Rate Of Population Change Research Articles

Change in monarch winter abundance over the past decade: A Red List perspective

Abstract Assessing invertebrate species for the IUCN Red List under Criterion A frequently involves fitting an appropriate statistical model to available abundance data and calculating a 10‐year change (TYC) estimate from predicted abundances. When the rate of change has not been constant across the entire time series, models that accommodate variable change rates are recommended. The monarch butterfly (Danaus plexippus) was recently added to the IUCN Red List (A2ab Endangered) based on analysis of data on winter abundances in Mexico and the western USA between 1993 and 2020. TYC estimates in the monarch assessment came from models that assumed constant change rates. We conducted a Bayesian analysis of the same data using models that accommodated variable change rates and used those models to compute TYC estimates. Our results suggested that monarch population change rates have not been constant over the study period. The analysis yielded a model‐averaged TYC estimate of +5.23%, which was not statistically distinguishable from 0% and was considerably different from values of −46% and −72% in the assessment. The Bayesian posterior probability of a TYC value below −30% (A2ab Vulnerable) was 0.15 and that of a TYC value below −50% (A2ab Endangered) was 0.03. We recommend that researchers evaluating monarch conservation status consider using abundance models with variable change rates, as models with constant change rates may not accurately predict the trajectory of monarch abundances into the future.

Determination of Population Change and Damage Rate of the Harmful Codling Moth (Cydia pomonella Linnaeus) (Lepidoptera: Tortricidae) in Apple Orchards in Malatya Province, Türkiye

Determination of Population Change and Damage Rate of the Harmful Codling Moth (Cydia pomonella Linnaeus) (Lepidoptera: Tortricidae) in Apple Orchards in Malatya Province, Türkiye

Urban modeling of shrinking cities through Bayesian network analysis using economic, social, and educational indicators: Case of Japanese cities.

Shrinking cities due to low birthrates and aging populations represent a significant urban planning issue. The research question of this study is: which economic, social, and educational factors affect population decline in Japanese shrinking cities? By modeling shrinking cities using the case of Japanese cities, this study aims to clarify the indicators that affect the population change rate. The study employed Bayesian network analysis, a machine learning technique, using a dataset of economic, social, and educational indicators. In conclusion, this study demonstrates that social and educational indicators affect the population decline rate. Surprisingly, the impact of educational indicators is more substantial than that of economic indicators such as the financial strength index. Considering the limitations in fiscal expenditures, increasing investment in education might help solve the problem of shrinking cities because of low birthrates and aging populations. The results provide essential insights and can function as a planning support system.

Spatial and temporal non-stationarity in long-term population dynamics of over-wintering birds of North America.

Understanding population changes across long time scales and at fine spatiotemporal resolutions is important for confronting a broad suite of conservation challenges. However, this task is hampered by a lack of quality long-term census data for multiple species collected across large geographic regions. Here, we used century-long (1919-2018) data from the Audubon Christmas Bird Count (CBC) survey to assess population changes in over 300 avian species in North America and evaluate their temporal non-stationarity. To estimate population sizes across the entire century, we employed a Bayesian hierarchical model that accounts for species detection probabilities, variable sampling effort, and missing data. We evaluated population trends using generalized additive models (GAMs) and assessed temporal non-stationarity in the rate of population change by extracting the first derivatives from the fitted GAM functions. We then summarized the population dynamics across species, space, and time using a non-parametric clustering algorithm that categorized individual population trends into four distinct trend clusters. We found that species varied widely in their population trajectories, with over 90% of species showing a considerable degree of spatial and/or temporal non-stationarity, and many showing strong shifts in the direction and magnitude of population trends throughout the past century. Species were roughly equally distributed across the four clusters of population trajectories, although grassland, forest, and desert specialists more commonly showed declining trends. Interestingly, for many species, region-wide population trends often differed from those observed at individual sites, suggesting that conservation decisions need to be tailored to fine spatial scales. Together, our results highlight the importance of considering spatial and temporal non-stationarity when assessing long-term population changes. More generally, we demonstrate the promise of novel statistical techniques for improving the utility and extending the temporal scope of existing citizen science datasets.

