The Experts below are selected from a list of 33882 Experts worldwide ranked by ideXlab platform
Amanda R Ridley - One of the best experts on this subject based on the ideXlab platform.
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hot droughts compromise interannual survival across all group sizes in a cooperatively Breeding Bird
Ecology Letters, 2020Co-Authors: Amanda R Bourne, Susan J Cunningham, Claire N Spottiswoode, Amanda R RidleyAbstract:Climate change is affecting animal populations around the world and one relatively unexplored aspect of species vulnerability is whether and to what extent responses to environmental stressors might be mitigated by variation in group size in social species. We used a 15-year data set for a cooperatively Breeding Bird, the southern pied babbler Turdoides bicolor, to determine the impact of temperature, rainfall and group size on body mass change and interannual survival in both juveniles and adults. Hot and dry conditions were associated with reduced juvenile growth, mass loss in adults and compromised survival between years in both juveniles (86% reduction in interannual survival) and adults (60% reduction in interannual survival). Individuals across all group sizes experienced similar effects of climatic conditions. Larger group sizes may not buffer individual group members against the impacts of hot and dry conditions, which are expected to increase in frequency and severity in future.
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hot droughts compromise interannual survival across all group sizes in a cooperatively Breeding Bird
bioRxiv, 2020Co-Authors: Amanda R Bourne, Susan J Cunningham, Claire N Spottiswoode, Amanda R RidleyAbstract:Increasingly harsh and unpredictable climate regimes are affecting animal populations around the world as climate change advances. One relatively unexplored aspect of species vulnerability to climate change is whether and to what extent responses to environmental stressors might be mitigated by variation in group size in social species. We used a 15-year dataset for a cooperatively-Breeding Bird, the southern pied babbler Turdoides bicolor, to determine the impact of temperature, rainfall, and group size on body mass change and interannual survival in both juveniles and adults. Hot and dry conditions were associated with reduced juvenile growth, mass loss in adults, and compromised survival between years in both juveniles (-86%) and adults (-60%). Individuals across all group sizes experienced similar effects of climatic conditions. Larger group sizes may not buffer individual group members against the impacts of hot and dry conditions, which are expected to increase in frequency and severity in future.
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costly reproductive competition between females in a monogamous cooperatively Breeding Bird
Proceedings of The Royal Society B: Biological Sciences, 2013Co-Authors: Martha J Nelsonflower, Amanda R Ridley, Philip A R Hockey, Colleen Oryan, Sinead English, Alex Thompson, Katharine Bradley, R RoseAbstract:In many cooperatively Breeding societies, only a few socially dominant individuals in a group breed, reproductive skew is high, and reproductive conflict is common. Surprisingly, the effects of this conflict on dominant reproductive success in vertebrate societies have rarely been investigated, especially in high-skew societies. We examine how subordinate female competition for Breeding opportunities affects the reproductive success of dominant females in a monogamous cooperatively Breeding Bird, the Southern pied babbler (Turdoides bicolor). In this species, successful subordinate reproduction is very rare, despite the fact that groups commonly contain sexually mature female subordinates that could mate with unrelated group males. However, we show that subordinate females compete with dominant females to breed, and do so far more often than expected, based on the infrequency of their success. Attempts by subordinates to obtain a share of Breeding impose significant costs on dominant females: chicks fledge from fewer nests, more nests are abandoned before incubation begins, and more eggs are lost. Dominant females appear to attempt to reduce these costs by aggressively suppressing potentially competitive subordinate females. This empirical evidence provides rare insight into the nature of the conflicts between females and the resultant costs to reproductive success in cooperatively Breeding societies.
