scholarly journals Efecto de la estacionalidad y lluvias en la avifauna del Chaco Serrano Austral, Argentina

2017 ◽  
Vol 65 (3) ◽  
pp. 953
Author(s):  
Gustavo Alfredo Fava ◽  
Juan Carlos Acosta ◽  
Graciela Mirta Blanco
Keyword(s):  
Bird Species ◽  
Reproductive Activity ◽  
Breeding Habitat ◽  
Bird Abundance ◽  
Group Management ◽  
Natural Park ◽  
Chaco Serrano ◽  
Site Survey ◽  
Migrant Bird ◽  
Resident Bird

In subtropical regions like the Chaco Serrano (33° S), rainfall has a marked seasonality, and water flood, caused by heavy rains, may have important consequences for dependent ecosystems. Conversely, the high pressure on available resources during dry periods can also affect the fauna diversity and distribution. Even though birds have shown to be excellent ecological indicators of these shifts in the environment, currently little is known about the avifauna of the Argentine Chaco Serrano phytogeographic district. Our aim was to study the resident bird population status in the Southern Chaco Serrano, its fluctuations in richness and abundance, and its relationship to seasonal variations, in monthly and annual hydroperiods. In order to assess the resident bird status over a two year period (2011 Mar.-2013 Feb.) we carried out 18 sampling surveys during pre-breeding (spring), breeding (summer) and non breeding periods (autumn-winter), in the Northeastern part of the Valle Fértil Natural Park, San Juan province, Argentina. During each site survey, we recorded bird assemblages found in six transects, and obtained bird abundance and species diversity. A mixed general linear model was employed to evaluate relationships between the studied variables. We found a total of 98 species of birds belonging to 33 families (44 resident species, 23 spring visitors, six summer visitors, two winter visitors and 23 with scarce registers). We also registered 68 of these species in both hydroperiods, 28 only during rainy periods and only two during the dry period. Both richness and abundance showed the highest values during the pre-breeding and rainy seasons, while different tendencies were detected during the isolated monthly rainfalls. These changes in bird densities were associated with the arrival of migratory species, mainly spring visitors, and probably in relationship with their reproductive activity, and to seasonal fluctuations in food resources. The Southern Chaco Serrano is a subtropical semiarid place that seems to be an important breeding habitat for many migrant bird species, which in turn promoted seasonal changes in species density and diversity, mainly during rainy years. This work contributed to our understanding on the causes of richness and abundance variations on birds, and will contribute to this important group management and conservation in this area.

Habitat openness and edge avoidance predict Saltmarsh Sparrow abundance better than habitat area

The Condor ◽  
2020 ◽  
Vol 122 (3) ◽  
Author(s):  
Hallie Marshall ◽  
Erik J Blomberg ◽  
Valerie Watson ◽  
Meaghan Conway ◽  
Jonathan B Cohen ◽  
...  
Keyword(s):  
Population Decline ◽  
Bird Species ◽  
Breeding Habitat ◽  
Tidal Marshes ◽  
Bird Abundance ◽  
Marsh Edge ◽  
Marsh Bird ◽  
Saltmarsh Sparrow ◽  
Habitat Features ◽  
Better Than

Abstract The Saltmarsh Sparrow (Ammospiza caudacuta) is a tidal marsh bird facing rapid population decline throughout its range, largely caused by degradation and loss of breeding habitat. Thus, there is a need to preserve tidal marshes in the northeastern United States, but to do so requires an understanding of the habitat features that support robust populations. Previous studies have shown Saltmarsh Sparrow abundance increases with marsh size, but in similar bird species, area sensitivity is more directly linked to edge avoidance. Whether additional landscape features affect the abundance of Saltmarsh Sparrows is unknown. We explored how the height of objects on the horizon, an index of habitat openness, affected the abundance of Saltmarsh Sparrows. Our primary goal was to determine whether the angle to the highest point on the horizon (“angle to maximum horizon”) predicted abundance better than marsh area or distance to the marsh edge. We used N-mixture models to evaluate the combination of spatial factors that best predicted Saltmarsh Sparrow abundance while also accounting for survey-level variables that could influence detection probability. We found that the interaction between distance to edge and angle to maximum horizon best predicted abundance. Taller objects on the horizon were negatively correlated with bird abundance, and this effect was strongest within 50 m of the marsh edge. When we considered the predictive powers of patch area, distance to edge, and angle to maximum horizon individually, angle to maximum horizon was the best single predictor. We found the highest abundance of Saltmarsh Sparrows at point locations where the angle to maximum horizon was 0.0°, and at angles greater than 12° the predicted abundance fell below 1 bird per survey point. We propose that managers should prioritize marsh openness and experimentally test the effect of marsh edge manipulations when making conservation decisions for this rapidly declining species.

