Carrion use by a reptile is influenced by season, habitat, and competition with an apex mammalian scavenger

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. In Australia, a notable reptilian scavenger is
the lace monitor (Varanus varius). 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
(Vulpes vulpes), and native apex predator, the dingo (Canis 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 was 1.67-times higher in summer than 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. Lace monitors were 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.