Population Dynamics Of Birds Research Articles

Overstayed Migratory Bird Species on The Coast of Banda Aceh City, Aceh Province

Bird migration is a critical ecological phenomenon influenced by various factors such as temperature changes, food availability, and reproductive cycles. Understanding the dynamics of migratory bird populations within specific regions is essential for conservation efforts. This study aims to identify migratory bird species within Banda Aceh City, focusing on the phenomenon of overstaying migratory birds. Conducted between April and June 2022, data collection took place in several locations, employing the concentration count method. Descriptive data analysis was performed to catalog bird species, and the Shannon-Wiener index was utilized to assess biodiversity. Results revealed the presence of four shorebird species. The study underscores the importance of protecting migratory bird populations in urban environments and highlights the potential impacts of their loss or disruption. Joint conservation efforts are crucial to safeguarding these species, and favorable conditions may encourage some individuals from commonly migrating species to remain in urban areas.

Ornithogenic sedimentary profiles of n-alkanes and PAHs constrain breeding penguin population dynamics at Cape Bird, Ross Island, Antarctica, over the past 1,500 years

Ornithogenic sediment may contain important paleoecological information concerning past bird population dynamics. In this paper, we analyse the distribution of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in two sedimentary profiles collected from abandoned penguin colonies at Cape Bird, Ross Island, Antarctica. The geochronology of the sediment profiles was determined using 210Pb and AMS 14C dating techniques, and spans the past 1500 years. We observe low levels of n-alkanes (0.93–2.67 μg g−1) and PAHs (20.5–46.8 ng g−1) concentrations dominated by short-chain n-alkanes, low-molecular-weight and alkyl PAHs. Principal Component Analysis (PCA) shows that the PC 1 scores for n-alkanes and PAHs are significantly correlated with the input intensity of penguin guano and penguin bioelements. Using these proxies in combination with Generalized Additive Model (GAM), we reveal that breeding penguin population growth reaches a historical peak during the Medieval Climate Anomaly (MCA) prior to 1550 CE. This growth in population size corresponds to the extent of sea ice cover and the activity of the local atmospheric-ocean circulation. Warming induced by El Niño and the positive phase of the Southern Annular Mode, along with the expansion of ice-free zones and increased oceanic nutrient and food availability, are considered primary factors contributing to the growth of breeding penguin populations. Additionally, variations in sea ice extent and Amundsen Sea Low significantly influence penguin population dynamics. Our study suggests that n-alkanes and PAHs may be valuable organic proxies for reconstructing historical changes in breeding penguin populations, with the local sea ice extent and atmospheric-oceanic circulation exerting a major influence on Antarctic penguin population dynamics.

Woody plant encroachment drives population declines in 20% of common open ecosystem bird species.

Grassy ecosystems cover more than 40% of the world's terrestrial surface, supporting crucial ecosystem services and unique biodiversity. These ecosystems have experienced major losses from conversion to agriculture with the remaining fragments threatened by global change. Woody plant encroachment, the increase in woody cover threatening grassy ecosystems, is a major global change symptom, shifting the composition, structure, and function of plant communities with concomitant effects on all biodiversity. To identify generalisable impacts of encroachment on biodiversity, we urgently need broad-scale studies on how species respond to woody cover change. Here, we make use of bird atlas, woody cover change data (between 2007 and 2016) and species traits, to assess: (1) population trends and woody cover responses using dynamic occupancy models; (2) how outcomes relate to habitat, diet and nesting traits; and (3) predictions of future occupancy trends, for 191 abundant, southern African bird species. We found that: (1) 63% (121) of species showed a decline in occupancy, with 18% (34) of species' declines correlated with increasing woody cover (i.e. losers). Only 2% (4) of species showed increasing population trends linked with increased woody cover (i.e. winners); (2) Open habitat specialist, invertivorous, ground nesting birds were the most frequent losers, however, we found no definitive evidence that the selected traits could predict outcomes; and (3) We predict open habitat loser species will take on average 52 years to experience 50% population declines with current rates of encroachment. Our results bring attention to concerning region-wide declining bird population trends and highlight woody plant encroachment as an important driver of bird population dynamics. Importantly, these findings should encourage improved management and restoration of our remaining grassy ecosystems. Furthermore, our findings show the importance of lands beyond protected areas for biodiversity, and the urgent need to mitigate the impacts of woody plant encroachment on bird biodiversity.

