USGS ScienceSearch

Geology topics

Ian Easterling

Publications and source records attributed to Ian Easterling.

2 recordsLinked to original sources

Characterizing the annual cycle of steroid hormones in males from an invasive vertebrate (Python bivittatus) of management concern

South Florida's subtropical climate has facilitated the establishment of numerous invasive species, including the Burmese python ( Python bivittatus ). Despite decades of efforts to manage the invasive python population across South Florida, we lack a comprehensive understanding of their reproductive physiology, limiting the development of targeted control strategies. Here, we characterized seasonal patterns of testosterone (T) and corticosterone (CORT) in free-ranging adult male pythons and evaluated environmental correlates of hormone variation. Results indicate that T peaks before the onset of the breeding season and declines through the season to baseline levels in the non-breeding season. CORT did not show a clear seasonal trend but showed greater variability during the breeding season. These findings reveal that photoperiod and ambient temperature are key environmental correlates of male hormone cycles, contributing to our understanding of the endocrine phenology of a tropical ectotherm in a novel environment.

Florida

Agkistrodon conanti (Florida Cottonmouth) and Python bivittatus (Burmese Python). Diet and Predation

Python bivittatus is established in the Greater Everglades Ecosystem in southern Florida, USA. Documented predators on pythons in Florida include Alligator mississippiensis (American Alligator; Snow et al. 2006. Herpetol. Rev. 37:81–81), Drymarchon couperi (Gulf Coast Indigo Snake; Andreadis et al. 2018. Herpetol. Rev. 49:341–342), Lynx rufus (Bobcat; McCollister et al. 2021. Southeast. Nat. 20:N55–N59), and possibly Ursus americanus floridanus (Florida Black Bear; McCollister et al. 2021. op cit.). We documented mortality events of hatchling and juvenile P. bivittatus while conducting radiotelemetry studies in the Greater Everglades Ecosystem.

Florida