Mammal populations are declining in biodiverse tropical regions. Global analyses have identified Indonesia as a hotspot of vertebrate decline, although relatively few data are available to substantiate these claims. We reviewed research articles published during 2000–2020 on 104 medium-sized to large terrestrial mammal species found in Indonesia to help inform conservation management and future research. We identified 308 peer-reviewed studies published in English or Bahasa Indonesia, with an increase in publication rate (articles published per year) over time. Studies of species distributions dominated the literature, followed by publications on abundance, species diversity and combinations of these topics. Most publications concerned single-species studies conducted at a single location and a single point in time. We identify four key issues that should be addressed by future research and conservation efforts: (1) disproportionate focus on a small number of species; (2) geographical bias towards west Indonesia (Sumatra, Kalimantan and Java–Bali), with few published studies from central (Sulawesi, Nusa Tenggara and Maluku) and east (Papua) Indonesia; (3) limitations to survey design, sampling effort and data analysis; and (4) lack of long-term wildlife population studies. We also note challenges local researchers face in publishing their studies in international journals because of language barriers and costs. Greater use of existing biodiversity data and continued capacity building for local researchers, particularly those in central and east Indonesia, are critical to effectively guide future wildlife monitoring and improve the conservation status of Indonesian mammals.

The Mediterranean flora is characterized by a high number of narrow endemic plant species that are often restricted to a few small populations. One of these species, Valeriana amazonum, a perennial plant occurring only in the Supramontes region of central eastern Sardinia, is categorized as Critically Endangered on the IUCN Red List because of its restricted range, small population size and an inferred decline caused by several threats. During 2007–2022, we monitored all mature individuals of this plant annually and surveyed ecologically suitable sites for the species. We identified two previously unknown populations and also learnt of two successful translocations carried out independently by an unknown local citizen. As our monitoring data indicate there has been no decline in the number of mature individuals over the period of monitoring, the species’ conservation status requires reassessment. We recommend that V. amazonum should be recategorized as Near Threatened as it seems to be poorly known rather than highly threatened. This could also be the case with other narrow Mediterranean endemics, especially those that grow in inaccessible habitats for which long-term studies are needed to assess conservation status.

Conservation monitoring is paramount for the gathering of information on species and populations in need of conservation actions. However, monitoring of the mountain bongo Tragelaphus eurycerus isaaci, a Critically Endangered antelope endemic to Kenya, has hitherto been limited to surveillance (i.e. focused on persistence of the species in particular areas), thus limiting the information that could be retrieved on the status and trends of these populations. Using a newly developed identification system, we implemented robust design mark–recapture using existing camera-trap records of four wild subpopulations of the bongo. We provide data on sex and age structure and the first estimates of population size in the wild. Males and calves seem to be suffering higher mortality than females, and only two of the four monitored populations include adults of both sexes and calves. The combined size of these two breeding populations is estimated to be 29–50. Our findings confirm the critical situation of the mountain bongo in the wild and highlight the need for conservation actions to reinforce the wild populations for the long-term conservation of this antelope.

Monitoring of cryptic or threatened species poses challenges for population assessment and conservation, as imperfect detection gives rise to misleading inferences about population status. We used a dynamic occupancy model that explicitly accounted for occupancy, colonization, local extinction and detectability to assess the status of the endemic Critically Endangered Bermuda skink Plestiodon longirostris. During 2015–2017, skinks were detected at 13 of 40 surveyed sites in Bermuda, two of which were new records. Ten observation-level and site-specific covariates were used to explore drivers of occupancy, colonization, extinction and detectability. Sites occupied by skinks tended to be islands with rocky coastal habitat and prickly pear cacti; the same variables were also associated with reduced risk of local extinction. The presence of seabirds appeared to encourage colonization, whereas the presence of cats had the opposite effect. The probability of detection was p = 0.45, and on average, five surveys were needed to reliably detect the presence of skinks with 95% certainty. However, skinks were unlikely to be detected on sites with cat and rat predators. Dynamic occupancy models can be used to elucidate drivers of occupancy dynamics, which in turn can inform species conservation management. The survey effort needed to determine population changes over time can be derived from estimates of detectability.

