Monitoring the population status of a secretive lizard,the threatened heath skink Liopholis multiscutata,in south-eastern Australia using surrogate metrics: An update

Our recent study compared monitoring data collected using surrogate metrics during 2014–2018 inclusive with baseline data from 2007 to evaluate the trajectory of the population status of the threatened heath skink Liopholis multiscutata in Victoria. The heath skink is a secretive burrowing species that is a habitat specialist and exists in north-western Victoria as a few small and highly disjunct populations on large dunes in semi-arid heathland or mallee. We re-assessed the trajectories of the Victorian populations with additional monitoring data collected in 2021 and found continuing decline across all four Victorian heath skink populations. Urgent management intervention is required to arrest this decline, likely due to predation, reduced availability of habitat and life history and demographic traits that make this species susceptible to decline.     

Six‐year demographic study reveals threat of stochastic extinction for remnant populations of a threatened amphibian

Sustained demographic studies are essential for early detection of species decline in time for effective management response. A paucity of such background data hindered the potential for successful conservation during the global amphibian decline and remains problematic today. The current study analysed 6 years of mark‐recapture data to determine the vital demographic rates in three habitat precincts of the threatened frog, Litoria aurea (Hylidae) and to understand the underlying causes of variability in population size. Variability in population size of L. aurea was similar to many pond‐breeding species; however this level of fluctuation is rare among threatened amphibians. Highly variable populations are at greater risk of local extinction and the low level of connectivity between L. aurea populations means they are at a greater risk of further decline due to stochastic extinction events and incapacity to recolonize distant habitat. We recommend that management of this species should encourage recolonization through creation of habitat corridors and reintroduction of L. aurea to areas where stochastic extinction events are suspected.     

All the eggs in one basket: Are island refuges securing an endangered passerine?

Refuges for threatened species are important to prevent species extinction. They provide protection from a range of environmental and biotic stressors, and ideally provide protection against all threatening processes. However, for some species it may not be clear why some areas are refuges and others are not. The forty‐spotted pardalote (Pardalotus quadragintus) is an endangered, sedentary, cryptic and specialised bird endemic to the island of Tasmania, Australia. Having undergone an extreme range contraction over the past century the species is now mostly confined to a few small offshore island refuges. Key threatening processes to the species include habitat loss, wildfire, competition and predation. The ways in which these processes have molded the species’ contemporary range have not been clearly evaluated. Furthermore, the security of the remnant population within refuges is uncertain. To overcome this uncertainty we assessed key threats and established the population status in known refuges by developing a robust survey protocol within an occupancy modelling framework. We discuss our results in the context of planning trial reintroductions of this endangered species in suitable habitat across its former range. We found very high occupancy rates (0.75–0.96) at two refuges and in suitable conditions, the species was highly detectable (p, 0.43–0.77). At a third location our surveys indicated a local extinction, likely due to recent wildfire. We demonstrate that all refuges are at high risk of one or more threatening processes and the current distribution across island refuges is unlikely to secure the species from extinction. We identified large areas of potential habitat across the species’ former mainland range, but these are likely too distant from source populations for natural recolonisation. We propose that establishing new populations of forty‐spotted pardalotes via reintroduction is essential to secure the species and that this is best achieved while robust source populations still exist.     

Artificial refuges for wildlife conservation: what is the state of the science?

Artificial refuges are human-made structures that aim to create safe places for animals to breed, hibernate, or take shelter in lieu of natural refuges. Artificial refuges are used across the globe to mitigate the impacts of a variety of threats on wildlife, such as habitat loss and degradation. However, there is little understanding of the science underpinning artificial refuges, and what comprises best practice for artificial refuge design and implementation for wildlife conservation. We address this gap by undertaking a systematic review of the current state of artificial refuge research for the conservation of wildlife. We identified 224 studies of artificial refuges being implemented in the field to conserve wildlife species. The current literature on artificial refuges is dominated by studies of arboreal species, primarily birds and bats. Threatening processes addressed by artificial refuges were biological resource use (26%), invasive or problematic species (20%), and agriculture (15%), yet few studies examined artificial refuges specifically for threatened (Vulnerable, Endangered, or Critically Endangered) species (7%). Studies often reported the characteristics of artificial refuges (i.e. refuge size, construction materials; 87%) and surrounding vegetation (35%), but fewer studies measured the thermal properties of artificial refuges (18%), predator activity (17%), or food availability (3%). Almost all studies measured occupancy of the artificial refuges by target species (98%), and over half measured breeding activity (54%), whereas fewer included more detailed measures of fitness, such as breeding productivity (34%) or animal body condition (4%). Evaluating the benefits and impacts of artificial refuges requires sound experimental design, but only 39% of studies compared artificial refuges to experimental controls, and only 10% of studies used a before-after-control-impact (BACI) design. As a consequence, few studies of artificial refuges can determine their overall effect on individuals or populations. We outline a series of key steps in the design, implementation, and monitoring of artificial refuges that are required to avoid perverse outcomes and maximise the chances of achieving conservation objectives. This review highlights a clear need for increased rigour in studies of artificial refuges if they are to play an important role in wildlife conservation.     

