Bird Population Density Research Articles

SPATIAL ORGANIZATION OF BIRD POPULATION OF THE URUP AND ITURUP ISLANDS (KURIL ISLANDS)

The ecological and geographical differentiation of the bird population at 18 sites of the Urup and Iturup islands was analyzed. The method of route accounting was applied. A total of 109 species were recorded, 62 of them on both islands. The coefficient of faunal commonality between the terrestrial habitats of the islands is 72%, and between the coastal-marine - 71%. The coefficient of similarity of the bird population between the land habitats of the islands is 36%, and between the coastal-marine - 29%. The values of bird population density on the islands are close both between terrestrial (610-757 ind./km2) and coastal-marine (536-607 ind./km2) habitats. The high population density is everywhere due to the abundance of numerically predominant species of the Far Eastern island and the Chinese fauna types. The total population of species of these faunas accounts for more than 50% of the population in terrestrial (282-469 ind./km2) and coastal marine (172-333 ind./km2) habitats. The spatio-temporal dynamics of the bird population is characteristic.

The Effect of Rainfall on the Population Densities and Community Structure of Birds in an Urbanized Zambezi Riparian Forest

The species which make up the avian community are governed by a multitude of environmental and internal influences, and the crucial role of community ecology is to discern and explain the patterns arising from these influences. Some such influences are habitat structure and seasonality. This study aimed to investigate the structure of the avian community and population densities of birds in relation to habitat changes made by man, and in relation to differential rainfall. The study was set up in an urbanized riparian forest on the Zambezi River, NE Namibia. The forest close to the river bank has been slightly altered by human activities, while the one laying further afield has been highly modified by human settlements. The avian community was quantified using the mapping method. Counts were conducted in two wet seasons in 2013/14 and 2015/16. The rainfall was higher in the 2013/14 (428 mm) than the 2014/15 (262 mm) rainy season. In both seasons, 113 bird species were recorded. However, in particular, 91 species were recorded in 2013/14 and 101 in 2015/16. The Sorensen Index of Similarity between those two seasons was I = 0.89. Also, the proportion of dominant species was similar in both seasons, and the group was composed of the Dark-capped Bulbul, Red-eyed Dove, Laughing Dove, Blue Waxbill, and Grey-headed Sparrow. The Community Dominance was identical in both seasons when compared. Also, the diversity indices were very similar in both seasons. Also, all three diversity indices were almost identical in both seasons. The overall density was only slightly higher in 2015/16 than in 2013/14. The proportions of particular nesting, feeding, habitat, and residency guilds were very similar in both seasons when compared. The overall density was slightly higher in 2015/16 than in 2013/14, but the difference was not statistically significant. Also, for any particular bird species, the differences in population density between the two seasons were not statistically significant. Several bird species showed, however, statistically significant differences in their population densities between the natural and transformed portions of the riparian forest. The avian assemblage is probably stable over the years in regard to the number of breeding species and their densities, irrespective of year-to-year differences in rainfall, as water is not a limiting factor in this habitat. Bird species classified as forest specialists appear to be negatively affected by habitat transformation, while generalists (ecotone species) probably benefit from this transformation.

Deep learning-based software for detecting population density of Antarctic birds

Monitoring populations of bird species living in Antarctica with current technologies is critical to the future of habitats on the continent. Studies of bird species living in Antarctica are limited due to climate, challenging geographic conditions, and transportation and logistical constraints. The goal of this study is to develop Deep Learning-based software to determine the population densities of Antarctic penguins and endangered albatrosses. Images of penguins and albatrosses obtained from internet sources were labeled using the segmentation technique. For this purpose, 4144 labeled data were trained with five different convolutional neural network architectures TOOD, YOLOv3, YOLOF, Mask R-CNN, and Sparse R-CNN. The performance of the obtained models was measured using the average precision (AP) metric. The experimental results show that the TOOD-ResNet50 model with 0.73 {$AP^{50}$} detects the Antarctic birds adequately compared to the other models. At the end of the study, a software was developed to detect penguins and albatrosses in real time