A comprehensive review on the impact of climate change on the ecology, breeding seasonality, abundance and distribution of birds and possible approaches to address and conserve bird populations

The purpose of this paper is to review and evaluate published literature on the impact of climate change on birds. A systematic method was utilized to access research works of literature on “Impact of Climate Change on Birds”. A total of sixty-seven (67) research papers published between the years 1962 to 2023 was accumulated and used for this review. A subjective approach was used to select the topics: impact of climate change and birds. In this paper, nine (9) threatening impacts of climate change on the bird populations were assessed and presented as well as three (3) detrimental impacts of climate change on birds inhabiting mangrove forests. Further, this paper assessed some birds that are threatened with extinction and it also provided a checklist of some migratory birds that are threatened due to the changing climate and that are found on the RED list of the IUCN. Approaches and strategies to enhance and address bird conservation to combat the effect of climate change was also presented in this review. The published works of literature established that the global bird population dynamics, ecology, breeding seasonality, abundance and distribution are all affected due to the threats of climate change. Climate change will affect birds indirectly in the future by modifying their habitats through sea level rise, changes in fire regimes, and changes in vegetation or land use. Birds are in particular vulnerable to environmental changes like climate change since they are subject to continuous changes that may be negatively connected. This review highlights the fact that more extensive studies on the impact of climate change on birds should be done in neotropical countries since there are gaps of such information on research and published data in these biodiversity rich regions.

Waterbird count at Narathali waterbody, Buxa Tiger Reserve in northern Bengal for a decade (2009–2019) with a note on raptors

This study presents insights from a comprehensive analysis of bird counts conducted at Narathali waterbody in Buxa Tiger Reserve between 2009 and 2019. Thirteen bird species were monitored, including six wintering duck species and seven resident waterfowl species. The population trends of these birds remained relatively constant throughout the study period. Additionally, the study documented raptor counts and compiled a checklist of waterbirds observed at the waterbody. These findings enhance our understanding of bird population dynamics in this significant habitat and provide valuable information for the conservation and management of the Buxa Tiger Reserve.

Comparison of Reproductive Strategies between Two Sympatric Copsychus Passerines.

Reproduction plays a crucial role in determining the development, fate, and dynamics of bird populations. However, reproductive strategies vary among species and populations. In this study, we investigated the reproductive strategies of the Oriental Magpie Robin (Copsychus saularis) and White-rumped Shama (C. malabarica), which are closely related passerines that reproduce in sympatric areas. We found that although these two species were both cavity nesting, their nest-site selection differed; the Shama preferred nesting close to trees and forests, whereas the Magpie Robin nested close to human residential areas. Furthermore, their egg incubation patterns differed; the Shama increased daily incubation frequency with incubation time, but the Magpie Robin maintained its daily incubation time regardless of changes in incubation frequency. However, the nestling heating patterns of these two species were similar, indicating a critical demand for regulating hatchling body temperature during this crucial stage. The feeding frequencies of male parents were strongly correlated with those of females in both species, suggesting equal contribution and good synchronization between the sexes. Nestling feeding frequency was also correlated with nest cleaning frequency, implying coordination between feeding and defecation by parents and offspring, respectively. This research explored the divergence and convergence of reproductive strategies between these two sympatric species, providing valuable insights into the niche differentiation theory.

