Winter habitat selection by a montane forest bird assemblage: the effects of solar radiation

A relationship between sunlight and bird abundance in cold climates may seem intuitive and perhaps obvious. However, there is, surprisingly, little or no evidence to support it. We investigated the effects of solar radiation on the winter abundance of insectivorous birds inhabiting a Mediterranean montane forest with a high frequency of cold, cloudless days. We censused birds by ear in 20 different forest tracts in which we simultaneously quantified a number of variables related to the availability of solar radiation, vegetation structure, arthropod abundance, and altitude. All variables related to solar radiation were reduced to a single principal component that attained high scores for south-facing transects, where many tree trunks received direct sunlight for a long period daily. The abundance of all bird species was positively related to the scores of transects on this component after the effects of vegetation structure, altitude, and prey availability were controlled for. Solar radiation was the main predictor of overall abundance and species richness of bird assemblages. Body mass and diet (insectivorous vs. mixed) explained 94.6% of interspecific variation in the strength of the relationship between solar radiation and bird abundance. We hypothesize that selecting forest sectors with a higher availability of sunlit patches allows birds to improve their winter survival by reducing the metabolic costs of thermoregulation, decreasing movement rates, and (or) increasing the time spent motionless in safe locations.

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Quantification of 27 yolk steroid hormones in seven shrubland bird species: interspecific patterns of hormone deposition and links to life history, development, and predation risk

Canadian Journal of Zoology ◽

10.1139/cjz-2017-0351 ◽

2019 ◽

Vol 97 (1) ◽

pp. 1-12 ◽

Cited By ~ 9

Author(s):

L. Merrill ◽

S.J. Chiavacci ◽

R.T. Paitz ◽

T.J. Benson

Keyword(s):

Life History ◽

Predation Risk ◽

Steroid Hormones ◽

High Performance ◽

Bird Species ◽

Principal Component ◽

Interspecific Variation ◽

American Robin ◽

Nestling Development ◽

Yolk Steroids

Steroid hormones play critical organizational and activational roles during vertebrate development, impacting everything from sexual differentiation to metabolic activity. For oviparous species such as birds, these hormones are transferred from female to egg during follicle maturation, and differences in relative and absolute concentrations of the steroid hormones may reflect differences in life history, developmental, and ecological conditions. Prior work on yolk steroid hormones has focused on a handful of candidate hormones (e.g., testosterone, androstenedione, and corticosterone), but we used high-performance liquid chromatography with tandem mass spectroscopy (LC–MS–MS) to quantify 27 yolk steroids from the eggs of seven shrubland bird species (American Robin, Turdus migratorius Linnaeus, 1766; Brown-headed Cowbird, Molothrus ater (Boddaert, 1783); Brown Thrasher, Toxostoma rufum (Linnaeus, 1758); Eastern Towhee, Pipilo erythrophthalmus (Linnaeus, 1758); Field Sparrow, Spizella pusilla (A. Wilson, 1810); Gray Catbird, Dumetella carolinensis (Linnaeus, 1766); Northern Cardinal, Cardinalis cardinalis (Linnaeus, 1758)). In addition to comparing steroid profiles across species, we conducted exploratory analyses to determine how the hormones clustered using a principal component (PC) approach and if PCs were correlated with aspects of egg resources (relative egg size, proportion yolk), life-history traits (embryonic and nestling development speed), and nest-predation risk (daily survival rate (DSR)). We documented substantial interspecific variation in both absolute and proportional endocrine profiles. PCAs indicated that glucocorticoids generally clustered together (PC1), but other classes of steroids did not. PC2 and PC3 strongly covaried with egg resources, DSR, and development speed, suggesting that they reflect adaptive patterns of maternal hormone deposition.