STUDI KEPADATAN POPULASI BURUNG ENDEMIK TIMOR DI SEPANJANG JALUR PATROLI DESA FATUMNASI, CAGAR ALAM MUTIS, KABUPATEN TIMOR TENGAH SELATAN, PROVINSI NUSA TENGGARA TIMUR

Birds are wild animals that play an important role in building the food chain, helping pollination, controlling insect pest populations, and seed dispersal agents that are useful for natural forest regeneration. An animal is said to be endemic if the species is a native species that can only be found in one place and not found in other places or areas as well as Endemic Birds that will be studied in the Mutis Nature Reserve Area. This study was conducted to determine the population density of Timor endemic birds along the Patrol Route to Padang I, Fatumnasi Village, Mutis Nature Reserve, South Central Timor Regency, East Nusa Tenggara Province. This research was conducted from April to May 2022. Data collection on the Population Density of Timor's Endemic Birds used the Point Count method. Bird population density data analysis used the Krebs formula and the Eisenberg formula. The results of this study recorded that 6 species of birds with the highest population density were Myzomela Timor (0.72 ind/ha), Timor Honeysucker (0.61 ind/ha), Timor Pergam (0.55 ind/ha), Opior Timor (0.50 ind/ha) and the lowest population density or the least in the Timor Kancilan (0.24 ind/ha) and Timor Anis (0.38 ind/ha). Over time, population density will decrease or increase according to the resilience of adaptation to changes in environmental conditions and competition with other organisms.

Accounting for spatial habitat and management boundaries when estimating forest bird population distribution and density: inferences from a soap film smoother.

Birds are often obligate to specific habitats which can result in study areas with complex boundaries due to sudden changes in vegetation or other features. This can result in study areas with concave arcs or that include holes of unsuitable habitat such as lakes or agricultural fields. Spatial models used to produce species' distribution and density estimates need to respect such boundaries to make informed decisions for species conservation and management. The soap film smoother is one model for complex study regions which controls the boundary behaviour, ensuring realistic values at the edges of the region. We apply the soap film smoother to account for boundary effects and compare it with thin plate regression spline (TPRS) smooth and design-based conventional distance sampling methods to produce abundance estimates from point-transect distance sampling collected data on Hawai'i 'Ākepa Loxops coccineus in the Hakalau Forest Unit of the Big Island National Wildlife Refuge Complex, Hawai'i Island, USA. The soap film smoother predicted zero or near zero densities in the northern part of the domain and two hotspots (in the southern and central parts of the domain). Along the boundary the soap film model predicted relatively high densities where 'Ākepa occur in the adjacent forest and near zero elsewhere. The design-based and soap film abundance estimates were nearly identical. The width of the soap film confidence interval was 16.5% and 0.8% wider than the width of the TPRS smooth and design-based confidence intervals, respectively. The peaks in predicted densities along the boundary indicates leakage by the TPRS smooth. We provide a discussion of the statistical methods, biological findings and management implications of applying soap film smoothers to estimate forest bird population status.