Early seral hardwood vegetation increases adult and fledgling bird abundance in Douglas-fir plantations of the Oregon Coast Range, USA

2012 ◽  
Vol 42 (5) ◽  
pp. 918-933 ◽  
Author(s):  
Tana M. Ellis ◽  
Andrew J. Kroll ◽  
Matthew G. Betts
Keyword(s):  
Forest Management ◽  
Pacific Northwest ◽  
Management Practices ◽  
Bird Species ◽  
Relative Magnitude ◽  
Breeding Habitat ◽  
Population Declines ◽  
Private Lands ◽  
Bird Abundance ◽  
Catharus Ustulatus

Recent evidence suggests that population declines of bird species associated with early-successional forest conditions may be associated with reduced quality of breeding habitat. Increasing intensity of forest management on private lands and decreased harvest rates on federal lands in the Pacific Northwest, USA, have resulted in a loss of diverse young forest stands, typically called early seral forest. Previous studies suggest that the amount of early seral broadleaf cover within conifer forests is linked to the composition of foliage-gleaning bird communities. However, information regarding productivity and juvenile use of post-breeding habitat in highly modified plantation habitat is lacking. We examined the relationship between vegetation structure resulting from intensive forest management practices and the abundance of five species of leaf-gleaning, neotropical migrants: orange-crowned warbler ( Oreothlypis celata (Say, 1823)), Wilson’s warbler ( Wilsonia pusilla (A. Wilson, 1811)), MacGillivray’s warbler ( Oporornis tolmiei (J.K. Townsend, 1839)), Swainson’s thrush ( Catharus ustulatus (Nuttall, 1840)), and black-headed grosbeak ( Pheucticus melanocephalus (Swainson, 1827)). All species, except MacGillivray’s warbler, showed positive associations with the amount of early seral hardwood cover as fledglings, breeding adults, or both. However, the relative magnitude of these associations varied, suggesting that other factors may also have influenced avian responses. Abundances of breeding pairs and young are likely to show positive responses to management practices that increase early seral hardwood cover in regenerating stands. If adopted at landscape and regional scales, such practices may positively influence population trends of several declining bird species.

scholarly journals Effects of forest heterogeneity on occurrence and abundance of the scale-backed antbird, Hylophylax poecilinotus (Aves: Thamnophilidae), in the Amazon forest

2008 ◽  
Vol 25 (4) ◽  
pp. 630-639 ◽  
Author(s):  
Renato Cintra ◽  
Jessica Cancelli
Keyword(s):  
Leaf Litter ◽  
Forest Structure ◽  
Bird Species ◽  
Individual Species ◽  
Amazon Forest ◽  
Bird Abundance ◽  
Canopy Opening ◽  
Neotropical Forest ◽  
Forest Heterogeneity ◽  
Resident Bird

Recently, a significant number of studies on neotropical forest bird communities have focused on factors influencing their richness, abundance, and habitat selection. However, few of them have considered populations or individual species, and how habitat structure affects their distribution and abundance. In this study, we investigated how the combined effects of some forest structure components affect the occurrence and abundance of a resident bird species, the scale-backed antbird Hylophylax poecilinotus (Cabanis, 1847). We tested the null hypothesis of no difference between the variation in forest structure components at locations where birds occurred and at locations where they did not. In a pristine Terra Firme forest at the Ducke Reserve, Manaus, we recorded bird occurrence and abundance using mist nets in 56 transects (1 km long each) within a 9 x 9 km trail grid covering 6400 ha. Also in the same 56 transects, we set 50 x 50 m plots and recorded the following seven components of forest structure and landscape: 1) canopy opening, 2) leaf litter, 3) tree abundance, 4) logs, 5) snags, 6) streams, and 7) elevation. We evaluated their effects on avian occurrence and abundance by using models of Multiple Logistic Regression (for bird occurrence) and Multiple Linear Regression (for bird abundance). The results suggested that H. poecilinotus occurred significantly more often in lowland areas, in areas located farther away from streams, and in areas bearing thicker leaf litter. Hylophylax poecilinotus was also more abundant in lowland areas and in areas located further away from streams. Overall, the results indicated that environmental heterogeneity produced by variation in forest structure components affects habitat use by this bird species in the Amazon forest.