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Occupancy of avian foraging guilds in soybean fields and borders in Entre Ríos, Argentina: responses to vegetation structure and prey resources

Avian Research ◽

10.1186/s40657-020-00235-4 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Andrea P. Goijman ◽

Michael J. Conroy ◽

Vanina D. Varni ◽

Jeffrey J. Thompson ◽

María Elena Zaccagnini

Keyword(s):

Ecosystem Services ◽

Vegetation Structure ◽

Prey Availability ◽

Wide Spectrum ◽

Bird Species ◽

Imperfect Detection ◽

Native Trees ◽

Foraging Guilds ◽

Field Borders ◽

Entre Rios

Abstract Background Reconciling agriculture and biodiversity conservation is a challenge given the growing demand for agricultural products. In recent decades, Argentina has witnessed agricultural expansion and intensification affecting biodiversity and associated ecosystem services. Within agroecosystems, the level of habitat quality is critical for birds, and may depend on vegetation structure, availability of invertebrate prey, and the use of pesticides. Although the relationship between vegetation structure and avian occurrence has been widely studied, to our knowledge, there are no studies that also incorporate prey availability throughout the cycle of soybean crops in Argentina. We estimated and predicted the effects of land cover and temporal variation on the occurrence of avian foraging guilds in Entre Ríos, Argentina, in order to guide management related to potential ecosystem services provided by birds. We also estimated temporal effects of vegetation structure and insecticides on the main arthropod orders consumed by birds to evaluate prey availability. Methods We conducted bird and arthropod surveys for 2 years along transects located in 20 randomly selected soybean fields (N = 60) and their adjacent borders (N = 78) throughout the crop growing season, in four seasons. We estimated avian occupancy, accounting for imperfect detection, and arthropod counts fitting generalized linear mixed models. Results The number of native trees in field borders positively influenced the occurrence of most bird species, mainly insectivores. Granivore foliage gleaners, also were positively affected by grass height. Salliers and aerial foragers were weakly affected by distance to forest and native trees. In general, the availability of invertebrates to birds was highest during the third season. Arthropod counts in borders were greater during the last three crop stages than during the pre-sowing period. Conclusions We found that with 10 to 15 native tree species in borders, coupled with a complex vegetation structure with shrubs and grasses, we could conserve a wide spectrum of insectivorous birds, and may contribute to the invertebrate pest control service. Vegetated field borders function as a refuge for arthropods, especially agriculturally beneficial taxa such as Hymenopterans. Finally, several groups of birds use the interior of the fields and could help control pests.

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Environmental factors affecting the densities of owls in Polish farmland during 1980–2005

Biologia ◽

10.2478/s11756-012-0114-x ◽

2012 ◽

Vol 67 (6) ◽

Cited By ~ 3

Author(s):

Michał Żmihorski ◽

Jerzy Romanowski ◽

Przemysław Chylarecki

Keyword(s):

Prey Availability ◽

Bird Species ◽

Principal Component ◽

Additive Models ◽

Published Data ◽

Factors Affecting ◽

Land Use Types ◽

Farmland Bird ◽

Forest Coverage ◽

Athene Noctua

AbstractDuring the last decades, farmland habitats in central European countries have changed significantly, seriously affecting populations of many farmland bird species. We compiled available published data on densities of three owl species, Athene noctua, Asio otus and Strix aluco collected in the Polish farmland. All results of censuses based on the playback method conducted between 1980–2005 were included in the analysis. The proportions of grassland, fields, built-up land and forest at each studied plot were estimated and used as predictors in additive models. Proportions of main land use types, extracted with the principal component analysis, explained much of the variation found in owl densities, although some of the relationships were nonlinear. In general, owl densities were found to be affected positively by a high percentage of grasslands and built-up land, and negatively by the amount of fields and forests. Little owl densities showed a significant negative trend over the study period. It seems that high prey availability is an important factor accounting for the positive relationship between grassland proportion and owl density. The significant decrease in grassland areas and increase in forest coverage that were recently recorded in Poland may thus negatively affect populations of the three owl species studied here.

