Bird Population Density Research Articles

Diversity and population density of birds at the Jahangirnagar University campus, Bangladesh

Rapid urbanization is changing the habitats of many wildlife species. Even so, certain species appear to adapt and now have thriving populations within cities. To look at the capacity for these spaces to provide “habitat” we examined population density of bird species using Jahangirnagar University campus close to the Dhaka mega city, Bangladesh. Four strip transects were surveyed from March 2008 to February 2009 (12 times/transect). A total of 101 species were found along the transect areas. The density of Lesser Whistling Duck (Dendrocygna javanica) was the highest 107.02indiv. /ha while Large-tailed Nightjar (Caprimulgus macrurus) was the lowest 0.01indiv. /ha among resident birds of Jahangirnagar University campus. Among the migratory birds, the density of Pintail Snipe (Gallinago stenura) and Common Stonechat (Saxicola torquata) were the highest (1.99indiv. /ha.) and the lowest (0.02indiv. /ha.), of the different available habitats, water bodies contained the highest density (318.59indiv. /ha) and grassland contained the lowest (2.48indiv./ha) of bird population. The percentage of average density of non-passerine and passerine birds was 65% and 35%, respectively. Future studies of avian composition and density is recommended at a regular interval to understand changes in the carrying capacity and avian community of the campus as a function of altering habitat due urbanization.
 Bangladesh J. Zool. 48(2): 289-300, 2020

Nutrient enrichment and trace element accumulation in sediments caused by waterbird colonies at a Mediterranean semiarid floodplain.

Waterfowl are vectors of nutrients, metals, and other pollutants (i.e. PCBs and microorganisms) on wetlands and other water bodies, especially when bird population density is high, e.g., in nesting, roosting or breeding periods. This work reports the effects caused by the increase in breeding pairs of herons and cormorants between 2010 and 2014 on sediments in an eutrophic Mediterranean wetland belonging to La Mancha Húmeda Biosphere Reserve. Nutrients, metals, metalloids, and isotopic composition (δ15N and δ13C) were analysed in sediments and faeces at several points in the Tablas de Daimiel National Park (TDNP), as well as in the nearby Navaseca wetland, which receives inputs from a wastewater treatment plant (WWTP). Sediments from Navaseca and from one site that is affected by heron colonies (Garcera) in the TDNP showed higher concentrations of organic matter, total organic carbon, total nitrogen, total phosphorus, Al, Co, Cu, Cr, Fe, Ni and Zn than the rest of the sampling sites. Significant correlations between these variables were found, probably suggesting that they have a common organic source. The highest δ15N values in sediments of the TDNP were registered in Guadiana, a site where there is no impact from colonies; these values might therefore be due to anthropogenic activities. Metal and metalloid content in sediments was lower than the regional reference values in soils, except for Se in the TDNP, and Zn and Cu in Navaseca. High Se level in TDNP sediment may be caused by seleniferous soils located upstream. Results showed a low impact of bird droppings compared to other sources of nutrients in the annual input in the TDNP.

Impacts of windstorm-induced forest loss and variable reforestation on bird communities

With climate change, the area affected by and the intensity of forest disturbances such as windthrow, insect outbreaks and fire will be increasing. Post-disturbance forest management will be varied, and it is difficult to predict how much natural succession will be allowed in comparison to reforestation. Both, disturbance and reforestation will affect forest biodiversity globally, but potential shifts in species distribution, abundance and community composition are poorly understood.We studied the response of breeding bird communities to windstorm-induced forest loss (windthrow followed by salvage logging) and different reforestation strategies in one of Central Europe’s largest contiguous windthrow areas created by storm Kyrill in 2007. A decade after the disturbance, we compared bird species diversity, population densities and community composition on plots in replanted beech, replanted conifers and secondary succession (all salvage-logged after the storm), with undisturbed mature (ca. 50–80 years old) Norway spruce Picea abies as a control, in the setting of a natural experiment.Of the stands blown down, 95% were Norway Spruce. Reforestation strategies varied, with Spruce and non-native conifers planted on twice the area that was replanted with European Beech Fagus sylvestris. Large areas were still dominated by successional tree species a decade after the storm, especially birch Betula spp., mirroring recommendations of sub-national forestry agencies to include secondary succession in future forest development. Birds responded strongly to windstorm-induced forest loss, with a pronounced community turnover. Species associated with high conifer stands reached significantly lower densities on sample plots in disturbed areas. Replanted areas were characterized by mostly ubiquitous bird species. Areas dominated by secondary succession, especially birch, were characterized by high densities of long-distance migrants (often species of conservation concern) and shrubland species, among them several indicator species.Our results suggest that an increase of forest disturbance across Central Europe will lead to a pronounced reorganisation of biodiversity. Strategies that allow more secondary succession, and avoid replanting allochthonous tree species are likely to benefit populations of depleted bird species, even at salvage-logged and cleared disturbance sites.

