scholarly journals Do Feeder Counts Reliably Indicate Bird Population Changes? 21 Years of Winter Bird Counts in Ontario, Canada

The Condor ◽  
2002 ◽  
Vol 104 (2) ◽  
pp. 255-270 ◽  
Author(s):  
Denis Lepage ◽  
Charles M. Francis
Keyword(s):  
North America ◽  
Sampling Error ◽  
Bird Species ◽  
Population Trends ◽  
Population Changes ◽  
Bird Abundance ◽  
Bird Populations ◽  
Continental Scale ◽  
Population Indices ◽  
High Consistency

Abstract Few monitoring programs in North America track bird populations at a continental scale during the winter, a critical stage of the life cycle for many species. To date, only Christmas Bird Counts (CBC) have been used to index bird abundance in winter across North America. We evaluated another continentwide program, Project FeederWatch (PFW), which monitors many bird species more intensively than CBC. PFW is a survey in which volunteers use standardized methods to count birds visiting feeders every two weeks from November through April. We compared population indices and trends from PFW and CBC data for 43 species in 3 regions of Ontario, Canada, over a 21-year period from 1976–1997. Annual population indices from PFW were significantly positively correlated with similar indices from CBC for about 80% of species for which annual variation in counts was substantially greater than sampling error. Log-linear population trends from both surveys were also well correlated, though the absolute value of the trend estimates tended to be higher for PFW. The high consistency between surveys suggests that both may be suitable for detecting population changes for many bird species in winter, especially irruptive species that show large annual fluctuations, and species with marked population trends. However, some species did not correspond between surveys, despite being measured fairly precisely, highlighting the value of having two independent surveys to corroborate patterns. Christmas Bird Counts have the advantage that they sample more species, but Project FeederWatch has a more consistent protocol and continues through the winter, allowing analysis of changes in populations through the winter. ¿Proveen los Conteos en Comederos Información Fidedigna sobre Cambios en las Poblaciones de Aves? 21 Años de Conteos Invernales de Aves en Ontario, Canadá Resumen. Pocos programas de monitoreo en América del Norte siguen a las poblaciones de aves a escala continental durante el invierno, cuando muchas especies pasan por una etapa crítica en su ciclo de vida. Hasta el presente, sólo los Conteos de Aves de Navidad (CAN) han sido usados para cuantificar la abundancia de aves en el invierno a lo largo de América del Norte. Nosotros evaluamos otro programa a nivel continental, el Proyecto de Observación de Comederos (POC), el cual sigue muchas especies de aves de modo más intenso que los CAN. El POC es un programa de muestreo en el cual voluntarios usan métodos estandarizados para contar las aves que visitan comederos, censándolas cada dos semanas entre noviembre y abril. Comparamos índices y tendencias poblacionales de los datos del POC y de los CAN para 43 especies en 3 regiones de Ontario, Canadá, a lo largo de un período de 21 años entre 1976 y 1997. Los índices poblacionales anuales del POC estuvieron positiva y significativamente correlacionados con índices similares de los CAN para alrededor del 80% de las especies, considerando aquellas para las que la variación anual en los conteos fue sustancialmente mayor que el error de muestreo. Las tendencias poblacionales de ambos muestreos, representadas de modo log-lineal, también estuvieron bien correlacionadas, aunque el valor absoluto de la tendencia estimada tendió a ser mayor para el POC. La alta consistencia entre los programas de muestreo sugiere que ambos pueden ser adecuados para detectar los cambios poblacionales de muchas especies de aves durante el invierno, especialmente para especies eruptivas que muestran grandes fluctuaciones anuales, y para aquellas con tendencias poblacionales marcadas. Sin embargo, algunas especies mostraron diferencias entre los programas de muestreo a pesar de haber sido medidas de modo bastante preciso, destacando el valor de tener dos métodos de muestreo independientes para corroborar los patrones. Los Conteos de Aves de Navidad tienen la ventaja de que muestrean más especies, pero el Proyecto de Observación de Comederos posee un protocolo más consistente y se prolonga a través del invierno, permitiendo analizar los cambios de las poblaciones a través de este período.

scholarly journals Environmental correlates of genetic variation in the invasive and largely panmictic European starling in North America