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Monitoring of Kilum-Ijim forest bird communities: initial findings

Bird Conservation International ◽

10.1017/s0959270903003198 ◽

2003 ◽

Vol 13 (3) ◽

pp. 255-271 ◽

Cited By ~ 9

Author(s):

Philip F. Forboseh ◽

Ernest C. Keming ◽

Clement L. Toh ◽

Innocent N. B. Wultof

Keyword(s):

Structural Changes ◽

Bird Species ◽

Bird Community ◽

Montane Forest ◽

Bird Communities ◽

Individual Species ◽

Bird Abundance ◽

The Status ◽

Abundance And Diversity ◽

The Relationship

The Kilum-Ijim forest is an excellent example of the ornithological riches of the Cameroon montane forest biome. The forest is also important to over 200,000 people who exert enormous pressure on the ecosystem. In 1995, the Kilum-Ijim Forest Project began systematic monitoring of birds, with the intention of using them as indicators of the overall condition of the forest, as well as monitoring the status of individual species. Analyses of data collected in 1999–2000 demonstrated some clear differences in habitat use, suggesting suites of bird species may be indicators of changes in vegetation. However, beyond this, little is known about the response of birds to habitat modifications, or the relationship between bird abundance and diversity of other organisms at Kilum-Ijim. It is argued that the objective of assessing changes in vegetation could be more satisfactorily pursued through direct measurement of structural changes in habitats. We highlight the necessity for a shift in the programme objectives to place greater emphasis on monitoring endemic and threatened bird species for their own status and on assessing changes in the bird community as a function of changes in the vegetation.

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Photo-selective shade nets on the production and quality of sugarcane plantlets

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v23n5p366-371 ◽

2019 ◽

Vol 23 (5) ◽

pp. 366-371 ◽

Cited By ~ 1

Author(s):

José J. F. Cordeiro Júnior ◽

Héliton Pandorfi ◽

José A. D. Barbosa Filho ◽

Alex S. Moraes ◽

Luiz A. de Almeida Neto ◽

...

Keyword(s):

Solar Radiation ◽

Substrate Temperature ◽

Principal Component ◽

Global Solar Radiation ◽

Saccharum Officinarum ◽

Low Density Polyethylene ◽

Low Density ◽

Randomized Design ◽

Completely Randomized Design

ABSTRACT Brazil is the world’s largest producer of sugarcane (Saccharum officinarum L.) and research aimed at propagation has promoted higher quality in production. The objective of this study was to investigate the effect of the variation of micrometeorological elements on the survival and quality of pre-sprouted sugarcane plantlets. The study was carried out in a protected environment (UFRPE). Plantlets of the cultivar RB92579 were obtained by the technique of production of pre-sprouted plantlets. The protected environments were divided into four modules covered with low-density polyethylene plastic + photo-selective shade nets and one module without shade net. Micrometeorological data of global and photosynthetically active solar radiation, air temperature, substrate temperature, relative humidity and the solar radiation spectrum were recorded in each module. The experiment was conducted in a completely randomized design and the principal component analysis was used to verify the association between the cultivation modules, micrometeorological variables and crop variables. Anti-UV low-density polyethylene plastic + freshnet led to lower transmittance of global solar radiation, higher percentage of photosynthetically active radiation and lower plantlet mortality. Substrate temperature above 30.2 °C resulted in higher plantlet mortality. Larger spectrum in the red range led to the production of better quality plantlet. The use of freshnet shade net promoted adequate conditions for the cultivation of sugarcane plantlets and allows obtaining better quality plantlets.

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Bird Abundance and Nesting Success in Iowa CRP Fields: The Importance of Vegetation Structure and Composition

The American Midland Naturalist ◽

10.2307/2426881 ◽

1996 ◽

Vol 135 (1) ◽

pp. 153 ◽

Cited By ~ 88

Author(s):

Matthew P. Patterson ◽

L. B. Best

Keyword(s):

Vegetation Structure ◽

Nesting Success ◽

Bird Abundance

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Vegetation structure and decreased moth abundance limit the recolonisation of restored habitat by the European Nightjar

Rethinking Ecology ◽

10.3897/rethinkingecology.3.29338 ◽

2018 ◽

Vol 3 ◽

pp. 25-39 ◽

Cited By ~ 4

Author(s):

Nathalie Winiger ◽

Pius Korner ◽

Raphaël Arlettaz ◽

Alain Jacot

Keyword(s):

