The influence of tropical seasonality on breeding phenology, growth, survival and movement of a large reptile (Varanus komodoensis)

Abstract

Terrestrial animals in global wet-dry tropical ecosystems experience year-round high temperatures but concentrated summer rainfall. This highly seasonal precipitation is expected to have major evolutionary and ecological consequences for animals. We considered how strong seasonal patterns of rainfall might influence the environment and biological attributes of the world’s largest predatory lizard, the Komodo dragon (Varanus komodoensis). We predicted that annual variation in rainfall or temperature may influence the seasonal phenology of vegetation, and in turn, the phenology of Komodo dragon reproduction and hatchling emergence. Similarly, seasonal environmental differences may affect Komodo dragon rates of somatic growth, body condition, survival and daily movement. Our results indicated evidence of strong seasonal variation in mean monthly rainfall and leaf area index for open deciduous forest and closed dense forest. These environmental variables were significantly correlated with female Komodo dragon nesting activity and hatchling emergence. Neither Komodo dragon somatic growth rate nor body condition exhibited seasonal differences. There was, however, increased daily movement rates of Komodo dragons during the dry season. This suggests dry season associated life-history activities or thermoregulatory efficiency might explain increased daily movement. Ultimately, the Komodo dragon showed differential sensitivities in its biology to seasonal environmental variation.

Seasonal Variation in the Thermoregulation Pattern of an Insular Agamid Lizard

“…Seasonal variations in environmental conditions, such as rainfall, wind intensity, temperature, and sunlight exposure may influence many of the behavioral and physiological attributes of lizards [13,14], including thermoregulation [15,16]. For example, subtropical lizards may shift their activity and thermoregulation effort as a response to weather fluctuations but are sensitive to extreme winter conditions [17].…”