A case of predation by a Marsh Frog, Pelophylax cf. ridibundus, on a subadult Western Spadefoot Toad, Pelobates cultripes, in France

Full text

Predation and competition for resources between
amphibian species is well known. This also holds
for introduced species, with their presence leading
to declines of native populations of rare or localised
species (Bucciarelli et al., 2014). Repeated introductions
of the genus Pelophylax Fitzinger, 1843 throughout
the world pose numerous ecological and genetic
consequences for native populations (Dusfresnes and
Dubey, 2020; Doniol-Valcroze et al., 2021). The genus
Pelophylax is present in most of France except for areas
with few water resources and the high mountainous
areas of the Pyrenees and Alps (Lescure and Massary,
2012). It has been present since 1908 in some parts
of Vaucluse (Mourgue, 1908) while it was still rare in
other departments (Olioso, 1980), though twenty years
later it was reported to be increasing and abundant
across the department (Peyre et al., 2005). Pelophylax
ridibundus (Pallas, 1771) is a species complex that is
invasive to France, and is known to occasionally feed
on adult salamanders and frogs as well as their larvae
(Pille et al., 2021). Pelobates cultripes (Cuvier, 1829)
is a particularly threatened native toad species, and is
listed as vulnerable on the IUCN Red List (IUCN, 2022)
and endangered in the Provence region (Marchand et
al., 2017). P. cultripes is often preyed upon by birds,
mammals, and snakes (Geniez and Cheylan, 2012),
and P. ridibundus has been documented to predate on
its tadpoles in the Larzac karst plateau in the Hérault
Département, France (Pille et al., 2021).
On 9 September 2017, a predation attempt by
Pelophylax cf. ridibundus on a moving subadult P.
cultripes was recorded during a nocturnal survey
targeting P. cultripes in the commune of Oppède in
the Vaucluse Département, France (43.859331ºN,
5.14725ºE; Fig. 1A). Although our photographs here
strongly suggest its identity as P. ridibundus, given the
presence of other native and introduced Pelophylax in
the area and its status as a species complex in the absence
of genetic testing, we use a tentative species designation
here. Despite the size of the P. cultripes individual, more
than half of its body was in the mouth of the Pelophylax
cf. ridibundus that was attempting to swallow it. Given
the disturbance caused by the photographer, the toad
was released shortly after the photos were taken. The
observations reported here demonstrate the effectiveness
of predation on metamorphosed individuals by P. cf.
ridibundus, which can severely injure its prey with
its dental lamina (Fig. 1B). To our knowledge, this
is the first documented case of attempted predation
by an individual of the P. ridibundus complex on a
metamorphosed P. cultripes.
Recent work on amphibian consumption by members
of the genus Pelophylax showed that this group tends
to be an occasional predator on frogs rather than a
specialist predator, with only 9% of 1062 stomachs
analysed containing amphibians (Pille et al., 2021). The
ecology of P. cultripes is rather atypical among European
amphibians as it is a slow-moving species, being not
very mobile and faithful to its territory outside of the
reproduction and juvenile-dispersion periods (Priol,
2015). Pelobates tadpoles attacked by P. ridibundus
(Pille et al., 2021) may also experience failed attacks
(Zamora-Camacho et al., 2019) and post-metamorphic
P. cultripes are diurnal burrowers (Recuero, 2014)
which probably allows them to escape diurnal predation
by other Pelophylax. However, the strong presence of
P. cf. ridibundus positioned at night around waterholes
(N. Fuento, pers. obs.), increases the likelihood of
predation on young moving individuals. A stomach
content study (e.g., Solé et al., 2005; Pille et al., 2021)
on P. cf. ridibundus in habitats important for Pelobates
Herpetology Notes, volume 16: 559-560 (2023) (published online on 01 August 2023)
A case of predation by a Marsh Frog, Pelophylax cf. ridibundus,
on a subadult Western Spadefoot Toad, Pelobates cultripes, in
France
Nicolas Fuento1,* and Grégory Deso2
1 Ligue pour la Protection des Oiseaux, 30 Avenue des frères
Roqueplan, 13370 Mallemort. France.
2 Association Herpétologique de Provence Alpes Méditerranée,
384 Route Caderousse, 84100 Orange, France.
* Corresponding author. E-mail: nicolas.fuento@lpo.fr
© 2023 by Herpetology Notes. Open Access by CC BY-NC-ND 4.0.