Insights into the population dynamics of Anastrepha obliqua and Anastrepha ludens in the neotropical limits of Mexico

AbstractAnastrepha obliqua Macquart and Anastrepha ludens Loew (Diptera: Tephritidae) represent persistent pests of quarantine significance affecting mango and citrus agroecosystems, respectively, in Mexico. We aimed to analyze the population dynamics of A. obliqua and A. ludens and the effects of endogenous and exogenous factors on the population regulation in the neotropical limits of Mexico. We explored endogenous dynamics of A. obliqua and A. ludens populations based on short sequences of time series data of adult captures from 2008 to 2010. Moreover, we analyzed the relationship between the rate of population change () and population density as an endogenous factor, and temperature, precipitation, fruit availability, and the North Atlantic Oscillation index (NAOi) as exogenous factors. Autocorrelation and partial‐rate correlation functions were used to evaluate the endogenous dynamics of populations. Generalized least square models including autoregressive–moving‐average structures were performed to assess the relationships between the and endogenous and exogenous factors. Results revealed annual patterns in the population fluctuation for both Anastrepha obliqua and A. ludens. Anastrepha obliqua and A. ludens population peaks occurred from August to September–October, and from January to July, respectively. The dynamics of the suggest persistent pest populations modulated by a first‐order feedback structure, although higher orders in feedback structures were also exhibited. Significant relationships between and population density, temperature, fruit availability, and the NAOi were observed. These findings may be a technical and ecological basis to design environmentally friendly strategies against wild populations under an area‐wide integrated pest management (AW‐IPM) approach.

Species life-history strategies affect population responses to temperature and land-cover changes.

Human-induced environmental changes have a direct impact on species populations, with some species experiencing declines while others display population growth. Understanding why and how species populations respond differently to environmental changes is fundamental to mitigate and predict future biodiversity changes. Theoretically, species life-history strategies are key determinants shaping the response of populations to environmental impacts. Despite this, the association between species life histories and the response of populations to environmental changes has not been tested. In this study, we analysed the effects of recent land-cover and temperature changes on rates of population change of 1,072 populations recorded in the Living Planet Database. We selected populations with at least 5 yearly consecutive records (after imputation of missing population estimates) between 1992 and 2016, and for which we achieved high population imputation accuracy (in the cases where missing values had to be imputed). These populations were distributed across 553 different locations and included 461 terrestrial amniote vertebrate species (273 birds, 137 mammals, and 51 reptiles) with different life-history strategies. We showed that populations of fast-lived species inhabiting areas that have experienced recent expansion of cropland or bare soil present positive populations trends on average, whereas slow-lived species display negative population trends. Although these findings support previous hypotheses that fast-lived species are better adapted to recover their populations after an environmental perturbation, the sensitivity analysis revealed that model outcomes are strongly influenced by the addition or exclusion of populations with extreme rates of change. Therefore, the results should be interpreted with caution. With climate and land-use changes likely to increase in the future, establishing clear links between species characteristics and responses to these threats is fundamental for designing and conducting conservation actions. The results of this study can aid in evaluating population sensitivity, assessing the likely conservation status of species with poor data coverage, and predicting future scenarios of biodiversity change.

Extreme Winter Storms Have Variable Effects on the Population Dynamics of Canopy Dominant Species in an Old-Growth Subtropical Forest

