Reproductive condition of an invasive snake in urban, savanna, and forest habitats

By

Durso, Andrew M.
Siers, Shane
Reed, Robert N.
Savidge, Julie

Type

Article

Date of Publication

2025-8-6

Original Publication

NeoBiota : advancing research on alien species and biological invasions

Volume

100

Pages

109--134

Subjects

Body condition , Boiga irregularis , Brown Treesnake , Guam , introduced , Reproduction , season

Contributed by

Pensoft Publishers

Language

English

Published by

Sophia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/neobiota.100.148230

 

Abstract

Predation by Brown Treesnakes (Boiga irregularis) has caused the decline or extinction of all native forest vertebrates on Guam, including birds, lizards, and bats. Loss of the highest-quality prey has caused shifts in Brown Treesnake size and life history. We sought to understand how reproductive condition varies among habitats island-wide, particularly comparing urban and savanna habitats (where some primarily non-native large prey remain) with prey-depauperate forest habitats. We dissected 100 snakes from each of 18 sites stratified by 6 habitat types and calculated a body condition index, relative follicle size (for females; N = 817) and relative testes size (for males; N = 992) for each. Low detection of reproductive females continues to hamper research on their biology, as only 11% of females had secondary vitellogenic follicles (N = 89). Although variation among sites within habitats was high, above-average reproductive development of both males and females was most frequently observed in urban and savanna habitats, emphasizing the potential for prey subsidies in these habitats to fuel population growth and affect invasive snake management objectives. Furthermore, the trade-off between body condition and reproductive condition appeared to be more severe in forested habitats and less severe in urban habitats for both males and females. There were few obvious seasonal patterns, although there was a slightly lower probability of females having secondary vitellogenic follicles in the wet season compared to the dry season.