Nicolas Fuento & Grégory Deso
560
cultripes should be carried out to better measure the
extent of predation on this highly threatened species.
Lastly, the increased difficulty in identifying invasive
Pelophylax encourages the use of adapted molecular
tools (Cuevas et al., 2022) to better estimate the extent
of their spread and to target management measures for
native batrachofauna.
Acknowledgments. We would like to thank Fabien Pille for his
pre-review but also Jesse Erens and an anonymous reviewer for
their numerous comments which helped to improve the quality
of this note.
References
Bucciarelli, G.M., Blaustein, A.R., Garcia, T.S., Kats, L.B. (2014):
Invasion complexities: the diverse impacts of nonnative species
on amphibians. Copeia 2014: 611–632.
Cuevas, A., Patrelle, C., Ciavatti, F., Gendre, T., Sourrouille,
P., Geniez, P., Doniol-Valcroze, P., Crochet, P.-A. (2022): A
new PCR-RFLP method for the identification of parental and
hybridogenetic western European water frogs including the
Pelophylax perezi-grafi system. Salamandra. 58: 218–230
Doniol-Valcroze, P., Mazepa, G., Grimal, F., Sourrouille, P., Perrin,
N., Litvinchuk, S.N., Crochet, P.A. (2021): Discovery of a
Pelophylax saharicus (Anura, Ranidae) population in Southern
France: a new potentially invasive species of water frogs in
Europe. Amphibia-Reptilia 42: 427–442.
Dufresnes, C., Dubey, S. (2020): Invasion genomics supports an
old hybrid swarm of pool frogs in Western Europe. Biological
Invasions 22: 205–210.
Geniez, P., Cheylan, M. (2012): Les Amphibiens et les Reptiles
du Languedoc-Roussillon et régions limitrophes. Atlas
biogéographique. Paris, Muséum National d’Histoire naturelle,
Mèze, Biotope.
IUCN (2022): Pelobates cultripes. The IUCN Red List of
Threatened Species. http://www.iucnredlist.org. Accessed on 23
February 2023.
Lescure, J., Massary, J.C. (2012): Atlas des Amphibiens et Reptiles
de France. Paris, Muséum National d’Histoire naturelle, Mèze,
Biotope.
Marchand, M-A,, Roy, C., Renet, J., Delauge, J., Meyer, D., Hayot,
C. (2017): Liste rouge régionale des amphibiens et reptiles
de Provence-Alpes-Côte d’Azur. Aix-en-Provence, France,
Conservatoire d’espaces naturels Provence-Alpes-Côte d’Azur.
Mourgue, M. (1908): Catalogue raisonné de la faune herpétologique
des environs de Sainte-Cécile Sérignan, Orange (Vaucluse). La
Feuille des Jeunes Naturalistes 38: 178–182.
Olioso, G., Volot, R., Gallardo, M. (1980): Contribution à l’étude
des vertébrés du Sud-Vaucluse. Première partie: Amphibiens,
reptiles et mammifères. Bulletin du CROP 3: 39–55.
Peyre, O., Olioso, G., Joubert, V. (2005): Atlas préliminaire de
répartition des reptiles et amphibiens du Vaucluse. Bulletin du
CROP 1: 68–95.
Pille, F., Pinto, L., Denoël, M. (2021): Predation pressure of
invasive marsh frogs: a threat to native amphibians? Diversity
13: 595.
Priol, P. (2015): Suivi d’une espèce rare en vue de sa conservation:
dynamique spatiale et temporelle de populations de Pélobate
cultripède (Pelobates cultripes) en Aquitaine. Unpublished
thesis, École Pratique des Hautes Études, Montpellier, France.
Recuero, E. (2014): Sapo de espuelas – Pelobates cultripes. In:
Enciclopedia Virtual de los Vertebrados Españoles. Salvador,
A., Martínez-Solano, I., Eds., Museo Nacional de Ciencias
Naturales, Madrid, Spain.
Solé, M., Beckmann, O., Pelz, B., Kwet, A., Engels, W. (2015):
Stomach-flushing for diet analysis in anurans: an improved
protocol evaluated in a case study in Araucaria forests, southern
Brazil. Studies on Neotropical Fauna and Environment 40:
23–28.
Zamora-Camacho, F.J., Aragón, P. (2019): Failed predator attacks
have detrimental effects on antipredatory capabilities through
developmental plasticity in Pelobates cultripes toads. Functional
Ecology 33: 846–854.
Figure 1. Pelophylax cf. ridibundus attempting to eat a subadult Pelobates cultripes. (A) Partially ingested. (B) After disturbance
and release of prey. Photographs by Nicolas Fuento.
Accepted by Jesse Erens