Extreme climatic events are predicted to increase in frequency and magnitude as global climate change continues. Extreme climatic events have profound impacts on community structure and dynamics, but their effects on the dominant species within a community remains unclear. To explore this issue, we analyzed changes in population dynamics and dead individuals’ spatial pattern for several dominant species (Castanopsis eyrei, Schima superba, Pinus massoniana, and Daphniphyllum oldhamii) among different habitats in a subtropical forest before and after a significant winter storm that occurred in February 2008. Using the Gutianshan 24-ha forest plot as a representative sample, we found that the plot-level DBH of P. massoniana and C. eyrei significantly increased after the winter storm, while the plot-level basal area of P. massoniana and S. superba decreased significantly. In addition, P. massoniana was most affected by the storm (mortality: 9.08%; population change rate: −8.93%), followed by C. eyrei (mortality: 6.93%; population change rate: −4.91%). Small-diameter individuals experienced higher mortality rates, but the diameter structure of the dominant species at the population level remained basically stable. The number of individuals, the density of the dominant population, the number of mortalities, and the mortality rate of the dominant species differed among habitats. The spatial point patterns of the dead individuals at each life stage were mainly aggregated in distribution, and the degree of aggregation tended to decrease with increasing scale. In conclusion, the population dynamics of dominant species were significantly altered following the winter storm, but the extent of the changes varied with species. Our study suggests that analyzing the dominant species of a community contributes to a better understanding of the biological response of forest ecosystems in the face of extreme climatic events.

County town shrinkage in China: Identification, spatiotemporal variations and the heterogeneity of influencing factors

Small town shrinkage has become a global social and economic phenomenon. County towns, which are characterized by large numbers, diverse types, important functions and wide distribution, are an indispensable component of small towns in China. The shrinkage of county towns in China is typical and unique in the global urban shrinkage system. Therefore, this study takes county towns in China as the basic unit, uses the rate of population change to identify shrinking towns, and analyzes the spatiotemporal patterns and distribution characteristics of the shrinking towns, from 2010 to 2018. Eleven indicators in six categories were selected, and temporal weighted regression (TWR) and geographically weighted regression (GWR) were used to explore the spatiotemporal heterogeneity of influencing factors. The results show that, during the study period, the number of shrinking towns in China increased. The phenomenon of urban shrinkage was common in seven geographical regions, mainly distributed in Northeast, Northwest, North and Southwest China during the study period. The shrinkage trajectory was dominated by two forms of shrinkage, namely potential shrinkage and segmented shrinkage. Both growing towns and shrinking towns were affected by population agglomeration, economic base, industrial structure, and space development. Traffic and location were unique factors that affected shrinking towns. The results also show that the influencing factors of shrinking towns were not significantly heterogeneous in time, but significantly heterogeneous in space. These findings help us to understand the complexity and diversity of small town shrinkage in China and also provide a reference for planners and decision makers to formulate corresponding governance strategies for shrinking towns in different regions.

Monitoring, modelling and managing beaver (Castor fiber) populations in the River Otter catchment, Great Britain

Abstract Eurasian beaver (Castor fiber) were nearly hunted to extinction but have recovered to occupy much of their former range. Beaver were extirpated from Great Britain c. 400 years ago but have recently been reintroduced. The River Otter catchment, Devon was the site of the first licensed wild release of beavers in England. With further releases being considered, there is a need to better understand population dynamics of this native, keystone species to inform conservation and management. Field signs were surveyed from 2015 to 2021. A semi‐automated territory detection method was adopted to estimate territory counts. A spatially explicit model was developed to estimate the ecological territory capacity of the catchment. Future territory expansion was modelled using logistic growth curves; initial growth rate was estimated from observed territory counts and the estimated territory capacity range was used to define the limiting value of the growth curve. Beaver territory removal was simulated, across a range of management intensities and start times, to determine potential impacts of translocation or lethal control upon population dynamics. Territory numbers increased from four to 18, inclusive of four additionally released individuals, during study period. In the absence of population management, the territory capacity of the catchment was estimated to range between 120 and 183; this may be reached between 2028 and 2057. Simulated territory removal, where territories were removed at a fixed rate from the sum of the estimated total population and the population increase for that year, demonstrated large uncertainties in predicted population responses. Simulations with territory removals >3/year all predicted potential population collapse. This finding emphasizes the need for caution when considering population management strategies; translocation of animals out of the catchment or culling should be considered only when populations are established and all alternatives have been considered. These results provide critical information for the expected rate and magnitude of beaver population change in the River Otter catchment. The methods provide a reproducible and generalizable approach for understanding beaver population change, which can inform policy on the reintroduction of beavers and the potential timing and intensity of future beaver population management.