Bird Population Dynamics during the Regenerative Succession of Mossy Pine Woodland in Southwestern Belarus

Bird Population Dynamics during the Regenerative Succession of Mossy Pine Woodland in Southwestern Belarus

Assessment of diversity, abundance, and seasonal variations of bird species in Bengaluru District, India during COVID-19 lockdown

The study investigates bird population dynamics in Bengaluru, India, post-lockdown, focusing on occurrence, seasonal abundance, species diversity, richness, dominance, and evenness. It covers 55 bird species across 52 genera, grouped into 32 families within 13 orders, with a notable peak in winter. Various indices, including Shannon Wiener, Margalef’s, Pielou’s, and Simpson’s, reveal significant seasonal differences in bird population characteristics. The Rock Pigeon Columba livia dominates, while the Black-headed Ibis Threskiornis melanocephalus is less prevalent. The study identifies Near Threatened species like Black-headed Ibis and Oriental Darter Anhinga melanogaster, along with Least Concern species per the IUCN Red List. Common species include Rock Pigeon, Large-billed Crow Corvus macrorhynchos, House Crow Corvus splendens, Black Drongo Dicrurus macrocercus, Brown Shrike Lanius cristatus, Common Myna Acridotheres tristis, Jungle Myna Acridotheres fuscus, Red-whiskered Bulbul Pycnonotus jocosus, and Streak-throated Swallow Petrochelidon fluvicola. The study aims to inform improved management and conservation strategies for Bengaluru’s diverse bird species.

Population links between an insectivorous bird and moths disentangled through national-scale monitoring data.

Insects are key components of food chains, and monitoring data provides new opportunities to identify trophic relationships at broad spatial and temporal scales. Here, combining two monitoring datasets from Great Britain, we reveal how the population dynamics of the blue tit Cyanistes caeruleus are influenced by the abundance of moths - a core component of their breeding diet. We find that years with increased population growth for blue tits correlate strongly with high moth abundance, but population growth in moths and birds is less well correlated; suggesting moth abundance directly affects bird population change. Next, we identify moths that are important components of blue tit diet, recovering associations to species previously identified as key food sources such as the winter moth Operoptera brumata. Our work provides new evidence that insect abundance impacts bird population dynamics in natural communities and provides insight into spatial diet turnover at a national-scale.

Disentangling the contemporary and historical effects of landscape on the population genomic variation of two bird species restricted to the highland forest enclaves of northeastern Brazil.

Investigating the impact of landscape features on patterns of genetic variation is crucial to understand spatially dependent evolutionary processes. Here, we assess the population genomic variation of two bird species (Conopophaga cearae and Sclerurus cearensis) through the Caatinga moist forest enclaves in northeastern Brazil. To infer the evolutionary dynamics of bird populations through the Late Quaternary, we used genome-wide polymorphism data obtained from double-digestion restriction-site-associated DNA sequencing (ddRADseq), and integrated population structure analyses, historical demography models, paleodistribution modeling, and landscape genetics analyses. We found the population differentiation among enclaves to be significantly related to the geographic distance and historical resistance across the rugged landscape. The climate changes at the end of the Pleistocene to the Holocene likely triggered synchronic population decline in all enclaves for both species. Our findings revealed that both geographic distance and historical connectivity through highlands are important factors that can explain the current patterns of genetic variation. Our results further suggest that levels of population differentiation and connectivity cannot be explained purely on the basis of contemporary environmental conditions. By combining historical demographic analyses and niche modeling predictions in a historical framework, we provide strong evidence that climate fluctuations of the Quaternary promoted population differentiation and a high degree of temporal synchrony among population size changes in both species.

Understanding population change: the value of the EuroCES constant-effort ringing programme

ABSTRACT Populations of many common bird species are declining in Europe and effective conservation measures require an understanding of both the environmental and demographic causes of these changes. Capture–mark–recapture analysis of data from standardised ringing sites allows estimation of key demographic parameters, including productivity, survival and population age structure. Volunteers in countries across Europe undertake standardised mist-netting of passerines during the breeding season, from which estimates of these can be derived at large, national spatial scales. The Euring EuroCES programme collates these data in a common format to facilitate the continent-wide analysis of bird population dynamics. Here, I outline the broad characteristics of Constant Effort Site (CES) ringing, and introduce an R package cesr that provides tools to read in and manipulate these data and to produce annual indices of abundance, productivity and survival, for monitoring purposes. These data have been used to identify how climatic and environmental change can affect bird populations, particularly of migratory species, at national and continental scales. I then provide some suggestions for how the programme might further be expanded and integrated with other data sets to provide evidence for the drivers of bird population change and hence benefit informed conservation management.