Global patterns and predictors of avian population density

AbstractAimHow population density varies across animal species in the context of environmental gradients, and associated migratory strategies, remains poorly understood. The recent influx of avian trait data and population density estimates allows these patterns to be described and explored in unprecedented detail. This study aims to identify the main macroecological drivers of population density in birds.LocationGlobal.Time period1970–2021.Major taxa studiedBirds (Aves).MethodsWe collated a dataset of 5072 local population density estimates for 1853 species and modelled population density as a function of trait and environmental predictors in a Bayesian framework accounting for phylogenetic and spatial autocorrelation. We explored the influence of body mass, diet, primary lifestyle, mating system, nesting behaviour, territoriality, and migratory behaviour on population density, accounting for a range of environmental variables, including preferred habitat type, primary productivity, precipitation and temperature. Based on this empirical baseline, we then predicted the mean population density for 9089 species of birds and estimated global geographic patterns of bird population density.ResultsPopulation density was lower in species with larger body mass and higher trophic levels, and also declined in territorial species, migratory species, brood parasites and species inhabiting resource‐poor habitat types (e.g., deserts). Conversely, population density increased in cooperative breeders. Environmental drivers were most influential for migratory birds, with precipitation and temperature both associated with higher population density. Overall, bird population densities were higher at lower latitudes.Main conclusionsOur results support previous findings on the role of body mass, diet and environmental gradients, but also reveal novel species‐specific drivers of avian densities related to reproduction, migration and resource‐holding behaviour. Substantial fine‐scale variation remains unexplained. We provide a global dataset of population density predictions for use in macroecological analyses and conservation assessments.

Effect of rainfall on the structure and population densities of birds breeding in a suburb of Windhoek, Namibia

A bird community was quantified in the suburb of Olympia (200 ha) in the city of Windhoek, Namibia. Two years (2014 and 2020) were selected to examine the impact of rainfall and sub- urb development on species diversity and population densities of the selected bird species in this community. The total amount of rainfall in Windhoek in 2014 was much higher than in 2020 (475 mm and 275 mm, respectively). In total, 36 breeding bird species were recorded in the study area in 2014 and 2020: 27 spe- cies in 2014 and 31 species in 2020. The number of species com- mon in 2014 and 2020 was 17. The Sörensen’s Similarity Index was therefore rather low (0.59). In overall, population density of 25 selected bird species was much higher in 2020 than in 2014. Population densities of the Laughing Dove, the Southern Masked Weaver, and Chestnut-vented Warbler in 2014 and 2020 were statistically different, whereas population densities of the Red- headed Finch were similar in both years compared.
 The breeding bird community in Olympia suburb does not ap- pear to be stable over years, both in regard to species composition and population densities of particular species. This instability may be linked to constant property development of this suburb and around it. Olympia suburb borders on the periphery of the city, which is a savanna slowly transformed into another suburb. Un- der drought conditions, some species from these surroundings may be attracted to the suburbs by water and food. Hence, con- trary to expectation, densities of some species in the suburbs in the year with low rainfall are higher.

Birds of forest ecosystems of Southern Baikal in the conditions of modern climate warming: Dynamics of population density and structure in summer

On the basis of long-term works (2010-2022), the materials of studying the influence of climate warming on the bird population of forest ecosystems in the summer period are presented. The main indicators of the bird population were studied: population density and species composition. The dynamics of these indicators of the bird population structure and the features of their structure depending on the level of climate change on the ascending branch of the heat-dry phase of the centuries-old climate cycle, close to completion, are considered. The intensity of bird eviction is associated with the localization of very severe, prolonged and extensive droughts. It is the intensity of evictions that determines the new species composition of birds of the studied territories. They are characterized by very low numbers and therefore there is no clear link between the population density of birds and their species richness. At the same time, the general tendency to preserve this pattern (with an increase in the number of species, the population density of birds increases) is noted in some of their main categories. The obtained materials allow us to find out the peculiarities of the dynamics of the biodiversity of birds in Eastern Siberia during periods of severe climatic anomalies. Such materials are extremely important, as they allow us to find out the real role of natural and climatic factors in the evolution of natural ecosystems and the maintenance of the overall biodiversity of large zoogeographic regions of the Earth.