Varied abundance and functional diversity across native forest bird communities in the Mariana Islands

The Mariana islands have a species-poor but functionally diverse and largely endemic bird assemblage that varies due to biogeographic legacy and anthropogenic impacts. The largest island in the chain, Guam, is the setting for one of the most extreme examples of recent avian population declines, indicating the capacity for avifaunal collapse and loss of function in neighboring islands. We performed a systematic survey of resident land birds in remnant karst forest on the Mariana Islands' 3 largest islands following Guam to assess the status of the avifauna in this habitat, characterize inter-island heterogeneity in bird communities, and consider the resulting differences in the functional roles of birds across the archipelago's native forests. We identified significantly greater functional diversity on Rota than either Saipan or Tinian, but lower bird population densities, species richness, and Shannon diversity. We recommend continued monitoring of avian population trends across the archipelago and assessments of ecosystem functions like pollination, seed dispersal, and food web dynamics.

Anthropogenic impacts on the composition and population density of migratory and resident birds of selected wetlands sectors in northern Nigeria

In recent times, there has been decrease in the number of migratory and resident birds in Hadejia-Nguru Wetlands in Nigeria. This, no doubt, is a subject of concern to conservationist and the country at large. The effect of anthropogenic activities on the composition and population density of migratory and resident birds in Hadejia-Nguru Wetlands, Nigeria, were undertaken for a period of two months. Point-count method was used in data collection in two sectors of the wetlands: Ox-Bow Lake and Marma Channel. Visual observation and interaction with the locals around the wetlands were used to assess the level of anthropogenic influences and scored on a scale of 0-5. Forty-five species of migratory and resident birds were recorded of which 25 were resident while 14 and 6 were migratory and Afro-migrant respectively. A total of 32,442 and 2,218 individual birds were recorded in Ox-Bow Lake and Marma Channel respectively. Garganey (Anas querquedula) was the highest recorded species during the survey and it was preponderant in Ox-Bow Lake. Garganey was also more densely populated (903.76 birds/hectares). Canonical correspondence analysis showed that washing/bathing and open defecation negatively affected the composition of Anas querquedula and Anas acuta. The study revealed Hadejia-Nguru Wetlands to be under threat. Therefore, appropriate enforcement of laws guiding migratory birds in Nigeria is hereby recommended.
 Keywords: Anthropogenic activities; bird population density; migratory birds; Garganey (Anas querquedula); Hadejia-Nguru Wetlands; Nigeria

Species structure of the bird communities of the middle Uzh river flow in Zakarpattia province of Ukraine in the nesting period

The article analyzes characteristics of the species structure of the bird communities in the middle Uzh river valley in the breeding period by the ratio of the number of species and their abundance, the shares of dominant, background and rare species, the types of nesting and feeding, landscape and ornitho-geographic aspects. The main factors for the formation of the species diversity and the peculiarities of the species structure of bird communities have been identified.The goal of the study was to investigate and analyze the species structure of bird communities to determine the intensity of the urbanization impact onto the natural ecosystems in this segment of the Uzh valley.Material and Methods. Data were collected during the 2016-2018 years during nesting periods. The bird censuses were conducted by the route method, followed by processing of the collected data.Results and discussion. Within the study period, 71 bird species have been identified here. The bird population density is 839.64 ind./km2. Birds of forest landscapes (47.9%) are dominant. Tree-nesting (in crowns, hollows, and shrubs) birds composed in total 60.6%. The share of zoophagous birds is 57.7%. By the fauna type, trans-Palearctic species are dominant: 42.3%.By the fauna type, transpalearctic species are dominant (42.3). The urbanization of the Uzh valley is evidenced by the presence of a group of synanthropic bird species, which are inseparably linked to rural settlements, located along the river (share of all species - 12.7%, share of total bird population - 17.15%).Conclusions. The species structure of birds communities during the nesting season in the middle Uzh river flow evidences that the impact of urbanization on natural ecosystems of the river valley is low despite the close location of villages