Reliably estimating population parameters for highly secretive or rare animals is challenging. We report on the status of the two largest remaining populations of the Critically Endangered Bermuda skink Plestiodon longirostris, using a robust design capture–mark–recapture analysis. Skinks were tagged with passive integrated transponders on two islands and captured on 15 sampling occasions per year over 3 years. The models provided precise estimates of abundance, capture and survival probabilities and temporary emigration. We estimated skink abundance to be 547 ± SE 63.5 on Southampton Island and 277 ± SE 28.4 on Castle Island. The populations do not appear to be stable and fluctuated at both sites over the 3-year period. Although the populations on these two islands appear viable, the Bermuda skink faces population fluctuations and remains threatened by increasing anthropogenic activities, invasive species and habitat loss. We recommend these two populations for continued monitoring and conservation efforts.

The illegal wildlife trade is driving declines in populations of a number of large, charismatic animal species but also many lesser known and restricted-range species, some of which are now facing extinction as a result. The ploughshare tortoise Astrochelys yniphora, endemic to the Baly Bay National Park of north-western Madagascar, is affected by poaching for the international illegal pet trade. To quantify this, we estimated population trends during 2006–2015, using distance sampling surveys along line transects, and recorded national and international confiscations of trafficked tortoises for 2002–2016. The results suggest the ploughshare tortoise population declined > 50% during this period, to c. 500 adults and subadults in 2014–2015. Prior to 2006 very few tortoises were seized either in Madagascar or internationally but confiscations increased sharply from 2010. Since 2015 poaching has intensified, with field reports suggesting that two of the four subpopulations are extinct, leaving an unknown but almost certainly perilously low number of adult tortoises in the wild. This study has produced the first reliable population estimate of the ploughshare tortoise and shows that the species has declined rapidly because of poaching for the international pet trade. There is an urgent need for increased action both in Madagascar and along international trade routes if the extinction of the ploughshare tortoise in the wild is to be prevented.

The spoon-billed sandpiper Calidris pygmaea, a migratory Arctic-breeding shorebird, is one of the rarest birds and its population has declined since the 1970s. We surveyed its most important known wintering area in the Upper Gulf of Mottama in Myanmar to estimate recent (2009–2016) changes in its numbers there. The total number of small shorebirds present in the Upper Gulf was counted and the proportion of them that were spoon-billed sandpipers was estimated from sample scans. These two quantities were multiplied together to give the estimated number of spoon-billed sandpipers in each of 4 years. Total numbers of combined small shorebird species tripled from 21,000 to 63,000 between 2009 and 2016, coincident with efforts to reduce hunting pressure on waterbirds. However, the proportion of small shorebirds that were spoon-billed sandpipers declined and their estimated absolute numbers fell by about half, from 244 to 112 individuals. It is probable that loss of intertidal habitat and shorebird hunting elsewhere on the migration route of the spoon-billed sandpipers wintering at Mottama is causing a continued decline, although this is occurring at a less rapid rate than that recorded from Arctic Russia before 2010. The number of spoon-billed sandpipers wintering on the Upper Gulf of Mottama remains the highest single-site total for this species from any known wintering site. Preventing resurgence of illegal shorebird hunting and ensuring long-term protection of the intertidal feeding habitats and roost sites in the Gulf are high priorities if extinction of this species is to be averted.

Information on the distribution and abundance of the forest elephant Loxodonta cyclotis is needed to allocate limited resources appropriately and set conservation goals for the species. However, monitoring at large scales in forest habitats is complicated, expensive and time consuming. We investigated the potential of applying interview-based occupancy analysis as a tool for the rapid assessment of the distribution and relative abundance of forest elephants in eastern Cameroon. Using single-season occupancy models, we explored the covariates that affect forest elephant occupancy and detectability, and identified spatial and temporal patterns in population change and occupancy. Quantitative and qualitative socio-demographic data offer additional depth and understanding, placing the occupancy analysis in context and providing valuable information to guide conservation action. Detectability of forest elephants has decreased since 2008, which is consistent with the decline in perceived abundance in occupied sites. Forest elephants occupy areas outside protected areas and outside the known elephant range defined by IUCN. Critical conservation attention is required to assess forest elephant populations and the threats they face in these poorly understood areas. Interview-based occupancy analysis is a reliable and suitable method for a rapid assessment of forest elephant occupancy on a large scale, as a complement to, or the first stage in, a monitoring process.

In 2015 10 Iberian lynxes Lynx pardinus were released in south-eastern Portugal, within the framework of a Spanish–Portuguese reintroduction project. We examined each individual's use of space and social interactions during the first year after their release. Lynxes were selected for reintroduction according to behavioural, genetic and health criteria and fitted with collars with VHF and global positioning systems. Both males and females went through an exploratory phase that lasted 65–105 days. The lynxes did not exhibit any movement directionality from the release site during the exploratory period. During August–December 2015 a stable nucleus comprising seven individuals (four males, three females) was established south-west of the release enclosure. Although the males had a slightly larger mean home range (11.18 ± SE 1.36 km2) than females (9.87 ± SE 8.71 km2), the difference was not significant. The knowledge obtained during the first year of the lynx reintroduction project in Portugal is critical to support the future of this reintroduction strategy. Our results suggest that once the soft release technique is no longer possible because of logistical constraints on the construction of more enclosures, new individuals should be released in unoccupied areas surrounded by occupied territories. This will promote strong social ties to the resident population and prevent lynx dispersal.

