Keywords :
Nest Depredation; Boiga cyanea; Forest Songbird; Radio-telemetry; Dynamic Brownian Bridge Movement Model
บทคัดย่อ :
Predator-prey interactions are fundamental drivers of population dynamics. Studying both
predator and prey species simultaneously yields particularly useful insights into these complex
interactions. Despite being significant, widespread avian nest predators, Southeast Asian snakes
are rarely simultaneously studied in relation to avian prey. The Green Cat Snake Boiga cyanea is a
primary nest predator, estimated to be responsible for 17-33% of forest songbird nest depredations
in Northeast Thailand. We explored both diurnal and nocturnal movements of 14 (5 male, 9
female) adult B. cyanea with radio-telemetry for an average of 68 (+-) 16 days per individual,
between 21 October 2017 and 8 June 2019 in the dry evergreen forest of the Sakaerat Biosphere
Reserve (SBR). We quantified horizontal movements (m) and area of space use (ha) and activity
through motion variance ((Shima)m2) during the study period using dynamic Brownian Bridge Movement
Models (dBBMMs) and reported our findings within the context of a simultaneously run
avian nest monitoring study initiated in 2013 within the same forest. On average, adult B. cyanea
moved 56.4 (+-) 10.4 m/day and used areas of 9.4 (+-) 3.4 ha, while their activity averaged 2.8 (+-) 0.8
(Shima)m2. Males moved 51.4 m/day farther than females, and in general, adult B. cyanea moved 50.3
m/day farther during the avian nesting season than the avian non-nesting season. We refrain from
inferring statistical differences with the dBBMM outputs between sexes and seasons within our
sample because of the unequal samples and sampling effort during the study period. Only two
individuals (one male and one female) were sufficiently radio-tracked across both seasons (the
avian nesting and non-nesting seasons), and these two displayed a clear increase in their
respective movements, space use and activity during the avian nesting season. This could suggest
that movements, space use and activity likely differ between the avian nesting and non-nesting
seasons for male and female B. cyanea, however it is only two individuals. All individuals were
exclusively nocturnal, moving throughout the night, and often descending from higher diurnal
refugia (> 2 m) to forage closer to the ground after sunset. Our openly available data may yield
further insight when combined with other major avian nest predator species like the congeneric
invasive Brown Tree Snake Boiga irregularis on the island of Guam.
เอกสารอ้างอิง :
D souza, A., Gale, G. A., Marshall, B. M., Khamcha, D., Waengsothorn, S., & Strine, C. T. (2021). Space use and activity of Boiga cyanea-A major songbird nest predator in a seasonal tropical forest in Thailand. Global Ecology and Conservation, 32, e01875.