Jörg Böhner - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Breeding Bird communities along an urban-rural gradient in Berlin, Germany, by Hasse Diagram Technique
Urban Ecosystems, 2007Co-Authors: Ute Simon, Sonja Kubler, Jörg BöhnerAbstract:Breeding Bird communities in Berlin were investigated at five study sites, which represent an structural urban-rural gradient, from densely built-up areas with sealed ground to green areas such as large parks. In this paper, we tested the Hasse Diagram Technique (HDT), an approach belonging to partial order theory, for its appropriateness to extract information about changes in species composition from our data set. As expected, the overall number of Bird species was positively correlated with the urban-rural gradient, increasing from 12 found in the city center to 28 in an urban park. By HDT analysis, four different sub-groups of Birds could be identified, contributing differentially to the increase in species number: (1) ubiquists, i.e., species found at each study site, (2) a sub-group, the species’ number of which was positively correlated with the urban-rural gradient, increasing with increasingly green areas, (3) a sub-group, the species’ number of which was negatively correlated with the urban-rural gradient, decreasing with a declining density of buildings, and (4) species, the distribution of which did not show any correlation with the urban-rural gradient. The results show that HDT is a suitable tool for formalized analysis of the pattern of species’ communities along an environmental gradient.
Jeffrey Hepinstall-cymerman - One of the best experts on this subject based on the ideXlab platform.
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Associations between multiscale landscape characteristics and Breeding Bird abundance and diversity across urban-rural gradients in Northeastern Georgia, USA
Urban Ecosystems, 2012Co-Authors: Michael C. Parrish, Jeffrey Hepinstall-cymermanAbstract:Urbanization is rapidly changing the southeastern US landscape, particularly in Georgia within and around the Atlanta metropolitan area, the fastest-growing Southeastern population center. Landscape characteristics related to human disturbance, landscape composition, and landscape configuration vary across the urban-rural gradient and are easily and inexpensively evaluated using geographic information systems (GIS). Previous studies have suggested that avian communities and populations respond in scale-dependent ways to urbanization-related landscape changes through changes in abundance and diversity. We conducted a 2-year study (2007–2008) of the response of Breeding Bird population abundance, community abundance, species richness, and relative diversity in young and mature single-family residential areas to 15 landscape characteristics measured at multiple spatial scales across urban-rural development intensity gradients near Athens, Georgia. We grouped Birds by species, entire site assemblage, and by functional guild affiliation. Our models suggest strong relationships between the landscape and both community and population abundance of Birds, as well as a somewhat weaker relationship with species richness. We detected only a weak relationship between Breeding season relative diversity and landscape characteristics; we hypothesize a possible seasonal component to that relationship based on an earlier study. Our results suggest that widely available geospatial metrics of human disturbance and landscape pattern can be used to model Breeding Bird abundance and diversity across urban-rural gradients. This study sets the framework for a landscape scale understanding of the effects of housing developments and development intensity on Breeding Birds in northeastern Georgia and such a landscape-based approach to modeling species numbers represents a valuable tool in natural resources management.
Cathryn H. Greenberg - One of the best experts on this subject based on the ideXlab platform.
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Breeding Bird response to season of burn in an upland hardwood forest
Forest Ecology and Management, 2019Co-Authors: Cathryn H. Greenberg, Tara L. Keyser, W. Henry Mcnab, Patrick ScottAbstract:Abstract Upland hardwood forest managers are increasingly burning during the growing-season in hopes of improving wildlife habitat and attaining or accelerating other restoration goals, highlighting the need for research addressing how season of burning affects wildlife, including Breeding Birds. We used 1-ha strip transects in nine units before (2011) and after (2013–2016) treatments to experimentally assess how Breeding Birds respond to early growing-season (26 April 2013; GSB) and dormant-season (5 March 2014; DSB) burns, and controls (C). Burn effects on forest structure were minor and transitory, regardless of burn season. Burns did not affect overstory or midstory tree basal area or density; shrub cover did not significantly differ among treatments, but within GSB and DSB it decreased for 1–2 years post-burn. A trend of reduced leaf litter depth immediately following both burn treatments was apparent, and recovery was rapid. Percent canopy cover decreased slightly in GSB within four years post-burn. Total Bird species richness and density did not differ among treatments or years, and no treatment × year interaction effects were detected. A treatment effect was detected for one of the 10 species tested; Red-bellied woodpecker density was greater in GSB than C in 2013 and 2015. No treatment × year interaction effect was detected for any tested species. Density of Birds within the tree-, cavity-, and shrub and midstory-nesting guilds were not detectably affected by either burn treatment, but ground-nester density was lower in GSB and DSB than C in 2014. Our results indicate that single, low-intensity burns, regardless of burn season, are not an effective tool in creating suitable forest structure for disturbance-dependent Breeding Bird species, or changing Breeding Bird community composition. In the short-term, substantial forest overstory reduction by timber harvests or high-severity burns will likely be required to improve forest conditions for disturbance-dependent species, and to increase species richness and abundance of Breeding Birds.
