NATURAL HISTORY NOTES
Fig. 1. Lithobates catesbeianus with predated female Zapus hudsonicus (Meadow Jumping Mouse).
Deer Mice), and Z. hudsonicus. To date, all these taxa except Z. hudsonicus have been reported as prey of bullfrogs. Zapus hudsonicus can be found in dry meadows but prefers moist meadows near streams and ponds with cattails, sedges, and grasses. In addition, this rodent swims well both under water and on the surface (Schwartz and Schwartz 2016. Wild Mammals of Missouri. University of Missouri Press, Columbia, Missouri. 396 pp.). Thus the likelihood that Z. hudsonicus and L. catesbeianus encounter one another should be fairly great. Despite this, I found no previous records of this rodent having been eaten by L. catesbeianus. This is likely due to the behavior of Z. hudsonicus. This rodent moves quickly by hopping in a zig-zag fashion often jumping up to 1 m off the ground. Furthermore, Z. hudsonicus is wary and nervous, capable of jumping up to 3.5 m off the ground when frightened (Schwartz and Schwartz 2016, op. cit.). A small farm pond was 50 m east of where the bullfrog was found. A dense stand of cattails and sedges covered the edge of the pond, and a large, dry pasture dominated by native warm weather grasses surrounded the wet habitat including the pond. This is ideal habitat for Z. hudsonicus to overlap with L. catesbeianus, thus increasing the chances that the two species could encounter each other. It is likely this female’s jumping abilities were hindered because of carrying the embryos; thus causing her to be more easily captured. JAMES J. KRUPA, Department of Biology, University of Kentucky, Lexington, Kentucky 40506, USA; e-mail: [email protected]
LITORIA DENTATA (Bleating Tree Frog) and LITORIA PERONII (Peron’s Tree Frog). INTERSPECIFIC AMPLEXUS. Interspecific amplexus can be a common occurrence in explosive breeding anurans but is rarer in prolonged breeders (Wells 1977. Anim. Behav. 25:666–693). This is due to the increased pressure to breed caused by the limited time frame in which suitable conditions occur. Litoria dentata and L. peronii are co-occurring hylid anurans of southeastern Australia with similar habitat usage (Anstis 2013. Tadpoles and Frogs of Australia. New Holland Publisher, Sydney, New South Wales. 832 pp.). Litoria dentata and L. peronii share typical tree frog morphology yet L. dentata is smaller with sizes ranging from 32–44 mm SVL while L. peronii are 44–65 mm SVL (Tyler and Knight 2011. Field Guide to Frogs of Australia. CSIRO Publishing, Sydney. 188 pp.). Both species have sexual dimorphism with females tending to be larger on average and both live a primarily arboreal life style, usually only descending to breed
Fig. 1. Amplexus between a male Litoria dentata and a female Litoria peronii.
Fig. 2. Male Litoria peronii competing for amplexus opportunity.
during the warmer months of spring and summer. These species have contrasting breeding strategies: L. dentata is an explosive breeder while L. peronii is a prolonged breeder (Lemckert and Mahony 2008. Herpetol. Conserv. Biol. 3:71–76). Here I document the first published observation of interspecific amplexus between a male L. dentata and a female L. peronii. At 2050 h on 16 January 2015, I observed a male L. dentata in amplexus with a female L. peronii sitting on a branch of a Banksia ericifolia (Fig. 1) at an ephemeral pond in Maddens Falls, Darkes Forest, New South Wales, Australia (34.2375°S, 150.9167°E, WGS84, 368 m elev., air temperature = 21°C). The sex of each frog was determined by observing the presence or absence of nuptial pads, a feature specific to male frogs. The pair remained in amplexus for ~2 h despite the presence of competing male L. peronii calling nearby (Fig. 2). The L. peronii female made no attempt to release itself from the amplecting male L. dentata but did move away from competing male L. peronii. No breeding attempts were observed. Interspecific amplexus of male L. dentata on female L. peronii is likely where dense aggregations of both species co-occur and may be attributed to similarities in morphology and habitat usage. CHAD BERANEK, School of Environmental and Life Sciences, Newcastle University, Callaghan, Newcastle, New South Wales 2308, Australia; e-mail: [email protected]
Herpetological Review 48(2), 2017