex predator, the dingo (). To do so, we deployed 80 macropod carcasses equally across seasons (summer and winter) and habitats (open and closed canopy) in a temperate bioregion and monitored vertebrate scavenging with camera traps. Lace monitor activity (visitation at carcass sites inclusive of both non-scavenging and scavenging events) was 1.67 times higher in summer than in winter, but it did not differ across closed and open habitats. Monitor activity occurred earlier after carcass deployment at sites deployed in summer than winter (1.47-fold earlier), and at carcasses in open than closed habitats (0.22-fold earlier). Lace monitors initially discovered carcass sites faster in summer than winter and before both red foxes and dingoes in summer. The species was active diurnally in both summer and winter, differing from the red fox, which was strictly a nocturnal scavenger and the dingo, which was significantly more active at night across both seasons. Finally, we found that lace monitor activity at carcass sites decreased slightly with higher rates of activity for dingoes (0.04-fold decrease as dingo activity increased), but not with red fox activity. Our results have implications for understanding lace monitor foraging and scavenging and highlight the value of monitoring carcasses to provide important insights into the behaviour of varanid lizards that scavenge.
对一系列脊椎动物物种来说，从本土顶级食肉动物到入侵物种甚至爬行动物，以腐肉为食至关重要且竞争激烈。在澳大利亚，一种著名的食腐爬行动物是巨蜥（lace monitor）。在本研究中，我们对巨蜥在尸体处的活动进行了量化，并将它们对资源的利用情况与同样会食腐的常见共生食肉动物进行了比较，这些共生食肉动物包括入侵的赤狐（red fox）和本土顶级食肉动物澳洲野狗（dingo）。为此，我们在一个温带生物区域的不同季节（夏季和冬季）和栖息地（开阔树冠和封闭树冠）平均部署了80具有袋动物尸体，并用相机陷阱监测脊椎动物的食腐情况。巨蜥的活动（包括非食腐和食腐事件在内的尸体现场访问）在夏季比冬季高1.67倍，但在封闭和开阔栖息地之间没有差异。在夏季部署的尸体现场，巨蜥在尸体放置后出现活动的时间比冬季早（早1.47倍），在开阔栖息地的尸体处比封闭栖息地的尸体处出现活动的时间早（早0.22倍）。在夏季，巨蜥最初发现尸体现场的速度比冬季快，且在夏季比赤狐和澳洲野狗都更早发现尸体现场。该物种在夏季和冬季都是日间活动，这与严格夜间食腐的赤狐以及在两个季节夜间活动都明显更多的澳洲野狗不同。最后，我们发现随着澳洲野狗活动率的提高，巨蜥在尸体现场的活动略有下降（随着澳洲野狗活动增加，下降0.04倍），但与赤狐的活动无关。我们的研究结果对于理解巨蜥的觅食和食腐行为具有重要意义，并突出了监测尸体对于深入了解食腐巨蜥行为的重要价值。