2019 ◽  
Author(s):  
Natalie R. Hofmeister ◽  
Scott J. Werner ◽  
Irby J. Lovette
Keyword(s):  
North America ◽  
Local Adaptation ◽  
North American ◽  
Winter Season ◽  
Bird Species ◽  
Genomic Diversity ◽  
Rapid Expansion ◽  
Continental Scale ◽  
High Dispersal ◽  
Local Selection

ABSTRACTPopulations of invasive species that colonize and spread in novel environments may differentiate both through demographic processes and local selection. European starlings (Sturnus vulgaris) were introduced to New York in 1890 and subsequently spread throughout North America, becoming one of the most widespread and numerous bird species on the continent. Genome-wide comparisons across starling individuals and populations can identify demographic and/or selective factors that facilitated this rapid and successful expansion. We investigated patterns of genomic diversity and differentiation using reduced-representation genome sequencing (ddRADseq) of 17 winter-season starling populations. Consistent with this species’ high dispersal rate and rapid expansion history, we found low geographic differentiation and few FST outliers even at a continental scale. Despite starting from a founding population of approximately 180 individuals, North American starlings show only a moderate genetic bottleneck, and models suggest a dramatic increase in effective population size since introduction. In genotype-environment associations we found that ∼200 single-nucleotide polymorphisms are correlated with temperature and/or precipitation against a background of negligible genome- and range-wide divergence. Local adaptation in North American starlings may have evolved rapidly even in this wide-ranging and evolutionarily young population. This survey of genomic signatures of expansion in North American starlings is the most comprehensive to date and complements ongoing studies of world-wide local adaptation in these highly dispersive and invasive birds.

scholarly journals Climatic dipoles drive two principal modes of North American boreal bird irruption

2015 ◽  
Vol 112 (21) ◽  
pp. E2795-E2802 ◽  
Author(s):  
Courtenay Strong ◽  
Benjamin Zuckerberg ◽  
Julio L. Betancourt ◽  
Walter D. Koenig
Keyword(s):  
North America ◽  
Seed Production ◽  
Warm Season ◽  
Bird Populations ◽  
Continental Scale ◽  
The North ◽  
Large Numbers ◽  
Seed Eating ◽  
One Year ◽  
Seed Crops

Pine Siskins exemplify normally boreal seed-eating birds that can be sparse or absent across entire regions of North America in one year and then appear in large numbers the next. These dramatic avian “irruptions” are thought to stem from intermittent but broadly synchronous seed production (masting) in one year and meager seed crops in the next. A prevalent hypothesis is that widespread masting in the boreal forest at high latitudes is driven primarily by favorable climate during the two to three consecutive years required to initiate and mature seed crops in most conifers. Seed production is expensive for trees and is much reduced in the years following masting, driving boreal birds to search elsewhere for food and overwintering habitat. Despite this plausible logic, prior efforts to discover climate-irruption relationships have been inconclusive. Here, analysis of more than 2 million Pine Siskin observations from Project FeederWatch, a citizen science program, reveals two principal irruption modes (North-South and West-East), both of which are correlated with climate variability. The North-South irruption mode is, in part, influenced by winter harshness, but the predominant climate drivers of both modes manifest in the warm season as continental-scale pairs of oppositely signed precipitation and temperature anomalies (i.e., dipoles). The climate dipoles juxtapose favorable and unfavorable conditions for seed production and wintering habitat, motivating a push-pull paradigm to explain irruptions of Pine Siskins and possibly other boreal bird populations in North America.

Long-term monitoring of landbirds on Aldabra Atoll indicates increasing population trends

2015 ◽  
Vol 26 (3) ◽  
pp. 337-349 ◽  
Author(s):  
JANSKE VAN DE CROMMENACKER ◽  
HEATHER RICHARDS ◽  
CATHERINA ONEZIA ◽  
TERENCE MAHOUNE ◽  
PHILIP HAUPT ◽  
...  
Keyword(s):  
Weather Conditions ◽  
Population Trends ◽  
World Heritage Site ◽  
Bird Populations ◽  
Heritage Site ◽  
Unesco World Heritage Site ◽  
Population Indices ◽  
Conservation Concern ◽  
Current Monitoring