Honeydew foraging by birds in tropical montane forests and pastures of Mexico

2010 ◽  
Vol 26 (3) ◽  
pp. 335-341 ◽  
Author(s):  
Heather A. Gamper ◽  
Suzanne Koptur
Keyword(s):  
Bird Species ◽  
Scale Insect ◽  
Scale Insects ◽  
Montane Forests ◽  
Tropical Montane Forests ◽  
Quantitative Measurements ◽  
Oak Trees ◽  
Migrant Bird ◽  
Highland Forests ◽  
Resident Bird

Abstract:A honeydew-producing scale insect, Stigmacoccus garmilleri (Margarodidae), is associated with oak trees (Quercus spp.) in highland forests of Mexico. Although feeding by ants on scale-insect honeydew is more frequently documented in the literature, the honeydew produced by feeding instars of S. garmilleri is sufficient to provide nourishment for birds. This study elucidates bird use of honeydew in the tropical montane forests near Chiconquiaco, Veracruz, Mexico, and uncovers patterns in honeydew foraging. Over a 2-mo period, 40 trees harbouring scale insects, located in both forest and pasture areas, were intensely studied (160 h of bird-foraging observations along with quantitative measurements of honeydew production). Fifteen resident bird species and 18 migrant species were observed visiting observation trees. Approximately 72% of the resident bird species and 83% of the migrant bird species observed were recorded to forage on scale-insect honeydew. Audubon's warbler (Dendroica coronata auduboni) was the most active consumer and defender of the resource. Of 118 aggressive chases observed, only 9.65% occurred in forest observation trees, and 90.3% in pasture trees. Audubon's warbler demonstrated preferential defence and territorial patrolling of scale-insect honeydew in scattered pasture trees.

scholarly journals Forest degradation, not loss, drives widespread avian population declines

2021 ◽  
Author(s):  
Matthew Betts ◽  
Zhiqiang Yang ◽  
Adam Hadley ◽  
Josee Rousseau ◽  
Joseph Northrup ◽  
...  
Keyword(s):  
Habitat Loss ◽  
Forest Cover ◽  
Bird Species ◽  
Forest Degradation ◽  
Breeding Habitat ◽  
Population Declines ◽  
Distribution Models ◽  
Eastern Canada ◽  
Bird Abundance

Abstract In many regions of the world, forest management has reduced old forest and simplified forest structure and composition via reliance on monoculture tree plantations. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has affected bird population declines. Back-cast species distribution models revealed that despite little change in overall forest cover, breeding habitat loss occurred for 66% of the 54 most common species from 1985-2020. This habitat loss was strongly associated with population declines for 72% of species, as quantified in an independent, long-term dataset. Since 1985, net forest bird abundance has declined in this region by an estimated 33-104 million birds due to habitat loss alone. The effects of forest degradation may therefore be a primary cause of biodiversity decline in managed forest landscapes.  

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

ISRN Ecology ◽  
2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
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.

scholarly journals Remotely sensed forest understory density and nest predator occurrence interact to predict suitable breeding habitat and the occurrence of a resident boreal bird species

2020 ◽  
Vol 10 (4) ◽  
pp. 2238-2252
Author(s):  
Julian Klein ◽  
Paul J. Haverkamp ◽  
Eva Lindberg ◽  
Michael Griesser ◽  
Sönke Eggers
Keyword(s):  
Bird Species ◽  
Remotely Sensed ◽  
Breeding Habitat ◽  
Forest Understory ◽  
Nest Predator

scholarly journals A Fixed-radius Point Count Method for Nonbreeding and Breeding Season Use