Citizen science monitoring programmes are making increasingly important contributions to wildlife conservation, often at spatial and temporal scales unachievable by individual or teams of researchers. They are particularly valuable in estimating population trends and management impacts, and thus informing effective conservation decisions for declining species. The quality and potential biases of citizen science data are of concern, however, and appropriate experimental design and analysis are needed to ensure that the maximum scientific value is extracted. We investigated these issues in a citizen science survey of the Endangered Carnaby's black-cockatoo Calyptorhynchus latirostris. Since 2010, citizen scientists have conducted synchronized annual counts of Carnaby's black-cockatoo at roost sites to estimate the population trend. Survey effort was substantial, with c. 150 sites surveyed by > 260 volunteers each year. Relatively few sites were occupied, however, and only 42 (16%) of the 265 sites surveyed in total accounted for 95% of all observations. Many sites were empty and survey effort was often inconsistent. Taking these issues into account, analysis showed a statistically significant decline in roost occupancy rate and a non-significant decline in the mean size of roosting flocks, with an estimated overall trend of 14% decline per annum in the number of roosting birds. We highlight three important issues for citizen science monitoring programmes: the need to maintain regular surveys of sample sites to avoid patchy data, use an appropriate model that accounts for variable survey effort, high frequency of zero counts, and sampling site turnover, and incorporate information on site characteristics to help explain variation.

Only two members of the genus Ribes L. (Grossulariaceae) occur in Sardinia, both endemic: R. sardoum and R. multiflorum subsp. sandalioticum. R. sardoum is categorized as Critically Endangered on the IUCN Red List and R. multiflorum subsp. sandalioticum is a rare species previously known from only a few localities. Both species grow only in mountainous areas. In 2006–2010 we carried out a field survey to verify the conservation status of R. sardoum and to estimate the number of individual plants, identify threats and assess the conservation status of R. multiflorum subsp. sandalioticum. R. sardoum is threatened by grazing, its small population, low seed viability and the activities of tourists, confirming its Critically Endangered status. We found R. multiflorum subsp. sandalioticum in 13 localities, three of which are new records, with the plants in scattered groups or singly, in three populations. The threats to R. multiflorum subsp. sandalioticum are overgrazing, the small populations, habitat fragmentation and the activities of tourists. We propose that R. multiflorum subsp. sandalioticum be categorized as Endangered on the IUCN Red List. Research activities and conservation measures for this genus on Sardinia have been proposed and some conservation actions have already commenced.

Integrated pest management strategies for cereal processing facilities often include both pheromone-baited pitfall traps and crack and crevice applications of a residual insecticide such as the pyrethroid cyfluthrin. In replicated pilot-scale warehouses, a 15-week-long experiment was conducted comparing population trends suggested by insect captures in pheromone-baited traps to direct estimates obtained by sampling the food patches in untreated and cyfluthrin-treated warehouses. Warehouses were treated, provisioned with food patches and then infested with all life stages of Tribolium castaneum (Herbst). Food patches, both those initially infested and additional uninfested, were surrounded by cyfluthrin bands to evaluate if insects would cross the bands. Results show that insect captures correlated with population trends determined by direct product samples in the untreated warehouses, but not the cyfluthrin-treated warehouses. However, dead insects recovered from the floor correlated with the insect densities observed with direct samples in the cyfluthrin-treated warehouses. Initially, uninfested food patches were exploited immediately and after six weeks harbored similar infestation densities to the initially infested food patches. These data show that pest management professionals relying on insect captures in pheromone-baited traps in cyfluthrin-treated structures could be deceived into believing that a residual insecticide application was suppressing population growth, when the population was actually increasing at the same rate as an untreated population.

