Paedophagic Cannibalism, Resource Partitioning, and Ontogenetic Habitat Use in Invasive Triceros jacksonii xantholophus in Hawaii

The study explores the impact of social structure on behavioral patterns such as dispersal, intraspecific niche partitioning, and resource utilization in the invasive lizard Trioceros jacksonii xantholophus in Hawaii. The authors investigate how juvenile-adult interactions, particularly through agonistic displays and paedophagic cannibalism, lead to juveniles avoiding adults, which in turn influences community structure and shifts in habitat use.To test the hypothesis that adult aggression drives niche separation and juvenile dispersal, the researchers conducted laboratory experiments. These included paired trials to observe paedophagic behavior and staged contests to assess aggression and responses. The findings revealed that 57 percent of adult chameleons consumed newborns when in proximity. Moreover, juveniles showed increased flight responses—fleeing further, faster, and more frequently—when faced with aggressive displays from adults compared to those from other juveniles.To evaluate the effects of antagonistic behaviors on juvenile movement and habitat shifts, the study utilized radio-telemetry and dietary comparisons to assess resource use between juveniles and adults. Although there was no significant difference in dispersal patterns, juveniles were found to perch at considerably lower heights and exploit different prey types than adults. These results suggest that resource partitioning is occurring, even though both juvenile and adult chameleons remain predominantly sedentary. The age-dependent habitat usage indicates that Trioceros jacksonii xantholophus occupies a broader ecological niche than previously recognized. This underscores the importance of studying behavioral patterns in different developmental stages of invasive species to better predict their ecological impacts and potential for range expansion.