This dataset captures a year-long journey through the Grand Canyon's night sky. Across 1,428 paired samples gathered over 611 nights at 410 riverine sites, field teams recorded the nocturnal calls of bats and collected flying insects along a 470 km stretch of the Colorado River. Temperature, lunar phase and river width were logged alongside each sample, bringing context to the rhythms of life in this red‑rock corridor.
Among the 26 bat species monitored, some dominated the soundscape. Parastrellus hesperus (PAHE) and unidentified calls (NOID) together represent half of all detected activity, while species like Myotis yumanensis (MYYU) and Lasionycteris noctivagans (LABL) appear in smaller numbers. These patterns hint at species-specific foraging strategies and habitat preferences, informed by the river's mosaic of canyon reaches.
The scatter plot compares the total number of bat calls to the combined abundance of aquatic and terrestrial insects in each sample. The weak correlation suggests that prey availability alone doesn’t dictate bat activity—factors like water temperature, vegetation structure and lunar illumination also play roles. Monthly trends reveal bursts of calling coinciding with spring and midsummer insect blooms, underscoring the timing of emergent caddisflies and mayflies.
Behind these numbers lie the contributions of dozens of scientists and volunteers. Each row represents a night under the stars: microphones and insect nets perched on sandbars, researchers recording data late into the dark, all to better understand the Colorado’s nocturnal food web. This study highlights the beauty and complexity of an ecosystem where bats, insects, water and rock weave a story together.