Short-Term Dispersal Response of an Endangered Australian Lizard Varies with Time of Year

Dispersal is an important component in the demography of animal populations. Many animals show seasonal changes in their tendency to disperse, reflecting changes in resource availability, mating opportunities, or in population age structure at the time when new offspring enter the population. Understanding when and why dispersal occurs can be important for the management of endangered species. The pygmy bluetongue lizard is an endangered Australian species that occupies and defends single burrow refuges for extended periods of time, rarely moving far from the burrow entrance. However, previous pitfall trapping data have suggested movement of adult males in spring and of juveniles in autumn of each year. In the current study we compared behaviours of adult lizards each month, over the spring-summer activity period over two consecutive field seasons, to provide deeper understanding of the seasonal dispersal pattern. We released adult pygmy bluetongue lizards into a central area, provided with artificial burrows, within large enclosures, and monitored the behaviour and movements of the released lizards over a four day period. There was a consistent decline in time spent basking, amount of movement around burrow entrances, and rates of dispersal from the central release area from early spring to late summer. Results could be relevant to understanding and managing natural populations and for any translocation attempts of this endangered lizard species.     

Is habitat management an effective tool for wild rabbit (<Emphasis Type="Italic">Oryctolagus cuniculus</Emphasis>) population reinforcement?

Wild rabbit scarcity in Spain is a serious problem due to its economic and ecological value; thus, management techniques to reinforce their populations are being implemented. Translocations are traditionally applied but high short-term mortality by predation makes them unsuccessful and increases their biological cost. An alternative to translocation would be to strengthen local reduced populations through habitat management (building artificial warrens and increasing food availability). Here, we test this method to determine its efficiency as an exportable protocol to recover wild rabbit populations. We compare two areas with and without artificial warrens and increased food availability and assess relative rabbit abundance by means of pellet counts. Results show that, during the 2 years following habitat management, rabbit numbers increased in the experimental plot in contrast to the not managed one, suggesting its effectiveness to reinforce low-density rabbit populations.     

New Zealand endemic open-habitat specialist,the Black-fronted Tern (Chlidonias albostriatus), experienced population expansion during Pleistocene glaciation and recent decline

Understanding how climatic and environmental changes, as well as human activities, induce changes in the distribution and population size of avian species refines our ability to predict future impacts on threatened species. Using multilocus genetic data, we show that the population of a threatened New Zealand endemic open-habitat specialist, the Black-fronted Tern Chlidonias albostriatus – in contrast to forest specialists – expanded during the last glacial period. The population has decreased subsequently despite the availability of extensive open habitat after human arrival to New Zealand. We conclude that population changes for open habitat specialists such as Black-fronted Terns in pre-human New Zealand were habitat-dependent, similar to Northern Hemisphere cold-adapted species, whereas post-human settlement populations were constrained by predators independent of habitat availability, similar to other island endemic species.     