РЕВИЗИЯ ФАУНЫ ПТИЦ ДОЛИНЫ ГЕЙЗЕРОВ НА КАМЧАТКЕ: ВИДОВОЙ СОСТАВ, ОСОБЕННОСТИ ЭКОЛОГИИ

In this paper, the author presents revision of the investigations of birds from the Valley of Geysers in Kamchatka, which summarizes data obtained for the past 50 years. According to the latest revision, the avifauna of this region includes 91 species (53 nesting species). There are no region-specific species. The discovery and status of the Grey crowned Rosy finch (Leucosticte tephrocotis) requires a reliable verification. The high species diversity of birds in a small area (31.5 km2) may be explained by the biotope diversity in the area, which is associated with the geothermal activity at the border of forest and subalpine vegetation. The weighted average bird population density is 211.8 pairs/km2. Its appearance is subalpine with a small proportion of forest species. Twelve (12) species are listed in the Red Data Books of Russia and (or) Kamchatka. The most significant findings are the regular wintering of the Solitary Snipe (Gallinago solitaria), the possible reproduction of the Golden Eagle (Aquila chrysaetos) and Peregrine Falcon (Falco peregrinus), the background status of the Rustic Bunting (Ocyris rusticus). The mudflow that passed through the Geysernaya Valley on June 7, 2007 had a catastrophic impact on the natural appearance of the central part of the Valley of Geysers. Variants of its effects on birds are discussed. Geothermal activity determines the possibility of wintering of a number of species in subalpine harsh conditions, a shift in the timing of periodic events in the life of birds, including earlier reproduction, the possibility of nesting on extremely warm ground, behavioral characteristics during incubation and other features of bird ecology.

Population Density and Stability of Breeding Birds in English Oak Woodland Over a 32-Year Period in Relation to Habitat Structure and Edges

Long-term breeding bird censuses in Białowieża National Park (BNP), north-east Poland, have revealed rather low densities of birds and high community stability which may be features of near-natural forest conditions. This paper reports on a long-term census of breeding birds in 50 ha of oak woodland in central England which contained both managed and undisturbed areas. New information is provided on breeding bird density and its spatial variation within English mature broadleaved woodland to address two questions: Under what circumstances are English woods likely to support higher densities than those occurring in BNP? Is there evidence that population and community stability is lower in English woodland? The overall bird density was lower than in the BNP oak-hornbeam stands, at the scale of both the whole study area and the undisturbed stands. Densities of three of the five dominant species (Cyanistes caeruleus, Parus major, Troglodytes troglodytes) were lower in BNP, Fringilla coelebs was higher, while Erithacus rubecula was similar. Within the undisturbed stands, densities of seven of 12 species, including T. troglodytes, were similar to those in BNP, two were considerably higher (C. caeruleus, P. major) and one much lower (F. coelebs). Selection of the external woodland edge by several species resulted in relatively high overall densities in the edge zone. The broad composition of the bird community remained fairly stable with the exception of declines in tropical migrants and increases in shrub layer nesters. Temporal abundance patterns of species showed much individuality. Trends of several species appeared to be driven by changes in habitat structure. However, the same species remained numerically dominant or characteristic of the wood throughout the study period. This suggests there was a core of resilient species, much as proposed for BNP. Although caution is needed in drawing conclusions from a single site, with the exception of a small number of species, in recent decades there is unlikely to have been a general pattern of higher densities of birds in English woodland than in BNP. However, some English woods with highly complex vegetation structures, or a high proportion of edge habitat, do have exceptionally high densities (> 100 territories/10 ha).

Recent population size of Timor Friarbird and resources utilization at three landscapes in West Timor Island, Indonesia

The Timor Friarbird is an endemic species of Timor Island that plays an important role in forest ecosystems, agriculture and other natural environments in the semiarid region. Although classified as an endemic species and declining population, the bird is protected by Indonesian law. This study aims to assess the density, group size, and population distribution of Timor Friarbird and resource uses in three landscape at Western Timor. Distance sampling methods with transect lines was used to estimate population density and bird distribution. The highest estimated bird population density (3.31 ind./ha) in the Baumata landscape and lowest (0.15 ind./ha) in Bipolo. Individual sizes per group of 1-4 individuals in all landscapes. Utilization of distributed feed resources in the main area, secondary and low potency area. The distribution of species in the rainy season is higher found in low-lying, higher dry seasons in lowlands. High anthropogenic pressures and changes in dominant habitats in the low-lying west Timor Island contribute to the rate of population decline of this species thus impacting crop productivity and conservation efforts of this species in the future.

