Temporal trends in Podarcis muralis and Lacerta bilineata populations in a fragmented landscape in western France: Results from a 14 year time series

Abstract

Identifying population changes is a prerequisite for any conservation efforts, but to evaluate trends requires long-term data sets. In this paper, changes in population numbers in two species of European lizards, Lacerta bilineata and Podarcis muralis, are described. The results are based on counts of mortalities and live lizard presence on roads collected over a 14 year period, which indicated wide annual fluctuations in numbers in both species, with inter-specific annual trends strongly correlated. Snout to vent lengths (SVL) in L. bilineata were generally longer when annual numbers were higher but not in P. muralis. Regression analysis of the logarithmic transforms of annual lizard numbers as dependent variables and year as the independent variable indicated that despite population fluctuations, numbers of both species were stable or increased during the period of observation. Jackknife analysis identified unusually high numbers of L. bilineata in 2012 and P. muralis in 2010, but data from these years had minimal influence on the general trends with the peudo-regression coefficients generated from the Jackknife analysis in agreement with the true regressions. The results were therefore congruent, indicating annual fluctuations in both species were underpinned by long-term population stability.

Ontogenetic Habitat Use and Density of the Green Lizard (Lacerta bilineata) in Contrasted Landscapes in France and Italy

“…If so, the juvenile green lizards may be pushed outside preferable perch sites within bushes and in the branches of the bushes that are possibly better from both the thermoregulation and the antipredation points of view. Juveniles were rare in the hedgerow in France (n = 2) where data also suggest potential conflict between adult males and also male aggression towards females especially when densities are high [9] (Figure 6). For example, the presence of a second male in the hedgerow, when the large "resident" male was present, occurred only once (June) and at the opposite end of the hedgerow from the resident male.…”

“…A heliotherm that sun basks primarily in the earlier part of the day, it operates as a sentinel predator [7], feeding on insects and even small lizards, including juvenile conspecifics [8]. It is highly territorial, with serious injury and potentially even death arising from male-male combat, but females may also be subject to injury from intra-specific aggression [9]. This suggests that population spacing, for example male, female, and juvenile ratios, are potentially important in determining densities.…”

“…This suggests that population spacing, for example male, female, and juvenile ratios, are potentially important in determining densities. Furthermore, L. bilineata usually occurs in sympatry with other species of reptiles and hence shares similar habitat requirements [9][10][11]. This suggests that L. bilineata can be regarded as an indicator species enabling some insight into population requirements from a conservation perspective.…”

“…The first population was studied in a natural environment of mixed forest and grassland situated 50 km north of Rome in central Italy, where global warming effects have recently been reported as a factor determining changes in phenology and population ecology in sympatric snakes and tortoises (Vipera aspis; Hierophis viridiflavus; Zamenis longissimus; Testudo hermanni [12][13][14][15][16]. The second population was studied in a hedgerow system in a fragmented landscape in western France [9,11]. Although the monocultures produced by agriculture have little value to most wildlife, the hedgerows that bisect agricultural land are often populated by both lizards and snakes and may serve as permanent home ranges or function as connection pathways to more useable habitat and are likely key in avoiding genetic isolation (e.g., [17]).…”

Herpetological Journal 2020 and beyond – Issue 30(1)

“…The current issue of The Herpetological Journal epitomises the range of studies in reptile and amphibian biology and spans the many topics that the journal covers. This issue has articles discussing taxonomic and phylogenetic relationships of snakes (Eskandarzadeh et al, 2020), how captivity affects skin colour in frogs (Passos et al, 2020), population changes in long term datasets of lizards (Meek, 2020), amphibian distribution and endemism in South America (Cabral et al, 2020;Ribeiro Morais et al, 2020), and a global review of monoand bispecific genera of amphibians (Amori et al, 2020).…”