Energy crops as a new bird habitat: utilization of oilseed rape fields by the rare Bluethroat (Luscinia svecica)

As part of the expanding cultivation of renewable primary products, oilseed rape has become a prominent part of the agricultural landscape of many European countries. However, the ecological impacts of increasing cultivation of oilseed rape have received little attention so far. In this study, we provide the first systematic investigation of the suitability of oilseed rape as a habitat for the Bluethroat (Luscinia svecica cyanecula), an endangered and highly specialized bird species. We conducted territorial mapping and a habitat analysis, revealing the distinct habitat requirements of L. s. cyanecula in oilseed rape fields over three breeding seasons. The soil type was identified as the crucial factor for habitat occupancy. It acts as a surrogate for soil moisture and this in turn decisively influences food availability. Ditches can further improve habitat quality, whereas reed is not a necessary structure, although it is a regular feature in the primary habitat of the Bluethroat. Occupied oilseed rape stands were structurally different from the semi-natural reed habitat, but provided similar essential habitat requirements, such as shelter from predation and moist, bare soil. Our results clearly demonstrate the utilization of oilseed rape by a rare and threatened wetland bird species and suggest that this crop may act as a secondary habitat.     

A PCR test for avian malaria in Hawaiian birds

The decline of native Hawaiian forest birds since European contact is attributed to factors ranging from habitat destruction to interactions with introduced species. Remaining populations of Hawaiian honeycreepers (Fringillidae: Drepanidinae) are most abundant and diverse in high elevation refuges above the normal range of disease-carrying mosquitoes. Challenge experiments suggest that honeycreepers are highly susceptible to avian malaria (Plasmodium sp.) but resistance exists in some species. In order to detect low levels of malarial infection and quantify prevalence of Plasmodium in high elevation natural populations of Hawaiian birds, a polymerase chain reaction (PCR) based diagnostic test was developed that identifies rRNA genes of Plasmodium in avian blood samples. Quantitative competitive PCR (QC-PCR) experiments indicate that the detection limit of our test is an order of magnitude greater than that reported for human malaria DNA blot tests. Compared with standard histological methods, the PCR test detected a higher prevalence of diseased birds at mid-elevations. Malaria was detected in three species of native birds living in a high elevation wildlife refuge on the island of Hawaii and in four species from Maui. Our results show that avian malaria is more widespread in Hawaiian forests than previously thought, a finding that has important conservation implications for these threatened species.     

Elevation and habitats: the potential of sites at different altitudes to provide refuges for phytophagous insects during climatic fluctuations

Uplands are expected to provide refuges for species subject to lowland habitat loss and projected climate changes. Here, we argue that upland populations also provide refuges when lowland sites are subject to climatic fluctuations and extreme events and that species with populations dispersed over adjoining uplands and lowlands spread their risk of extinction. A proviso is that development is sufficiently lagged with altitude but that development rates are compatible. Emergence patterns and development of the butterfly Anthocharis cardamines and its larval host plant Cardamine pratensis show these characteristics, and coupled with the butterfly’s capacity to migrate between isolated populations present a case where upland and lowland populations can act as sources when one or the other area is adversely affected by extreme events.     

European rabbits as ecosystem engineers: warrens increase lizard density and diversity

Mammals that build extensive open burrow systems are often classified as ecosystem engineers, since they have the potential to modulate the availability of resources for themselves and other organisms. Lizards may benefit from the heterogeneity created by these structures, especially if coupled with an increased offer of sites for refuge and thermoregulation. However, information about these engineering effects by burrowing animals is scarce. We investigated the influence of European rabbit burrows on several parameters of a Mediterranean lizard community (abundance, density, diversity and body condition) in three different habitats (open pastures, holm oak and scrub patches). We found that lizards were positively associated with burrows, and that burrows determined lizard presence at otherwise unfavourable habitats. Moreover, community parameters such as density and species richness were higher in sites with burrows. Burrows influenced lizard species in different ways, and were also relevant for other Mediterranean vertebrates, as revealed by questionnaires to experts. We also explored the possible resources provided by burrows for lizards. Warrens offer relatively abundant prey and appropriate retreat sites for refuge and thermoregulation. Warrens may have further implications within the ecosystem, acting as stepping stones, allowing lizards to reach otherwise inaccessible habitat patches. This study shows that European rabbit warrens have a positive influence on lizard density and diversity, and confirms the role of rabbits as ecosystem engineers. This reinforces the need for appropriate conservation measures for rabbits, especially given their threatened status in the Iberian Peninsula. Furthermore, our study highlights that taking into account the influence of engineering activities increases our awareness of species interactions, and may translate into more adequate conservation measures for the preservation of biodiversity.     

