Predicting Rain with Monkey Calls? Investigating Zoological Predictors of Weather with Bioacoustics.

ANNA KURTIN; SILVY VAN KUIJK; LUCIANA OKLANDER; ANTHONY DI FIORE

AUSTIN, TX

Simposio; UT Undergraduate Research Forum; 2021

University of Texas at Austin

Howler monkeys (Alouatta seniculus) are one of the loudest mammals in the world, famous for their long-range vocalizations. These ?howls? function in intergroup communication and are theorized to also play a role in mate defense, infanticide prevention, predator defense and group cohesion. This study tests a widely held belief in Central and South America: howler monkey long-range calls predict the onset of rainfall. Our hypothesis is that there will be a significantly greater number of howler monkey calls that are followed by rain events than howler monkey calls that are not followed by rain events. To address this question, we analyzed 50 days of passive acoustic monitoring recordings collected at the Tiputini Biodiversity Station, using the software Audacity to create spectrograms from which we extracted the timestamp of howling and rainfall onsets. Descriptive statistics showed that there were 19 days when howler calls and rain occurred on the same day, 17 days when rain occurred and no howler calls, and 6 days with howler calls and no rain. Additionally, rain onset peaked in the midafternoon, when the onset of howling was the least frequent. We are further investigating the relationships of rain and howling within each day using a permutation test to analyze how many rainfall events are preceded by howling within one hour of the start of rain. If the hypothesis is supported by the results of the permutation test, future studies could elucidate why rain is significant enough to prompt the production of energetically expensive calls and what potential applications this local ecological knowledge has for community adaptability to climate change.