Acoustic Monitoring for Two Rare Frog Species in Northwest Louisiana

Science Center Objects

WARC researchers are using automated recording units to monitor southern crawfish frogs and Strecker's chorus frogs in Louisiana.

The Science Issue and Relevance: This monitoring effort focuses on the southern crawfish frog (Lithobates areolatus areolatus) and Strecker's chorus frog (Pseudacris streckeri). Only one remaining confirmed population of southern crawfish frogs exists in Louisiana, and Strecker's chorus frogs have not been confirmed in the state since 1982. Habitat loss through anthropogenic alteration of wetlands and wet prairies is the main cause of declines across the range of both species. Crawfish frogs are listed as Near Threatened by the International Union for Conservation of Nature (IUCN) and as S1 (critically imperiled because of extreme rarity; 5 or fewer known extant populations) in the state of Louisiana. Although Strecker’s chorus frogs are listed as Least Concern by the IUCN, they are ranked as S1 in Louisiana.

Acoustic Monitoring for Two Rare Frog Species

Automated recording unit (ARU) at the location of the only known population of southern crawfish frogs in Louisiana

(Credit: Brad M. Glorioso. Public domain.)

 

Methodology for Addressing the Issue: In late 2015, upon discovery of a 2011 photo of a southern crawfish frog in northwest Louisiana, we immediately installed automated recording units (ARUs) at the site to determine their status at the site. We confirmed a small population in early 2016 and continue to monitor its status using ARUs. We have placed ARUs at two additional sites in the former known range of these species, including one at the last known locality for Strecker’s chorus frog in Louisiana, in the hopes of rediscovery.

Though not closely related, both species spend most of their lives in underground burrows. This unique life history makes using active monitoring techniques to detect the species, such as visual encounter surveys, largely ineffective. Automated recording units give us a more complete assessment of frog vocalizations in these areas, as they record audio nightly without the need for us to be present, except to periodically swap out memory cards and batteries. We use automated vocalization identification software to process the recordings generated by our ARUs to greatly reduce the time needed to listen to recordings.

 

Future Steps: We will continue monitoring and analyzing recordings collected from our ARUs.