SummaryLong-term survey data can provide important information on temporal and spatial changes in bird populations and are needed for conservation management. We investigate population indices of seven landbird species using an 11-year dataset from the UNESCO World Heritage Site of Aldabra Atoll. We analysed the associations of location, season and habitat with abundance, assessed population trends, and examined the influence of monitoring circumstances on results. Populations of all species except for the Aldabra Drongo Dicrurus aldabranus increased over this period. Abundance was associated with season and habitat, and interactions were found between season and location that differed for each species. Bird count results were affected by the timing of monitoring, number of observers and weather conditions. We use the results to review the strengths and weaknesses of the current monitoring programme and make recommendations for improvements. Overall our results indicate no immediate cause for conservation concern for the Aldabra landbird species monitored.

scholarly journals Farmland bird communities in the Baltic region: impact of agricultural intensification and farmers’ attitudes

2008 ◽  
Author(s):  
Irina Herzon
Keyword(s):  
Agricultural Development ◽  
Agricultural Land ◽  
Bird Species ◽  
Agricultural Policies ◽  
Farmland Birds ◽  
Bird Abundance ◽  
Bird Populations ◽  
Farmland Bird ◽  
The Baltic ◽  
The Eu

Intensification of agricultural land-use was shown to be the key reason behind declines in wildlifespecies associated with farmland. I looked at scenarios of agricultural development across the Baltic states ofEstonia, Latvia and Lithuania, and the ways they are seen to affect farmed environments as a habitat offarmland bird species. Community richness and abundance of many farmland bird species were positivelyrelated to the number of non-cropped elements within farmland, the local mixture of annual crop and grassfields, and the variety of field types. The above positive associations were strongest in open landscapes.There was a clear indication that the more intensively farmed areas across the region provided habitat forfewer bird species and individuals. The difference could partly be explained by the more heterogeneouslandscape and field areas in the latter. Within homogenous arable fields intensification of field managementwas reflected in a tangible decrease in farmland bird abundance, especially in species in need of edgestructures.Based on the interviews in Estonia and Finland I explored farmers’ interest in and knowledge offarmland wildlife, their understanding of the concept of biodiversity, and awareness of the potential causesbehind declines of farmland birds. Many farmers viewed biodiversity from a narrow perspective oftenexcluding species directly related to farming. In Finland farmers expressed concern about the decline incommon farmland species, but Estonian farmers did not, which might be related to the fact that these speciesare still very common. In both countries farmers rated intensification of agriculture as the major drivingforce behind farmland bird declines. The expressed interest in wildlife positively correlated with willingnessto undertake wildlife-friendly measures. Only farmers with agri-environment contracts targeted specificallyat biodiversity enhancement were more knowledgeable about practical on-farm activities favouring wildlife,and were more willing to employ them that the rest.The results suggest that, by contributing to simplification of the farmland structure, homogenisationof crops, and increase in intensity of field use EU agricultural policies will have a detrimental effect onfarmland bird populations in Eastern Europe. Farmers are on the whole positive to the idea of supportingwildlife in the fields, and are concerned about its decline, but they require payments to offset their incomeloss and extra work. Biodiversity conservation should be better integrated into the agri-environmentprogrammes if it to serve as awareness tool for farmers. I argue that with a foreseen tripling of cereal yieldsacross the region, the EU Council’s Göteborg target of slowing biodiversity decline by 2010 may not berealistic unless considerable improvements are made into the EU agricultural policy for the region.

Changes in bird abundance following Common Myna control on aNew Zealand island

2007 ◽  
Vol 13 (3) ◽  
pp. 202 ◽  
Author(s):  
S. David Tindall ◽  
C. John Ralph ◽  
M. N. Clout
Keyword(s):  
Bird Species ◽  
Small Island ◽  
Relative Role ◽  
Bird Abundance ◽  
Bird Populations ◽  
The North ◽  
Common Myna ◽  
Acridotheres Tristis ◽  
Land Bird ◽  
And Control

We censused land bird populations on a small island during a year of intense trapping of the Common Myna Acridotheres tristis. We successfully removed mynas on Moturoa Island, Bay of Islands, with populations on the island decreasing In most areas, while holding steady on other, nearby islands where no trapping was conducted. The populations of many other bird species increased coincidently with the removal of mynas. This was most notable in the Tui Prosthemadera novaeseelandiae, Grey Warbler Gerygone igata, and Blackbird Turdus merula. Of 60 species-route comparisons, we found that 23 (38%) increased, 33 (55%) had no change, and only four (7%) decreased. The relative role of rats Rattus spp. and succession is also discussed. Tile historical decline of many species in the North Island of New Zealand may have been related to the concomitant increase of tile myna, and control of this species may be warranted in some cases, especially where restoration of the native fauna is the objective.

