Avian nest success, mammalian nest predator abundance, and invertebrate prey availability in a fragmented landscape

2011 ◽  
Vol 89 (6) ◽  
pp. 517-528 ◽  
Author(s):  
S. Richmond ◽  
E. Nol ◽  
D. Burke
Keyword(s):  
Nest Success ◽  
Positive Association ◽  
Landscape Composition ◽  
Percent Cover ◽  
Wood Thrush ◽  
Explanatory Variables ◽  
Prey Biomass ◽  
Predator Abundance ◽  
Avian Nest ◽  
Nest Predator

Avian nest success is largely determined by predation, but factors affecting the abundance of potential nest predators are rarely studied. We used an information–theoretic approach to assess relative support for models including invertebrate biomass, mammalian nest predator abundance, and percent cover at nests as explanatory variables for nest success of Ovenbirds ( Seiurus aurocapilla (L., 1766)) and Wood Thrush ( Hylocichla mustelina (J.F. Gmelin, 1789)). We ranked models including local vegetation characteristics and landscape composition at two spatial scales (100 and 2000 m) as explanatory variables for the abundance of mammalian nest predator groups and for prey biomass. The nest success of Ovenbirds was best explained by a positive association with percent cover by forbs and seedlings, whereas a positive relationship with prey biomass best explained the nest success of Wood Thrush. Most mammal genera were associated with landscape composition within 100 m of the study sites, and most were positively associated with housing density. Prey biomass was best explained by a positive association with less intensive agriculture within 2000 m. Implementing silvicultural techniques that preserve important habitat features within fragmented forests, limiting housing density within 100 m, and increasing the amount of less intensive agriculture within 2000 m of forest fragments may improve nest success for forest songbirds.

Local- versus landscape-scale effects on the demography of three forest-breeding songbirds in Ontario, Canada

2012 ◽  
Vol 90 (7) ◽  
pp. 815-828 ◽  
Author(s):  
S. Richmond ◽  
E. Nol ◽  
D. Burke
Keyword(s):  
Spatial Scales ◽  
Nest Success ◽  
Landscape Scale ◽  
Landscape Composition ◽  
Multiscale Approach ◽  
Forest Fragments ◽  
Wood Thrush ◽  
Complex Species ◽  
American Robins ◽  
Vegetation Characteristics

Reproductive success of songbirds breeding in forest fragments can be influenced by local habitat characteristics and by anthropogenic land uses in the surrounding matrix such as exurban development and agriculture. Effectively managing these songbirds requires an understanding of which spatial scales most strongly influence their demography. We conducted a multiscale study to investigate the relative influence of local vegetation characteristics and landscape composition at two spatial scales (100 and 2000 m) in a predominantly agricultural landscape on songbird demography. Density, pairing success, nest success, and productivity were assessed for Ovenbirds ( Seiurus aurocapilla (L., 1766)), Wood Thrush ( Hylocichla mustelina (J.F. Gmelin, 1789)), and American Robins ( Turdus migratorius L., 1766) in 16 deciduous forest fragments in southeastern Ontario. Demography of Ovenbirds was most strongly associated with local vegetation characteristics, while demography of Wood Thrush and American Robins was most strongly related to landscape composition within a 2000 m buffer. For all three species, cross-scale correlations influenced nest success, although other demographic parameters were less affected. We conclude that relationships between local- and landscape-scale metrics and songbird demography are complex, species-specific, and differ among reproductive parameters, necessitating a multiscale approach to management.

scholarly journals Arboreal aperitifs: Space use and activity of a major songbird nest predator in a tropical Thailand forest

2021 ◽  
Author(s):  
Anji D’souza ◽  
George Gale ◽  
Benjamin Michael Marshall ◽  
Daphawan Khamcha ◽  
Surachit Waengsothorn ◽  
...  
Keyword(s):  
Brownian Bridge ◽  
Radio Telemetry ◽  
Space Use ◽  
Evergreen Forest ◽  
Boiga Irregularis ◽  
Forest Fragment ◽  
Predator Species ◽  
Avian Nest ◽  
Nest Predator ◽  
Nesting Season