Vegetation Structure ◽

Habitat Restoration ◽

Stand Structure ◽

Prey Availability ◽

Population Declines ◽

Major Transitions ◽

Slowing Down ◽

Open Forest ◽

Mineral Soils ◽

Management Recommendations

Woodland ecosystems of Europe have undergone major transitions in the last centuries. Changes in land use and the loss of natural forest dynamics have often led to structurally poor, uniform and dense stands. Not surprisingly, open forest species relying on a heterogeneous stand structure have suffered dramatic population declines. The European Nightjar Caprimulguseuropaeus, a nocturnal insectivorous bird, has undergone such a decline in its main Swiss stronghold in Valais. Despite the species’ potential to colonize new sites and habitat restoration measures implemented since 2001, recolonisation of restored sites has not taken place, suggesting problems with the current habitat restoration strategy. In order to refine management recommendations, we compared habitat structure and moth abundance, a key Nightjar food source, at sites that are still occupied and at sites that had been abandoned but have recently been restored. Vegetation structure was more heterogeneous and moth abundance greater at occupied than at abandoned sites. More specifically, occupied sites harboured a greater coverage of bare ground, while abandoned sites exhibited a higher amount of regeneration and intermediate shrub layer. The occurrence of natural perches was also higher in occupied sites. Abandoned sites are thus characterised by lower prey abundance and denser vegetation cover, the combination of which is likely to lead to lower prey availability for hunting Nightjars. Restoration action would benefit from maintaining snags and dead branches and by targeting unproductive habitats characterised by mineral soils, thereby slowing down regeneration and shrub regrowth. For future successful management of Nightjar habitats, it seems thereby essential trying to find the balance between actions that allow opening the lower and mid-strata of the forest while sustaining high moth populations.

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Habitat and Landscape Suitability as Indicators of Bird Abundance in Created and Restored Wetlands

ISRN Ecology ◽

10.5402/2011/297684 ◽

2011 ◽

Vol 2011 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Jordan W. Mora ◽

John N. Mager III ◽

Douglas J. Spieles

Keyword(s):

Bird Species ◽

Land Development ◽

Logistic Models ◽

Field Measurements ◽

Road Density ◽

Bird Abundance ◽

Aerial Photos ◽

Landscape Variables ◽

Buffer Width ◽

Landscape Scales

We used aerial photography, field measurements, and bird surveys to evaluate 7 Ohio mitigation wetlands for their capacity to support avian guilds at both local and landscape scales. At the local scale, we assessed each wetland with habitat suitability indices (HSI) for eight wetland-dependent bird species as indicators for four guilds: wading, diving, dabbling, and emergent dependent. We characterized landscapes within 2.5 km of each wetland by measuring the buffer width, road density, connectedness, and anthropogenic land development. The changes in landscape variables over time were determined by comparison of aerial photos taken near the time of wetland construction and near the time of this study. Bird abundance data were poorly correlated with HSI scores but were well described with logistic models of buffer width, wetland area, and road density. Our results suggest that landscape variables are better predictors of bird abundance than HSI scores for these guilds in these wetlands.

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Brain regions associated with visual cues are important for bird migration

Biology Letters ◽

10.1098/rsbl.2015.0678 ◽

2015 ◽

Vol 11 (11) ◽

pp. 20150678 ◽

Cited By ~ 11

Author(s):

Orsolya Vincze ◽

Csongor I. Vágási ◽

Péter L. Pap ◽

Gergely Osváth ◽

Anders Pape Møller

Keyword(s):

Visual Cues ◽

Optic Lobe ◽

Brain Size ◽

Relative Size ◽

Bird Species ◽

Interspecific Variation ◽

Brain Regions ◽

Long Distance ◽

Migration Distance ◽

Whole Brain

Long-distance migratory birds have relatively smaller brains than short-distance migrants or residents. Here, we test whether reduction in brain size with migration distance can be generalized across the different brain regions suggested to play key roles in orientation during migration. Based on 152 bird species, belonging to 61 avian families from six continents, we show that the sizes of both the telencephalon and the whole brain decrease, and the relative size of the optic lobe increases, while cerebellum size does not change with increasing migration distance. Body mass, whole brain size, optic lobe size and wing aspect ratio together account for a remarkable 46% of interspecific variation in average migration distance across bird species. These results indicate that visual acuity might be a primary neural adaptation to the ecological challenge of migration.

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