Monitoring Seabirds in the North Atlantic

Phenomenon of bird droppings by Hirundo sp. in UiTM Negeri Sembilan has now become a crucial issue as their droppings not only caused unsightly messes and property damages but also possed a serious threat to students’ and staff’s health. In order to overcome the problem, the actual number of the birds, especially Hirundo tahitica, needs to be assessed so that a suitable way to control the population size of the birds can be implemented. Therefore, a study on the population size of H. tahitica had been conducted by using a multiple captures of Jolly-Seber method, as this method allows natality, mortality, immigration, and emigration are suitable for assessment of open population. A variety of trapping methods were used to maximize the number of birds captured including mist nets, sweep nets, and fish nets and they were released back to population after marked. Analyses of data on 656 individual of H. tahitica captured during eight sampling periods between November 2012 and February 2013 showed that the total population size is 23, 157 birds. Five morphological traits of the species also were recorded namely wing length, tail length, body length, wing span, and body weight as they are important in sex and age determination of the birds. Among the birds captured, 255 of them are male and 401 are female. Morphological traits measurement recorded showed that only tail length have significant difference between male and female of H. tahitica (male-7.53 ± 1.26 g, female-4.96 ± 0.70 g) whereas other traits are slightly different.

The vegetation of the Tamagawa-josui Canal, which is a precious urban green belt running through an area of Tokyo, varies according to tree management practices. We recorded the species and individual numbers of birds (seven times) and measured tree diameters (18 plots) at four sites along the canal in 2021. At Mitaka and Kodaira, where woods along the canal were rich and green patches were also available near the canal, the bird communities were rich. In contrast, at Suginami, where the canal was sandwiched between heavily used roads and green patches were limited, species numbers and populations of birds were comparatively poor. The Azure-winged Magpie (Cyanopica cyanus), the Jungle Crow (Corvus macrorhynchos) and the Rock Dove (Columba livia) were relatively abundant. The bird community was poorest at Koganei, where only cherry trees were planted and other trees were cleared, although a big park was available near the canal. Forest dwelling birds were particularly few and only birds adaptable to urbanized environments, such as the White-cheeked Starling (Sturnus cineraceus) and the Tree Sparrow (Passer montanus) were relatively abundant. The pattern of seasonal changes in bird populations at Tamagawa-josui Canal closely resembled those seen at the Imperial Palace and Akasaka Imperial Residence in central Tokyo. The Brown-eared Bulbul (Hypsipetes amaurotis) and other forest dwelling birds decreased in summer. The results of the present study suggest that the bird communities along the Tamagawa-josui Canal are affected by the ambient vegetation, which is a direct result of anthropogenic management practices. We note the necessity to evaluate this perspective on biodiversity for the future vegetation management of this canal.

BackgroundThe global decrease in wildlife populations, especially birds, is mainly due to land use change and increasing intensity of land use (Parmesan and Yohe 2003). However, impacts of management tools to mitigate biodiversity loss at regional and global scales are less apparent in forest regions that have a constant forest area, and which did not suffer from habitat degradation, and where forests are sustainably managed, such as in Central Europe or the northeastern USA. A biodiversity assessment for Germany suggested, for example, that bird populations were constant (Bundesamt für Naturschutz 2015).ResultsThis study shows that changes in the environment and in forest management over the past 45 years have had a significant, positive effect on the abundance of non-migratory forest bird species in Central Europe. Economy (timber prices and GDP), forest management (timber harvest and mixed forest area), and environmental factors (atmospheric CO2 concentration and nitrogen deposition) were investigated together with changes in abundances of migratory and non-migratory forest birds using partial least squares path modeling. Climate change, resulting in longer seasons and milder winters, and forest management, promoting tree diversity, were significantly positively related to the abundance of non-migratory forest birds and explained 92% of the variation in their abundance in Europe. Regionally-migrating forest birds had stable populations with large variation, while birds migrating across continents declined in recent decades, suggesting significant, contrasting changes in bird populations in Europe. In northeastern North America we also found evidence that non-migratory forests have experienced long-term increases in abundance, and this increase was related to management. The increase of populations of non-migratory forest birds in Europe and North America is associated with an increase in structural diversity and disturbances at the landscape level.ConclusionsOur results suggest that reports about bird decline in forests should separate between migratory and non-migratory bird species. Efforts to mitigate the general decline in bird abundance should focus on land-use systems other than forests and support sustainable forest management independent of economic conditions.

