Wordbirds: Developing a Web-based Data Collection System for the Global Monitoring of Bird Distribution and Abundance

There is an urgent need to develop simple and effective methods for monitoring bird populations that are cheap to deploy in resource-poor countries. This paper describes a newly developed system, provisionally referred to as, Wordbirds, that will provide a platform for the collection, storage and retrieval of new and existing data from bird observations recorded worldwide. This Internet-based global network of databases will capture field lists and ad hoc sightings routinely gathered by individuals observing birds recreationally and professionally. Huge numbers of lists are collected annually and could provide information on population trends spanning many years. By collecting these records, a valuable resource will be secured with the potential to map and monitor bird distributions and estimate trends in species abundance. An erratum to this article is available at .     

Combining citizen science and recreational hunters to monitor exotic ungulates and native wildlife in a protected area of northeastern Argentina

Monitoring wildlife population trends is essential for resource management and invasive species control, but monitoring data are hard to acquire. Citizen science projects may monitor species occurrence patterns in time and space in a cost-effective way. A systematic management program of exotic wild boar (Sus scrofa) and axis deer (Axis axis) in a protected area of northeastern Argentina (El Palmar National Park) provided a framework for implementing a wildlife monitoring system based on park-affiliated hunters. We assessed the level of agreement between three indices of relative abundance: hunter sightings and camera trapping for wild boar, axis deer, capybaras (Hydrochoerus hydrochaeris), brown brocket deer (Mazama guazoubira), and crab-eating and pampas foxes combined (Cerdocyon thous and (Lycalopex gymnocercus), and catch per unit effort (CPUE) for both exotic ungulates only. Most (74%) hunting parties participated in the monitoring program and contributed to its sustainability. Bland-Altman plots displayed large levels of agreement between methods across species, with larger systematic differences between sighting and camera-trapping indices for native species. Restricting camera-trapping to the same time window as hunter sightings substantially increased the agreement between methods across species. Sighting and CPUE indices revealed similar temporal trends and large variations in spatial patterns between species. Comparison of the number of sighted and killed exotic ungulates indicated that, on average, 17% of wild boar and 75% of axis deer escaped hunters. The three indices were appropriate metrics for management purposes and corroborated the sustained, high-level abundance of axis deer and low numbers of wild boar in recent years.

     

Site-occupancy models may offer new opportunities for dragonfly monitoring based on daily species lists

Monitoring biodiversity is necessary but difficult to achieve in practice, in part because standardized field work is often demanding for volunteer field workers. Collecting opportunistic data on presence and absence of species is much less demanding, but such data may suffer from a number of biases, such as variation in observation effort over time. Here we explore whether site-occupancy models may be helpful to reduce such biases in opportunistic data, especially those caused by temporal variation of observation effort and by incomplete reporting of sightings. Site-occupancy models represent a generalisation of classical metapopulation models to account for imperfect detection; they estimate the probability of sites to be occupied (and of the rates of change, colonisation and extinction rates) while taking into account imperfect detection of a species. The models require so-called presence–absence data from replicated visits for a number of sites (e.g., 20–50). We tested whether these models provide reliable trend estimates if collectors of opportunistic data do not report all species detected. We applied the models to three opportunistic datasets of dragonfly species (1999–2007) in the Netherlands: (1) one-species records, (2) short daily species lists and (3) comprehensive daily species lists. Trend estimates based on a fourth dataset from a standardized monitoring scheme were used as a yardstick to judge the results.The analyses showed that occupancy trends based on comprehensive daily species lists in combination with site-occupancy models were generally similar to those based on the monitoring scheme. But trends based on one-species records and short daily lists were too imprecise to be very useful. In addition, site-occupancy models lead to more realistic occupancy estimates than those obtained from conventional logistic regression analysis. We conclude that comprehensive daily species lists can be useful surrogates for monitoring schemes to assess distributional trends.     