ABSTRACTPredator-prey interactions are fundamental drivers of population dynamics, yet rarely are both predator and prey species simultaneously studied. Despite being significant, widespread avian nest predators, research on the ecology of Southeast Asian snakes in relation to birds remains scarce. The green cat snake (Boiga cyanea) is a primary nest predator, responsible for ≈24% of forest songbird depredation in Northeast Thailand. We explored both diurnal and nocturnal movements of 14 (5 male, 9 female) adult B. cyanea with radio-telemetry for an average of 68 ± 16 days per individual, between 21 October 2017 and 8 June 2019 in the dry evergreen forest of the Sakaerat Biosphere Reserve (SBR). We quantified area of space use (ha) and activity through motion variance (Ϭm2) during the study period using dynamic Brownian bridge movement models, and linked our findings to a simultaneously-run avian nest monitoring study, initiated in 2013 within the same forest fragment. On average, movements, space use and activity differed between males and females, and between the avian nesting and non-nesting seasons. Males moved 51.37 m/day farther than females. They used areas 15.09 ha larger than females, and their activity was 3.91 Ϭm2 higher than that of females. In general, individuals moved 50.30 m/day farther during the nesting season than the non-nesting season. The snakes used areas 9.84 ha larger during the nesting season than the non-nesting season, and their activity during the nesting season was 3.24 Ϭm2 higher than that during the non-nesting season. All individuals were exclusively nocturnal, moving throughout the night, and often descending from higher diurnal refugia (>2 m) to forage closer to the ground after sunset. Boiga cyanea activity followed a similar trend to that of the recorded nest depredations at SBR. Our study links snake activity to nest depredations in SBR. Our openly-available data may yield further insight when combined with other major avian nest predator species like the congeneric invasive brown tree snake (Boiga irregularis) on the island of Guam.

scholarly journals Demographic Variables are Poor Indicators of Wood Thrush Productivity

The Condor ◽  
2002 ◽  
Vol 104 (1) ◽  
pp. 92-102 ◽  
Author(s):  
Todd J. Underwood ◽  
Roland R. Roth
Keyword(s):  
Nest Success ◽  
Temporal Trends ◽  
Significant Proportion ◽  
Demographic Variables ◽  
Hylocichla Mustelina ◽  
Wood Thrush ◽  
Return Rates ◽  
Annual Productivity ◽  
Productivity Indices ◽  
Population Indices

Abstract We tested the ability of 29 indices of productivity to predict and track actual productivity of a Wood Thrush (Hylocichla mustelina) population for 21 years and to detect year-to-year changes in that productivity. Of 29 indices tested, only the productivity of nests initiated in May showed promise. This index reasonably predicted productivity, correctly tracked two out of three temporal trends in productivity, and detected a significant proportion of year-to-year changes in actual productivity. Although they were not useful for predicting annual productivity, other indices based on nest data tracked trends in productivity moderately well, and all, except percent nest success, detected a significant proportion of year-to-year changes in productivity. Productivity indices based on non-reproductive variables, such as abundance of males or females, return rates, and veteran:novice ratios, did not reflect productivity trends or changes. From these results, we recommend that only an intensive measure of actual productivity or a partial measure of it, such as May productivity, be used to make inferences about annual productivity of a population. Indices based on other nest data should be used only for tracking productivity trends. Non-reproductive indices are unreliable for making any inferences about productivity. Las Variables Demográficas son Malas Indicadoras de la Productividad de Hylocichla mustelina Resumen. Pusimos a prueba la capacidad de 29 índices de productividad para predecir y seguir las variaciones anuales en la productividad real de una población de Hylocichla mustelina por un período de 21 años. De los 29 índices probados, sólo el de la productividad de los nidos iniciados en mayo resultó promisorio. Este índice predijo la productividad razonablemente bien y detectó correctamente dos de tres tendencias temporales en la productividad y una proporción significativa de los cambios anuales en la productividad real. Aunque no fueron útiles para predecir la productividad anual, otros índices basados en datos de nidos siguieron las tendencias en la productividad aceptablemente bien. Con excepción del porcentaje de nidos exitosos, todos estos índices detectaron una proporción significativa de las variaciones anuales de la productividad. Por su parte, los índices de productividad basados en variables no reproductivas como la abundancia de machos y hembras, las tasas de regreso y el cociente de aves veteranas: novatas no reflejaron las tendencias o cambios en la productividad real. Con base en estos resultados recomendamos que para hacer inferencias sobre la productividad anual de una población sólo se utilice una medida intensiva de la productividad, o una medida parcial de ésta (i.e., la productividad en mayo). Los índices basados en otros datos de nidos deben ser utilizados únicamente para monitorear las tendencias en la productividad. Los índices no reproductivos son poco confiables para hacer inferencias sobre la productividad.