Eight populations of Drosophila serrata were used in a factorial design of the type 2 x 2 x 2 to study the influence of some environmental and genetic factors on the productivity and total size of a population under conditions of severe competition. The variables studied were two temperatures (25 C versus 19 C), two feeding schedules (2 versus 3 food units per week), and two genetic compositions (single strain versus two strain hybrid population). The parameters measured were the number of flies, the biomass produced per food unit, and the total population size. The results show that the amount of food is the main factor controlling the number of flies and the biomass produced by a population. The higher temperature has a slight favorable effect on the number of flies, but not on the biomass produced; that is, at 25 C a few more flies are produced but they are lighter. When the flies oviposit in the bottle for a longer time, the number of flies and the biomass produced are increased. The main factor controlling the population size seems to be the living space. An increase of 50 % in the amount of food provided to the population only increases the population size slightly. At the lower temperature, there is an increase in the population size, possibly due to a decrease in the activity of the flies. The hybrid populations are considerably superior to the single strain populations, both in productivity and in total size, presumably owing to the greater genetic variability they offer to the action of natural selection

Globally, agriculture is the greatest source of threat to biodiversity, through both ongoing conversion of natural habitat and intensification of existing farmland. Land sparing and land sharing have been suggested as alternative approaches to reconcile this threat with the need for land to produce food. To examine which approach holds most promise for grassland species, we examined how bird population densities changed with farm yield (production per unit area) in the Campos of Brazil and Uruguay. We obtained information on biodiversity and crop yields from 24 sites that differed in agricultural yield. Density-yield functions were fitted for 121 bird species to describe the response of population densities to increasing farm yield, measured in terms of both food energy and profit. We categorized individual species according to how their population changed across the yield gradient as being positively or negatively affected by farming and according to whether the species' total population size was greater under land-sparing, land-sharing, or an intermediate strategy. Irrespective of the yield, most species were negatively affected by farming. Increasing yields reduced densities of approximately 80% of bird species. We estimated land sparing would result in larger populations than other sorts of strategies for 67% to 70% of negatively affected species, given current production levels, including three threatened species. This suggests that increasing yields in some areas while reducing grazing to low levels elsewhere may be the best option for bird conservation in these grasslands. Implementing such an approach would require conservation and production policies to be explicitly linked to support yield increases in farmed areas and concurrently guarantee that larger areas of lightly grazed natural grasslands are set aside for conservation.

We propose a stochastic logistic model with mate limitation and stochastic immigration. Incorporating stochastic immigration into a continuous time Markov chain model, we derive and analyze the associated master equation. By a standard result, there exists a unique globally stable positive stationary distribution. We show that such stationary distribution admits a bimodal profile which implies that a strong Allee effect exists in the stochastic model. Such strong Allee effect disappears and threshold phenomenon emerges as the total population size goes to infinity. Stochasticity vanishes and the model becomes deterministic as the total population size goes to infinity. This implies that there is only one possible fate (either to die out or survive) for a species constrained to a specific community and whether population eventually goes extinct or persists does not depend on initial population density but on a critical inherent constant determined by birth, death and mate limitation. Such a conclusion interprets differently from the classical ordinary differential equation model and thus a paradox on strong Allee effect occurs. Such paradox illustrates the diffusion theory's dilemma.