국가균형발전 지표에 의한 지역유형 분류 및 특성 분석

This study is significant in that it provides basic data for enforcing relevant policy by classifying basic local governments across the country into types according to the Balanced National Development Index. The analysis results reveal that, out of the 229 analysis target areas, 62 centering on Si(city) were classified as cluster 1, 73 centering on GU(borough) were classified as cluster 2, and 94 areas centering on GUN(county) were classified as cluster 3. A look into characteristics depending on regional type shows how cluster 1 demonstrated relatively more positive outcomes than clusters 2 and 3 in terms of ‘changing trends within the period’ such as rate of change in population and rate of change in the number of businesses. Next, cluster 2 indicated more positive outcomes than clusters 1 and 3 in terms of ‘facility access’, such as the percentage of infants and young children within daycare center service areas, the percentage of school-aged children within elementary school service areas, and the population percentage within library service areas. Cluster 3 exhibited a high level of outcomes in indices based on population numbers, such as the number of schools per 1,000 students and the number of cultural infrastructure facilities per 10,000 population. As cluster 3 centers on gun areas, these outcomes paradoxically assume the realities of local extinction as a result of population decreases in gun areas.

Comparing Life Histories of the Shortest-Lived Turtle Known (Chicken Turtles, Deirochelys reticularia) with Long-Lived Blanding's Turtles (Emydoidea blandingii)

Evolutionary theories predict major differences in life-history trait values of long- and short-lived organisms. Such comparisons have not been possible for chelonians because no short-lived turtle was known until research revealed that chicken turtles (Deirochelys reticularia; DR) have a maximum longevity of 21 yrs. Life-history trait values of DR females are 1) age at maturity of females = 5–6 yrs; 2) clutches per season = 1.6; 3) annual fecundity = 6–8 female eggs per female; 4) average juvenile survivorship from age 1 to maturity = 0.60; and 5) low average annual adult survivorship = 0.66. We compared DR with the very long-lived Blanding's turtles (Emydoidea blandingii; EB) in Michigan. Over 14 yrs with no mortality (the minimum age at maturity of EB), the maximum potential fecundity produced by a single female embryo and her mature female offspring was 5 female eggs for EB and 1040 eggs for DR. Comparisons of life table output for approximately stable populations of DR and EB resulted in cohort generation times of 7 and 37 yrs, respectively. The life-history prediction that short-lived organisms should produce smaller offspring was not supported. Average wet mass of eggs is 10 g (8.4–11.3 g) for DR and 12 g (10–14 g) for EB; and average wet mass of hatchlings is 7.3 g (6–9 g) for DR and 9.3 g (6–13 g) for EB. Both differences are smaller than expected based on the difference in longevity. Short-lived female DR have an unusual tactic of investing in high fecundity and making substantial body size-specific investment in large eggs, which may reflect why juvenile survivorship had greater influence on population change rates than did adult survivorship. In contrast, adult survivorship had the greatest influence on population change rates of EB. Comparison of cohorts of 1000 female DR and EB hatchlings highlights the differences in life histories of short- and long-lived turtles: all DR would be dead by the time the last female EB had reached maturity at 21 yrs of age.

Niche overlap in rodents increases with competition but not ecological opportunity: A role of inter-individual difference.