Population densities of birds breeding in an urban environment dominated by allotment gardens and other ‘green’ areas in a Central European city

Abstract A total of 50 breeding bird species were recorded in 2017 in an urban environment (589 ha) in the city of Wrocław, SW Poland. This environment was dominated by green habitats, such as allotment gardens (41.2%), parklnds (13.4%) and forests (2.7%). For 41 species, population densities were estimated. A high population densities were recorded for Phoenicurus phoenicurus (9.2 pairs / 100 ha), Sylvia atricapilla (7.3), Turdus merula (6.6), Phoenicurus ochruros (6.3), Luscinia megarhynchis (5.3.), Sylvia curruca (4.1) and Serinus serinus (3.7). In the alltment gardens, much higher population density of Pica pica (14.5) than Corvus cornix (6.5); and higher population density of Columba palumbus (2.8) than Streptopelia decaocto (1.2) were recorded.

Assessment of Avian Biodiversity and Bird strikes to Aircrafts at Bacha Khan International Airport, Peshawar KP, Pakistan

Birds inside or outside the airport is big threat to the aircraft. The main objective of this study was toidentify hazards of bird species, population density and richness of birds around BACHA KHANINTERNATIONAL AIRPORT. The methods being used were point count/vantage point method for thepopulation estimation. The Study was based upon two sites (Site A Airport Premises) spreading over anarea of 30 acres and (Site B which is within Airport) spreading over an area of 7.5 Acres. Total Samplingpoints (Observation Points) were 120 and every sampling point was visited for 15-20 minutes and birdswere counted for three to five minutes in a fixed radius. Transact line method spreading over 500 meterswas used to analyze the data. Birds were observed every 100 meters. Primary and Secondary data wascollected using questionnaire. The study identified the reasons for Bird Air strikes at the Airport and exploredpossible mitigation measures of avian hazards in Peshawar airport premises. This data will be useful forthe aviation authorities in preparing managed bird control program. In this study hypothesis were given incomparison with other attractants tree attracts more birds in Peshawar Airport. Averages of 30 specieswere observed in Site A and 15 in Site B monthly respectively. The highest Relative Abundance observed atSite A was of House Crow species which is 16.8463612% and in Site B Kite species with relative abundance21.4953271%. The Highest number of Bird strike occurred at Runway followed by strikes outside the fencewith reference to Bird strike report 2021-22. Pigeon and Doves were observed in Flight over the airportpremises. 36 Bird’s diversity observed around airport in rainfall and cloud cover assessed through Shannondiversity index as 3.024 which indicate good diversity of birds in the study area which might be a potentialthreat to the aircraft? The study revealed that effective management plan should also be taken intoconsideration. The Population density of Site A outside the airport premises (30 Acres) is 24.13/Acre andfor Site B within Airport which is 7.5 Acres is 14.2/Acre respectively.

Bird summer distribution patterns on islands in Onega Bay, White Sea

We studied avian populations and distribution patterns on 20 islands in Onega Bay, White Sea, with transect surveys completed to register selected biotic and abiotic factors in July 2020. Bird population densities proved to be the highest on small secluded islands rarely visited by humans and on treeless islands. We also found positive correlations between the species richness and the island size, presence of woody vegetation, and human visitation. It is noteworthy that although human interference can cause species diversity on the islands to increase, the relative abundance of birds declined. Furthermore, species diversity increased due to the arrival of species atypical of this region and, hence, lacking the complete set of requisite adaptations. Further human pressure on the islands can eventually destabilise their avifaunal complexes and aggravate the current transformation of northern communities in response to climate change.

