Long-term species richness-abundance dynamics in relation to species departures and arrivals in wintering urban bird assemblages

Temporal dynamics of local assemblages depend on the species richness and the total abundance of individuals as well as local departure and arrival rates of species. We used urban bird survey data collected from the same 31 study plots and methods during three winters (1991–1992; 1999–2000 and 2009–2010) to analyze the temporal relationship between bird species richness and total number of individuals (abundance). We also evaluated local departures and arrivals of species in each assemblage. In total, 13,812 individuals of 35 species were detected. The temporal variation in bird species richness followed the variation in the total number of individuals. The numbers of local departure and arrival events were similar. Also, the mean number of individuals of the recently arrived species (8.6) was almost the same as the mean number of individuals of the departed species (8.2). Risk of species departure was inversely related to number of individuals. Local species richness increased by one species when the total abundance of individuals increased by around 125 individuals and vice versa. Our results highlight the important role of local population departures and arrivals in determining the local species richness-abundance dynamics in human-dominated landscapes. Local species richness patterns depend on the total number of individuals as well as both the departure-arrival dynamics of individual species as well as the dynamics of all the species together. Our results support the more individuals hypothesis, which suggests that individual-rich assemblages have more species

Urbanization and species occupancy frequency distribution patterns in core zone areas of European towns

More and more of the globe is becoming urbanized. Thus, characterizing the distribution and abundance of species occupying different towns is critically important. The primary aim of this study was to examine the effect of urbanization and latitude on the patterns of species occupancy frequency distribution (SOFD) in urban core zones of European towns (38 towns) along a 3850-km latitudinal gradient. We determined which of the three most common distributional models (unimodal-satellite dominant, bimodal symmetrical, and bimodal asymmetrical) provides the best fit for urban bird communities using the AICc-model selection procedure. Our pooled data exhibited a unimodal-satellite SOFD pattern. This result is inconsistent with the results from previous studies that have been conducted in more natural habitats, where data have mostly exhibited a bimodal SOFD pattern. Large-sized towns exhibited a bimodal symmetric pattern, whereas smaller-sized towns followed a unimodal-satellite dominated SOFD pattern. The difference in environmental diversity is the most plausible explanation for this observation because habitat diversity of the study plots decreased as urbanization increased. Southern towns exhibited unimodal satellite SOFD patterns, central European towns exhibited bimodal symmetric, and northern towns exhibited bimodal asymmetric SOFD patterns. One explanation for this observation is that urbanization is a more recent phenomenon in the north than in the south. Therefore, more satellite species are found in northern towns than in southern towns. We found that core species in European towns are widely distributed, and their regional population sizes are large. Our results indicated that earlier urbanized species are more common in towns than the species that have urbanized later. We concluded that both the traits of bird species and characteristics of towns modified the SOFD patterns of urban-breeding birds. In the future, it would be interesting to study how the urban history impacts SOFD patterns and if the SOFD patterns of wintering and breeding assemblages are the same

Differential Long-Term Population Responses of Two Closely Related Human-Associated Sparrow Species with Respect to Urbanization

Urban planning and management need long-term population level studies for evaluating how urbanization influences biodiversity. Firstly, we reviewed the current population trends of the House Sparrow (Passer domesticus) and the Eurasian Tree Sparrow (Passer montanus) in Europe, and evaluated the usefulness of citizens’ science projects to monitor these species in Finland. Secondly, we conducted a long-term (1991–2020) winter field study in 31 urban settlements along a 950 km north–south extent in Finland to study how latitude, weather and urbanization influence on sparrow’s growth rates. The House Sparrow is declining in 15 countries, and increasing in 5, whereas the Eurasian Tree Sparrow is declining in 12 and increasing in 9 European countries. The trend of the House Sparrow was significantly negative in continental Europe. However, the trend of the Eurasian Tree Sparrow was not significant. Both species have declined simultaneously in six countries, whereas in four countries, their trends are opposite. Citizen-based, long-term (2006–2020) winter season project data indicated that House Sparrow has decreased, whereas Eurasian Tree Sparrow has increased in Finland. However, the short-term (2013–2020) breeding season citizen-based project data did not indicate significant changes in the occupation rate of sparrows. Our long-term (1991–2020) field study indicated that wintering populations of the House Sparrow have decreased, whereas the Eurasian Tree Sparrows have both expanded their wintering range and increased their population size. Based on our winter count data, latitude and weather did not significantly influence the growth rates of sparrows. When the human population increased within the study plot, House Sparrow populations decreased, and vice versa. There was also a trend that a decreasing number of feeding sites has decreased the House Sparrow numbers. Urban-related factors did not influence the growth rate of the Eurasian Tree Sparrow. Our results indicate that the colonization of a new, even closely related species does not influence negatively on earlier urbanized species. It is probable that the niches of these sparrow species are different enough for allowing them to co-occur. The House Sparrow mainly nests on buildings, whereas the Eurasian Tree Sparrow can easily accept, e.g., nest boxes. Urban planning should take care of both the food availability and nest sites availability for both sparrow species

