In this installment of In the Field, we’re taking a peek at the research of Patrick Kleeman and Gary Fellers of the US Geological Survey.

WHERE: Primarily in Pt. Reyes and Yosemite National Park

WHY: They are looking for possible causes of the decline of amphibian populations in Northern California. The study is intended to be a long-term look at how breeding periods may change over time, possibly due to changes in climate.

HOW: Patrick and Gary are looking at vocalizations of frogs and toads to better understand their breeding habits and ecology.

WHAT THEY USED: Among their arsenal of research tools, the two had Wildlife Acoustics Song Meters and hydrophones. In specific, they used:

• 3 Song MeterSM1 recorders at different ponds in Pt. Reyes National Seashore Park
• 2 Song Meter SM2+ recorders, which travelled between Pt. Reyes and Yosemite depending on the season and the species being studied.

The SM2+ units also had hydrophones attached to record red-legged frog vocalizations both above and below water.

The microphones and hydrophones allowed the team to compare the frequency and nature of the calls above versus below water.

WHAT THEY’VE SEEN SO FAR:

• Different species that call at the same time use vocal portioning by vocalizing in mostly non-overlapping frequencies.
• The frogs have different preferences in vocalizing above or below water based on their respective locations. Because they recorded amphibians by the ocean as well as some by the interior valley, the differences could be due to increased predation risk above water or simply noise level if they are by the ocean.