Indicators of avian nest predation and parental activity in a managed boreal forest: an assessment at two spatial scales

2005 ◽  
Vol 35 (2) ◽  
pp. 374-382 ◽  
Author(s):  
Jacques Ibarzabal ◽  
André Desrochers
Keyword(s):  
Landscape Structure ◽  
Nest Predation ◽  
Spatial Scales ◽  
Edge Length ◽  
Nesting Success ◽  
Tamiasciurus Hudsonicus ◽  
Indirect Measure ◽  
Indirect Measures ◽  
Total Core Area ◽  
Nest Predators

Studies of avian nesting success at the landscape level often use a single indirect measure to evaluate nest predation or parental activity. During two summers at Forêt Montmorency, Quebec, we analyzed and compared three indirect measures of nest predation risk: detection of two nest predators, (1) red squirrel (Tamiasciurus hudsonicus Erxleben) and (2) gray jay (Perisoreus canadensis L.), (3) depredation of bait, and direct observations of parental activity (mostly food transported by adults) at 316 stations over a 230-km2 area. We assessed the relationship between these indicators and three landscape-structure variables (total forested area, total core area, and total edge length) at two spatial scales (83 and 1610 ha). Nest predators were generally present at <30% of stations, <20% of baits were depredated, and >40% of stations exhibited evidence of broods. Bait depredation and the detection of jays or squirrels were correlated, but we found no associations between nest predation and parental activity indicators. Indicators of nest predation and parental activity were not significantly heterogeneous over the study area, despite substantial variation of landscape structure. We argue that parental activity indicators may be more reliable than nest predation indicators, but only as a coarse way to detect variation in nesting success.

Edge effects on nest predators in two forested landscapes

2004 ◽  
Vol 82 (12) ◽  
pp. 1943-1953 ◽  
Author(s):  
Michelle L Smith
Keyword(s):  
Species Richness ◽  
Edge Effects ◽  
Spatial Scales ◽  
Forest Edge ◽  
Tamiasciurus Hudsonicus ◽  
Brood Parasite ◽  
Camera Systems ◽  
Total Species Richness ◽  
Edge Response ◽  
Nest Predators

Few studies have systematically examined edge effects on nest predators, although many invoke these processes as potential mechanisms for decreased nesting success of songbirds. Species richness and relative abundance of avian and mammalian nest predators were compared between forest edge and interior in two landscapes, Allegan State Game Area and Fort Custer Training Center (FCTC), in southwest Michigan. One avian predator, the American crow (Corvus brachyrhynchos Brehm, 1822), was more abundant at edges than forest interior at FCTC; however, other predators did not demonstrate an edge response. Abundance of the brood parasite (Molothrus ater (Boddaert, 1783)) was greater at edges in FCTC. Overall abundance was higher at FCTC in both years; however, this could not be attributed to a greater extent of fragmentation. Total species richness for both landscapes did not differ between edge and interior. Remote-camera systems captured three predation events, two involving red squirrels (Tamiasciurus hudsonicus (Erxleben, 1777)) and one involving a blue jay (Cyanocitta cristata (L., 1758)). Vegetation characteristics were similar between edge and interior sites, which suggests that vegetation structure did not influence edge response. The variability in response indicates a need to assess patterns of predator distributions through long-term studies at multiple spatial scales.

scholarly journals Consequences of Habitat Utilization by Nest Predators and Breeding Songbirds Across Multiple Scales in an Urbanizing Landscape

The Condor ◽  
2007 ◽  
Vol 109 (3) ◽  
pp. 516-534 ◽  
Author(s):  
John M. Marzluff ◽  
John C. Withey ◽  
Kara A. Whittaker ◽  
M. David Oleyar ◽  
Thomas M. Unfried ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Nest Predation ◽  
Multiple Scales ◽  
Spatial Scales ◽  
Habitat Associations ◽  
Forest Patch ◽  
Use Of Resources ◽  
Neighborhood Scale ◽  
Patch Scale ◽  
Nest Predators

Abstract Abstract. Nest predation may influence habitat selection by birds at multiple spatial scales. We blended population and community ecology to investigate this possibility for 15 species of forest songbirds and their diurnal nest predators (corvids and sciurids) in 28 1 km2 sites near Seattle, Washington, from 1998 to 2004. We determined whether songbirds were positively or negatively associated with nest predators at three spatial scales, and whether their co-occurrence affected reproductive success. At the largest ‘neighborhood’ scale (1 km2 areas that included suburban and exurban development and second-growth forest remnants), nest predators and their prey were positively or negatively correlated according to general species-specific habitat associations. At the intermediate ‘forest patch’ scale (among remnant forested areas 0.5 to 70 ha), associations between predators and prey were generally weak. At the smallest ‘within patch’ scale (multiple 50 m radius survey plots within each forest patch), some songbird species avoided areas with greater predator use, particularly by Steller's Jays (Cyanocitta stelleri). Failed nests and territories tended to be in locations of higher predator occurrence (especially of corvids) than successful ones, but at the largest 1 km2 neighborhood scale relative abundance of nest predators was not correlated with the fate of nesting attempts or annual reproductive success. Reproductive success was generally high, with 52% of all nests and 49% of all territories fledging at least one young (for all species and years combined). Nest predation influenced some species' use of resources, but was not a strong influence on overall reproductive success or community structure.