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Breeding Bird assemblages of hurricane created gaps and adjacent closed canopy forest in the southern appalachians
Forest Ecology and Management, 2001Co-Authors: Cathryn H. Greenberg, Drew J LanhamAbstract:Abstract We studied Breeding Bird assemblages in forest gaps created in 1995 by Hurricane Opal at the Bent Creek Experimental Forest in Asheville, NC. We hypothesized that forest gaps and adjacent closed-canopy forest would differ in Bird density, richness, diversity, and relative abundances of some species. To test this hypothesis we censused Breeding Bird assemblages for 2 years in 12 gaps (0.1–1.2 ha) and 12 adjacent closed canopy controls using strip transects. Gaps had more coarse woody debris, shrub cover, brushpiles, and pit and mound microtopography than controls. Canopy cover was lower in gaps than controls, but remained high ( 69.4 ± 2.1% versus 89.6 ± 1.7% ). Bird assemblage similarity was high. Total density and species richness of Birds were higher in gaps than in controls, but species diversity did not differ between treatments. Shrub (primarily Carolina Wrens) and bark-foragers, and cavity shrub and canopy-nesters were more abundant in gaps than in controls. Densities of gap-associated (Indigo Bunting, Hooded Warbler, Carolina Wren) and edge (Eastern Towhee) species were more abundant in gaps. Abundance of interior species including Red-eyed Vireo and Scarlet Tanager were about equal in gaps and controls. Only OvenBirds were more abundant in controls than gaps. Species that require larger patches of young second-growth forest, such as Prairie Warbler, and Yellow-breasted Chat, did not occur in gaps; but neither are they abundant in the Asheville basin. No Brown-headed CowBirds were observed in gaps or controls. Unpublished data indicate that parasitism of artificial ground nests did not occur, and predation rates did not differ between gaps and controls. Juvenile Birds and other evidence of Breeding were observed more often in gaps than in controls, suggesting that gaps attract Bird families for foraging and provide microsites that attract Breeding pairs. Gap size was positively correlated with Bird density, species richness, and diversity. This study suggests that small openings and interior edge habitat created by treefall gaps within a forested matrix do not adversely affect Breeding Birds as measured by the abundance of individual species or community indices. We suggest that canopy gaps increase avian diversity at a landscape scale by providing habitat patches for some species that require young, second-growth forest, and serve as magnets for recruitment and foraging.
John R. Sauer - One of the best experts on this subject based on the ideXlab platform.
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The first 50 years of the North American Breeding Bird Survey
The Condor, 2017Co-Authors: John R. Sauer, Keith L. Pardieck, David J. Ziolkowski, Adam C. Smith, Marie-anne R. Hudson, Vicente Rodriguez, Humberto Berlanga, Daniel K. Niven, William A LinkAbstract:ABSTRACT The vision of Chandler (Chan) S. Robbins for a continental-scale omnibus survey of Breeding Birds led to the development of the North American Breeding Bird Survey (BBS). Chan was uniquely suited to develop the BBS. His position as a government scientist had given him experience with designing and implementing continental-scale surveys, his research background made him an effective advocate of the need for a survey to monitor pesticide effects on Birds, and his prominence in the Birding community gave him connections to infrastructure—a network of qualified volunteer Birders who could conduct roadside surveys with standardized point counts. Having started in the eastern United States and the Atlantic provinces of Canada in 1966, the BBS now provides population change information for ∼546 species in the continental United States and Canada, and recently initiated routes in Mexico promise to greatly expand the areas and species covered by the survey. Although survey protocols have remained unchange...
