Croaking Science: Pond habitat creation and its value to amphibians and other freshwater species
Amphibians are globally threatened, with the International Union for Conservation of Nature (IUCN) Red List reporting roughly a third of all amphibian species being threatened or extinct. In addition, another 24.5% of amphibian species do not hold sufficient data available to make a judgement on their status – which, according to the IUCN, is a major predicator that these species are also under threat.
One of many threats amphibians face is a loss of habitat – habitat they need in particular to breed and develop in their larval stage. Many species of amphibian around the world and all our native UK frogs, toads and newts require freshwater ponds in order to breed and develop. With this in mind, the UK has lost 50% of its ponds in the 20th century and 80% of our remaining ponds were deemed to be in a poor state. These ponds are not only of extreme importance to amphibians but can also support up to two-thirds of all freshwater species. Favourable ponds are lost for a variety of reasons including in-filling, fish-stocking, pollution, mis-management or desiccation.
One of Froglife’s key aims is the creation and restoration of ponds at sites across the UK, and many other organisations also work to increase this habitat within the UK and Europe to halt and reverse the decline of ponds. Here we showcase some examples highlighting the importance of habitat work for our amphibians.
Evanton Wood in the Highlands, Scotland is one of Froglife’s Scottish Dragon Finder project sites. The area was lacking in freshwater habitat – with some wetter areas available that would often dry out in summer so plans were made to create a network of 4 ponds, varying in size and depth, to benefit biodiversity in the area. These works were completed in 2014 and surveys were conducted in 2013 and 2016 with an opportunity to monitor the impacts of the new ponds. Results were positive showing a marked increase in numbers of Palmate Newt, Lissotriton helveticus, in 2016 with a high count one evening of 224 adult individuals as opposed to just 3 recorded in 2013. A greater or equal amount of frogspawn was also recorded in all ponds compared to results in 2013. Good water quality and a wide variety of aquatic invertebrates were recorded to show the excellent additions these ponds made to the area.
Froglife’s Glasgow and North Lanarkshire Living Water projects ran from 2009 – 2013 to create and restore ponds across these two areas on 37 sites. Monitoring of eight of these sites from 2012 – 2015 showed the presence of Common Frog, Rana temporaria, and Smooth Newt, Lissotriton vulgaris, or Palmate Newt at all sites and Common Toad, Bufo bufo, at five of the eight sites. Locally rare aquatic invertebrates were recorded whilst 159 floral species were observed which had colonised the ponds. These results showed the benefit to biodiversity over a number of years as a result of pond creation and restoration works.
These positive results are echoed elsewhere – studies conducted in Oxfordshire at Pinkhill Meadows by Williams et al. (2008) recorded 20% of all UK wetland plants and macroinvertebrates within 40 new ponds monitored over 7 years, including eight Nationally Scarce invertebrates. The benefits of pond creation and restoration works can be seen outside of the UK too. Studies in Estonia by Rannap et al. (2009) recorded 6.5 times the number of Common Spadefoot Toad, Pelobates fuscus, 2.5 times the number of Moor Frog, Rana arvalis, and 2.3 times the number of Great Crested Newt, Triturus cristatus, following pond creation works in six protected areas in the south and south-east of the country.
All of these case studies also mention the importance that terrestrial habitats play for amphibians. It is easy to forget that many amphibians, including our UK natives, often spend more time out of water throughout the year than in the water as adults, and without good areas linked to ponds amphibians will struggle to take shelter, forage, overwinter and ultimately survive. The presence of good hibernacula nearby and connectivity to favourable habitat for amphibians cannot be understated.
Ponds contribute significantly to biodiversity at a landscape level and well-designed pond complexes can greatly enhance freshwater biodiversity and increase numbers of target species if management is directed towards their habitat needs. The rapid colonisation of many species that utilise ponds means positive effects can be seen in the short term and into the future. It is however extremely important that habitat works for amphibians and ponds are monitored consistently, preferably before and after works, to ensure the lasting benefits these projects provide are delivered and any mistakes are learnt from in the process.
O’Brien D. & A. Miro, 2016. Amphibian survey – Evanton Community Woods. Unpublished manuscript
Rannap R., A. Lohmus & L. Briggs, 2009. Restoring ponds for amphibians: a success story. Hydrobiologia 634: 87 – 95
Stead J., 2015. Glasgow and North Lanarkshire Living Water project: Amphibian Monitoring Survey 2015. Unpublished manuscript
Watson K., 2015. Botanical survey of ponds in Glasgow & North Lanarkshire, 2015. Unpublished manuscript
Williams P., M. Whitfield & J. Biggs, 2008. How can we make new ponds biodiverse? A case study monitored over 7 years. Hydrobiologia 597: 137 – 148