The dynamics of the bird population in the forest ecosystems of Eastern Siberia (South Baikal) under the conditions of the modern climate changes

The work was carried out on a key site with an area of more than 50 km2 on the right bank of the source of the Angara river (South Baikal) in 2010-2020 The studies were carried out in winter and summer periods, based on the standard technique used in Russia for these purposes. The studies fall on a period of strong warming close to the maximum, most likely a centuries-old climate cycle. It is shown that the dynamics of population density and species diversity of birds in the winter and summer seasons at this time are very different. The summer period is by wavelike (cyclical) changes characterized, without a pronounced trend. In winter, on the contrary, there is a well-pronounced trend towards a noticeable decrease in these indicators. The different responses of birds to climate changes are undoubtedly by the initial factors operating at their areas determined. In the summer period - the drying up of the territory of Central Asia and the resettlement of birds, especially waterfowl and waterfowl, to the northern borders of their areas. In the winter period - by situations in the optima of wintering habitats, which also shifted somewhat to the north (even in sedentary bird species). These materials indicate the strong impact of climate change on the environment.

Characterizing Avian Species Richness Patterns in Colorado

Recently, many ecologists have focused their efforts on studying how urbanization impacts bird populations (Lee et al., 2021; Marques et al., 2020; Torres et al., 2016; Waltert et al., 2004). Urbanization and linear infrastructure (roads and power lines) can negatively affect bird population densities and avian species richness (total number of species at a site) (Benítez-López et al., 2010; Lee et al., 2021; Marques et al., 2020; Trammell & Bassett, 2012; Waltert et al., 2004). Studies have found that in areas with higher levels of urbanization, avian species richness (ASR) is lower (Lee et al., 2021; Waltert et al., 2004). Similarly, other studies show that major road density and proximity to linear infrastructure negatively affect ASR and overall abundance (BenítezLópez et al., 2010; Torres et al., 2016; Trammell & Bassett, 2012). Studying the relationship between ASR and proximity to linear infrastructure is incredibly important for informing decisions regarding the construction of new roads and power lines in areas with little human disturbance (Benítez-López et al., 2010; Marques et al., 2020; Torres et al., 2016; Trammell & Bassett, 2012).

Многолетняя динамика фауны и населения птиц аэропорта Челябинск (Баландино)

Over 30-year study period (1990–2021), 144 bird species, including 54 nesting species, were registered on the territory of the Chelyabinsk International Airport Balandino. Total bird population density varied from 147 ind./km² in 1990 to 215 ind./km² in 2020. In different years, dominant species in this area were Alauda arvensis, Motacilla flava, Saxicola rubetra, S. torquata, and Passer montana. In the first years of research, a significant decrease in the number of the most widespread species (Corvus frugilegus, C. monedula, Columba livia, Larus barabensis, L. canus, and L. ridibundus), crossing the airfield during seasonal and diurnal (forage) migrations, was revealed. This was caused both by decrease of population of some species (C. frugilegus) in the European and Ural-Siberian parts of their range, and by the deterioration of the state of forage lands on the airport territory after the elimination of solid waste landfills and a decrease of farmland areas nearby.

Nest predation pressure on Chinese Bulbuls decreases along the urbanization gradient in Hangzhou, China

Nest predation is an essential factor affecting bird population density, reproductive ecology and life cycle. However, there are still contradictory results about how nest predation pressure changes with urbanization. One of the reasons for the controversy is that previous studies often use artificial nests to investigate nest predation, but the result of artificial nests is often biased and contrary to that of natural nests. Therefore, it is important to perform nest predation experiments simultaneously with both natural and artificial nests. In this study, we examined the change of nest predation pressure on the Chinese Bulbul (Pycnonotus sinensis) along the urbanization gradient in Hangzhou, China. We detected 148 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013. After the breeding season, we placed artificial eggs in natural nests of Chinese Bulbuls to investigate the changes in nest predation pressure and used infrared cameras to record the predators. We then calculated the urbanization synthetic index (USI) as the measure of the degree of urbanization and examined its relationship with nest predation pressure. We found that no matter whether natural nests or artificial eggs were used, the nest predation pressure always decreased significantly with the degree of urbanization. The average height of shrubs within 10 ​m of the nest differed significantly between the predated and unpredated nests, which also affected the risk of nest predation. Our study highlights the importance of using natural and artificial nests simultaneously to conduct nest predation experiments, which can reduce the bias or errors caused by only using artificial nests. We also recommend the use of infrared cameras in future nest predation studies, which has obvious advantages in monitoring and identifying potential predators.