Selection of food patches by sympatric herbivores in response to concealment and distance from a refuge

Small herbivores face risks of predation while foraging and are often forced to trade off food quality for safety. Life history, behaviour, and habitat of predator and prey can influence these trade‐offs. We compared how two sympatric rabbits (pygmy rabbit, Brachylagus idahoensis; mountain cottontail, Sylvilagus nuttallii) that differ in size, use of burrows, and habitat specialization in the sagebrush‐steppe of western North America respond to amount and orientation of concealment cover and proximity to burrow refuges when selecting food patches. We predicted that both rabbit species would prefer food patches that offered greater concealment and food patches that were closer to burrow refuges. However, because pygmy rabbits are small, obligate burrowers that are restricted to sagebrush habitats, we predicted that they would show stronger preferences for greater cover, orientation of concealment, and patches closer to burrow refuges. We offered two food patches to individuals of each species during three experiments that either varied in the amount of concealment cover, orientation of concealment cover, or distance from a burrow refuge. Both species preferred food patches that offered greater concealment, but pygmy rabbits generally preferred terrestrial and mountain cottontails preferred aerial concealment. Only pygmy rabbits preferred food patches closer to their burrow refuge. Different responses to concealment and proximity to burrow refuges by the two species likely reflect differences in perceived predation risks. Because terrestrial predators are able to dig for prey in burrows, animals like pygmy rabbits that rely on burrow refuges might select food patches based more on terrestrial concealment. In contrast, larger habitat generalists that do not rely on burrow refuges, like mountain cottontails, might trade off terrestrial concealment for visibility to detect approaching terrestrial predators. This study suggests that body size and evolutionary adaptations for using habitat, even in closely related species, might influence anti‐predator behaviors in prey species.     

Microhabitat selection in the common lizard: implications of biotic interactions,age, sex,local processes,and model transferability among populations

Modeling species' habitat requirements are crucial to assess impacts of global change, for conservation efforts and to test mechanisms driving species presence. While the influence of abiotic factors has been widely examined, the importance of biotic factors and biotic interactions, and the potential implications of local processes are not well understood. Testing their importance requires additional knowledge and analyses at local habitat scale. Here, we recorded the locations of species presence at the microhabitat scale and measured abiotic and biotic parameters in three different common lizard (Zootoca vivipara) populations using a standardized sampling protocol. Thereafter, space use models and cross‐evaluations among populations were run to infer local processes and estimate the importance of biotic parameters, biotic interactions, sex, and age. Biotic parameters explained more variation than abiotic parameters, and intraspecific interactions significantly predicted the spatial distribution. Significant differences among populations in the relationship between abiotic parameters and lizard distribution, and the greater model transferability within populations than between populations are in line with effects predicted by local adaptation and/or phenotypic plasticity. These results underline the importance of including biotic parameters and biotic interactions in space use models at the population level. There were significant differences in space use between sexes, and between adults and yearlings, the latter showing no association with the measured parameters. Consequently, predictive habitat models at the population level taking into account different sexes and age classes are required to understand a specie's ecological requirements and to allow for precise conservation strategies. Our study therefore stresses that future predictive habitat models at the population level and their transferability should take these parameters into account.     

The effects of agriculture and the availability of edge habitat on populations of Helmeted Guineafowl Numida meleagris and on the diversity and composition of associated bird assemblages in KwaZulu-Natal province, South Africa

We investigated the effects of agriculture and the availability of edge habitat on populations of Helmeted Guineafowl Numida meleagris and associated avian diversity and species composition in woodland and grassland biomes in the Midlands of KwaZulu-Natal province, South Africa. Study sites within woodland biome had greater species diversity than those in grassland, whereas adjacent, high-quality, protected habitat in grassland sites, enhanced diversity within this biome. Both guineafowl populations and overall avian diversity declined with increasingly intensive agriculture and disappearance of edge habitat and associated, optimally fragmented habitat mosaic. Furthermore, traditional agriculture in the form of contouring in a pesticide-free environment, resulted in extensive edge habitat that appeared to provide additional food and cover for birds. This, in turn, caused an increase in overall bird diversity, and in guineafowl populations in particular. The widespread decline in Helmeted Guineafowl populations in the Midlands that started in the 1980s, and possibly the decline in species associated with this variegated landscape, was therefore caused by the loss of the habitat mosaic to intensive, modern, monoculture, crop agriculture. Maintaining species diversity and healthy guineafowl populations within these habitats requires the persistence or re-creation of a habitat mosaic and the resulting edge habitat on a landscape scale.     

