On Understanding Anuran Communities: Sampling Acoustic Data for the Probability of Detection of Species Presence

Abstract

The calculation of probabilities of detection based on calling behavior can be used for assessment and monitoring of cryptic amphibians. I monitored ten species of anurans nightly from 1 January to 31 December 2015 in Colorado County, Texas. I monitored the environmental factors that influence the calling phenology of the Blanchard’s cricket frog (Acris blanchardi), Green treefrog (Hyla cinerea), Cajun chorus frog (Pseudacris fouquettei), Eastern narrow-mouth toad (Gastrophryne carolinensis), Southern leopard frog (Lithobates sphenocephalus), Crawfish frog (Lithobates areolatus), Gulf coast toad (Incilius nebulifer), American bullfrog (Lithobates catesbeianus), Green frog (Lithobates clamitans), and Squirrel treefrog (Hyla squirella). I analyzed acoustic data coupled with environmental covariates at eight ponds to determine the detection probability and sampling effort of each species. The models I produced indicate that air temperature at the time of the survey and pond depth can influence the detection probability of eight of the ten species of frogs I found during my study. My study suggests conducting night surveys for five of the ten species of frogs when the pond depth is approximately 0.5 meters and when the air temperature is between 20 – 25 °C. My models predict that ten or more repeated surveys are necessary to reliably detect a specific species whose probabilities of detection are less than 0.3 during the species’ active season. My models predict that no more than ten repeated surveys are necessary to reliably detect species whose probabilities of detection are greater than 0.3 during the species’ active calling season.