Ectothermic vertebrates face many challenges of thermoregulation. Many species rely on behavioral thermoregulation and move within their landscape to maintain homeostasis. Understanding the fine-scale nature of this regulation through tracking techniques can provide a better understanding of the relationships between such species and their dynamic environments. The use of animal tracking and telemetry technology has allowed the extensive collection of such data which has enabled us to better understand the ways animals move within their landscape. However, such technologies do not come without certain costs: they are generally invasive, relatively expensive, can be too heavy for small sized animals and unreliable in certain habitats. This study provides a cost-effective and non-invasive method through photo-identification, to determine fine scale movements of individuals. With our methodology, we have been able to find that male eastern water dragons (Intellagama leuseurii) have home ranges one and a half times larger than those of females. Furthermore, we found intraspecific differences in the size of home ranges depending on the time of the day. Lastly, we found that location mostly influenced females’ home ranges, but not males and discuss why this may be so. Overall, we provide valuable information regarding the ecology of the eastern water dragon, but most importantly demonstrate that non-invasive photo-identification can be successfully applied to the study of reptiles.

Translocation of individuals is a widely used tool in the conservation of threatened species. The movement behaviours of translocated individuals in their new environment are a key factor that can influence translocation success (i.e. survival and reproduction). In this study, eel-tailed catfish (Tandanus tandanus) and Murray cod (Maccullochella peelii) movements were monitored using fine-scale acoustic telemetry over a 5-month period in two lowland rivers in eastern Australia. Fine-scale movement and habitat selection were compared among translocated lacustrine and resident riverine T. tandanus and between species. We found no difference in finescale movement behaviours between translocated and resident T. tandanus; however, there was some variation in movement response to environmental variation between species. In contrast, habitat selection varied not only between the two species, but also between resident and translocated T. tandanus individuals. Notably, activity was significantly lower in the first day after release compared to the remainder of the study period. Although T. tandanus translocated from a reservoir had never experienced the environmental fluctuations of a riverine system, individuals still responded in the same way as resident riverine fish, suggesting an innate behavioural response. However, this was not the case for habitat selection, where translocated individuals preferred habitats more common in their source population's lacustrine environment. The findings of this study are important in guiding future conservation efforts involving the translocation of wild-caught fish, primarily the importance of the suitable habitat at the release site to ensure the success and persistence of translocated populations.

Despite providing considerable benefits to society, dams and weirs threaten riverine ecosystems by disrupting movement and migration of aquatic animals and degrading riverine habitats. Whilst the ecological impacts of large dams are well studied, the ecological effects of low-head weirs that are periodically drowned out by high flows are less well-understood. Here we examine the effects of a lowhead weir on fine-and broad-scale movements, habitat use, and breeding behaviour of three species of native freshwater fish in the Nymboida River in coastal eastern Australia. Acoustic telemetry revealed that eastern freshwater cod (Maccullochella ikei) and eel-tailed catfish (Tandanus tandanus) made few large-scale movements, but Australian bass (Percalates novemaculeata) upstream of the weir were significantly more mobile than those below the weir. Within the weir pool, all three species displayed distinctive patterns in fine-scale movement behaviour that were likely related the deeper lentic environment created by the weir. No individuals of any species crossed the weir during the study period. Tandanus tandanus nesting behaviour varied greatly above and below the weir, where individuals in the more lentic upstream environment nested in potentially sub-optimal habitats. Our results demonstrate the potential effects of low-head weirs on movement and behaviour of freshwater fishes. open Scientific RepoRtS | (2020) 10:6817 | https://doi.org/10.1038/s41598-020-63005-8www.nature.com/scientificreports www.nature.com/scientificreports/ local habitat use and movement patterns. Similarly, little is also known of how a barrier may obstruct, or how a reservoir may affect routine fish movements at a local-scale. These studies have only investigated position of fish in relation to the barrier and distance of movements 24 , excluding metrics of movement such as orientation or rate of movement (ROM). Considering these aspects of movement may offer insights on how barriers affect fundamental components of fish life histories, such as foraging behaviours or energetic expenditure. The physical barrier of dams to reproductive migrations is well established 25 , however the ecological effect of instream barriers on reproduction has seldom been considered 26 . The reservoir created by a barrier may alter or delay abiotic cues, such as water temperature or river discharge, to reproductive behaviours in fish, and may also alter suitable nesting habitat for some species.This study focuses on the movement behaviour of three species of freshwater fish: eastern freshwater cod (Maccullochella ikei), freshwater catfish (Tandanus tandanus), and Australian bass (Percalates novemaculeata). All three species are endemic to eastern Australia, with M. ikei and P. novemaculeata only occurring in coastal rivers, while the range of T. tandanus extends inland to include the Murray-Darling Basin. Maccullochella ikei is a nationally listed threatened species 27 and has undergone a dramatic decline in population size since European settlement, due in part to ha...

Summary Assessing the causal factors underpinning the distribution and abundance of wildlife road‐induced mortality can be challenging. This is particularly ubiquitous for rare or elusive species, because traffic strikes occur infrequently for these populations and information about localized abundance, distribution and movements are generally lacking. Here, we assessed whether citizen‐collected sightings data may serve as a low cost and efficient means of gathering long‐term animal roadside presence and road‐crossing information, which could then be used to assess the causative factors and direct mitigation actions aimed at reducing wildlife traffic strike frequency. We explored this principle using two decades of traffic strike records and citizen‐collected sightings of the southern cassowary Casuarius casuarius johnsonii. Roads have bisected the cassowaries’ rain forest habitat and despite considerable investment into mitigation strategies for this species, road‐induced mortality is considered one of the primary threatening processes affecting the population. Using a Bayesian approach and controlling for spatial autocorrelation with conditional autoregressive models, we demonstrate that traffic strikes are primarily a density‐dependent process in the southern cassowary. That is, traffic strike clusters occurred along stretches of road where cassowaries were most frequently sighted. There were, however, road stretches where traffic strike frequency was greater than predicted by the number of roadside sightings, illustrating when and where density‐independent processes increased the mortality potential for a road‐crossing cassowary. Synthesis and applications. This is the first time that citizen‐collected sightings data have been used to systematically inform upon the abundance and distribution of wildlife traffic strike. The technique not only predicts where incidents are likely to occur but also helps us to understand the factors responsible for strike clustering. While not a replacement for systematic surveys, we highlight citizen‐collected sightings data as a low‐cost option when assessing contributing factors to vehicle‐induced mortality. Accounting for density‐dependent and density‐independent processes will ensure the most effective allocation of resources when implementing wildlife traffic strike mitigation.

No abstract