Archives for May 2017

The Amphibians and Reptiles of Scotland by Chris McInerny & Pete Minting

The first ever book devoted to the herpetofauna of Scotland, written mainly by Chris McInerny and Pete Minting and published by Glasgow Natural History Society (it can be seen free on the Society’s web-site) is now available in hard copy; order from Chris McInerny –price £27.50 including P and P or purchase from HERE. As well as detailed abundantly-illustrated species accounts, the 320 page book includes a section on habitat improvement, partly written by Froglife’s James Stead on the Living Waters projects in Glasgow and North Lanarkshire.

A detailed review will appear in Natterchat, but don’t wait, the book is highly recommended!

by Roger Downie

The scent of predation: amphibian embryos respond to predator cues

Parental care is relatively rare within amphibians with documented cases only occurring within 20% of salamanders and 6% of anurans. Those that do provide parental care usually lay small clutches of relatively large eggs and one or more of the parents provide protection from potential predators in the form of egg attendance and transport. The vast majority of amphibian species lay their eggs providing little protection from predators. However, the developing embryos and newly emerged larvae may respond to changing environmental conditions including temperature and light. There is increasing evidence that developing embryos can respond to the presence of predators in a variety of ways such as altering hatching rate and size or stage of development.

The streamside salamander Ambystoma barbouri from the United States lays its eggs on the underside of rocks at the bottom of fast flowing streams (Figure 1). The newly emerged larvae are highly vulnerable to predation from flatworms and rates of larval mortality are high. However, when the salamander embryos come close to hatching they are able to detect the presence of the flatworms through chemical cues emitted by the predator. If the embryos detect that flatworms are nearby, they postpone hatching, resulting in the salamander larvae emerging at a larger size and a later stage of development. This results in faster swimming speeds and an increased ability to evade the flatworms. This plasticity in development relative to the presence of predators is a highly adaptive response, allowing greater survival of this species.

Figure 1: The streamside salamander Ambystoma barbouri from the United States. (Insert: the eggs which are laid on the underside of rocks at the bottom of fast flowing streams)

When eggs are prone to predation, the responses of the developing embryos may be different. The southern leopard frog Lithobates sphenocephalus from the United States breeds in ponds and other freshwater habitats and the eggs are vulnerable to attack from crayfish (Figure 2). When in the presence of these predators, eggs of the leopard frog increase their rate of development, resulting in a faster hatching time and larvae are able to escape at a smaller stage of development. In addition, if egg masses are being attacked, the mechanical stimulation, along with chemical cues from conspecific larvae, triggers hatching of the remaining embryos. Stress chemicals released by conspecifics who are being attacked has been documented in other amphibian species. If embryos of the common frog Rana temporaria are under attack, they release chemical alarm signals which trigger the hatching of nearby embryos. Although these may not be at their full stage of development, it allows these newly hatched larvae to move away from the point of attack.

Figure 2: A southern leopard frog Lithobates sphenocephalus from the United States laying her eggs in a pond.

Although the responses of embryos and larvae are usually adaptive, on occasion, non-adaptive responses to the presence of predators may occur. Predator-induced stress has been documented in a number of amphibian species and may occur in synergy with other stressors such as pollutants, UV radiation and temperature changes. For example, newly hatched gray treefrog tadpoles Dryophytes versicolor developing in the ponds of south-eastern Canada which had been contaminated with the pesticide carbaryl, exhibit a stress response, resulting in mortality. This mortality is further increased when in the presence of the predatory salamander Ambystoma maculatum. A similar predator-induced stress response has been documented in the great crested newt Triturus cristatus in the UK. Under laboratory conditions embryos of this species exhibit significantly higher mortality when in the presence of the chemical cues from predatory three-spined sticklebacks. This increase in mortality may have impacts on larval recruitment and subsequent population dynamics.

Both adaptive and non-adaptive responses to predators in the early stages of development are increasingly being documented in amphibian species. In general we know very little about how widespread these occur and the potential positive or negative impacts at the population level. In particular, further research examining the synergies between various stressors such as UV or chemical contaminants with predator chemical cues is required and may increase our understanding of how amphibian species will respond in a changing environment.

References

Crump, M. L. (1995) Parental Care. In: H. Heatwold (ed) Amphibian Biology Volume 2: Social Behaviour. Pp: 518-567. Surrey Beatty & Sons, Australia.

Jarvis, L. E. (2010) Non-consumptive effects of three-spined stickleback (Gasterosteus aculeatus) on great crested newt embryos (Triturus cristatus). Herpetological Journal, 20 (4): 271-275.

Mandrillon, A. L. & Saglio, P. (2007) Effects of embryonic exposure to conspecific chemical cues on hatching and larval traits in the common frog (Rana temporaria). Chemoecology, 17: 169-175.

Relyea, R. A. & Mills, N. (2001) Predator-induced stress makes the pesticide carbaryl more deadly to gray treefrog tadpoles (Hyla versicolor). Proceedings of the National Academy of Sciences of the USA, 98 (5): 2491-2496.