scholarly journals Population trends of wintering waterbirds in Lombardy between 2002 and 2013

2015 ◽  
Vol 84 (2) ◽  
Author(s):  
Violetta Longoni ◽  
Diego Rubolini ◽  
Guido Pinoli ◽  
Mauro Fasola
Keyword(s):  
Protected Areas ◽  
Land Use Planning ◽  
Economic Value ◽  
Ecological Status ◽  
Bird Species ◽  
Population Trends ◽  
Italian Population ◽  
Ramsar Convention ◽  
Factors Affecting ◽  
Bird Populations

Birds are among the most important biological components of wetlands. They play a key role in their ecology and are an important cultural resource for the public, in part because some species can be legally hunted. The conservation of waterbirds is especially important in terms of land use planning, in light of their ecological, cultural, and economic value. Here we summarize the results of wintering waterbirds censuses carried out in Lombardy between 2002 and 2013, using the standardized International Waterbird Census methodology. Our goals were to identify priority sites for waterbirds; estimate population sizes; define demographic trends; and provide a technical framework for making administrative and legislative decisions on the management and conservation of wetlands and their bird species. Lombardy hosts substantial numbers of wintering waterbirds, and many of its wetlands qualify as areas of conservation interest under Ramsar Convention criteria, as they host >1% of the Italian population of one or more species. Trends for the 20 species of highest conservation or hunting interest showed stable or increasing populations in most cases, with the exception of Black-necked Grebe, Common Pochard, and Eurasian Coot, which instead decreased in 2002-2013. The favourable population trends for most species suggest that the ecological status of Lombardy’s wetlands is essentially stable, but it could be improved by simple measures to improve the natural value of the shorelines and bottoms of major lakes and flooded gravel pits. Hunting was one of the main factors affecting the distribution and abundance of wintering waterbirds, which concentrate in protected areas - over 50% of all birds, rising to over 70% for species of conservation interest concentrate there, despite the fact that protected areas only account for 43% of sites surveyed. Overall, protected areas hosted bird densities that were almost seven times higher than those managed primarily for hunting, while mixed-use areas hosted intermediate densities of birds. The presence of protected and unprotected areas within the same wetland mitigates the effects of hunting on bird populations and species diversity, and may help maintain adequate conditions for their conservation.

Drivers of population change in common farmland birds in Germany

2020 ◽  
Vol 30 (3) ◽  
pp. 335-354 ◽  
Author(s):  
MALTE BUSCH ◽  
JAKOB KATZENBERGER ◽  
SVEN TRAUTMANN ◽  
BETTINA GERLACH ◽  
RAINER DRÖSCHMEISTER ◽  
...  
Keyword(s):  
Breeding Season ◽  
Population Change ◽  
Bird Species ◽  
Weather Conditions ◽  
Population Trends ◽  
Mixed Effect ◽  
Bird Population ◽  
Bird Populations ◽  
Positive Effects ◽  
Farmland Bird

SummaryFarmland bird populations in Germany are declining at a higher speed than species inhabiting other habitats. We studied potential causes for bird population changes based on data from standardised German breeding bird monitoring schemes. We related population trends to covariates describing the changes in the agricultural landscape in Germany, weather conditions during the breeding season and for some migratory species, conditions at stopover and wintering sites. Linear mixed effect models were used to analyse effect strength at species level and conclusions are drawn for the overall group of farmland bird species. The area of grassland and fallow land was shown to have the strongest positive effects and the area of maize and rapeseed the strongest negative effects on farmland bird population trends. The results obtained also indicate that despite the consistent influence of weather conditions during the breeding season, land-use changes had a stronger impact on bird populations than weather. Conditions at Sahel wintering sites did not show a consistent effect on population trends. Based on these findings the study quantitatively underpins and ranks key factors shaping farmland bird populations in Germany.

scholarly journals Significance of the globally threatened Straw-headed Bulbul Pycnonotus zeylanicus populations in Singapore: a last straw for the species?

