Wood Frog Life History 



45 



60 



50 



40 



30 



- 20 



10 



S36 



□ R.sylvatica 



• R.sphenocephala 



1 



18 



27 



7 



15 



22 



29 



MAR 



MAR 



MAR 



APR 



APR 



APR 



APR 



date 



Fig. 3. Larval development of Rana sylvatica and Rana sphenocephala in Pas- 

 ture Pond, Tallapoosa County, Alabama. Numerals preceded by the letter S 

 indicate the developmental stage in tadpoles at the time of collection. 



however, indicating that all larvae were transformed at this time. This 

 would give a maximum transformation period of 73 days in the field. 

 Most individuals had probably transformed by 29 April (or somewhat 

 earlier); only four tadpoles were collected in the pond at that time. This 

 would indicate a transformation time of about 66 days. 



Various vertebrates and invertebrates preyed on wood frog larvae, 

 though not all predators were present at each breeding pond. All inver- 

 tebrate predators were insects. Adult back swimmers (Notonectidae) 

 and predaceous diving beetles (Dytiscidae) were often seen preying on 

 small tadpoles. Nymphal notonectids and larval dytiscids also probably 

 preyed on wood frog larvae, as observed by Dickerson (1906). Herreid 

 and Kinney (1966) noted extensive predation on wood frog larvae by 

 Dytiscus spp. in Alaska. Formanowicz and Brodie (1982) found no sur- 

 vival of stage 42 and younger wood frog tadpoles when subjected to 

 predation by larval Dytiscus verticalis in the laboratory. Increased sur- 

 vivorship in older tadpoles and froglets (stage 42 to 46) was attributed 

 to unpalatability, a result of the development of active granular glands 

 during later stages of metamorphosis. Other potential insect predators 



