Croissance, nutrition et reproduction des ouaouarons Rana catesbeiana Shaw (Amphibia Anura) des Laurentides au nord de Montréal

Abstract

About 2600 bullfrogs have been captured in three small lakes of the Laurentian region and 1863 among them have been marked and released. The study of the body length growth has been made by three methods (age lecture on pterygoïds, body length histograms, mark–recapture), which give concordant results: 59 mm at 1 year, 81 mm at 2 years, 108 mm at 3 years, 125 mm at 4 years, 137 mm at 5 years, 143 mm at 6 years. The biggest, measuring 162 mm, might have been 8 or 9 years old. The growth rate is the most important between 2 and 3 years, when bullfrogs reach sexual maturity. The body weight is 18 g at 1 year and 40 g at 2 years. At 3 years, the females weigh 101 g and the males 96 g. and at 5 years, the weights are respectively 215 and 194 g. Bullfrogs between 45 and 65 mm eat mostly in sects and the biggest ones eat mostly frogs, tadpoles, fish, and crayfish. The mating calls were heard by the end of May and the spawning occurs between the 20th of June and the 10th of July. The number of eggs (3 826 to 23 540) depends on the size of the individual. Sexual maturity is generally reached at 3 years when bullfrogs measure between 95 and 110 mm. However, some individuals reach sexual maturity at 2 years and some others at 4 years. Our results were compared with those of the literature.