Population density and structure of birds breeding in an urban habitat dominated by large baobabs (Adansonia digitata), Northern Namibia

Large baobabs are regarded as key plant species in the savannah biome. In this study their role in shaping the avian community has been evaluated. The territory mapping method has been employed to quantify the avian breeding community in the town Outapi (ca. 130 ha), Northern Namibia, well-endowed with large baobabs. A total of 29 breeding bird species were recorded. The alien House Sparrow was by far the most numerous species comprising 48.4% of all breeding birds. The Blue Waxbill and African Palm Swift were also classified as dominant species, comprising together 17.4%. Granivores were by far the most numerous feeding guild, comprising 77.2% of all birds breeding, while the insectivores comprised only 11.8%. Birds nesting in/on buildings comprised 52.7%, those nesting on trees/shrubs – 42.0%. The population densities of many bird species (e.g. doves from the genus Stepropelia, bulbuls, weavers) were comparatively low. Such a situation could have been caused by the exceptionally high population density of the Pied Crow. In the study area, there were 15 breeding pairs and about 100–150 non-breeding individuals. The baobabs may provide them with a feeding resource in the form of the sweet fruits. The crows, as nest predators, feed also on the eggs and nestlings of other birds. Doves seem to be especially prone to such predation, as their nests are easily to detect and destroy. As a result, they have to breed in low density. This in turn, may release other dominant granivores in the study area, namely sparrows. They are not vulnerable to crow nest predation, as their nests are usually well-concealed under eaves and in holes of buildings.

Landscape–Ecological Trends of Spatial Changes in the Bird Communities of Central Siberia

Population density, species richness, and total biomass of birds in Central Siberia increase toward the south. The greatest values are noted in terrestrial natural landscapes: for the total abundance of birds, they are in the southern forest type of communities; for species richness, they are in the meadow–field type; and for total biomass, they are in the subarctic plain–tundra type. In industrial–technogenic and southern residential types, the density and biomass of bird communities increase and the species richness decreases in comparison with natural ornithocomplexes. In aquatic habitats, the total abundance of birds and their species richness decrease and biomass increases when compared with terrestrial ones. The representation of types of fauna in bird communities (by number of individuals) is determined by the zones of their landscape preference, which have ecological similarity with the areas of their formation. Since birds actively choose tiers with the most favorable thermal, trophic, and protective conditions, their vertical biotopic distribution to some extent does not correspond to the tier structure of their habitats.

Modeling the population impacts of avian malaria on Hawaiian honeycreepers: Bifurcation analysis and implications for conservation

Avian malaria is a mosquito-borne parasitic disease of birds caused by protists of the genera Plasmodium, most notably Plasmodium relictum. This disease has been identified as a primary cause of the drastic decline and extinctions of birds, in particular Hawaiian honeycreepers (Drepanidinae), where rates of mortality may exceed 90%. We formulate an epizootiological model of the transmission dynamics of avian malaria between populations of bird hosts and mosquito vectors using a system of compartmental ordinary differential equations. We derive the basic reproduction number as well as criteria for the existence and local stability of disease-free and enzootic equilibria. These results provide useful information for evaluating management strategies. A local sensitivity analysis of certain model invariants to uncertain parameter values is performed to ascertain which biological factors have the largest impact on ecological outcomes and, in particular, long-term bird population densities. We discuss and compare the effectiveness of two disease control and conservation strategies: captive propagation of honeycreepers and larval mosquito habitat reduction. We provide examples of combinations of these strategies that either are predicted to eliminate enzootic avian malaria or to increase predicted bird density above a given ecologically meaningful threshold.

Diversity and population densities of coraciiform birds in Zambezi riparian forest

A territory mapping method was used in 2015 to assess the population density of coraciiform species breeding in a riparian forest on the Zambezi River near Katima Mulilo, NE Namibia. The forest, c. 280 ha in surface area, was partly transformed by human settlement and arable grounds. A total of 13 species and 42 breeding pairs were recorded. Population densities were (pairs/100 ha) as follows: grey–headed kingfisher 4.3; giant, pied and woodland kingfisher, each one with 1.1; malachite kingfisher 0.7; striped kingfisher 0.4; white–fronted bee–eater 1.4; little bee–eater 1.1; lilac–breasted roller 0.7; broad–billed roller 1.1; African hoopoe 0.7; red–billed wood–hoopoe 1.1; and scimitar–billed wood–hoopoe 0.4. Data published through GBIF (Doi: 10.15470/s9rlud).