Brood survival in the Red-backed Shrike Lanius collurio in eastern Poland

Brood survival as an expression of breeding success is a component of bird fitness and the principal parameter underlying bird population dynamics. The main factor limiting brood survival is predation pressure, and birds have developed anti-predator strategies by selecting safer places for building nests and breeding. Here, we examined whether nest location affected the level of predation pressure. To do so, we analyzed brood survival in a Red-backed Shrike (RBS) Lanius collurio population breeding in the low-intensive agricultural landscape of eastern Poland. The mean survival probability for the whole nesting period was 0.540 and was higher for the incubation period (0.787) than for the nestling period (0.696). Cox’s proportional hazard model did not show any significant traits describing the location of the nesting shrub or the nest’s position in the shrub that could have affected RBS brood survival. We consider the composition of the local predator community to influence brood survival more than the location of a nest in the bush. The Eurasian Magpie Pica pica is mainly responsible for RBS brood predation. Red-backed Shrikes do not defend their broods against Magpies using acoustic signals and direct contact. Since Magpies search the bushes thoroughly, the shrikes’ nest concealment strategies are ineffective in the face of this predator.

Bird population dynamics during the regenerative succession of mossy pine woodland in southwestern Belarus

Disturbed forest ecosystems are characterized by significant spatial and temporal changes. As a part of the study on bird communities, changes in bird abundance during the secondary succession of a cleared mossy pine woodland in southwestern Belarus were investigated. The purpose of the work was to determine the inter-annual dynamics of bird species abundance and to assess the variability of individual species abundance during the secondary succession of the mossy pine woodland. The material was collected in 2000–2019. Line transects were set to conduct bird counts in ecosystems at different stages of succession. For the data processing, generally accepted methods of statistical analysis were used. The species diversity of birds was found to increase from 8 to 42 species, the overall abundance from 171.7 to 587.1 birds/km2 during the succession (6 stages, from 1 to 90 years in age). The abundance of species (birds/km2) and inter-annual variability during 11 seasons were determined. The coefficient of variation (CV) was the highest (71.00–82.50%) for species whose abundance did not exceed 1.0 birds/km2. The average abundance of species varied considerably, e.g., among passerines at the 80–90-year old stage from 1.1 birds/km2 (Little Flycatcher) to 153.7 birds/km2 (Chaffinch). Bird populations with high abundance turned out to be the most stable, for example at the last two successional stages the CV of the Chaffinch is 6.02 and 7.16%. For species with average abundance the variability is found to be low or medium (varies from 11.90 to 36.20%), for species with low abundance the CV varies from 17.68 to 82.50%. All six stages of succession were dominated by nesting migratory birds, which account for 75.0% of the species in the first stage of succession to 52.4% in the fifth and sixth stages. Near and distant migrants form the basis of the bird community at all stages. Populations of sedentary species and distant migrants are more stable than those of near migrants.

Post-fledging survival of Tengmalm’s owl offspring in boreal forests: Interactive effects of varying dynamics of main prey and habitat composition

The knowledge about the mortality rate of offspring is crucial for estimating bird population dynamics and conserving species with declining populations. Parents of predatory birds provide food for their offspring during the post-fledging dependency period, which is frequently described as essential due to inexpert flying skills. Using radio telemetry, we studied fledglings’ probability of dying by starvation and predation in Tengmalms’ owls (Aegolius funereus). Nestlings (21 and 39) from 10 and 14 broods in 2019 and 2021, respectively, were equipped with leg-mounted tags and monitored throughout the post-fledging dependency period in west-central Finland. In total, 28 out of 60 fledglings did not survive the post-fledging dependency period (12 died due to starvation, and 16 were predated). The fledglings’ probability of dying by starvation and predation was 3.7 and 2.4 times higher, respectively, in the decreasing (2019) than during the increasing (2021) abundance of main foods (voles), showing that prey availability is essential for survival during the post-fledging dependency period. The probability of starvation increased with augmenting agricultural lands in the home range and increasing precipitation after fledging, which indicated that parent owls avoided hunting in open areas and during rainy nights. The predation rate during the post-fledging dependency period increased with augmenting cover of old-growth forests in the home range. This result suggested that coverage of old-growth forests is nowadays so small in the study area that they act as ecological traps for newly-fledged owlets. The reason is that the main avian enemies of Tengmalm’s owls’ (goshawks and Ural owls) also prefer old-growth forests for breeding and hunting.

