Population density and structure of a breeding bird community in a suburban habitat in the Cuvelai drainage system, northern Namibia

In a suburb (c. 100 ha) of Ongwediva, a total of 30 breeding bird species were recorded in 2018. Shannon’s Diversity Index was 2.01. Passer domesticus comprised almost half of all breeding pairs (36.4 pairs / 10 ha). Granivores were by far the most numerous feeding guild, comprising 77.5 % of all birds breeding. Birds nesting on/in buildings were represented by two species only, but they comprised almost half (49.9 %) of all breeding birds. In comparison with other southern African towns, the number of bird species breeding in Ongwediva was low. This was compensated by high population densities of some species.

Do Citizen Science Methods Identify Regions of High Avian Biodiversity?

Citizen science may offer a way to improve our knowledge of the spatial distribution of biodiversity and endemism, as the data collected by this method can be integrated into existing data sources to provide a more robust understanding of broad scale patterns of species richness. We explored whether data collected by citizen scientists agree on identifying regions of high avian species richness in a well-studied state. We compiled and examined the number of bird species detected in each of the 77 counties of Oklahoma based on published range maps, museum collections, and by five citizen science methods: the USGS Breeding Bird Survey, the Oklahoma Breeding Bird Atlas, eBird, the Oklahoma Winter Bird Atlas, and National Audubon Society Christmas Bird Counts. We also quantified the number of species of conservation concern recorded by each method in each county. A total of 460 species were reported across the state, with the total number of species detected by each method ranging from 40% of this total (Winter Bird Atlas) to 94% of this total (eBird). In general, species totals were poorly correlated across methods, with only six of 21 combinations (28.6%) showing significant correlations. Total species numbers recorded in each county were correlated with human population density and county area, but not with mean annual temperature or precipitation. The total number of species of conservation concern was correlated with the total number of species detected, county area, and precipitation. Most of the citizen science methods examined in this study were not explicitly designed to identify regions of high biodiversity and so efforts to use these methods for this purpose should be employed only cautiously and with a thorough understanding of potential biases.

On selection-regulated population dynamics in birds and mammals

I use the North American Breeding Bird Survey (Sauer et al. 2017) to construct 462 population trajectories with about 50 yearly abundance estimates each. Applying AIC model-selection, I find that selection-regulated population dynamics is 25,000 (95%:0.42-1.7e17) times more probable than density-regulated growth. Selection is essential in 94% of the best models explaining 82% of the population dynamics variance across the North American continent. Similar results are obtained for 111, 215, and 420 populations of British birds (BTO 2020), Danish birds (DOF 2020), and birds and mammals in the Global Population Dynamic Database (GPDD 2010). The traditional paradigm---that the population dynamic growth rate is a function of the environment, with maximal per-capita growth at low population densities, and sub-optimal reproduction from famine at carrying capacities with strong competition for limited resources---is not supported. Selection regulation generates a new paradigm where the world is green and individuals are selected to survive and reproduce at optimal levels at population dynamic equilibria with sufficient resources. It is only the acceleration of the population dynamic growth rate, and not the growth rate itself, that is determined by the density-dependent environment, with maximal growth occurring at the densities of the population dynamic equilibrium.

Bird community monitoring at Wilson’s Creek National Battlefield, Missouri: Status report 2008–2020