Saenz, D., Johnson, J. B., Adams, C. K. & Jaylon, G. H. (2003) Accelerated hatching of Southern Leopard Frog (Rana sphenocephala) eggs in response to the presence of a crayfish (Procambarus nigrocinctus) Copeia, 2003 (3): 446-649.

Sih, A. & Moore, R. D. (1993) Delayed hatching of salamander eggs in response to enhanced larval predation risk. American Naturalist, 142: 947-960.

Froglife Volunteer and Wildlife Artist, Samantha Marais, has shared her next set of wildlife drawings with us, this time tackling the remaining 3 UK native amphibian species, the newts!

Smooth Newt (Lissotritan vulgaris)

Smooth Newts are the most widespread newt species and can be found throughout Britain and Ireland. Unlike the similar looking Palmate Newt they do not tolerate as dry conditions, so they tend to be found nearer wet areas. On land, their skin takes on a velvety appearance and they are sometimes mistaken for lizards. Just like Common Frogs they are usually quite quick colonise garden ponds.

Palmate Newt (Lissotriton helveticus)

Palmate Newts look very similar to Smooth Newts but they have more of a preference for shallow ponds on acidic soils. They’re patchily distributed and found on heathland in the south and west of the UK, and on moorland and bogs in the north; they’re quite common in Scotland, Wales and southern England but absent from much of central England. Palmate Newts can tolerate drier conditions and tend to be found further from water.

Great Crested Newt (Triturus cristatus)

Great Crested Newts are widely distributed throughout Britain but this distribution is extremely patchy; they’re absent from Ireland and have disappeared from many sites across Europe. They are the largest of our native newt species. During the breeding season males develop a jagged crest which has a break at the base of the tail and females take on a ‘bulky’ appearance.

To find out more about the UK’s native amphibian and reptile species click HERE

OR

If you think you’ve spotted any of these species download the DRAGON FINDER APP and record your sightings.

Cala Homes’ Warren O’Callaghan cuts the ribbon to open the trail assisted by James Fisher (Peterborough City Council Wildlife Officer) and Kathy Wormald (CEO, Froglife) and watched by local residents, Froglife volunteers and donors. (Photo: Tim George)

Wildlife conservation charity Froglife are delighted to announce the launch of an exciting new Hoppy Families Nature Trail, right in the heart of Peterborough!

Boardwalks and Thorpe Meadows Local Nature Reserve, located just off Thorpe Road, recently welcomed guests to the premiere of its new nature walk, designed to engage, educate and inspire.

On the trail (L to R) : Catherine Duerden (Froglife Project Officer), Alex Kirby-Lambert (Froglife Trainee) and Cala Homes’ Warren O’Callaghan. (Photo: Tim George)

Opening the trail, CALA Homes’ sales manager, Warren O’Callaghan said: “We were delighted to be able to support this community project and it’s wonderful to see so many months of hard work come to fruition. Our aim is to not only build aspirational homes but to invest and contribute to the communities and environments in which we build. The nature trail will bring fun, adventure and learning opportunities to many families in Peterborough. The new interpretation boards are eye-catching and engaging and allow visitors to gain more from their visits.”

Encouraging visitors of all ages to explore the reserve and find out more, the nature trail includes challenge cubes, interpretation boards, and wildlife themed rubbing plates. Local artists Jeni Cairns, Keely Mills and Stuart Payn were involved in the creative process, working with young people from Froglife’s Green Pathways scheme to turn their ideas into reality. Additionally, young offenders on their community reparation orders helped install seating, bat and bird boxes, and a new dipping platform, and tree works took place to let more light into pond areas, improving conditions for amphibians and dragonflies.

A map and activity sheet to accompany the nature trail are available to download from: www.froglife.org/what-we-do/froglife-reserves/boardwalks/

(Photo: Tim George)

The project would not have been possible without the generosity of funders, including backing from over 80 fantastic ‘crowdfunders’, corporate supporters CALA Homes, the Stone King Foundation, and Modern Scaffolding Services, a Tesco ‘Bags of Help’ award voted for by the public, and a grant from the Dulverton Trust. Thanks should also go to all the volunteers who help with habitat management and surveying at the site – if you would like to join them, please get in touch!

Jenny Tse-Leon, Head of Learning and Communications at Froglife, said: “We are hugely grateful to everyone that contributed towards this project. Boardwalks was an underused site in the centre of the city and we wanted to make it easier for people to explore by creating the Hoppy Families Nature Trail. Getting outside and experiencing nature has been shown to have a wide range of benefits for our health and wellbeing.”

Boardwalks is a free, publicly accessible Nature Reserve and can be found across the bridge from the Boathouse Pub in Thorpe Meadows, or by following National Cycle Route 63 along the River Nene in a westerly direction from Rivergate. It has been managed by Froglife on behalf of Peterborough City Council since 2015 when extensive pond restoration and creation work took place.