Comparative use of active searches and artificial refuges to detect amphibians in terrestrial environments

Artificial refuges (cover boards) are commonly used to survey and monitor herpetofauna in many parts of the world. Despite the extensive use of artificial refuges in mesic environments, their effectiveness for detecting amphibians in temperate zones has rarely been examined. We compared amphibian detection probabilities between two survey methods; active searches of natural habitat and artificial refuges of three different types (corrugated steel, roofing tiles and timber railway sleepers). Our study area included five bioregions encompassing a 1180‐km latitudinal gradient across a modified, temperate eucalypt woodland vegetation community in south‐eastern Australia. We deployed 14 778 artificial refuges in terrestrial environments, within patches of remnant vegetation, and collected presence and abundance data on herpetofauna between 1999 and 2017. We used Bayesian logistic regression to identify the most effective survey method for detecting frog species across all bioregions. We modelled frog detections by fitting survey method, time since refuge deployment and rainfall prior to each survey. We detected 3970 individuals from 18 frog species. Overall, we found active searches and timber substrates most effective for detecting a broad range of species, although detection rates were driven by the numerically abundant spotted marsh frog Limnodynastes tasmaniensis. Timber refuges were effective for detecting several burrowing species, whereas active searches were effective at detecting habitat generalists. Quadratic effects of rainfall prior to survey as opposed to linear effects of time since artificial refuge placement was important in explaining frog detection rates in some bioregions. Active searches, timber railway sleepers and sheets of corrugated steel provide complimentary survey methods for detecting amphibians, although detection rates are influenced by rainfall patterns. Artificial refuges provide a time‐effective and standardized method for studying amphibians in their non‐breeding terrestrial environment and should be incorporated into future surveys and biodiversity monitoring programmes.     

Recovering the Reptile Community after the Mine-Tailing Accident of Aznalcóllar (Southwestern Spain)

Ecosystem restoration requires that habitat requirements of all species be considered. Among animal communities in Mediterranean ecosystems, reptiles, as ectothermic vertebrates, need refuges for avoidance of extreme environmental temperatures, concealment from predators, and oviposition sites. In 1998, a massive amount of tailings broke out of the holding pond of the Aznalcóllar mine (southwestern Spain) and polluted the Guadiamar river valley. After the accident, a soil- and vegetation restoration program began, and the Guadiamar Green Corridor was created to connect two huge natural areas, Doñana National Park and the Sierra Morena. Within this corridor, the reptile community remained dramatically impoverished, probably because of elimination of all natural refuges during the soil restoration program. To test this hypothesis, we set an array of artificial refuges (logs) in a large experimental plot. During the 5 years of the experiment (2002–2006), the area managed with artificial refuges exhibited a better and faster recovery of the reptile community in species richness and individual abundance than did the control area with no artificial refuges. Moreover, reptile colonization of the Guadiamar Green Corridor was transverse rather than lineal—that is, it did not act as a corridor for reptiles, at least in the first stages of colonization. This suggests that landscape restoration programs should not neglect refuge availability, a limiting resource for reptile species.     

Assessing the importance of artificial nest‐sites in the population dynamics of endangered Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas using stochastic simulation models

Habitat availability might be the most important determinant of success for a species reintroduction programme, making investigation of the quality and quantity of habitat needed to produce self‐sustaining populations a research priority for reintroduction ecologists. We used a stochastic model of population dynamics to predict whether attempts to improve existing breeding territories using artificial nest platforms improved the population growth rate and persistence of a reintroduced population of Northern Aplomado Falcons Falco femoralis septentrionalis in South Texas. We further assessed whether the creation of new territories, i.e. conversion of entire areas to suitable habitat and not simply the erection of nest platforms, would lead to a subsequent increase in the nesting population. Our model was able to reproduce several characteristics of the wild population and predicted the number of breeding pairs per year strikingly well (R² = 0.97). Simulations revealed that the addition of nest platforms improved productivity such that the population would decline to extinction without them but is stable since their installation. Moreover, the model predicted that the increase in productivity due to nest platforms would cause the population to saturate available breeding territories, at which point the population would contain a moderate proportion of non‐territorial birds that could occupy territories if new ones become available. Population size would therefore be proportional to the increase in available territories. Our study demonstrates that artificial nest‐sites can be an effective tool for the management of reintroduced species.     