Temporal variation in the annual survival rates of six granivorous birds with contrasting population trends

To identify the environmental changes responsible for the declines in abundance shown by many granivorous bird species, the demographic mechanism through which the changes have acted must be determined. Ring-recovery data were used to estimate the annual survival rates (since 1962) of six seed-eating bird species with contrasting population trends to identify whether variations in survival could have been the mechanism behind population change. The survival rates of Bullfinch Pyrrhula pyrrhula , Chaffinch Fringilla coelebs , Goldfinch Carduelis carduelis , Greenfinch C. choris , Linnet C. cannabina and House Sparrow Passer domesticus were estimated using models allowing age- and time-specificity in survival (reporting rates could be assumed to be constant). Three tests of the importance of variations in survival in determining population trend were conducted: (1) simple population models with constant productivity showed whether temporal changes in survival were sufficient alone to explain observed trends in abundance, (2) survival models incorporating changes in abundance as a covariate identified whether annual survival rates were associated with population changes, and (3) mean survival rates found in objectively identified periods of increase, decline and stability in each species' population trend were compared. These analyses suggested that environmental change has led to the observed population trends for Goldfinch and House Sparrow largely through effects on survival. Weaker relationships between variations in survival and population trend were found for Bullfinch, Chaffinch and Linnet, but other factors such as breeding success are likely to have been at least as important for these species, and also for Greenfinch. Checking analyses incorporating density-dependence did not alter these conclusions.     

Designing a winter bird atlas field methodology: issues of time and space in sampling and interactions with habitat

Faunal and floral atlases can provide invaluable information on species distributions and relative abundance, and have played a key role in detecting and diagnosing population changes. Most atlases rely on simple but effective field methods that can be employed by large numbers of volunteer surveyors so as to make the best use of their finite effort. For ornithological atlases, such methods have been modified to better quantify relative abundance in the breeding season. Here, we evaluate how effort should be invested in space (number of samples) and time (time per sample) in order to optimise species lists and relative abundance estimation for birds in Britain and Ireland in winter. Species accumulation curves show only slight differences in the ability to derive complete species lists whether effort is invested in time or in space. However, relative abundance precision is markedly improved if effort is invested in space at the expense of time. These results give clear guidance on the general way in which methods should be devised (i.e. more samples, each for less time), but analyses relating the shape of species accumulation curves to habitat diversity suggest the precise trade-off between surveying in space and time varies between landscapes. Designers of atlases must therefore optimise their study design for the landscape of the particular region in question.     

Monitoring butterfly abundance: beyond pollard walks

Most butterfly monitoring protocols rely on counts along transects (Pollard walks) to generate species abundance indices and track population trends. It is still too often ignored that a population count results from two processes: the biological process (true abundance) and the statistical process (our ability to properly quantify abundance). Because individual detectability tends to vary in space (e.g., among sites) and time (e.g., among years), it remains unclear whether index counts truly reflect population sizes and trends. This study compares capture-mark-recapture (absolute abundance) and count-index (relative abundance) monitoring methods in three species (Maculinea nausithous and Iolana iolas: Lycaenidae; Minois dryas: Satyridae) in contrasted habitat types. We demonstrate that intraspecific variability in individual detectability under standard monitoring conditions is probably the rule rather than the exception, which questions the reliability of count-based indices to estimate and compare specific population abundance. Our results suggest that the accuracy of count-based methods depends heavily on the ecology and behavior of the target species, as well as on the type of habitat in which surveys take place. Monitoring programs designed to assess the abundance and trends in butterfly populations should incorporate a measure of detectability. We discuss the relative advantages and inconveniences of current monitoring methods and analytical approaches with respect to the characteristics of the species under scrutiny and resources availability.     

Do population indicators work? Investigating correlated responses of bird populations in relation to predator management

Using population indicators to evaluate conservation achievements is widely practised, yet seldom empirically tested. If populations are consistently correlated in response to a shared ecological driver, the indicator species approach can be used as a cost-effective, ecologically-based shortcut to measuring the effects of conservation management. Long-term monitoring of forest bird populations associated with mammalian pest control programmes in New Zealand provides a useful framework for testing the population indicator species concept. We evaluated population trends in 21 bird species vulnerable to predation by introduced mammals (primarily mustelids and rodents) at managed and unmanaged beech (Nothofagus) forest sites. Correlated population trends between species pairs were detected at individual sites. However, neither positive nor negative correlations in species trends could be predicted by life history traits and predator management did not produce consistent, correlated population trends among sites. Our results do not support the use of a population indicator approach to management and reporting for forest birds in New Zealand. Relationships between purported indicator taxa and other species need to be understood for various management scenarios before population indicators can be confidently applied to measuring conservation achievement.     

