Age and growth in a European flagship amphibian: equal performance at agricultural ponds and favourably managed aquatic sites

Abstract

In human-modified landscapes, little is known about the influence of aquatic habitat types on the demographic structure of residing amphibian populations. In the present paper, we focus on a European flagship urodele species (the great crested newt Triturus cristatus) at the northwestern range of its distribution, applying the method of skeletochronology to compare the ages of individuals retrieved from agricultural ponds with individuals retrieved from aquatic sites favourably managed for T. cristatus presence. Median ages ranged between 4.5 and 10.0 years depending on sex and population, and did not differ between the two site categories. Females were on average older than males at both agricultural ponds as well as favourably managed sites. Median ages at sexual maturity (3 years for females and 2 years for males) were 4 years below the most commonly observed age cohort in both sexes, suggesting that young adults regularly forgo reproduction. Mean body size did not differ between agricultural ponds and favourably managed sites. However, the former were characterised by a higher variance in body size, which is possibly linked to more unstable ecological conditions in agricultural settings. Taken together, our findings confirm that under suitable conditions agricultural ponds can harbour sustainable populations, an important finding for the broad-scale conservation management of T. cristatus which does not usually take population demographies into account.

A co‐development approach to conservation leads to informed habitat design and rapid establishment of amphibian communities

“…This should not have markedly affected our inferences, as T. cristatus, while otherwise rare in Scotland, most commonly occurs in ponds in agricultural areas (e.g. Miró et al, 2017;Orchard, Tessa, & Jehle, 2019) and regularly co-occurs with all other investigated amphibians whenever their ranges overlap (e.g. Arntzen, Abrahams, Meilink, Iosif, & Zuiderwijk, 2017;Denoël, Perez, Cornet, & Ficetola, 2013).…”

Age, size and body condition do not equally reflect population response to habitat change in the common spadefoot toadPelobates fuscus

“…We fitted the von Bertalanffy's growth model and estimated growth parameters (VBGPs) by nonlinear least squares, and two estimated VBGPs were considered significantly different at the 0.95 level when their confidence intervals (CI 95%) did not overlap (Stănescu et al, 2016). The growth model and parameters were estimated in R Studio v. 1.1.423 (R Core Team, 2017), with the packages FSA (Ogle, 2016) and nlstools (Baty et al, 2015).…”

Policy Recommendation for the Conservation of the Suweon Treefrog (Dryophytes suweonensis) in the Republic of Korea

“…The only conservation project to reintroduce the species was unsuccessful (Borzée et al, 2018c) and despite plans for ex-situ breeding facilities having been drafted (Noh, 2017), conservation of populations in the wild would simplify the protection of the species (Snyder et al, 1996). Additionally, the species and other anuran species can adequately take advantage of the artificial flooding of rice paddies for agricultural purposes (Fujioka and Lane, 1997;Machado and Maltchik, 2010;Naito et al, 2013;Holzer, 2014;Orchard et al, 2019).…”