Long-Term Winter Population Trends of Corvids in Relation to Urbanization and Climate at Northern Latitudes

SIMPLE SUMMARY: Corvids (e.g., crows, magpies and jays) are an important part of urban settlements, especially during winter. To understand the factors affecting the long-term population trends of corvids, we counted wintering corvids in 31 human settlements along a 920 km latitudinal gradient in Finland during four winters between 1991 and 2020. We detected a total of five corvid species, from which the Hooded Crow, the Eurasian Magpie and the Eurasian Jackdaw were found to be common. During the study period, the number of Eurasian Jackdaws increased, and their distribution range moved northwards. No corresponding changes were observed for the Hooded Crow or the Eurasian Magpie. Neither the local-level urban-, climate- nor food-related factors correlated with the changes in the numbers and growth rates of the corvids. No interspecific interactions were observed. We assume that the Eurasian Jackdaw has benefitted from the decreased persecution, and probably also from the large-scale climate warming. Our results suggest that urban settlements are quite stable wintering environments for generalist and omnivorous corvids. ABSTRACT: Corvids (crows, magpies, jays) live in a close association with humans, and therefore knowledge about their population status and changes will be an essential part of monitoring the quality of urban environments. Wintering bird populations can track habitat and climate changes more rapidly than breeding populations. We conducted a long-term (1991–2020) winter census of corvid species in 31 human settlements along a 920 km latitudinal gradient in Finland. We observed a total of five corvid species: the Eurasian Magpie (occurring in 114 surveys out of 122; total abundance 990 ind.), the Hooded Crow (in 96 surveys; 666 ind.), the Eurasian Jackdaw (in 51 surveys; 808 ind.), the Eurasian Jay (in 5 surveys; 6 ind.) and the Rook (in 1 survey; 1 ind.). Only the numbers of the Eurasian Jackdaw differed between the study winters, being greater at the end of the study period (2019/2020) than during the earlier winters (1991/1992 and 1999/2000). The average growth rate (λ) of the Eurasian Jackdaw increased during the study period, whereas no changes were observed in the cases of the Hooded Crow or the Eurasian Magpie. The growth rate of the Eurasian Jackdaw was greater than that observed in the Finnish bird-monitoring work, probably because our data came only from the core area of each human settlement. Even though the number of buildings and their cover increased in the study plots, and the winter temperature differed between winters, the average growth rate (λ) of corvid species did not significantly correlate with these variables. These results suggest that urban settlements are stable wintering environments for the generalist corvids. The between-species interactions were all positive, but non-significant. Despite the total number of winter-feeding sites being greater during the winter of 1991/1992 than during the winter of 2019/2020, the changes in the numbers of feeding stations did not correlate with the growth rates of any corvid species. We assume that the Eurasian Jackdaw has benefitted from the decreased persecution, and probably also from large-scale climate warming that our study design was unable to take in to account. Our results indicated that wintering corvid populations succeed well in the human settlements in Finland. We recommend conducting long-term corvid research, also during breeding season, to understand more detailed causes of the population changes of corvids along an urban gradient. Without year-round long-term monitoring data, the conservation and management recommendations related to the corvid species in urban habitats may be misleading

Temporally Stable Species Occupancy Frequency Distribution and Abundance–Occupancy Relationship Patterns in Urban Wintering Bird Assemblages

Urbanization is negatively affecting biodiversity worldwide, and general ecological patterns may also differ between urban and more natural areas. The main aim of this study was to examine if urbanization has effects on the wintering species occupancy frequency distribution (SOFD) and species abundance–occupancy relationship (SAOR), and if the observed patterns varied between winters, different sizes of towns, and regionally in Finland. In this study, temporal variation of the SOFD and SAOR patterns was studied in 29 town and village centers along a 950-km (60–68°N) latitudinal gradient during mid-winters in Finland. Wintering birds were counted during three winters (1991–1992, 1999–2000, and 2009–2010) from the same study sites and with the same survey methods. A total of 35 wintering bird species and 13,285 individuals were detected. The bimodal symmetric SOFD pattern explained best the distribution of species in the pooled data, and the observed pattern was constant between the study winters, different sizes of towns, and towns located in southern and northern Finland. Three species (Parus major, Pica pica, and Passer domesticus) were core species during all winters, irrespective of the size of town or latitude. There was a slightly higher number of species belonging in satellite species group in the southern than in the northern towns. No changes of species from the core to satellite species were detected, and vice versa. However, the occupancy rate of some species belonging to the intermediate species group either moved toward satellite species or core species across winters. The SAOR pattern was positive and stable over study winters and did not differ between different sizes of towns or town location. Our results indicated that urbanization leads a structure of winter bird community, where there are few widely distributed sedentary core species and many partially migratory or migratory satellite species with a restricted distribution. Our results also demonstrated that urbanization stabilizes between-winter community structure, probably because of intensive winter feeding activities. Our results give support to the metapopulation model, which predicts a bimodal SOFD pattern