2017 ◽  
Vol 28 (1) ◽  
pp. 133-144 ◽  
Author(s):  
DING LI YONG ◽  
KIM SENG LIM ◽  
KIM CHUAH LIM ◽  
TRIXIE TAN ◽  
SIYANG TEO ◽  
...  
Keyword(s):  
Bird Species ◽  
Management Plan ◽  
Peninsular Malaysia ◽  
Population Trends ◽  
Ex Situ ◽  
Area Network ◽  
Forest Patches ◽  
The Status ◽  
Population Indices

SummaryThe globally threatened Straw-headed Bulbul Pycnonotus zeylanicus is one of South-East Asia’s most imperilled songbirds due to the surging demand for the species in the regional bird trade. Recently uplisted from Vulnerable to Endangered, populations of the Straw-headed Bulbul have been extirpated from Java, Thailand and possibly Sumatra while those in Borneo and Peninsular Malaysia are in decline. Intriguingly, a significant yet rarely documented population of this species persists in Singapore. A major stronghold in Singapore is Ubin Island where a population is known since the 1920s. Using a long-term citizen science dataset rarely available for South-East Asian bird species, we determined the status and population trends of the Straw-headed Bulbul in Singapore over a 10–15 year period using Poisson regression models and standardised population indices. We found that the Straw-headed Bulbul population has increased at a rate of 3.69 ± 1.21% per annum on Ubin Island, while the population on Singapore Island remained stable (0.56% per annum) from 2000 to 2016. The population trends in Singapore contrast starkly with the declines reported elsewhere in South-East Asia. We estimated the population in Singapore to be a minimum of 202 individuals, distributed over multiple forest patches. The largest subpopulation of about 110 adult individuals persists on Ubin and which alone forms between 6.5–18.3% of the estimated global population in 2016. Given this unique situation, we recommend a number of conservation measures for the Straw-headed Bulbul to better protect the species, including: (1) an expansion of the protected area network in Singapore to include Ubin as a reserve, (2) the development of an endangered species management plan and, (3) the establishment of ex-situ conservation programmes in zoological institutions and wildlife centres in the region.

scholarly journals Poor evidence-base for assessment of windfarm impacts on birds

2007 ◽  
Vol 34 (1) ◽  
pp. 1-11 ◽  
Author(s):  
GAVIN B. STEWART ◽  
ANDREW S. PULLIN ◽  
CHRISTOPHER F. COLES
Keyword(s):  
Climate Change ◽  
Negative Impact ◽  
Renewable Energy Sources ◽  
Habitat Type ◽  
Bird Species ◽  
Evidence Base ◽  
Systematic Review Methodology ◽  
Bird Abundance ◽  
Bird Populations ◽  
The Impact

Concerns about anthropogenic climate change have resulted in promotion of renewable energy sources, especially wind energy. A concern raised against widespread windfarm development is that it may negatively impact bird populations as a result of bird collision with turbines, habitat loss and disturbance. Using systematic review methodology bird abundance data were synthesized from 19 globally-distributed windfarms using meta-analysis. The effects of bird taxon, turbine number, power, location, latitude, habitat type, size of area, time since operation, migratory status of the species and quality of evidence were analysed using meta-regression. Although the synthesized data suggest a significant negative impact of windfarms on bird abundance, there is considerable variation in the impact of individual windfarm sites on individual bird species, and it is unclear if the negative impact is a decline in population abundance or a decline in use owing to avoidance. Anseriformes experienced greater declines in abundance than other taxa, followed by Charadriiformes, Falconiformes and Accipitriformes, and Passeriformes. Time since windfarms commenced operation also had a significant impact on bird abundance, with longer operating times resulting in greater declines in abundance than short operating times. Other variables, including turbine number and turbine power either had very weak but statistically significant effects or did not have a significant effect on bird abundance. Windfarms may have significant biological impacts, especially over longer time scales, but the evidence-base is poor, with many studies being methodologically weak, and more long-term impact assessments are required. There is clear evidence that Anseriformes (wildfowl) and Charadriiformes (waders) experience declines in abundance, suggesting that a precautionary approach should be adopted to windfarm development near aggregations of these taxa in offshore and coastal locations. The impact of windfarm developments on bird populations must also be viewed in the context of the possible impact of climate change in the absence of windfarms.

scholarly journals Artificial night light and anthropogenic noise interact to influence bird abundance over a continental scale

2021 ◽  
Author(s):  
Ashley A. Wilson ◽  
Mark A. Ditmer ◽  
Jesse R. Barber ◽  
Neil H. Carter ◽  
Eliot T. Miller ◽  
...  
Keyword(s):  
Anthropogenic Noise ◽  
Bird Abundance ◽  
Continental Scale
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