Conservation Assessment of Guaiacum sanctum and Guaiacum coulteri: Historic Distribution and Future Trends in Mexico

Guaiacum sanctum and Guaiacum coulteri are long‐lived Mesoamerican timber tree species heavily exploited throughout their range and considered to be at risk of extinction. Both species are included on the IUCN Red List and on CITES Appendix II, but there has been no formal assessment of the conservation status of either species. We used ecological niche modeling and rapid assessments of local density and population size structure to provide such evaluations. For the year 2000, we estimated geographic range sizes for G. sanctum and G. coulteri of 95,422 and 130,973 km², respectively. The main core remaining habitat for G. sanctum occurs in Campeche State (Yucatan Peninsula), where populations exhibit high adult abundance and profuse regeneration. Several areas along the Mexican Pacific coast remain with suitable habitat for G. coulteri. Guaiacum coulteri is at greater risk as only 1.3 percent of its current habitat is protected, which contrasts with the 13.2 percent of current habitat protected for G. sanctum. We projected that available habitat for G. sanctum and G. coulteri will decline by a further 30–50 percent by 2020 if estimated habitat loss rates continue. We suggest that under the IUCN criteria, the conservation status of G. sanctum and G. coulteri should be updated to near threatened and vulnerable, respectively. Additionally, we conclude that the amount of protected habitat needs to be increased to safeguard both species. Our study provides a quantitative basis for updating the conservation status of both species and illustrates an assessment framework that could be applied to other threatened tree species.     

Grain sowing aimed at wild rabbit Oryctolagus cuniculus L. enhancement in Mediterranean environments

Although habitat management practices focussed on the enhancement of hunting and protection of threatened species are common, the scientific validation of such practices is scarce. The wild European rabbit Oryctolagus cuniculus L., a hunted and threatened species in its native range, is at the same time a key species for the preservation of threatened Mediterranean predators. Cereal sowing is one of the most common practices to augment the food supply of rabbits, and it is used not only by hunters but also by conservationists. At present, limited scientific information is available regarding the effectiveness of cereal sowing. To evaluate its effectiveness, we analysed data on sowing trials conducted in 125 plots, located in 14 private estates throughout central Spain, most of them with low density populations. Brush was cleared from 44 of these plots prior to sowing. Our results indicated that rabbits preferentially selected sown areas over control (unsown) areas. This selection increased in plots that represented suitable habitats for rabbits, such as pasturelands, as well as when thicket islands and natural or artificial shelters were available within the sown plots. Local enhancement of rabbit populations was also observed. These positive results were also obtained regardless of the initial habitat conditions, not only in the treatment plots but also in the surrounding area. Our recommendations can be broadly applied for managing rabbit-dependent threatened species.     

Mitochondrial DNA and microsatellite loci data supporting a management plan for a critically endangered lizard from Brazil

Endemic and endangered species are highly vulnerable to habitat perturbations and may be subject to variations in their population size. Management plan for these species is crucial to avoid population decline, loss of genetic variability, inbreeding and ultimately extinction. The sand lizard, Liolaemus lutzae, is endemic to a habitat of sandy coastal plain (restinga). Its geographical distribution extends for only 200 km stretch of the coast of Rio de Janeiro state, Brazil, one of South America’s most densely populated regions. Extensive development and degradation of the beaches where the species inhabits, have led to the species becoming critically endangered. We used mitochondrial DNA sequences and microsatellite loci to resolve patterns of population connectivity and genetic variation within the species in order to provide a platform for a species management plan. Our results indicate the existence of three main populations, separated from each other by the Guanabara Bay and by the Arraial do Cabo Peninsula. The low microsatellite genetic variation and heterozygosity witnessed in each of the three populations, together with high levels of inbreeding and low effective population sizes suggest that the species is in urgent need of intensive management. Based on the results of this study we propose strong measures to protect existing restinga fragments and the implementation of programmes of captive breeding and reintroduction of individuals from the heavily threatened regions to protected refugia. Such measures may be the only way of ensuring the continuity of the species.