AVIAN NEST SUCCESS IN MIDWESTERN FORESTS FRAGMENTED BY AGRICULTURE

The Condor ◽  
10.1650/7358 ◽  
2004 ◽  
Vol 106 (1) ◽  
pp. 116 ◽  
Author(s):  
Melinda G. Knutson ◽  
Gerald J. Niemi ◽  
Wesley E. Newton ◽  
Mary A. Friberg
Keyword(s):  
Nest Success ◽  
Avian Nest

Avian Nest Box Selection and Nest Success in Burned and Unburned Southwestern Riparian Forest

2007 ◽  
Vol 71 (2) ◽  
pp. 411-421 ◽  
Author(s):  
D. MAX SMITH ◽  
JEFFREY F. KELLY ◽  
DEBORAH M. FINCH
Keyword(s):  
Riparian Forest ◽  
Nest Success ◽  
Nest Box ◽  
Avian Nest

The importance of disturbance and forest structure to bird abundance in the Black Hills

The Condor ◽  
2019 ◽  
Vol 121 (1) ◽  
Author(s):  
Elizabeth A Matseur ◽  
Joshua J Millspaugh ◽  
Frank R Thompson ◽  
Brian E Dickerson ◽  
Mark A Rumble
Keyword(s):  
Forest Structure ◽  
Vegetation Type ◽  
Positive Association ◽  
Black Hills ◽  
Ground Vegetation ◽  
Percent Cover ◽  
Bird Abundance ◽  
Vegetation Characteristics ◽  
Percent Area ◽  
Landscape Level

Abstract Many North American birds associated with forest disturbances such as wildfire and mountain pine beetle (Dendroctonus ponderosae) outbreaks are declining in abundance. More information on relationships between avian abundance and forest structure and disturbance is needed to guide conservation and management. Our objective was to determine densities of American Three-toed Woodpecker (Picoides dorsalis), Black-backed Woodpecker (Picoides arcticus), Red-breasted Nuthatch (Sitta canadensis), Brown Creeper (Certhia americana), and White-winged Junco (Junco hyemalis aikeni) in relation to vegetation characteristics and disturbance at the point and landscape level in the Black Hills and Bear Lodge Mountains of South Dakota and Wyoming. We conducted 3 point counts from late March to late June 2015 and 2016 at more than 2,300 locations distributed across a gradient of forest structure and disturbance types. We estimated densities using 3-level hierarchical time-removal models that simultaneously estimated abundance, availability, and detection probability. Black-backed Woodpeckers were positively related to percent area in 1- to 3-year-old wildfires and Brown Creepers were positively associated with percent area in 4- to 5-year-old wildfires; however, Red-breasted Nuthatches were negatively related to percent area in 3- to 5-year-old wildfires. With the exception of American Three-toed Woodpeckers, species were positively related to percent cover of beetle-killed trees. Brown Creepers, White-winged Juncos, and Red-breasted Nuthatches had mixed responses to percent overstory canopy cover. White-winged Juncos also had a positive association with percent ground vegetation at the point and landscape level. Brown Creepers were strongly linked with spruce vegetation type. American Three-toed Woodpeckers, which are thought to occupy spruce forest in the Black Hills, did not show a strong relationship with any covariates. Maintaining some areas of natural disturbances along with heterogeneity of vegetation characteristics within stands and at the landscape scale will benefit the needs of a diverse bird community in the Black Hills.

scholarly journals Copula geoadditive modelling of anaemia and malaria in young children in Kenya, Malawi, Tanzania and Uganda

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Danielle J. Roberts ◽  
Temesgen Zewotir
Keyword(s):  
Young Children ◽  
Joint Probability ◽  
Positive Association ◽  
Spatial Effects ◽  
African Countries ◽  
Dependency Structure ◽  
Explanatory Variables ◽  
Childhood Morbidity ◽  
Sub Saharan ◽  
The Relationship

Abstract Background Anaemia and malaria are the leading causes of sub-Saharan African childhood morbidity and mortality. This study aimed to explore the complex relationship between anaemia and malaria in young children across the districts or counties of four contiguous sub-Saharan African countries, namely Kenya, Malawi, Tanzania and Uganda, while accounting for the effects of socio-economic, demographic and environmental factors. Geospatial maps were constructed to visualise the relationship between the two responses across the districts of the countries. Methods A joint bivariate copula regression model was used, which estimates the correlation between the two responses conditional on the linear, non-linear and spatial effects of the explanatory variables considered. The copula framework allows the dependency structure between the responses to be isolated from their marginal distributions. The association between the two responses was set to vary according to the district of residence across the four countries. Results The study revealed a positive association between anaemia and malaria throughout the districts, the strength of which varied across the districts of the four countries. Due to this heterogeneous association between anaemia and malaria, we further considered the joint probability of each combination of outcome of anaemia and malaria to further reveal more about the relationship between the responses. A considerable number of districts had a high joint probability of a child being anaemic but not having malaria. This might suggest the existence of other significant drivers of childhood anaemia in these districts. Conclusions This study presents an alternative technique to joint modelling of anaemia and malaria in young children which assists in understanding more about their relationship compared to techniques of multivariate modelling. The approach used in this study can aid in visualising the relationship through mapping of their correlation and joint probabilities. These maps produced can then help policy makers target the correct set of interventions, or prevent the use of incorrect interventions, particularly for childhood anaemia, the causes of which are multiple and complex.

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