Avifauna of Mountains in Northeastern Siberia

This study analyzes the ecological patterns of the altitudinal belts of differentiation of avian fauna and population in the mountains of northeastern Siberia. Data were collected during expeditions conducted in the summers of 2014–2016 in regions with distinct forest, subalpine, and alpine altitudinal belts. There are 150 species of breeding avifauna in the region. We have specified the distribution ranges of 26 bird species. Avifauna of the northeastern Siberia mountains develops in a framework of general zonal–landscape and altitudinal zonal patterns. The species diversity of birds decreases in the northern direction and from foothills to the mountain tops. The forest belt, subalpine belt, and alpine belt are breeding areas of 63–64 species (89–97%), 13–33 species (20–47%), and 8–15 species (12–21%), respectively. The wide vertical distribution of many bird species predetermines great general biodiversity, even in high-altitude belts with extreme environment conditions. In the northeastern Siberia mountains, the population density of birds and their abundance progressively decrease with altitude in most species. The bird population density is 312–594 ind./km2 for the forest belt, 57–266 ind./km2 for the subalpine belt, and 40–111 ind./km2 for the alpine belt.

Effect of anthropogenic light on bird movement, habitat selection, and distribution: a systematic map protocol

BackgroundAnthropogenic light is known or suspected to exert profound effects on many taxa, including birds. Documentation of bird aggregation around artificial light at night, as well as observations of bird reactions to strobe lights and lasers, suggests that light may both attract and repel birds, although this assumption has yet to be tested. These effects may cause immediate changes to bird movement, habitat selection and settlement, and ultimately alter bird distribution at large spatial scales. Global increases in the extent of anthropogenic light contribute to interest by wildlife managers and the public in managing light to reduce harm to birds, but there are no evidence syntheses of the multiple ways light affects birds to guide this effort. Existing reviews usually emphasize either bird aggregation or deterrence and do so for a specific context, such as aggregation at communication towers and deterrence from airports. We outline a protocol for a systematic map that collects and organizes evidence from the many contexts in which anthropogenic light is reported to affect bird movement, habitat selection, or distribution. Our map will provide an objective synthesis of the evidence that identifies subtopics that may support systematic review and knowledge gaps that could direct future research questions. These products will substantially advance an understanding of both patterns and processes associated with the responses of birds to anthropogenic light.MethodsThe protocol describes the steps taken to ensure the search for evidence is comprehensive, transparent and replicable. We will find relevant studies in the grey and peer-reviewed literature using publication databases, Google Scholar, stakeholder suggestions, and organizational websites. We will select studies for inclusion in the map by identification of relevant: (i) population including any species of bird; (ii) intervention or exposure to anthropogenic light; and (iii) outcomes including changes in bird movement, habitat occupancy, population density, or distribution. We will extract and organize metadata into a systematic map that can support subsequent search by interested individuals. The quantity of evidence on particular topics will be characterized through heat maps and narrative syntheses, but subsequent work will be needed to evaluate evidence validity.

Wind turbines in high quality habitat cause disproportionate increases in collision mortality of the white-tailed eagle

The increasing number of wind farms for energy production raises concerns about their effects on wildlife and particularly on birds. To date it is unclear whether models that combine data on wind turbine densities and habitat suitability can explain the actual spatial occurrence of collision fatalities and how well these models perform in comparison to models including measures of bird population densities (e.g., the distribution and density of nest sites). Here we analysed whether collision mortality increases with wind turbine density and whether a high population density or habitat suitability in the vicinity of wind turbines amplifies the effect of wind turbine density on collision mortality. We combined opportunistic records of dead White-tailed Eagles by the public in Northeast Germany during the period 2003 to 2014 with data on the distribution of wind turbines, nest sites and habitat suitability. As expected, wind turbine density was a strong predictor of collision mortality. In addition, we found that wind turbine density and habitat suitability had synergistic effects on collision mortality, so that the effect of wind turbine density was amplified in areas of high habitat suitability. Moreover, combining wind turbine density and habitat suitability allowed for better predictions of collision mortality than combining wind turbine density and nest site density. These results suggest that assessments of the spatial occurrence of collision fatalities based on models that combine data on wind turbine densities and habitat suitability can be useful for the strategic planning of wind farm development on regional scales. In particular, our study highlights that wind turbines should not be placed in core population areas of vulnerable bird species because synergies between wind turbine densities and habitat suitability may cause disproportionate increases in mortality. This might undermine the positive effects of parallel conservation efforts.

