Wood Frog (IMAGE) Penn State Caption Penn State researchers have documented that wood frog numbers have declined at Pennsylvania sites they have monitored in the last two decades. Credit Michael Antonishak, Penn State Usage Restrictions non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.