Niche variation at population level mediates niche packing (i.e. patterns of species' spread within the niche space) and species coexistence at community level. Competition and ecological opportunity (resource diversity) are two of the main mechanisms underlying niche variation. Dense niche packing could occur through increased niche partitioning or increased niche overlap. In this study, we used stable carbon and nitrogen isotope data of 635 individual rodents from four species across nine sites in the montane region of a subtropical island to test the effects of competition and ecological opportunity on population isotope niche size, inter-individual niche difference within population and interspecific niche overlap within community. We used the Bayesian Standard Ellipse Area (SEAB, the ellipse area enclosed by carbon and nitrogen isotope values of organisms on a bi-plot) to estimate population niche size and interspecific niche overlap. Inter-individual niche difference within population was quantified as isotopic divergence and isotopic uniqueness. We used rodent abundance (the number of unique individuals captured) to measure competition and plant isotope niche size (plant SEAB) to measure ecological opportunity. The rodents experienced competition as evidenced by a negative relationship between population change rate and conspecific abundance. Rodent population niche size increased with ecological opportunity but not competition. The inter-individual niche difference (isotopic uniqueness) increased with competition (interspecific competition only) but not ecological opportunity. At community level, interspecific niche overlap (herbivore-omnivore pair only) increased with competition (the combined abundance of the pair) but not ecological opportunity. This study demonstrated that isotope niche variation of the rodents could be hierarchically influenced by ecological opportunity and competition, with the former setting the limit of population niche size across communities and the latter shaping inter-individual niche difference and interspecific niche overlap within communities. Under strong intraspecific competition and limited ecological opportunity for niche expansion, individuals may choose to increase their isotopic uniqueness from conspecifics at the cost of overlapping with heterospecifics of different trophic roles within the community niche space as overall competition increases. Denser niche packing of these rodent communities might be achieved through increased niche overlap.

Until the wilting day: an analysis of urban population changes in provincial cities in Thailand from 2010 to 2019

ABSTRACT Population change is an important indicator of city status and can guide urban planning. Based on population changes, each city is categorised as “a growing city,” “a stagnant city,” or “a shrinking city.” Although shrinking and stagnant cities are common, city planning based on the pro-growth paradigm often omits them, causing negative impacts on the performance of urban policy, especially in less-developed countries. To fulfil the limited understanding of the population changes in those countries, this study aims to investigate the population change patterns between 2010 and 2019 using provincial cities in Thailand as a case study. All the provincial cities were categorised based on their annual population change rate. Cluster analysis was performed to categorise sub-clusters based on the status of urban population concentration and its changes. The results reveal that, although Thailand is rapidly urbanising, only 7 out of 76 provincial cities are in the growing city cluster. Most provincial cities are in the stagnant or shrinking city cluster, with urban concentration decline happening as a result. This evidence indicates that several provincial cities may be shrinking. Related government organisations should shift the paradigm of urban management based on population changes.

Evidence of widespread declines in Kenya's raptor populations over a 40-year period

Kenya's wildlife has been declining substantially for decades, due to rapid human population growth and its associated impacts on natural habitats. Predators and scavengers are particularly sensitive to anthropogenic pressures, and their changing status has corresponding impacts on the ecosystem services they provide. To estimate rates of change in Kenya's raptor populations we compared linear encounter rates (individuals 100 km−1) recorded during road surveys conducted in 1970–1977 and 2003–2020. Encounter rates for 19 out of 22 species examined had fallen, by a median of 70% among those showing a significant or near-significant change. No species had increased significantly. Declines had occurred among all vulture and large eagle species, and were especially pronounced among once-common small and medium-sized raptors. Our findings demonstrate the importance of protected areas (PAs) for Kenya's remaining raptor populations. The median encounter rate for vultures and large eagles had dropped by 23% within PAs and by 76% in unprotected areas. Smaller species showed divergent trends in relation to PA status, their median encounter rate increasing by 104% within PAs while declining by 85% elsewhere. Based on projected declines over three generation lengths, 45% of the species examined would qualify as nationally Endangered or Critically Endangered. Key threats include electrocution/collision with energy infrastructure, deliberate and incidental poisoning, and impacts associated with habitat degradation. Kenya's raptor declines could be reversed through enhanced management of PAs, mitigation of specific threats and the implementation of species recovery plans; all requiring steadfast government commitment and close collaboration with conservation stakeholders.

