The Bull Frog Story

by Philippe Henry
December 13, 2024

The lakes of la Mauricie national park are home to a large population of bull frogs by Philipe Henry ©

Fig. 01. The lakes of la Mauricie National Park are home to a large population of bull frogs.

Not long ago, I was leading canoe trips for European tourists who came to Quebec to observe wildlife. One day, in La Mauricie National Park, several of them were surprised to hear strange sounds that they had never heard before and could not pinpoint where they were coming from. I led them to an expanse of aquatic vegetation and there, they were surprised to hear the songs of bullfrogs, deep songs uttered by the males half-hidden under the plants.


bull frogs gather on the park’s lakes where Nymphoides cordata, the little floating heart grows. by Phiolipe Henry ©

 
Fig. 02. From the beginning of June, hundreds of bull frogs gather on the park’s lakes where Nymphoides cordata, the little floating heart grows.

For nearly three months in summer, this is the breeding season for Lithobates catesbeianus. The males sing to attract females and to mark their aquatic territory. It is these songs, which resemble the bellowing of bulls, that gave the species its name. In Quebec, they are called “ouaouaron” which is a word of Iroquoian origin and which perfectly translates their song.

bullfrog does not have pronounced dorsolateral folds by Philippe Henry ©
Fig. 03. Unlike the green frog, the bullfrog does not have pronounced dorsolateral folds.

The Bull Frog is the largest frog in North America and the second largest in the world after the Goliath frog and certainly the most voracious with a diet that makes it a formidable predator for various native species. And it is its voracity that makes it a threat in the many countries where it has been introduced to breed for consumption, to combat insect pests or simply for the curiosity of aquarists.

Bull Frogs by Philippe Henry ©

Fig. 04.

Bull Frogs by Phlippe Henry ©

Fig. 05. In Canada, bull frogs are numerous in the lakes of southern Ontario, southern Quebec, New Brunswick and Nova Scotia. The species has been introduced in British Columbia where it has spread along the lower mainland and Vancouver Island.

Banned from importation into the European Union since 1997, these frogs are nevertheless present in a large part of western Europe (Belgium, Greece, France, Germany, etc.) but also in China, Japan and the Antilles. It is considered a very harmful invasive species in all countries in which colonies have been recorded.

Bull Frogs by Philippe Hearny ©

Fig. 06."Invasive species are species that have been introduced outside their original range, directly or indirectly by humans, and have been able to reproduce in their host region, while creating damage to the ecosystem." (Boudouresque, 2012)

To speak only of France, this species was voluntarily brought back from the United States in 1968, by an individual (Armand Lotti), owner of a castle in Gironde and who wanted about ten individuals to decorate the pond in his park. This introduction seems to be at the origin of the populations known in the southwest of France.

Bull Frogs by Philippe Henry ©

Fig. 07.

Bull Frogs by Philippe Henry ©

Fig. 09.

Bull Frogs by Philippe Henry ©

Fig. 09.

The problems already caused by bull frogs are linked to the adaptability of the species. The rate and success of reproduction, the ability to move and the pressure it exerts on other species – through predation rather than competition (Werner et al., 1995)– threaten native wetland populations. Risks of transmission of pathogenic agents to related species have also been highlighted (Blaustein and Kiesecker, 2002; Mazzoni et al., 2003), such as chytridiomycosis, of which it is a healthy carrier and which is a major cause of extinction for other amphibians (Berger et al, 1999).

Philippe Henry ©

Fig. 10.

Bull frogs need bodies of water for breeding and hibernation. The destruction of their habitat for agriculture and urban uses, along with pollution, is detrimental to their population as well as population of other frogs.

Bull Frog eaten by Birda Philippe Henry ©

Fig. 11.

Bull Frog eaten by Otter ©

Fig. 12.

Bullfrogs may seem like little terrors but they often have to deal with larger predators. I have been photographing and filming wildlife for years in La Mauricie National Park and elsewhere in Quebec and I can say that they are also a popular prey for common mergansers, otters and even foxes and minks.

Merganser eating a Bull Forg by Philipee Henry ©

Fig. 13.

Mergansers eating a Bull Frog by Philipe Henry ©

Fig. 14.

During summer 2024, I went to the same lake by canoe every day for a two weeks period of time. I wanted to follow a common merganser family -female and six chicks- and see what they fed on. Every day they swallowed a very large quantity of tadpoles, small fish and frogs including a large number of bullfrogs.

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Authors Biography & Contact Information

Philippe Henry by Veronique AmiardBio:  Philippe Henry is a photographer specialized in wildlife and conservation, a writer and a filmmaker. He is based in La Mauricie, in Quebec. You can follow his photography on his facebook page. Photo of Philippe by Veronique Amiard.

 

 

 

 

 

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