On the effects of migration and spatial heterogeneity on single and multiple species

Observations on the effects of low-flying aircraft at seabird colonies on the coast of Aberdeenshire, Scotland

The global road network, currently over 45 million lane‐km in length, is expected to reach 70 million lane‐km by 2050, while the number of vehicles utilizing it is expected to double. Roads have been shown to affect a range of wildlife, including birds, but most studies have been relatively small scale. We use data from across Great Britain to analyse the relationships between roads and the spatial distributions of bird populations. We model counts of 51 common and widespread species from the U.K. Breeding Bird Survey in relation to road exposure, which we calculated for each count site using the density, distance and traffic volume of all roads within a 5‐km radius. In these models, we incorporate other factors known to affect bird populations, including agricultural intensity, human population, habitat and climate. Importantly, we also account for differences in detectability of birds near to roads. The abundances of 30 species were strongly significantly related to exposure to either major or minor roads. Species were generally in higher abundances with increasing exposure to minor roads (20/28). In contrast, most significant associations between major road exposure and bird abundance were negative (7/8). For species with significant effects of road exposure, we assessed how estimated abundance changed across the central 50% of road exposure experienced for each species. The mean decrease in abundance was 19% and the mean increase was 47%. These changes in bird abundance were up to half as large as those associated with increasing agricultural intensity, a factor often cited as a major cause of bird population changes. Synthesis and applications. Our research shows many species to vary in abundance with increasing road exposure. This suggests that roads may modify bird populations on a national scale and that their potential as drivers of biodiversity change should not be overlooked. Our work highlights the need for appropriate mitigation of roads, particularly in areas important for avian biodiversity. This could include efforts to reduce impacts of road noise and/or collisions, such as reduced speed limits or quieter road surfaces in sensitive areas.

Studies in recent decades, including some based on mist-net counts, have suggested that populations of certain Neotropical migrants have been declining. Many of these studies utilize total birds per net hour as an index of actual population levels. However, other factors besides banding effort, such as weather, should be considered when determining changes in bird populations. In an attempt to calculate a standardized index of Catchability, I analyzed a series of weather factors and warbler captures to assess if changes in weather could bias interpretations of population trends of Neotropical-Nearctic migrant warblers in western Kansas during the fall migratory seasons of 1966 through 2000. Warbler captures varied throughout the 1966-1998 banding seasons, revealing the highest captures in the first six years of that time interval, from 1966 to 1972. Lower numbers and slight fluctuations in captures characterized the next ten years, from 1973 to 1983. From 1984 to 1991, numbers remained lower than in previous years. The last seven years of the study, 1992 to 1998, have shown fluctuations in numbers; however, they appear to be increasing. When recent banding seasons of 1998 through 2000 were examined using four intervals of the banding season as groups, certain patterns between weather and captures of warblers were observed. High captures appeared to correspond to total seasonal precipitation, although no within-year patterns were observed at the interval level. When examined at a daily scale, changes in temperature, both drops and increases, appeared to be associated with a higher capture success, although no statistically significant relationship was found through analyses. Minimum temperatures did not share any patterns with warbler captures, but high variability in minimum temperatures in Interval III, Julian days 269-286, of each year did seem to occur with higher warbler captures. Daily barometric pressure lows and ranges did not share any patterns with warbler captures when examined at the interval level. When the effects of both Julian days and significant temperature drops were examined, high warbler captures occurred in Interval III of the banding season, but not all days with high temperature drops within that time period resulted in high warbler captures. Multiple regression analyses of 1998-1999 data resulted in a significant relationship among warbler captures and weather variables tested, explaining 27.8% of the variation. The variables of Julian day, precipitation, and temperature contributed most significantly to this variation in warbler captures. A multiple regression of 1998-2000 data, excluding barometric pressure variables resulted in a significant equation, explaining only 12.8% of the variation. Precipitation and minimum temperature differential had significant coefficients. Discriminant function analyses resulted in inadequate separation of zero capture, medium capture, and high capture groups using the same weather variables. Data are incomplete for the 2000 banding season. Once more data are received, further analyses will be conducted to examine the influence of important weather variables on warbler captures. Perhaps, regional weather patterns or climatic changes may need to be examined in addition to local weather. A Catchability index may be calculated using a multiple regression model to standardize annual captures according to weather variables and Julian days. It may then be used to assess actual population changes as well as predict warbler captures according to weather conditions.