Spatial and temporal non-stationarity in long-term population dynamics of over-wintering birds of North America.

Understanding population changes across long time scales and at fine spatiotemporal resolutions is important for confronting a broad suite of conservation challenges. However, this task is hampered by a lack of quality long-term census data for multiple species collected across large geographic regions. Here, we used century-long (1919-2018) data from the Audubon Christmas Bird Count (CBC) survey to assess population changes in over 300 avian species in North America and evaluate their temporal non-stationarity. To estimate population sizes across the entire century, we employed a Bayesian hierarchical model that accounts for species detection probabilities, variable sampling effort, and missing data. We evaluated population trends using generalized additive models (GAMs) and assessed temporal non-stationarity in the rate of population change by extracting the first derivatives from the fitted GAM functions. We then summarized the population dynamics across species, space, and time using a non-parametric clustering algorithm that categorized individual population trends into four distinct trend clusters. We found that species varied widely in their population trajectories, with over 90% of species showing a considerable degree of spatial and/or temporal non-stationarity, and many showing strong shifts in the direction and magnitude of population trends throughout the past century. Species were roughly equally distributed across the four clusters of population trajectories, although grassland, forest, and desert specialists more commonly showed declining trends. Interestingly, for many species, region-wide population trends often differed from those observed at individual sites, suggesting that conservation decisions need to be tailored to fine spatial scales. Together, our results highlight the importance of considering spatial and temporal non-stationarity when assessing long-term population changes. More generally, we demonstrate the promise of novel statistical techniques for improving the utility and extending the temporal scope of existing citizen science datasets.

Nesting success and potential nest predators of the red Junglefowl (Gallus gallus jabouillei) based on camera traps and artificial nest experiments

Breeding success is an important factor determining fecundity with nest predation being the main factor limiting avian breeding success. Understanding of nest predation and its influencing factors are highly significant to explore the dynamics of bird populations and developing appropriate conservation strategies. In two breeding seasons of the year 2020 and 2021, natural nests of the red junglefowl (Gallus gallus jabouillei) were systematically searched and monitored using infrared camera, in two nature reserves (Datian and Bangxi) of tropical Hainan island, China. Results showed that breeding season of the red junglefowl is mainly from March to July, with April being the breeding peak. The clutch size was 5.15 ± 1.28 (n = 13), and nesting success of natural nests was 31.2%, with nest predation accounting for 45.4% of nest failure. Artificial nest experiments showed that predation rates of artificial nests were 25% (Datian, 2020), 6.67% (Datian, 2021), and 0% (Bangxi, 2020). Rodents, reptiles, and coucals are the main nest predators of red junglefowls, while activities of Hainan Eld’s deers (Panolia siamensis) may interfere with the reproduction of red junglefowls. We suggest that the conservation management policies should consider the impacts on junglefowls’ breeding success when reconstructing the suitable habitat of the Hainan Eld’s deer.

Decomposing trends in bird populations: Climate, life histories and habitat affect different aspects of population change

AbstractAimDespite the complexity of population dynamics, most studies concerning current changes in bird populations reduce the trajectory of population change to a linear trend. This may hide more complex patterns reflecting responses of bird populations to changing anthropogenic pressures. Here, we address this complexity by means of multivariate analysis and attribute different components of bird population dynamics to different potential drivers.LocationCzech Republic.MethodsWe used data on population trajectories (1982–2019) of 111 common breeding bird species, decomposed them into independent components by means of the principal component analysis (PCA), and related these components to multiple potential drivers comprising climate, land use change and species' life histories.ResultsThe first two ordination axes explained substantial proportion of variability of population dynamics (42.0 and 12.5% of variation in PC1 and PC2 respectively). The first axis captured linear population trend. Species with increasing populations were characterized mostly by long lifespan and warmer climatic niches. The effect of habitat was less pronounced but still significant, with negative trends being typical for farmland birds, while positive trends characterized birds of deciduous forests. The second axis captured the contrast between hump‐shaped and U‐shaped population trajectories and was even more strongly associated with species traits. Species migrating longer distances and species with narrower temperature niches revealed hump‐shaped population trends, so that their populations mostly increased before 2000 and then declined. These patterns are supported by the trends of total abundances of respective ecological groups.Main ConclusionAlthough habitat transformation apparently drives population trajectories in some species groups, climate change and associated species traits represent crucial drivers of complex population dynamics of central European birds. Decomposing population dynamics into separate components brings unique insights into non‐trivial patterns of population change and their drivers, and may potentially indicate changes in the regime of anthropogenic effects on biodiversity.