scholarly journals Nesting Success and Nest Predators in Forest Fragments: A Study Using Real and Artificial Nests

The Auk ◽  
2000 ◽  
Vol 117 (2) ◽  
pp. 445-454 ◽  
Author(s):  
Liana Zanette ◽  
Bert Jenkins
Keyword(s):  
Nest Predation ◽  
Agricultural Land ◽  
Fragment Size ◽  
Nesting Success ◽  
Forest Fragments ◽  
Artificial Nests ◽  
Area Sensitivity ◽  
Avian Nest ◽  
Nest Predator ◽  
Nest Predators

Abstract Area sensitivity in songbirds is commonly attributed to increased nest predation in forest fragments. In 1995 and 1996, we tested whether the nest predators and nesting success of an area-sensitive forest bird, the Eastern Yellow Robin (Eopsaltria australis), varied with fragment size, and we also conducted an artificial nest experiment. The study occurred in two small (55 ha) and two large (>400 ha) forest fragments in a matrix of agricultural land in New South Wales, Australia. Predation accounted for 95% of all failures of 282 robin nests, and the survival of robin nests was negatively correlated with how frequently we observed avian nest predators near nests (i.e. nest-predator activity). Of 461 artificial nests, 84% were depredated, nearly all (99%) by birds. Thus, birds were important predators of nests. The abundance, species richness, and activity of avian nest predators were not related to fragment size. Survival of robin nests averaged 19%; nests in small fragments had a 22% chance of producing at least one fledgling compared with 15% in large fragments, but the difference was not significant. Survival of artificial nests averaged 12% in both small and large fragments. Nest-predator activity accounted for the most variation (68%) in the fate of robin nests, followed by the cumulative density of open-cup nesters (16%). The placement of robin nests had no influence on nest fate. We conclude that nest predation was not area dependent and propose food supply as an alternative hypothesis to explain area sensitivity. We suggest that, rather than being related to fragment size, nest predation increases with decreasing forest cover in a landscape. Increased nest predation in fragmented compared with contiguous landscapes may lower the population viability of songbirds in a region, and hence regional numbers. Therefore, the spatial scale at which fragmentation influences nest predation and songbird populations must be considered carefully.

Direct and Indirect Measures of Poverty

1988 ◽  
Vol 17 (3) ◽  
pp. 351-365 ◽  
Author(s):  
Stein Ringen
Keyword(s):  
Low Income ◽  
Relative Deprivation ◽  
Poverty Line ◽  
Income Poverty ◽  
Indirect Measure ◽  
Indirect Measures ◽  
Direct Definition ◽  
Logical Line

ABSTRACTPoverty can be defined and measured either directly (in terms of consumption) or indirectly (in terms of income). The relative deprivation concept of poverty is a direct concept; poverty is understood as visible poverty, that is, a low standard of consumption. The income poverty line is an indirect measure; poverty is established as low income. It is argued that recent mainstream poverty research combines a direct definition and an indirect measure. This causes there to be no logical line of deduction between definition and measurement and, along with other problems in the approach, renders the statistics produced invalid.

Landscape Heterogeneity and Dynamics

2019 ◽  
pp. 42-126
Author(s):  
Kimberly A. With
Keyword(s):  
Landscape Ecology ◽  
Spatial Heterogeneity ◽  
Landscape Structure ◽  
Landscape Heterogeneity ◽  
Spatial Scales ◽  
Anthropogenic Disturbances ◽  
Ecological Processes ◽  
Disturbance Dynamics ◽  
Wide Range ◽  
Over Time

Heterogeneity is a defining characteristic of landscapes and therefore central to the study of landscape ecology. Landscape ecology investigates what factors give rise to heterogeneity, how that heterogeneity is maintained or altered by natural and anthropogenic disturbances, and how heterogeneity ultimately influences ecological processes and flows across the landscape. Because heterogeneity is expressed across a wide range of spatial scales, the landscape perspective can be applied to address these sorts of questions at any level of ecological organization, and in aquatic and marine systems as well as terrestrial ones. Disturbances—both natural and anthropogenic—are a ubiquitous feature of any landscape, contributing to its structure and dynamics. Although the focus in landscape ecology is typically on spatial heterogeneity, disturbance dynamics produce changes in landscape structure over time as well as in space. Heterogeneity and disturbance dynamics are thus inextricably linked and are therefore covered together in this chapter.