Increased abundance and range expansion of harlequin ducks Histrionicus histrionicus wintering in Eastern Canada

The eastern population of harlequin duck Histrionicus histrionicus in Canada has been designated a species of special concern since 2001 and as endangered from 1991 to 2001, largely due to low and declining wintering numbers detected in the 1980s. Our objectives were to summarize the current state of knowledge of harlequin duck abundance and distribution in Eastern Canada, and assess trends in wintering abundance across regions over the past 30+ years. Abundance estimates were generated from targeted surveys with thorough spatial coverage of major wintering areas on insular Newfoundland (NL), Nova Scotia (NS), and New Brunswick (NB) between 2015 and 2018, complemented by regional trends estimated from Christmas Bird Count (CBC) data collected at 12 sites across the same wintering range between 1988 and 2021. Overall, targeted surveys indicated that numbers have increased and distributions have expanded beyond historically surveyed regions, particularly in NS. This was supported by trends from CBC data, with steep average increases (mean λ > 1.05) on most CBC circles in Eastern Canada since 1988 or later. Using localized annual rates of mean population change from CBC data to project counts from dedicated surveys, we suggest wintering areas in the provinces of NL, NS, and NB may currently be supporting a combined total of 5682 birds (95% CI 5065-6354) in 2022, well exceeding the recovery target of 3000 individuals listed in the 2007 management plan. Our findings indicate that the eastern population is in recovery, but also emphasize that a consistent, dedicated monitoring program would enable managers to confidently evaluate management actions, and to respond most effectively should regional trends slow or reverse.

Waterfowl Population Trends in the Major Rivers of Chitwan National Park, Nepal

The waterfowl populations that visit segments of the Rapti and Narayani Rivers in Chitwan National Park, Nepal were systematically counted from 2010 to 2019 to calculate yearly indices and population trends. Eighteen species of waterfowl were identified, out of which eight were regular visitors. Ruddy Shelduck (Tadorna ferruginea) was 80% of the total waterfowl population. The Rapti and Narayani Rivers provided winter habitat for 15.5% of the Ruddy Shelduck in the South Asian Flyway. Along with Ruddy Shelduck, these rivers individually and regularly supported more than 1% of the population threshold of Goosander (Mergus merganser) in the South Asian Flyway, designating the rivers in Ramsar Criteria 6 in the RAMSAR convention (Wetlands International 2017). Out of eight regular species, six species had an increasing population trend. The long-term trend of Ruddy Shelduck showed a strong increase in the annual rate of population change by + 10.14%. A strong increase was also shown by Bar-Headed Goose (Anser indicus; + 18.96%), Gadwall (Anas strepera; + 12.06%), Mallard (A. platyrhynchos; + 12.44%), and Common Teal (A. crecca; + 12%). Goosander (+ 4.94%) showed a moderate increase, while Lesser Whistling Duck (Dendrocygna javanica; - 12.85%), and Northern Pintail (A. acuta; - 10.80%) showed steep declines in their long-term trends. This work can provide a baseline for management and conservation of the waterfowl of Chitwan National Park, as there is no continuous data available there.

The pace of modern life, revisited.

Wild populations must continuously respond to environmental changes or they risk extinction. Those responses can be measured as phenotypic rates of change, which can allow us to predict contemporary adaptive responses, some of which are evolutionary. About two decades ago, a database of phenotypic rates of change in wild populations was compiled. Since then, researchers have used (and expanded) this database to examine phenotypic responses to specific types of human disturbance. Here, we update the database by adding 5675 new estimates of phenotypic change. Using this newer version of the data base, now containing 7338 estimates of phenotypic change, we revisit the conclusions of four published articles. We then synthesize the expanded database to compare rates of change across different types of human disturbance. Analyses of this expanded database suggest that: (i) a small absolute difference in rates of change exists between human disturbed and natural populations, (ii) harvesting by humans results in higher rates of change than other types of disturbance, (iii) introduced populations have increased rates of change, and (iv) body size does not increase through time. Thus, findings from earlier analyses have largely held-up in analyses of our new database that encompass a much larger breadth of species, traits, and human disturbances. Lastly, we use new analyses to explore how various types of human disturbances affect rates of phenotypic change, and we call for this database to serve as a steppingstone for further analyses to understand patterns of contemporary phenotypic change.

