| Abstrakt: |
Considering the conservation attention needed to keep viable the few remaining wild populations of the Critically Endangered northern white‐cheeked gibbon (Nomascus leucogenys), there has been a serious paucity of research undertaken for the species. To improve the effectiveness of surveys of this and other gibbon species, and ultimately their conservation, it is important to better understand the variables that affect their singing behavior—the feature that is currently used in most gibbon population surveys. We collected singing and meteorological data from 320 days, between October 2020 and March 2021, at 80 different locations, during an auditory presence/non‐detection survey of N. leucogenys in northeastern Lao PDR. Songs were detected on 100 of the 320 days, a total of 154 song bouts. We analyzed the differences in song bout frequency, song bout timing (in relation to sunrise), and song bout length in relation to the meteorological variables of temperature, relative humidity, cloud cover, rain, fog, and wind. We found song bout frequency to be significantly greater on mornings with cloud cover (as a function of improved detection), on mornings without fog, on mornings without rain, and on warmer mornings. We found song bouts to start significantly earlier on mornings without fog and on warmer mornings when fog was present. Finally, we found song bouts lasted longer on mornings with fog and on warmer mornings. We did not find any significant relationships with relative humidity or wind. These patterns fit with prior research on behavioral responses of gibbons to weather and improve the understanding of gibbon vocal behavior to better prepare researchers for designing auditory surveys of Nomascus and other gibbon species. Highlights: Northern white‐cheeked crested gibbons were found to sing less on mornings with rain, with fog, and on cooler mornings.Songs of the northern white‐cheeked gibbon in Nam Et‐Phou Louey National Park, Lao PDR, were observed to start later on mornings with fog but earlier on mornings with fog when the temperature was warmer.Cloud cover was found to correlate positively with detection of gibbon songs.Gibbon songs were observed to last longer on mornings with fog and on warmer mornings. [ABSTRACT FROM AUTHOR] |
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