The timing of these events can be influenced by a combination of factors including rainfall, soil, water and air temperature, moisture levels and photoperiod. In central Pennsylvania there are three distinct periods in which potential species can be expected to begin breeding. These periods, and the species that breed in them are as follows:

Early Spring (March 15 - April 15)

In most years this period typically begins in mid-March and lasts until mid-April. Depending on the temperatures and precipitation patterns over the winter some species can emerge as early as mid- February and begin calling in early March. Species that chorus during this period include:

• spring peeper (usually the first to begin chorus - peaks in April)
• northern leopard frog
• wood frog (very short chorus period - sometimes only a week)
• American toad

Spring (April 15 - May 15)

• mountain chorus frog (requires air temp >41° F)
• green frog
• pickerel frog

Summer (May 15 - August)

In most years this period typically begins in mid-May and lasts through the summer months. Species that chorus during this period include:

• Fowler's toad
• gray treefrog (peaks in June)
• bullfrog