Does the Scale or Speed of Immigration Generate Nativism? Evidence from a Comparison of New Zealand Regions

Nativism, the belief that the rights of those who came first should be prioritized over immigrants, is an increasingly important driver of the rise of far-right populism. It is also leading to hate crimes and even terrorist attacks against immigrants. However, it remains unclear when and why local communities come to oppose immigration. One important set of questions concerns whether nativism is most likely to emerge in societies in which immigrants constitute a higher proportion of the total population or those where there is rapid growth in the immigrant population, even if absolute numbers or their proportion of society remain low. This paper employs multivariate analysis to test these two hypotheses. We use data from a survey of nativist (and populist) sentiment in New Zealand conducted in 2020 along with population data from the national censuses of 2013 and 2018. We compare the results from all New Zealand regions. Our findings strongly support the second hypothesis regarding the importance of the rate of growth in the immigrant population. Those regions that have the highest rate of change in immigrant populations present the highest levels of nativist sentiment, despite their immigrant populations being both small in size and as a proportion of the local population. Conversely, those regions where immigrant numbers are high or they constitute a large proportion of the local population return low levels of nativist sentiment.

Vertebrate population trends are influenced by interactions between land use, climatic position, habitat loss and climate change.

Rapid human-driven environmental changes are impacting animal populations around the world. Currently, land-use and climate change are two of the biggest pressures facing biodiversity. However, studies investigating the impacts of these pressures on population trends often do not consider potential interactions between climate and land-use change. Further, a population's climatic position (how close the ambient temperature and precipitation conditions are to the species' climatic tolerance limits) is known to influence responses to climate change but has yet to be investigated with regard to its influence on land-use change responses over time. Consequently, important variations across species' ranges in responses to environmental changes may be being overlooked. Here, we combine data from the Living Planet and BioTIME databases to carry out a global analysis exploring the impacts of land use, habitat loss, climatic position, climate change and the interactions between these variables, on vertebrate population trends. By bringing these datasets together, we analyse over 7,000 populations across 42 countries. We find that land-use change is interacting with climate change and a population's climatic position to influence rates of population change. Moreover, features of a population's local landscape (such as surrounding land cover) play important roles in these interactions. For example, populations in agricultural land uses where maximum temperatures were closer to their hot thermal limit, declined at faster rates when there had also been rapid losses in surrounding semi-natural habitat. The complex interactions between these variables on populations highlight the importance of taking intraspecific variation and interactions between local and global pressures into account. Understanding how drivers of change are interacting and impacting populations, and how this varies spatially, is critical if we are to identify populations at risk, predict species' responses to future environmental changes and produce suitable conservation strategies.

Moth species richness and diversity decline in a 30-year time series in Norway, irrespective of species\u2019 latitudinal range extent and habitat

IntroductionInsects are reported to be in decline around the globe, but long-term datasets are rare. The causes of these trends are elusive, with changes in land use and climate among the top candidates. Yet if species traits can predict rates of population change, this can help identify underlying mechanisms. If climate change is important, for example, high-latitude species may decline as temperate species expand. Land use changes, however, may impact species that rely on certain habitats.Aims and methodsWe present 30 years of moth captures (comprising 97,032 individuals of 808 species) from a site in southeast Norway to test for population trends that are correlated with species traits. We use time series analyses and joint species distribution models combined with local climate and habitat data.Results and discussionSpecies richness declined by 8.2% per decade and total abundance appeared to decline as well (−9.4%, p = 0.14) but inter-annual variability was high. One-fifth of species declined, although 6% increased. Winter and summer weather were correlated with annual rates of abundance change for many species. Opposite to general expectation, many species responded negatively to higher summer and winter temperatures. Surprisingly, species’ northern range limits and the habitat in which their food plants grew were not strong predictors of their time trends or their responses to climatic variation. Complex and indirect effects of both land use and climate change may play a role in these declines.Implications for insect conservationOur results provide additional evidence for long-term declines in insect abundance. The multifaceted causes of population changes may limit the ability of species traits to reveal which species are most at risk.