Functional traits and environment jointly determine the spatial scaling of population stability in North American birds.

Understanding the spatial scaling of population stability is critical for informing conservation strategies. A recently proposed metric for quantifying how population stability varies across scales is the invariability-area relationship (IAR), but the underlying drivers shaping IARs remain unclear. Using 15-year records of 249 bird species in 1035 survey transects in North America, we derived the IAR for each species by calculating population temporal invariability at different spatial scales (i.e., number of routes) and investigated how species IARs were influenced by functional traits and environmental factors. We found that species with faster life history traits and reduced flight efficiency had higher IAR intercepts (i.e., locally more stable), whereas migratory species exhibited higher IAR slopes (i.e., a faster gain of stability with increasing spatial scale). In addition, spatial correlation in temperature and vegetation structure synchronized bird population dynamics over space and thus decreased IAR slopes. By demonstrating the joint influence of functional traits and environmental factors on bird population stability across scales, our results highlight the need for dynamic conservation strategies tailored to particular types of species in an era of global environmental changes.

The climatic drivers of long-term population changes in rainforest montane birds.

Climate-driven biodiversity erosion is escalating at an alarming rate. The pressure imposed by climate change is exceptionally high in tropical ecosystems, where species adapted to narrow environmental ranges exhibit strong physiological constraints. Despite the observed detrimental effect of climate change on ecosystems at a global scale, our understanding of the extent to which multiple climatic drivers affect population dynamics is limited. Here, we disentangle the impact of different climatic stressors on 47 rainforest birds inhabiting the mountains of the Australian Wet Tropics using hierarchical population models. We estimate the effect of spatiotemporal changes in temperature, precipitation, heatwaves, droughts and cyclones on the population dynamics of rainforest birds between 2000 and 2016. We find a strong effect of warming and changes in rainfall patterns across the elevational-segregated bird communities, with lowland populations benefiting from increasing temperature and precipitation, while upland species show an inverse strong negative response to the same drivers. Additionally, we find a negative effect of heatwaves on lowland populations, a pattern associated with the observed distribution of these extreme events across elevations. In contrast, cyclones and droughts have a marginal effect on spatiotemporal changes in rainforest bird communities, suggesting a species-specific response unrelated to the elevational gradient. This study demonstrated the importance of unravelling the drivers of climate change impacts on population changes, providing significant insight into the mechanisms accelerating climate-induced biodiversity degradation.

Acadia National Park Winter Birds: 51 Years of Change along the Coast of Maine

There is a long history of recording bird observation in Acadia National Park, ME. These studies and resulting long-term data sets provide evidence of changes happening within and around the park, as well as an opportunity to compare local dynamics with trends detected in regional to continental-scale studies. Over 51 years (1971–2021), community volunteers in and around Acadia National Park engaged in annual Christmas bird counts (CBC), collecting valuable information to assess winter bird-population dynamics and species trends. We analyzed the cumulative data from 2 CBC circles that encompass Acadia and the surrounding lands and waters to generate a combined summary of early winter population-trend estimates for 162 species. We found a 43% reduction in the total number of birds over the 51-year study, with 42 species exhibiting declines, and 33 species showing increasing abundance. The annual number of species observed has declined by over 7%; however, the cumulative species in the full dataset continues to increase as newly observed species are added in most years. Our study complements many other studies from Acadia documenting ongoing changes in the physical environment and coastal biota. Conservation and management actions take place at the local level (e.g., Acadia National Park), and local resource data and trends are critical to synthesize and share for effective decision making.