Subbaraj R, Chandrashekaran M K
School of Biological Sciences, Madurai University, 625021, Madurai, India.
Oecologia. 1977 Dec;29(4):341-348. doi: 10.1007/BF00345807.
The timing of the emergence activity of a colony of the bat Taphozous melanopogon occupying a cave environment in Madurai (lat. 9°58' N, long. 78°10' E) and consisting of approximately 150-180 animals of both sexes was studies at 10-day intervals for one year. Even though the time of sunset during the eyar varied over a range of 41 min, the bats displayed an astonishingly 'rigid' time of emergence that was restricted to a narrow 'gate' of 16 min from 18:25 to 18:41 h. The timing of the termination of the activity was less precise in all seasons. Light/dark cycles are clearly the Zeitgeber. Even so, the bats began flying when it was very dark (0.1 lx) during shorter days, and they flew out as the sun was disappearing in the evening horizon (50 or more lx) during long days. Evidently there is no invariant, 'fixed' lower threshold intensity that uniformly elicits the onset of activity throughout the year as reported earlier by other authors (Aschoff, 1969; Erkert, 1974). It is proposed that the bats undergo a systematic seasonal shift in the threshold sensitivity to light in response to the photic Zeitgeber of the environment. The result is a remarkable precision in terms of the hours of the civil/calendar day in the emergence of Taphozous melanopogon.
对栖息在马杜赖（北纬9°58′，东经78°10′）一个洞穴环境中的黑髯墓蝠群体的出飞活动时间进行了研究，该群体约有150 - 180只雌雄个体，研究为期一年，每隔10天进行一次。尽管一年中日落时间变化范围达41分钟，但蝙蝠的出飞时间惊人地“固定”，限制在从18:25至18:41这一16分钟的狭窄“时间段”内。活动终止时间在所有季节都不那么精确。光/暗周期显然是授时因子。即便如此，在较短的日子里，当天非常黑暗（0.1勒克斯）时蝙蝠就开始飞行，而在较长的日子里，当太阳在傍晚地平线消失时（50勒克斯或更高）它们才飞出去。显然，不存在如其他作者（阿绍夫，1969；埃克特，1974）早期所报道的那种一成不变的、“固定”的较低阈值强度能在全年一致地引发活动开始。有人提出，蝙蝠会根据环境的光授时因子，在对光的阈值敏感性上经历系统性的季节性变化。结果是黑髯墓蝠出飞在民用/日历日的时间上具有显著的精确性。