The Long-Term Monitoring of Bird Populations on Kolguev Island in the Barents Sea

Kolguev Island (69˚05′ N 49˚15′ E) is located in the Pechora Sea, the southeastern part of the Barents Sea. The island’s ecosystem is unusual due to the total absence of rodents and specialized predators such as weasels, while non-specialized predators such as Arctic (Vulpes lagopus) and red (V. vulpes) foxes and Rough-legged Hawk (Buteo lagopus) are common. Currently, 111 bird species have been registered here, of which 58 are nesting. The absence of rodents and the relatively stable predation pressure have resulted in the high abundance of many bird species: Willow Ptarmigan (Lagopus lagopus), several goose species, some waders, and passerines. Over the 125-year history of ornithological studies on Kolguev, the island avifauna has changed significantly. The trend of an increase in the proportion of widespread and Siberian species together with a decrease in the proportion of Arctic species was observed. Since 2006, a thorough monitoring of Kolguev avifauna has been carried out, during which the dynamics of the bird population densities have been traced. The abundance of Black-bellied Plover (Pluvialis squatarola) and Dunlin (Calidris alpina) decreased, while the numbers of Barnacle Goose (Branta leucopsis) have increased sharply since the 1980s. The breeding density of Rough-legged Hawk has also increased in recent years. The long-term monitoring of Kolguev ecosystems has indicated the high international conservation value of the island due to the high breeding density of many bird species. Our study, covering more than a century of avifaunal studies with almost annual monitoring over the past three decades, provides an unusually long and detailed time-series for an Arctic island.

Scaling up private land conservation to meet recovery goals for grassland birds.

Long‐term population declines have elevated recovery of grassland avifauna to among the highest conservation priorities in North America. Because most of the Great Plains is privately owned, recovery of grassland bird populations depends on voluntary conservation with strong partnerships between private landowners and resource professionals. Despite large areas enrolled in voluntary practices through U.S. Department of Agriculture's Lesser Prairie‐chicken (Tympanuchus pallidicinctus) Initiative (LPCI), the effectiveness of Farm Bill investments for meeting wildlife conservation goals remains an open question. Our objectives were to evaluate extents to which Conservation Reserve Program (CRP) and LPCI‐grazing practices influence population densities of grassland birds; estimate relative contributions of practices to regional bird populations; and evaluate percentages of populations conserved relative to vulnerability of species. We designed a large‐scale impact‐reference study and used the Integrated Monitoring in Bird Conservation Regions program to evaluate bird population targets of the Playa Lakes Joint Venture. We used point transect distance sampling to estimate density and population size for 35 species of grassland birds on private lands enrolled in native or introduced CRP plantings and LPCI‐prescribed grazing. Treatment effects indicated CRP plantings increased densities of three grassland obligates vulnerable to habitat loss, and LPCI grazing increased densities of four species requiring heterogeneity in dense, tall‐grass structure (α = 0.1). Population estimates in 2016 indicated the practices conserved breeding habitat for 4.5 million birds (90% CI: 4.0–5.1), and increased population sizes of 16 species , totaling 1.8 million birds (CI: 1.4–2.4). Conservation practices on private land benefited the most vulnerable grassland obligate species (AICc weight = 0.53). By addressing habitat loss and degradation in agricultural landscapes, conservation on private land provides a solution to declining avifauna of North America and scales up to meet population recovery goals for the most imperiled grassland birds.