Spatial and temporal changes in occupancy frequency distribution patterns of freshwater macrophytes in Finland

A useful method for characterizing biological numerous assemblages at regional scales is the species occupancy frequency distribution (SOFD). An SOFD shows the number or proportion of study sites each species occurred. Species that occur at only a few sites are termed satellite species, while species that occur at many sites are termed core species.This study is the first to document and assess SOFD patterns in aquatic macrophytes. It characterizes SOFD patterns of freshwater macrophyte assemblages in Finland at two spatial and two temporal scales. For this, I analyzed three published datasets on freshwater macrophyte distributions: two from studies conducted at a local scale and the third from large national surveys. One local study and the national study also included data on temporal variation in species occupancy frequencies.In the national study, the number of core and satellite species varied slightly between the older and the newer survey, respectively. Among the 113 waterbodies surveyed as part of the national study, the SOFD followed a unimodal satellite pattern. However, for the older dataset (from the 1930s), a bimodal symmetric pattern also fit the SOFD data well. At the local scale, I observed geographical variation in SOFD patterns. The dataset from southern Finland followed a unimodal satellite SOFD pattern; data from central Finland instead displayed a bimodal symmetric SOFD pattern, although they also fit equally well with a bimodal truncated pattern. Moreover, temporal patterns in central Finland seemed to demonstrate a shift from a bimodal symmetric to a bimodal asymmetric SOFD probably.Geographical variation in the SOFD pattern may be due to variation in the regional species pool. The temporal changes in SOFD pattern may be due to lake eutrophication and anthropogenic disturbance around waterbodies, which may increase number of macrophyte species.</p

Designs for the Quality of Service Support in Low-Energy Wireless Sensor Network Protocols

A Wireless Sensor Network (WSN) consists of small, low cost, and low energy sensor nodes that cooperatively monitor physical quantities, control actuators, and perform data processing tasks. A network may consist of thousands of randomly deployed self-configurable nodes that operate autonomously to form a multihop topology. This Thesis focuses on Quality of Service (QoS) in low-energy WSNs that aim at several years operation time with small batteries. As a WSN may include both critical and non-critical control and monitoring applications, QoS is needed to make intelligent, content specific trade-offs between energy and network performance. The main research problem is defining and implementing QoS with constrained energy budget, processing power, communication bandwidth, and data and program memories. The problem is approached via protocol designs and algorithms. These are verified with simulations and with measurements in practical deployments. This Thesis defines QoS for WSNs with quantifiable metrics to allow measuring and managing the network performance. The definition is used as a basis for QoS routing protocol and Medium Access Control (MAC) schemes, comprising dynamic capacity allocation algorithm and QoS support layer. Dynamic capacity allocation is targeted at reservation based MACs, whereas the QoS support layer operates on contention based MACs. Instead of optimizing the protocols for a certain use case, the protocols allow configurable QoS based on application specific requirements. Finally, this Thesis designs sensor self-diagnostics and diagnostics analysis tool for verifying network performance. Compared to the related proposals on in-network sensor diagnostics, the diagnostics also detects performance problems and identifies reasons for the issues thus allowing the correction of problems. The results show that the developed protocols allow a clear trade-off between energy, latency, throughput, and reliability aspects of QoS while incurring a minimal overhead. The feasibility of results for extremely resource constrained WSNs is verified with the practical implementation with a prototype hardware platform having only few Million Instructions Per Second (MIPS) of processing power and less than a hundred kBs data and program memories. The results of this Thesis can be used in the WSN research, development, and implementation in general. The developed QoS definition, protocols, and diagnostics tools can be used separately or adapted to other applications and protocols

Differential Long-Term Population Responses of Two Closely Related Human-Associated Sparrow Species with Respect to Urbanization

