Population dynamics and emergence of black-bearded tomb bat Taphozous melanopogon Temminck, 1841 at Samaesan Islands, Chonburi Province

Abstract

This study aimed to investigate population dynamics and emergence activity of Taphozous melanopogon in 2 maternity colonies (the Kham and Changkleua colonies) at Samaesan Islands, Chonburi Province. From January 2015 to April 2016 using emergence counts from infrared video camera and mark and recapture method were conducted at cave entrance, the results showed that T. melanopogon resided in studied caves throughout the year and exhibited variation on colony size, composition and movement. Increasing of colony size and proportion of male bats into colonies during November 2015–February 2016 probably indicated mating season. From March to October 2015, colony size and proportion of male bats declined concordant with observing pregnant females during April–June 2015 and lactating female during June–August 2015. Fledgling juveniles were captured from June to August 2015 and late juveniles were captured from August to December 2015. Results from mark and recapture method revealed that only 26 individuals were recaptured from a total of 581 banded adult bats. Colony size fluctuation and low fidelity on roosts suggested the complexity of movement pattern and roost network in this species. Observation on emergence activities indicated that sunset time had greatly impact on bat emergence. In addition, weather conditions, which were wind speed and cloud cover, influenced on bat emergence as well. Late emergence times were observed in windy evening due to unsuitable condition for flight. Late emergence were also observed in cloudy nights, but reason for this was unclear. Change in colony composition also affected to bat emergence. The Results revealed that emergence duration tended to longer during April–July 2015. The reason was that pregnant and lactating females tended to emerge later than other individuals due to less flight maneuverability, which increased predation risks. Early emergence during August–December 2015 were observed because juveniles tended to emerge early to find food which is important for their growth and development compared to adults bats.