Agricultural Influences on Movement and Habitat Selection 
by Northern Leopard Frogs (Rana pipiens)

Narration:  Farm ponds have been used to water livestock, raise fish, provide recreation, 
and prevent soil erosion, but their value is often overlooked.  Although they are 
constructed, not natural wetlands, farm ponds provide a wide range of conservation and 
wildlife habitat value.  During the field seasons of 2001 and 2002, USGS biologists used 
radio telemetry to track northern leopard frogs at two sites in southeastern Minnesota 
and documented their post-breeding movement and habitat use.

Shawn Weick:  We selected two farm ponds, one in a natural setting and then the other 
one in an agricultural setting like this pond here.  The two ponds were selected from the 
greater farm pond project where we looked at 40 ponds.

Melinda Knutson:  Very little is known about frog movements after they leave breeding 
ponds.  Very few studies had been conducted prior to this, where they attached radios to 
frogs.

Shawn Weick:  The idea behind the study, was to capture them while they were 
breeding and monitor their movements throughout post breeding into the summer.

Narration:  41 frogs, 22 at the agricultural site, and 19 at the natural wetland site were 
captured, implanted with transmitters, and tracked throughout the summer of 2002.  4 
frogs were tracked until hibernation in October.

Shawn Weick:  We implanted internal transmitters into the peritoneal cavity of the 
northern leopard frogs, and the transmitters weighed 1.85 grams.

Brian Pember:  By implanting radio transmitters into northern leopard frogs and tracking 
their movements over a period of weeks to several months, we were able to determine a 
couple things: where do they go; when do they move; and how much habitat and what 
habitats do they use.

Shawn Weick:  We tracked their daily movements using the radio telemetry equipment 
and recording their locations with a global positioning system.  We recorded that 
information, along with habitat type, frogs’ health information, and air temperature and 
ground temperature.

Narrator:  One objective was to identify factors that influence leopard frog movements.  It 
was documented that frogs tended to move especially long distances during rainy 
weather.  

Shawn Weick: Here are the tracking data for a frog at our agricultural site plotted on a 
color infrared photograph.  There were two frogs that were tracked from the breeding 
pond and over six days migrated ¾ of a mile to a grazed pond where they spent the 
remainder of the summer and they eventually hibernated in that pond.

Narration: Frogs encounter many hazards that threaten their survival, including 
predation, crossing of roads, and farm practices.  4 frogs died as a result of mowing 
alfalfa fields.  Crew leader Shawn Weick describes an example of bird predation.

Shawn Weick:  One interesting thing we saw, as we got closer to a frog’s signal an 
American Bittern rose from the agricultural pond site and as it flew away, so did the 
signal.

Narration:  Over the course of the study, researchers gained insight into the extent of 
leopard frogs’ post breeding movements, and habitat use.  Agricultural ponds with small 
grass buffers may force individuals to travel longer distances because of competition for 
breeding or food.  Natural ponds have enough high-quality habitat to sustain smaller 
home ranges.  Traveling shorter distances reduces contact with hazardous situations.

Melinda Knutson: That information about how they move across the landscape during 
the summer season helps us figure out how they might be at risk, and how land 
management practices by landowners could help or hurt frog populations.

Narration: The project was possible thanks to the cooperation of private landowners, in 
allowing access to their farm ponds.  During the field seasons several landowners 
expressed their appreciation and enjoyment of the wildlife that their land attracts.

Farmer Kerry: Every summer it’s not unusual to see eagles down there, hawks, looking 
for, you know, food, whatever.  And, like in the fall, the ducks and geese in fall migration 
it’s not unusual to see 50-100 geese down there, Canadian Geese down there, on a 
regular basis.

Narrator: For more information on this, and other USGS studies, visit the website on 
your screen.

http://www.umesc.usgs.gov/