The Endangered Madagascar giant jumping rat, Hypogeomys antimena, has suffered a major decline in distribution and is now restricted to two seemingly unconnected sub-populations in the largest remaining fragment of deciduous, seasonally dry forest in Menabe, western Madagascar. In a previous study a rapid decrease in numbers of H. antimena was observed in relatively intact forest, suggesting a factor of population decline additional to habitat loss, and provoking fears of a negative trend occurring across its remaining range. In the current study we conducted extensive line transect surveys to estimate active H. antimena burrow density in 2004 and 2005 as an index of population size, and trapping to estimate mean group size, as a multiplier for population size estimation. Within the surveyed areas we estimated the combined size of the two H. antimena sub-populations in 2005 to be c. 36,000, considerably larger than previously assumed. There was no evidence that active burrow density across the species’ known range changed between 2000 and 2005. H. antimena was not uniformly distributed, with higher densities of active burrows found in forest with the highest canopy in areas furthest from forest edges. These core forest areas are vital for the species’ conservation and the recent declaration that the Menabe forest will receive statutory protection provides hope that H. antimena may be safeguarded. However, given its restricted range and low reproductive output, among other factors, H. antimena remains threatened and requires close future monitoring.

The Madagascar flat-tailed tortoise Pyxis planicauda is threatened with extinction through loss of its deciduous, dry forest habitat and illegal collection for the pet trade. Little is known of the population status of this species as no systematic survey across its range has previously been conducted. Surveying P. planicauda is problematic as it has cryptic colouration, is only active during the wet season, and spends periods of time hidden under leaf litter. In this study we designed a line transect survey, which incorporated an approximation of the amount of time tortoises were available for sampling, to produce an unbiased estimate of population size. We estimated density of P. planicauda in the main forest block in central Menabe, which represents the majority of its range, to be 0.40 ha-1 with a total population size of nearly 28,000 individuals (95% confidence interval 16,323-47,669). This estimate is substantially higher than previous predictions of <10,000 individuals. Nevertheless, the species faces ongoing threats from deforestation and probably from illegal collection, although the recent designation of the Menabe forest as a protected area will probably help reduce these threats. This study provides a baseline density estimate of P. planicauda and a survey protocol for monitoring future population trends.

Monitoring rare species of wild ungulates is critical for their conservation management. The Italian roe deer Capreolus capreolus italicus was recently confirmed to be a subspecies in Mediterranean habitats of central and southern Italy. We have monitored this subspecies at Castelporziano, near Rome, since 1988, and detected an abrupt population decline in 2001. We compared distance sampling surveys undertaken before and after the population crash to determine the ability of this method to detect variations in animal density and to investigate which factors may influence the precision of the estimates. We used radio tagged roe deer to evaluate the accuracy of our surveys, comparing distance sampling and mark-resight estimates at the same site, and studying the behavioural reaction of the animals to the presence of an observer. We found that before the crash distance sampling surveys attained a good precision but that the survey conditions influenced both precision and accuracy. Post-crash surveys were less precise, but the difference in density, before and after the crash was highly significant, indicating the potential of the method to quickly detect density variations and so to allow wildlife managers to react without delay to a crisis. The direct test of distance sampling assumptions showed that estimates were almost unbiased. We conclude that the methodology was successful for monitoring this population and that it may be used in other situations where ungulates are rare and efficient monitoring must be attained with restricted budgets.

The relationship between colony area and population density of Adélie penguins Pygoscelis adeliae was examined to determine whether colony area, measured from aerial or satellite imagery, could be used to estimate population density, and hence detect changes in populations over time. Using maps drawn from vertical aerial photographs of Adélie penguin colonies in the Mawson region, pair density ranged between 0.1 and 3.1 pairs m−2, with a mean of 0.63 ± 0.3 pairs m−2. Colony area explained 96.4% of the variance in colony populations (range 90.4–99.6%) for 979 colonies at Mawson. Mean densities were not significantly different among the 19 islands in the region, but significant differences in mean pair density were observed among colonies in Mawson, Whitney Point (Casey, East Antarctica) and Cape Crozier (Ross Sea) populations. The relationship between colony area and population may be locality-and/or species-specific, and a robust data set is required to validate the relationship.

A binary mixture of (Z)-ll-hexadecenal and (Z)-13-octadecenal was first identified as the sex pheromone components of female Chilo suppressalis. Later, an additional component was identified as (Z)-9-hexadecenal, which markedly enhanced the attractiveness to males when it was mixed to the binary mixture. Rubber septa containing ca. 0.3–1.0 mg of a mixture of the above three components in the natural ratio have been shown to keep up significantly higher attractiveness than virgin females for at least one month. It has also been shown that the pheromone trap is much more effective than a light trap, where both traps usually showed similar trap catch patterns. Several factors affecting trap catch, such as trap type, trap placement, etc., have been examined. Feasibility of the population monitoring with the synthetic pheromone was discussed.