The consequences of land sparing for birds in the United Kingdom

Abstract Land sparing has been proposed as a strategy to reconcile biodiversity conservation with agricultural production, with empirical studies on five continents indicating that most species would benefit if food demand was met through high‐yield farming combined with the protection or restoration of natural habitat. Most such studies come from landscapes covered by large areas of natural habitat and without a long history of intense human modification. However, much of Europe consists of human‐dominated landscapes, where biodiversity responses to land sparing may differ. To test this, we use estimates of bird population density in different (semi‐)natural habitats, and forecasts of population density in farmland habitat, to assess the future consequences for birds of land‐sparing scenarios in the United Kingdom. Our scenarios predict that whilst up to 18 of the 156 species assessed (predominantly farmland associated species) might decline in UK conservation status under land sparing, up to 35 UK bird species (mainly woodland and wetland species) might improve in status. This contrasts with a maximum of eight species likely to improve in conservation status without land sparing, with up to seven species deteriorating. Combining land sparing with demand management measures (reducing food waste and the consumption of animal products) led to more positive population changes under all scenarios. Synthesis and applications. Land sparing has the potential to benefit UK bird populations in aggregate but would likely have negative impacts on farmland bird species. These findings are likely to be applicable across human‐dominated landscapes beyond the UK, though effects on other taxa, implementation mechanisms and the sustainability of higher yields all require careful consideration.

Comparative urbanization of birds in China and Europe based on birds associated with trees.

Urbanization effects on living organisms are spatially heterogeneous. Here we quantified the abundance of birds per tree in forested urban and rural habitats for 85,829 trees mainly in China and Europe. A population model was based on the assumption that: 1) birds have a normally distributed habitat preference; 2) an increase in population size linked to the habitat preference; 3) a population size dependent on the habitat preference; and 4) the removal of a certain fraction of individuals giving rise to extinction. We tested for large-scale differences in the impact of urbanization on the frequency distribution of the difference in abundance between urban and rural habitats in China and parts of Europe. The difference in the frequency distribution of urban population density of birds in trees minus rural population density of birds in trees in China and Europe was statistically significant, suggesting that the abundance of birds differed between trees in urban and rural habitats, but more so in China than in Europe. We hypothesize that more pronounced differences in China than in Europe may have arisen due to the Four Pests Campaign in 1958–1962 that resulted in death of hundreds of millions of birds (mainly tree sparrows Passer montanus, but also numerous other less common species that were starting to become urbanized around 1960). Species that were less common in 1960 could not sustain reductions in population size in urban areas and hence these species are still rare or absent in urban areas today 60 years later.

Fenced sanctuaries deliver conservation benefits for most common and threatened native island birds in New Zealand

AbstractIsland species are disproportionately threatened with extinction, and invasive species are the primary driver of biodiversity loss. Globally, eradicating invasive mammals from small oceanic islands has led to the recovery of threatened populations, but eradicating mammals from large islands and continents is more challenging. In New Zealand, conservation organizations have established a large network of fenced sanctuaries that use predator‐proof fencing to exclude invasive mammals and conserve native flora and fauna. Yet, critics question if sanctuaries meet these targets, given a lack of evidence on outcomes. We surveyed birds in three sanctuaries and three paired sites on New Zealand's North Island to investigate whether sanctuaries increase bird population densities relative to sites with minimal mammal control. Densities of nine endemic bird species were higher in sanctuaries compared to unprotected sites (0.27–9.00 more birds/ha), but we found no significant difference in mean population densities for introduced and biogeographically recent native species. These findings provide compelling evidence that fenced sanctuaries effectively conserve native island bird populations, and affirm predictions that native species are more likely to benefit from invasive mammal eradications than introduced species. New Zealand's novel approach to recovering rare species holds great promise for conserving biota at risk from invasion in other global hotspots of endemism.

