Data from: Live fast, die young: Life history traits of an apex predator exacerbate the ecological impact of a toxic invader

Abstract We studied a population of large varanid lizards (yellow-spotted
monitors Varanus panoptes) on a floodplain in tropical Australia. Growth
records from radio-tracked lizards show that despite their large adult
body sizes (to > 7 kg in males), these lizards attained sexual
maturity at less than one year of age, and rarely lived for more than two
years (females) or four years (males), even before mortality increased due
to the arrival of toxic cane toads. This is a “faster” life-history than
has been reported for other species of large monitors. Growth was
especially rapid in males during the wet-season. The low survivorship
prior to toad invasion was due to predation by pythons; communal nesting
by female varanids may render them especially vulnerable. The life history
of yellow-spotted monitors requires high feeding rates, favouring the
evolution of “risky” tactics such as consuming novel prey items (such as
cane toads); and the combination of high abundance (> 20 adult
lizards per square kilometre) and high feeding rates (> 9.9 kg of
prey per lizard per annum) means that these giant lizards play a critical
role in energy and nutrient flow within the floodplain ecosystem. As a
result, foodwebs with the yellow-spotted monitor as an apex predator are
more vulnerable to disruption by cane toads than is the case in other
parts of the toad’s invasive range, where the varanid species affected by
toads have “slower” life histories.