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bayesian cross validation for model evaluation and selection with application to the north american Breeding Bird survey
Ecology, 2015Co-Authors: William A Link, John R. SauerAbstract:The analysis of ecological data has changed in two important ways over the last 15 years. The development and easy availability of Bayesian computational methods has allowed and encouraged the fitting of complex hierarchical models. At the same time, there has been increasing emphasis on acknowledging and accounting for model uncertainty. Unfortunately, the ability to fit complex models has outstripped the development of tools for model selection and model evaluation: familiar model selection tools such as Akaike's information criterion and the deviance information criterion are widely known to be inadequate for hierarchical models. In addition, little attention has been paid to the evaluation of model adequacy in context of hierarchical modeling, i.e., to the evaluation of fit for a single model. In this paper, we describe Bayesian cross-validation, which provides tools for model selection and evaluation. We describe the Bayesian predictive information criterion and a Bayesian approximation to the BPIC known as the Watanabe-Akaike information criterion. We illustrate the use of these tools for model selection, and the use of Bayesian cross-validation as a tool for model evaluation, using three large data sets from the North American Breeding Bird Survey.
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modeling trends from north american Breeding Bird survey data a spatially explicit approach
PLOS ONE, 2013Co-Authors: John R. Sauer, Keith L. Pardieck, Florent Bled, Paul F Doherty, Andy J RoyleAbstract:Population trends, defined as interval-specific proportional changes in population size, are often used to help identify species of conservation interest. Efficient modeling of such trends depends on the consideration of the correlation of population changes with key spatial and environmental covariates. This can provide insights into causal mechanisms and allow spatially explicit summaries at scales that are of interest to management agencies. We expand the hierarchical modeling framework used in the North American Breeding Bird Survey (BBS) by developing a spatially explicit model of temporal trend using a conditional autoregressive (CAR) model. By adopting a formal spatial model for abundance, we produce spatially explicit abundance and trend estimates. Analyses based on large-scale geographic strata such as Bird Conservation Regions (BCR) can suffer from basic imbalances in spatial sampling. Our approach addresses this issue by providing an explicit weighting based on the fundamental sample allocation unit of the BBS. We applied the spatial model to three species from the BBS. Species have been chosen based upon their well-known population change patterns, which allows us to evaluate the quality of our model and the biological meaning of our estimates. We also compare our results with the ones obtained for BCRs using a nonspatial hierarchical model (Sauer and Link 2011). Globally, estimates for mean trends are consistent between the two approaches but spatial estimates provide much more precise trend estimates in regions on the edges of species ranges that were poorly estimated in non-spatial analyses. Incorporating a spatial component in the analysis not only allows us to obtain relevant and biologically meaningful estimates for population trends, but also enables us to provide a flexible framework in order to obtain trend estimates for any area.
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the north american Breeding Bird survey 1966 2011 summary analysis and species accounts
North American Fauna, 2013Co-Authors: John R. Sauer, William A Link, Keith L. Pardieck, Jane E Fallon, David J. ZiolkowskiAbstract:Abstract The North American Breeding Bird Survey is a roadside, count-based survey conducted by volunteer observers. Begun in 1966, it now is a primary source of information on spatial and temporal patterns of population change for North American Birds. We analyze population change for states, provinces, Bird Conservation Regions, and the entire survey within the contiguous United States and southern Canada for 426 species using a hierarchical log-linear model that controls for observer effects in counting. We also map relative abundance and population change for each species using a spatial smoothing of data at the scale of survey routes. We present results in accounts that describe major Breeding habitats, migratory status, conservation status, and population trends for each species at several geographic scales. We also present composite results for groups of species categorized by habitats and migratory status. The survey varies greatly among species in percentage of species' range covered and precisio...
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analysis of the north american Breeding Bird survey using hierarchical models
The Auk, 2011Co-Authors: John R. Sauer, William A LinkAbstract:ABSTRACT. We analyzed population change for 420 Bird species from the North American Breeding Bird Survey (BBS) using a hierarchical log-linear model and compared the results with those obtained through route-regression analysis. Survey-wide trend estimates based on the hierarchical model were generally more precise than estimates from the earlier analysis. No consistent pattern of differences existed in the magnitude of trends between the analysis methods. Survey-wide trend estimates changed substantially for 15 species between route-regression and hierarchical-model analyses. We compared regional estimates for states, provinces, and Bird Conservation Regions; differences observed in these regional analyses are likely a consequence of the route-regression procedure's inadequate accommodation of temporal differences in survey effort. We used species-specific hierarchical-model results to estimate composite change for groups of Birds associated with major habitats and migration types. Grassland, aridland, ...