Sound localization for estimating population densities of birds: Progress, challenges, and opportunities

Autonomous recording units (ARUs) are seeing rapid adoption as a research tool to estimate population densities of birds. One challenge for estimating population density is that the distance to the vocalizing bird is unknown. An emphasis has been placed on assessing the detection radius for different species on ARUs, and more recent work has had success relating sound amplitude to distance. We argue, however, that the true variable of interest is not density, per se, but the relationship between density and habitat type or other variables. In an ideal world, ARUs would collect information on the absolute location of each sound source, rather than the number of each species within earshot of the microphone, since the detection radius of an ARU commonly encompasses multiple habitat types. Sound localization is a promising solution to this problem, with some localization methods allowing sound sources to be pinpointed within 1m of their true location. We will present localization results comprising several thousand songs from several species in the Boreal forest, to highlight how localization data can be translated into estimates of population density. We will also highlight several challenges and opportunities for future contributions in the field of sound localization.

Birds in boreal protected areas shift northwards in the warming climate but show different rates of population decline

Climate change has the potential to have wholesale impacts on species populations, driving them polewards and upwards, and even affecting populations occurring within protected area (PA) networks. We studied population changes in bird species in the boreal PA network of Finland based on extensive bird census data collected in the years 1981–1999 and in 2000–2017. Between these time periods, the mean annual temperature increased in Finland by 1.1 °C, and the mean weighted density of the species shifted 28.5 km (1.8 km/year) northwards in the PA network. However, the total bird population density simultaneously declined by approximately 10%. The decline was most pronounced in long-distance migrants, which showed strongest population contraction in southern boreal regions. In contrast, resident species increased between the two time slices, particularly in larger PAs. While the PA network of boreal native habitats appears to be successful in preserving resident species, climate-induced changes have also caused a decline in the populations of migrants in the PAs. Thus, life-history characteristics of species can significantly affect the success of conservation efforts in a warming climate. To enhance future survival of resident and migrant bird species moving to Finland and northwards, the PAs should be larger and the connectivity of the PA network improved in southern and central Finland. In addition, international actions are needed to enhance the survival of long-distance migrants during the migratory period and in overwintering grounds.

Importance of Old Forest Stands for Diversity of Birds in Managed Pine Forests – A Case Study from Augustów Forest (NE Poland)

We assessed the assemblages of birds inhabiting pine-dominated managed forest, aged between 1–5 years and above 140 years. Birds were counted on study plots representing eight different phases to the forest's development, with nesting, foraging and migratory guild categories recognised. Numbers of bird species and population densities, both increased markedly with stand age (respectively r = 0.988 and r = 0.936, P < 0.001). While numbers of ground-nesting bird species failed to correlate with stand age, successively older stands did support ever-greater proportions of species in the assemblage that nested in tree crowns (r = 0.976, P < 0.005) or tree holes (r = 0.833, P < 0.005). Raptors were most abundant in forest at the oldest stages of growth, and there was an age-gradient-related increase in the shares of both plant-eating species (r = 0.952, P < 0.005) and raptors (r = 0.764, P < 0.005). Resident birds were most numerous in the oldest forest. PCA for ten selected variables (relating to guild type) showed that the two principal components explained almost 98% of the variation among groups of bird guilds in relation to forest age. On the basis of their suitability for birds it was possible to distinguish three categories of stand by age group, of which the first encompasses the initial stage, the second a broad interval involving middle-aged stands of between 16 and 140 years, and the third forest more than 140 years old. The presence of the oldest stands of all can thus be seen to play a very important role in maintaining high-diversity populations of birds in managed forest.

The dynamics of fauna and population of birds in agricultural landscapes on the border of Kazan International Airport

The dynamics of fauna and population of birds from agricultural lands near Kazan International Airport has been studied for one year. A total of 60 bird species have been registered, of which 26 species must be considered as highly dangerous to flying aircraft. With regard to seasonal activity, the nesting period (April – June) is the most hazardous, since it is characterized by maximum species richness and total population density of birds, as well as their high species diversity. Furthermore, a serious danger is posed by the period of postnesting nomadic movements and the onset of migrations (July – September) when the species diversity turns out to be the highest and the total population density begins to decrease. It has been recommended based on the obtained results that the current crops should be replaced by cultivars that will be less attractive to birds. In spring and autumn, certain bird hazing and frightening measures must be taken on a more regular basis.