Apparent breeding success drives long-term population dynamics of a migratory swan

The ability of a species to adapt to environmental change is ultimately reflected in its vital rates – i.e. survival and reproductive success of individuals. Together, vital rates determine trends in numbers, commonly monitored using counts of species abundance. Rapid changes in abundance can give rise to concern, leading to calls for research into the biological mechanisms underlying variations in demography. For the northwest European population of Bewick's swan Cygnus columbianus bewickii, there have been major changes in the population trends recorded during nearly five decades of monitoring (1970–2016). The total number of birds increased to a maximum of ca 30 000 in 1995 and subsequently decreased to about 18 000 individuals in 2010. Such large fluctuation in population numbers is rare in long-lived species and understanding the drivers of this population change is crucial for species management and conservation. Using the integrated population model (IPM) framework, we analysed three demographic datasets in combination: population counts, capture–mark–resightings (CMR) and the proportion of juveniles in winter over a period of ~50 years. We found higher apparent breeding success in the years when the population had a positive growth rate compared to years with a negative growth rate. Moreover, no consistent trend in adult and yearling survival, and an increasing trend in juvenile survival was found. A transient life-table response experiment showed that apparent breeding success and adult survival contributed most to the variation in population trend. We explored possible explanatory variables for the different demographic rates and found a significant association between juvenile survival both with the water level in lakes during autumn migration, which affects food accessibility for the swans, and with summer temperatures. Such associations are important for understanding the dynamics of species with fluctuating population sizes, and thus for informing management and conservation decisions.     

Declining population trends of European mountain birds

Mountain areas often hold special species communities, and they are high on the list of conservation concern. Global warming and changes in human land use, such as grazing pressure and afforestation, have been suggested to be major threats for biodiversity in the mountain areas, affecting species abundance and causing distribution shifts towards mountaintops. Population shifts towards poles and mountaintops have been documented in several areas, indicating that climate change is one of the key drivers of species’ distribution changes. Despite the high conservation concern, relatively little is known about the population trends of species in mountain areas due to low accessibility and difficult working conditions. Thanks to the recent improvement of bird monitoring schemes around Europe, we can here report a first account of population trends of 44 bird species from four major European mountain regions: Fennoscandia, UK upland, south‐western (Iberia) and south‐central mountains (Alps), covering 12 countries. Overall, the mountain bird species declined significantly (?7%) during 2002–2014, which is similar to the declining rate in common birds in Europe during the same period. Mountain specialists showed a significant ?10% decline in population numbers. The slope for mountain generalists was also negative, but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and Iberian populations were on average declining, while in United Kingdom and Alps, trends were nonsignificant. Temperature change or migratory behaviour was not significantly associated with regional population trends of species. Alpine habitats are highly vulnerable to climate change, and this is certainly one of the main drivers of mountain bird population trends. However, observed declines can also be partly linked with local land use practices. More efforts should be undertaken to identify the causes of decline and to increase conservation efforts for these populations.     

气候变化对冬季东海外海中下层游泳动物群落结构及重要经济种类的影响

以全球气候变暖为主要特征的全球气候变化对海洋生物和海洋生态系统造成的影响已引起国际学者的高度关注。根据中国14家国营渔业公司底拖网渔业生产和渔业资源大面定点调查获得的17种中下层渔业数据,结合1960—2011年东海北部水域海表温度的变化情况,利用Fox模型移除捕捞效应产生的趋势变化后,分析了气候变化对中、下层游泳动物群落结构及几种重要经济种类的影响。通过气候跃变检验分析发现,海表温度在整体变暖的趋势上叠加有年代际波动,研究水域分别在1982/1983年发生了从寒冷期(1960—1982年)向升温期(1983—1998)、经由1998/1999年再到温暖期(1999—2011年)的跃变。群落结构变化特征显示:相比于寒冷期,温暖期间底层类和大型捕食类资源指数降低,中层类和无脊椎类升高;暖水种资源指数升高,暖温种降低;生物多样性指数略有增加。移除捕捞效应后,对不同生态属性种类CPUE与海表温度距平进行相关分析显示:底层类、中层类和无脊椎类残差与海表温度距平均呈正相关关系,其中中层类与海表温度距平显著正相关,而大型捕食类则呈负相关关系;暖水种残差与海表温度距平呈正相关,而暖温种则呈负相关关系。中层类中的黄鲫(Setipinna taty)、银鲳(Pampus argenteus)的CPUE残差均与海表温度距平呈显著正相关关系,近底层类中的带鱼(Trichiurus japonicus)和头足类(Squid)的CPUE残差均与海表温度距平呈正相关关系,而底层类小黄鱼(Larimichthys polyactis)和对虾(Shrimp)则呈负相关关系。在气候变化的大背景下,需加强其对海洋生态系统结构和功能影响的研究,查明渔业资源对气候变化的响应机制和机理,制定科学有效的渔业管理制度,实现渔业资源的可持续发展。