Farmland bird population trends were examined on a sample of lowland English farms to assess the relative importance of habitat loss and habitat degradation. Data were extracted from 11 farms surveyed by territory mapping between 1966 and 1986 as part of the British Trust for Ornithology's Common Birds Census. The population size of 38 bird species was quantified for each farm in each year. The extents of five non-crop habitats were measured at 4-yearly intervals on each farm. The farms were selected because some had undergone extensive removal of non-crop habitats while others had undergone little or none. Although declines were commonest on farms where the severest habitat loss had taken place, we found no evidence that habitat loss was the main factor causing population declines: all 11 farms had significant numbers of declining species, even where habitat loss was minimal. Furthermore, general linear modelling found no significant effects of habitat loss on population trends and principal-components analysis found limited effects of habitat extent on community composition. These results suggest that habitat loss is of secondary importance in causing farmland bird population declines. We suggest that other processes, such as habitat degradation, may have caused a baseline population decline in at least 10 farmland bird species and that declines may have been exacerbated by localised habitat loss.

Relatively few studies have examined the ecological effects of group-selection timber harvesting, and nearly all have been short-term and have lacked experimental manipulations that allow pre- and posttreatment comparisons. We have been documenting the effects of a group-selection timber harvest on bird abundance in a Maine forest for 24 years (preharvest, 1983-1987; postharvest, 1988-2006). Here we characterized the trends in bird abundance over the first 20 years of the study in the managed and control halves of the 40-ha study area. Species responses to the group-selection harvest were idiosyncratic, but in general the mature-forest bird community was retained and species dependent on early successional habitat temporarily (</=8 years) benefited. The Eastern Wood-Pewee (Contopus virens), Winter Wren (Troglodytes troglodytes), Pine Warbler (Dendroica pinus), and White-throated Sparrow (Zonotrichia albicollis) increased in abundance in the managed half of the study area following timber harvest, whereas the Veery (Catharus fuscescens) decreased. The Black-and-White Warbler (Mniotilta varia), Nashville Warbler (Vermivora ruficapilla), and Common Yellowthroat (Geothlypis trichas) responded positively to harvesting, as indicated by decreases in abundance in the control area and more protracted declines or stable abundances in the managed area. This study constitutes the longest experimental investigation to date of the effects of a group-selection harvest on birds and thus provides important information on the strength, direction, and duration of temporal changes in bird populations following forest management.

Importance of set-aside for breeding birds of open farmland in Finland

Aim: Yearly summaries of the North American Breeding Bird Survey (BBS) indicate that populations of many North American bird species are in decline. Determining the causes of these declines is the focus of much current research in avian conservation. Forest fragmentation has been linked to declines in populations of many species. In this study, the effects of forest fragmentation and connectivity as well as slope and physiographic features on two migratory bird species are explored. Location: This study area is Virginia, USA. Taxon: The species focused on are Wood Thrush (Hylocichla mustelina) and the Ovenbird (Seiurus aurocapilla). Methods: We used the Markov Chain Monte Carlo Generalized Linear Mixed Models (MCMCglmm) package with a Poisson distribution and a Bayesian data analysis model with a 95% probability interval. Using the Repeated Measures ANOVA, the independent and treatment variables included time at 3 different levels in 2001, 2006 and 2011; three different forest types—Core, Connected and Fragmented; 8 slope categories and 5 physiographic regions. Results: Results indicate that forest fragmentation has a significant impact on population sizes of Wood Thrush and Ovenbirds in Virginia and that recent changes in Virginia’s landscape have had negative impacts on the populations of these bird species. Specifically, slope characteristics that influence rates of urbanization are correlated with changes in bird populations. The Coastal Plain region in Virginia contributes significantly to the populations of both the Wood Thrush and Ovenbird currently. Main Conclusions: Core forests areas in Virginia are in decline and this process affects the populations and distributions of Ovenbird and Wood thrush in the state.

Using habitat-specific population trends to evaluate the consistency of the effect of species traits on bird population change