The Auk ◽  
1986 ◽  
Vol 103 (3) ◽  
pp. 593-602 ◽  
Author(s):  
Richard L. Hutto ◽  
Sandra M. Pletschet ◽  
Paul Hendricks
Keyword(s):  
Bird Species ◽  
Common Species ◽  
Bird Abundance ◽  
Point Count ◽  
Bird Density ◽  
Count Method ◽  
Species Abundances ◽  
Fixed Radius ◽  
Point Count Method ◽  
A Site

Abstract We provide a detailed description of a fixed-radius point count method that carries fewer assumptions than most of the currently popular methods of estimating bird density and that can be used during both the nonbreeding and breeding seasons. The method results in three indices of bird abundance, any of which can be used to test for differences in community composition among sites, or for differences in the abundance of a given bird species among sites. These indices are (1) the mean number of detections within 25 m of the observer, (2) the frequency of detections within 25 m of the observer, and (3) the frequency of detections regardless of distance from the observer. The overall ranking of species abundances from a site is similar among the three indices, but discrepancies occur with either rare species that are highly detectable at great distances or common species that are repulsed by, or inconspicuous when near, the observer. We argue that differences in the behavior among species will preclude an accurate ranking of species by abundance through use of this or any other counting method in current use.

Diet and Breeding Seasonality among a Population of Sharp-Tailed Munias, Lonchura striata, in Malaysia

The Auk ◽  
1980 ◽  
Vol 97 (1) ◽  
pp. 160-166
Author(s):  
Michael L. Avery
Keyword(s):  
Food Habits ◽  
Bird Species ◽  
Reproductive Activity ◽  
Peninsular Malaysia ◽  
Rice Cultivation ◽  
Filamentous Alga ◽  
Field Observations ◽  
Insect Abundance ◽  
Breeding Seasonality ◽  
Natural Cycles

Abstract From April 1975 through March 1977, the food habits and breeding seasonality of a population of Sharp-tailed Munias (Lonchura striata) were studied in northwestern peninsular Malaysia. The abundance of munias on the study area varied in accordance with the 6-month rice-growing cycle there. The population peaked in March and September when juvenile birds were most numerous and when rice was most plentiful. Field observations and stomach analyses showed that the munias ate rice and the green filamentous alga, Spirogyra, almost exclusively. The primary periods of algae eating occurred in January and June-August, coinciding with the munias' two peak periods of reproductive activity, as determined by gonadal examination. Apparently munias on the study area ate Spirogyra as a source of protein to enable them to become physiologically ready for breeding, much as othe tropical bird species eat insects. Thus, unlike other species, Sharp-tailed Munias' breeding seasonality is determined by manmade cycles of rice cultivation rather than by natural cycles of rain and insect abundance.

scholarly journals Fire effects on the composition of a bird community in an amazonian Savanna (Brazil)

2005 ◽  
Vol 65 (4) ◽  
pp. 683-695 ◽  
Author(s):  
R. Cintra ◽  
T. M. Sanaiotti
Keyword(s):  
Species Richness ◽  
Community Composition ◽  
Spatial Scales ◽  
Bird Species ◽  
Bird Community ◽  
Fire Effects ◽  
Bird Abundance ◽  
Bird Species Richness ◽  
Byrsonima Crassifolia ◽  
Mist Net

The effects of fire on the composition of a bird community were investigated in an Amazonian savanna near Alter-do-Chão, Pará (Brazil). Mist-net captures and visual counts were used to assess species richness and bird abundance pre- and post-fire in an approximately 20 ha area. Visual counts along transects were used to survey birds in an approximately 2000 ha area in a nearby area. Results using the same method of ordination analysis (multidimensional scaling) showed significant effects of fire in the 20 ha and 2000 ha areas and strongly suggest direct effects on bird community composition. However, the effects were different at different spatial scales and/or in different years, indicating that the effects of fire vary spatially and/or temporally. Bird community composition pre-fire was significantly different from that found post-fire. Using multiple regression analysis it was found that the numbers of burned and unburned trees were not significantly related to either bird species richness or bird abundance. Two months after the fire, neither bird species richness nor bird abundance was significantly related to the number of flowering trees (Lafoensia pacari) or fruiting trees (Byrsonima crassifolia). Since fire is an annual event in Alter-do-Chão and is becoming frequent in the entire Amazon, bird community composition in affected areas could be constantly changing in time and space.

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