Ornamental Phoenix palm trees as habitat for fauna in the Mediterranean Region - results from a full year monitoring

In the European Mediterranean Region, palm trees are a common element in cities and semi-urban landscapes and have become important habitat structures for local fauna. This study aimed to monitor the invertebrate and vertebrate fauna occurring on and associated with ornamental palms of the genus Phoenix, over the course of one year. Five study sites were used in southern Spain, with varying levels of management. Several complementary methods were applied monthly in order to assess the vertebrates and invertebrates associated with the full seasonal cycle of palms, including flowering and fruiting. The study resulted in the identification of 216 invertebrate families from seven different classes and 89 vertebrate species, consisting of 62 bird, 20 mammal (including bats), six reptile and one amphibian species associated with Phoenix palms. It thus highlights that Phoenix palms provide a habitat for many species and individuals over the course of one year.

Temporal trends in reptile occurrence among temperate old-growth, regrowth and replanted woodlands

Reptiles are an important part of the vertebrate fauna in the temperate woodlands of south-eastern Australia. However, compared to birds and mammals, the long-term occurrence of reptiles across woodland growth types-old growth, regrowth, and replantings-remains poorly understood. Here, using 18-years of data gathered at 218 sites across 1.5 million hectares in New South Wales South West Slopes bioregion, we sought to quantify patterns of temporal change in reptile occurrence and determine if such changes varied between woodland growth types. Despite extensive sampling, almost 75% of our 6341 surveys produced no detections of reptiles. Significant survey effort exceeding 2000 surveys was needed over a prolonged period of time to record detections of 26 reptile species in our study area. Our analyses showed a temporal increase in estimated reptile species richness and abundance over 18 years. Such increases characterized all three vegetation structural types we surveyed. At the individual species level, we had sufficient data to construct models for five of the 26 species recorded. Three of these species were least commonly detected in replantings, whereas the remaining two were most often detected in replantings relative to old growth and regrowth woodland. We found evidence of a temporal increase in two skink species, a decline in one gecko species, and no change in the remaining two skink species. Although detections were consistently low, active searches were the best survey method, and we suggest using this method in habitats known to be hotspots for reptiles, such as rocky outcrops, if the aim is to maximize the number of individuals and species detected. Our findings highlight the value of all three broad vegetation structure types in contributing to woodland reptile biodiversity.

Use of artificial bark covers to investigate the distribution and abundance of arboreal lizards in a floodplain environment

Arboreal lizards, especially species that inhabit flood-prone environments, have been poorly surveyed worldwide. We examined spatiotemporal patterns in arboreal lizard abundance and factors driving detection rates in floodplain environments using artificial bark covers, a non-destructive and cost-effective survey method. In total, 112 flexible, closed-cell foam bark covers were installed on eucalypt trees in 13 wetlands in the Murrumbidgee River floodplain of southern New South Wales, Australia, stratified by two inundation frequency treatments. Of four arboreal lizard species detected, the southern marbled gecko (Christinus marmoratus) (n = 41) and the tree dtella (Gehyra versicolor) (n = 8) were restricted to the mid-Murrumbidgee region, whereas the crevice skink (Egernia striolata) (n = 19) was restricted to the lower-Murrumbidgee region and did not co-occur with either gecko species. Mean detection rates of lizard species did not differ between frequently and infrequently inundated treatments but their abundance beneath covers varied significantly by month. For all detected lizard species, the presence/absence of the arachnid Holconia murrayensis represented a significant variable in explaining lizard occurrence patterns, particularly that of C. marmoratus. Artificial bark covers are a useful survey method for collecting distribution, abundance, and occupancy data on floodplain reptiles, although detection rates can be affected by the month, predator–prey interactions, and survey effort. Adopting passive, non-destructive reptile survey methods would greatly improve our knowledge of species’ distributions and abundance patterns in vegetation communities subject to disturbance events.

Comparative survey techniques for a cryptic Australian snake (Hoplocephalus bitorquatus)

Ecologists endeavour to develop survey techniques that are cost-effective for the species they target and robust enough for statistical analysis. Using time as a measure of effort, we compared visual encounter surveys with artificial cover objects (strapped to trees), targeting an arboreal elapid, the pale-headed snake (Hoplocephalus bitorquatus) and its potential prey (geckos). Within a red gum forest vegetation community with relatively high snake density, capture rates were 0.6 ± 0.1 (s.e.) snakes/person-hour using visual encounter surveys, compared with only 0.1 ± 0.1 snakes/person-hour using cover objects. The probability of detection of pale-headed snakes was estimated from occupancy modelling at 0.70 ± 0.06 in visual encounter surveys and 0.19 ± 0.09 in cover object surveys. Gecko capture rates (among all vegetation communities) were significantly greater (P < 0.001) using cover objects. The probability of detection of geckos was estimated from occupancy modelling at 0.77 ± 0.05 in visual encounter surveys and 0.97 ± 0.02 in cover object surveys. Geckos favoured (P < 0.001) cover objects facing south during all seasons except winter. Artificial cover objects may provide some value in detecting pale-headed snakes in vegetation communities where habitat resources are limited; however, where resources are plentiful, visual encounter surveys are likely to remain the most cost-effective survey option.