Urban planning and management need long-term population level studies for evaluating how urbanization influences biodiversity. Firstly, we reviewed the current population trends of the House Sparrow (Passer domesticus) and the Eurasian Tree Sparrow (Passer montanus) in Europe, and evaluated the usefulness of citizens’ science projects to monitor these species in Finland. Secondly, we conducted a long-term (1991–2020) winter field study in 31 urban settlements along a 950 km north–south extent in Finland to study how latitude, weather and urbanization influence on sparrow’s growth rates. The House Sparrow is declining in 15 countries, and increasing in 5, whereas the Eurasian Tree Sparrow is declining in 12 and increasing in 9 European countries. The trend of the House Sparrow was significantly negative in continental Europe. However, the trend of the Eurasian Tree Sparrow was not significant. Both species have declined simultaneously in six countries, whereas in four countries, their trends are opposite. Citizen-based, long-term (2006–2020) winter season project data indicated that House Sparrow has decreased, whereas Eurasian Tree Sparrow has increased in Finland. However, the short-term (2013–2020) breeding season citizen-based project data did not indicate significant changes in the occupation rate of sparrows. Our long-term (1991–2020) field study indicated that wintering populations of the House Sparrow have decreased, whereas the Eurasian Tree Sparrows have both expanded their wintering range and increased their population size. Based on our winter count data, latitude and weather did not significantly influence the growth rates of sparrows. When the human population increased within the study plot, House Sparrow populations decreased, and vice versa. There was also a trend that a decreasing number of feeding sites has decreased the House Sparrow numbers. Urban-related factors did not influence the growth rate of the Eurasian Tree Sparrow. Our results indicate that the colonization of a new, even closely related species does not influence negatively on earlier urbanized species. It is probable that the niches of these sparrow species are different enough for allowing them to co-occur. The House Sparrow mainly nests on buildings, whereas the Eurasian Tree Sparrow can easily accept, e.g., nest boxes. Urban planning should take care of both the food availability and nest sites availability for both sparrow species.</p

Long-Term Winter Population Trends of Corvids in Relation to Urbanization and Climate at Northern Latitudes

Simple Summary Corvids (e.g., crows, magpies and jays) are an important part of urban settlements, especially during winter. To understand the factors affecting the long-term population trends of corvids, we counted wintering corvids in 31 human settlements along a 920 km latitudinal gradient in Finland during four winters between 1991 and 2020. We detected a total of five corvid species, from which the Hooded Crow, the Eurasian Magpie and the Eurasian Jackdaw were found to be common. During the study period, the number of Eurasian Jackdaws increased, and their distribution range moved northwards. No corresponding changes were observed for the Hooded Crow or the Eurasian Magpie. Neither the local-level urban-, climate- nor food-related factors correlated with the changes in the numbers and growth rates of the corvids. No interspecific interactions were observed. We assume that the Eurasian Jackdaw has benefitted from the decreased persecution, and probably also from the large-scale climate warming. Our results suggest that urban settlements are quite stable wintering environments for generalist and omnivorous corvids. AbstractCorvids (crows, magpies, jays) live in a close association with humans, and therefore knowledge about their population status and changes will be an essential part of monitoring the quality of urban environments. Wintering bird populations can track habitat and climate changes more rapidly than breeding populations. We conducted a long-term (1991-2020) winter census of corvid species in 31 human settlements along a 920 km latitudinal gradient in Finland. We observed a total of five corvid species: the Eurasian Magpie (occurring in 114 surveys out of 122; total abundance 990 ind.), the Hooded Crow (in 96 surveys; 666 ind.), the Eurasian Jackdaw (in 51 surveys; 808 ind.), the Eurasian Jay (in 5 surveys; 6 ind.) and the Rook (in 1 survey; 1 ind.). Only the numbers of the Eurasian Jackdaw differed between the study winters, being greater at the end of the study period (2019/2020) than during the earlier winters (1991/1992 and 1999/2000). The average growth rate (lambda) of the Eurasian Jackdaw increased during the study period, whereas no changes were observed in the cases of the Hooded Crow or the Eurasian Magpie. The growth rate of the Eurasian Jackdaw was greater than that observed in the Finnish bird-monitoring work, probably because our data came only from the core area of each human settlement. Even though the number of buildings and their cover increased in the study plots, and the winter temperature differed between winters, the average growth rate (lambda) of corvid species did not significantly correlate with these variables. These results suggest that urban settlements are stable wintering environments for the generalist corvids. The between-species interactions were all positive, but non-significant. Despite the total number of winter-feeding sites being greater during the winter of 1991/1992 than during the winter of 2019/2020, the changes in the numbers of feeding stations did not correlate with the growth rates of any corvid species. We assume that the Eurasian Jackdaw has benefitted from the decreased persecution, and probably also from large-scale climate warming that our study design was unable to take in to account. Our results indicated that wintering corvid populations succeed well in the human settlements in Finland. We recommend conducting long-term corvid research, also during breeding season, to understand more detailed causes of the population changes of corvids along an urban gradient.Without year-round long-term monitoring data, the conservation and management recommendations related to the corvid species in urban habitats may be misleading.</p