Spatial ecology of endangered big‐headed turtles (Platysternon megacephalum): Implications of its vulnerability to illegal trapping

Abstract

Most populations of big-headed turtles (Platysternon megacephalum), a species distributed in 6 countries in Southeast Asia, have been heavily depleted because of severe hunting pressure for the food and pet trade. As with many other Southeast Asian turtles, low densities of individuals and few remaining populations have limited our ability to study, and thus understand, the ecology of this stream-dwelling species. We conducted a radiotelemetry study on 31 adult big-headed turtles to investigate their home range, movements, and habitat use. The home ranges of big-headed turtles were small, with a mean 100% homerange length of 97 m and 100% minimum convex polygon size of 996 m 2 . Movements by male and female big-headed turtles did not differ and both sexes moved longer distances in wet seasons than in dry seasons. Both males and females showed non-random habitat use, preferring to stay in pools rather than in other instream or terrestrial habitats. Stream width and depth, and substrate type affected microhabitat use. Bigheaded turtles were highly aquatic and movements in terrestrial habitats were rare. Thus, turtle populations are concentrated in streams where they may be easily targeted by illegal trappers. We recommend increasing patrol efforts along streams to remove any traps or fish hooks. Innovative methods, such as installation of infrared-triggered cameras equipped with remote viewing near or along streams, may be needed to tackle illegal turtle trapping effectively. Ó 2015 The Wildlife Society.

Diet of the endangered big-headed turtlePlatysternon megacephalum

“…In previous research on this species’ spatial ecology (Sung, Hau & Karraker, 2015a), we found that individuals are highly aquatic and make few movements away from the stream. However, we believe that we probably underestimated terrestrial movements because turtles were occasionally observed in terrestrial habitats during/after extreme storm events in the monsoonal wet season, when these high velocity, torrential streams are far too dangerous to be visited by researchers.…”

“…Captive breeding of P. megacephalum has been attempted by various zoos and hobbyists, yet few instances of this species successfully breeding in captivity have occurred (Shelmidine, Murphy & Massarone, 2016; Sung, Hau & Karraker, 2014; Wei et al, 2016), which may be due to our limited knowledge about their natural history (Sung, Hau & Karraker, 2014). Only recently have researchers begun studying this species in the wild including distribution (Pipatsawasdikul, Voris & Thirakhupt, 2010), spatial ecology (Shen, Pike & Du, 2010; Sung, Hau & Karraker, 2015), growth (Sung et al, 2015) and reproduction (Sung, Hau & Karraker, 2014). The information gained from these studies will benefit conservation programs for the species, but much remains unknown.…”

Unique multiple paternity in the endangered big‐headed turtle (Platysternon megacephalum) in an ex situ population in South China

“…Investigating the mating systems of P. megacephalum could improve our understanding of the species' reproductive ecology and aid captive breeding programs. However, it is almost impossible to investigate the mating systems of P. megacephalum in the wild because this species lives in rocky mountain streams (Shen et al, ; Sung, Hau, & Karraker, ), which makes behavioral observation, egg collection, and study of mating systems extremely difficult. Even if the mating behavior can be observed, it is difficult to determine the genetic mating system because of potential extra‐pair copulation, sperm competition, and unsuccessful mating (Pearse & Avise, ; Rossi Lafferriere et al, ).…”

The home range of adult Phrynops geoffroanus (Testudines, Chelidae) in relation to sex and body mass

“…Understanding how home ranges are arranged in the landscape helps us to identify the most important habitat traits influencing the ecology of a given species (Powell 2000). For example, we can study which habitat traits lead individuals to select or avoid a certain place (Sung et al 2015;De la Quintana et al 2017). Besides, assessing the degree of overlap between home ranges could reveal mating sys-them with multiple males (Harless et al 2009;Bower et al 2012).…”