Breeding bird surveys were initiated on Wilson’s Creek National Monument, Missouri, in 2008 to assess temporal changes in the species composition and abundance of birds on the park and to improve our understanding of relationships between breeding birds and their habitat and the effects of management actions, such as invasive plant species control and tree thinning, on bird populations. Birds were sampled using point counts with 38 variable circular plots located on a systematic grid of 400 x 400-m cells (originating from a random start point). All birds seen or heard on a plot during a 5-min sampling period were recorded. In the 13 years since initiating our breeding bird survey, birds were surveyed on as many of the 38 variable circular plots as possible each year, resulting in 444 cumulative plot visits. Surveys have yielded records for 119 different species of birds. Ninety-eight of the species recorded are classified as permanent or summer residents to the area, 18 are classified as transients in the area, and 3 as winter residents to the area. Eight breeding species recorded are considered species of conservation concern for the Central Hardwoods Bird Conservation Region, the bird conservation region in which Wilson’s Creek National Battlefield is located. Of the 98 breeding species recorded, 12 species in grassland habitat and 15 in woodland habitat occurred in numbers large enough to calculate annual abundances with some degree of confidence. Trends in abundance were classified as uncertain for most species, which means that no significant increases or decreases occurred but it is not certain that trends were <5% per year. The Indigo Bunting (Passerina cyanea) population in grassland habitat was stable. The Eastern Towhee (Pipilo erythrophthalmus) and Eastern Wood-pewee (Contopus virens) populations in woodland habitat were in moderate decline. Comparing population trends on the park with regional trends for the Central Hardwoods Bird Conservation Region suggests that the bird community at Wilson’s Creek National Battlefield is faring similarly to that of the region as a whole. Stable diversity, richness, and evenness values suggest that the park’s habitat has remained consistent in its ability to meet the requirements of many of the park’s breeding bird species. Any decline in species richness could reflect habitat management practices, but it could also reflect the influences of larger-scale factors such as weather or climatic conditions on vegetation. Therefore, continued monitoring of birds and their habitats on Wilson’s Creek National Battlefield as management and weather and climatic conditions change is essential for park management.

Bird community monitoring at George Washington Carver National Monu-ment, Missouri: Status report 2008–2020

Breeding bird surveys were initiated on George Washington Carver National Monument, Missouri, in 2008 to assess temporal changes in the species composition and abundance of birds on the park and to improve our understanding of relationships between breeding birds and their habitat and the effects of management actions, such as invasive plant species control and tree thinning, on bird populations. Birds were sampled using point counts with 70 variable circular plots located on a systematic grid of 100 x 100-m cells (originating from a random start point). All birds seen or heard on a plot during a 5-min sampling period were recorded. In the 13 years since initiating our breeding bird surveys on the park, birds were surveyed on as many of the 70 variable circular plots as possible each year, resulting in 520 cumulative plot visits. Surveys have yielded records for 100 different species of birds. Ninety-seven of the species recorded are classified as permanent or summer residents to the area, two are classified as transients in the area, and one as a winter resident to the area. Six breeding species recorded are considered species of conservation concern for the Central Hardwoods Bird Conservation Region, the bird conservation region in which George Washington Carver National Monument is located. Of the 97 breeding species recorded, ten species in grassland habitat and six in woodland habitat occurred in numbers large enough to calculate annual abundances with some degree of confidence. Trends in abundance were classified as uncertain for most species, which means that there were no significant increases or decreases, but it is not certain that trends were < 5% per year. The Northern Cardinal (Cardinalis cardinalis) in woodland habitat was stable. The Eastern Meadowlark (Sturnella magna) in grassland habitat was in moderate decline, and the Northern Bobwhite (Colinus virginianus) in grassland habitat was in steep decline. Comparing population trends (i.e., changes in population size over time) on the park with regional trends for the Central Hardwoods Bird Conservation Region suggests that the bird community at George Washington Carver National Monument is faring similarly to that of the region as a whole. Trends in the park’s popula-tions of Field Sparrow (Spizella pusilla) and Indigo Bunting (Passerina cyanea) in grassland habitat and Carolina Wren (Thryothorus ludovicianus) in woodland habitat were uncertain, whereas they declined significantly in the larger region, which could be a result of management on George Washington Carver National Monument. Red-bellied Woodpecker (Melanerpes carolinus) population trends, while uncertain in grassland habitat on the park, increased significantly in the region. The Red-bellied Woodpecker utilizes trees for foraging, which are sparse in the grassland habitat on the park. Declining diversity and richness values suggest that park habitat is declining in its ability to meet the requirements of many of the park’s breeding bird species. This decline in species richness could reflect habitat management practices, but it could also reflect the influences of larger-scale factors such as weather or climatic conditions on vegetation. Therefore, continued monitoring of birds and their habitats on George Washington Carver National Monument as management and weather and climatic conditions change is essential for park management.

Features of formation bird population structure in Minsk in the time aspect

The structure of bird population of urbanized areas is determined by the diversity of habitats within the city, the diversity of bird species in suburban biotopes, and regional processes of dispersal of birds closely associated with human settlements. The analysis of the dynamics of the breeding bird species richness in Minsk showed that its formation progressed in different ways. All in all, since 1946, 141 bird species have been recorded nesting (including allegedly) in the territory of Minsk.The breeding bird assemblages is dominated by dendrophilous (45.0 % of all species) as well as wetland and semi-aquatic (29,3 %) bird species, with more than half of all the breeding bird species (50.3 %) associated with trees and shrubs. In different periods, the breeding bird species richness varied, by now, it has noticeably increased (from 77 to 132 species). This happened due to the expansion of the administrative boundaries of the city with the inclusion of bird species of suburban habitats, an increase in the diversity of habitats suitable for bird nesting (for example, the formation of large water bodies) as well as due to active colonization of urban ecosystems by various bird species. At the same time, after 2000, 9 bird species stopped nesting and 17 bird species started nesting. Active processes of synurbization of some bird species on the European continent observed in recent decades have become the reason for the addition of new species to the avifauna in Minsk, although the basis of the current structure of bird population was formed back in 1986–1999. At the same time, the synurbized groups of various bird species may be of autochthonous, allochthonous, or mixed origin.

Standardised empirical dispersal kernels emphasise the pervasiveness of long-distance dispersal in European birds

Dispersal is a key life-history trait for most species and essential to ensure connectivity and gene flow between populations and facilitate population viability in variable environments. Despite the increasing importance of range shifts due to global change, dispersal has proved difficult to quantify, limiting empirical understanding of this phenotypic trait and wider synthesis. Here we aim to estimate and compare empirical dispersal kernels for European breeding birds considering average dispersal, natal (before first breeding) and breeding dispersal (between subsequent breeding attempts), and test whether different dispersal properties are phylogenetically conserved. We standardised and analysed data from an extensive volunteer-based bird ring-recoveries database in Europe (EURING) by accounting for biases related to different censoring thresholds in reporting between countries and to migratory movements. Then, we fitted four widely used probability density functions in a Bayesian framework to compare and provide the best statistical descriptions of the average, the natal and the breeding dispersal kernels for each bird species. The dispersal movements of the 234 European bird species analysed were statistically best explained by heavy-tailed kernels, meaning that while most individuals disperse over short distances, long-distance dispersal is a feature in almost all bird species. The overall phylogenetic signal in both median and long dispersal distances was low (Pagel lambda < 0.40), implying a high degree of taxonomic generality in our findings. As expected in birds, natal dispersal was 5 Km greater as an average than breeding dispersal for most species (88% species analysed). Our comprehensive analysis of empirical kernels indicates that long-distance dispersal is common among European breeding bird species and across life stages. The dispersal estimates offer a first guide to selecting appropriate dispersal kernels in range expansion studies and provide new avenues to improve our understanding of the mechanisms and rules underlying dispersal events.

Temporal variation in the behaviour of a cooperatively breeding bird, Jungle Babbler (Argya striata) at diel and seasonal scale

Time is an important and limited resource that can drive the trade-off between various essential activities in the lives of animals. Group-living animals need to perform different behaviour to meet their individual needs and also participate in group activities. They must, therefore, partition the available time between these activities which may vary considerably with environmental and ecological conditions. We examined time-activity budget of a cooperative passerine, Jungle Babbler (Argya striata) and how their behaviour vary across diel and seasonal scales. A repertoire of 13 behaviour was recorded of which 12 behaviour that occur throughout the year were examined further in detail. This included individual behaviour such as foraging, grooming, rest, shower and group behaviour such as allogrooming, movement, play, sentinel, mobbing and inter-group fight. Our results indicate that most of the time (about 70%) was spent performing individual behaviour and the remaining time (about 30%) was allocated to social behaviour. We also found almost all behaviour varied across diel and seasonal scale with respect to proportion of time spent performing them. This highlights the impact of environmental factors on how animals partition their time to perform various activities. Our study also lays the foundation for future studies examining the role of ecological factors such as habitat type and predation pressure in driving these patterns of behaviour in Jungle Babblers.