Predation on different-sized quail eggs in an artificial-nest study in western Newfoundland

1999 ◽  
Vol 77 (7) ◽  
pp. 1170-1173 ◽  
Author(s):  
Keith P Lewis ◽  
William A Montevecchi
Keyword(s):  
Japanese Quail ◽  
Small Mammals ◽  
Nest Predation ◽  
Egg Size ◽  
Tamiasciurus Hudsonicus ◽  
Buffer Strips ◽  
Artificial Nest ◽  
Red Squirrels ◽  
Artificial Nests ◽  
Riparian Buffer Strips

In artificial-nest studies, Japanese Quail (Coturnix japonica) eggs have been used as surrogates for passerine eggs, although small mammals that prey on passerine eggs may be unable to consume Japanese Quail eggs. To determine the influence of egg size on nest predation in different landscapes on insular Newfoundland, we placed either a Japanese Quail egg or a smaller Chinese Painted Quail (Xexcalfactoris chinensis) egg in artificial ground nests along lakeshore forest edges and along riparian buffer strips. Clay eggs were used to identify nest predators. Levels of predation on nests with Japanese Quail and Chinese Painted Quail eggs were similar. Based on clay eggs, predation was attributed to red squirrels (Tamiasciurus hudsonicus), and we found no evidence that smaller mammals preyed on artificial nests. We conclude that the Japanese Quail egg is acceptable for use in artificial-nest studies in Newfoundland, and we discuss the implications of egg size and small mammals in nest-predation experiments.

scholarly journals A Possible Role for Red Squirrels in Structuring Breeding Bird Communities in Lodgepole Pine Forests

The Condor ◽  
2006 ◽  
Vol 108 (1) ◽  
pp. 232-238 ◽  
Author(s):  
Adam M. Siepielski
Keyword(s):  
Nest Predation ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Bird Communities ◽  
Pine Forests ◽  
Tamiasciurus Hudsonicus ◽  
Breeding Bird ◽  
Bird Abundance ◽  
Red Squirrels ◽  
Cavity Nesters

Abstract Nest predation is thought to play an important role in structuring certain breeding bird communities. One potential consequence of nest predation is lower recruitment in breeding birds, which may be manifested as lower breeding bird abundance. Lodgepole pine (Pinus contorta ssp. latifolia) forests east and west of the Rocky Mountains became isolated following glacial retreat 12 000 years ago and differ in whether or not red squirrels (Tamiasciurus hudsonicus), which are a key nest predator, are present. Breeding bird abundance in lodgepole pine forests was compared between four ranges with red squirrels and four ranges without red squirrels. Species grouped into canopy and understory nesting guilds were, on average, two and three times more abundant, respectively, in forest ranges without red squirrels than in ranges with red squirrels; no statistically significant differences were found for midstory, ground, or cavity nesters. These results suggest that geographic variation in the presence or absence of red squirrels is likely important in structuring breeding bird communities in lodgepole pine forests across the landscape.

scholarly journals Demography of Bell's Vireos in Missouri Grassland-Shrub Habitats

The Auk ◽  
2000 ◽  
Vol 117 (4) ◽  
pp. 925-935 ◽  
Author(s):  
Joel M. Budnik ◽  
Mark R. Ryan ◽  
Frank R. Thompson III
Keyword(s):  
Nest Predation ◽  
Molothrus Ater ◽  
Nesting Success ◽  
Growth Potential ◽  
Population Declines ◽  
Annual Survival ◽  
Rate Of Increase ◽  
Study Population ◽  
Breeding Seasons ◽  
Seasonal Fecundity

Abstract Numbers of Bell's Vireos (Vireo bellii) have declined throughout much of the breeding range in recent years, yet little information exists to determine factors that are causing these declines. We studied Bell's Vireos nesting in grassland-shrub habitats at two study areas in central Missouri to determine reproductive performance, survival, and population growth potential. Birds were color banded and observed during the breeding seasons of 1996, 1997, and 1998 to determine seasonal fecundity. We monitored 124 breeding pairs (127 pair years) and 213 nests. Density declined from 1.00 to 0.80 territories per 10 ha at the first site and increased from 1.11 to 1.33 at the second site during the study. Mean nesting success was 31 ± SE of 0.03% overall and ranged from 13 to 42% among years and study areas; 57% of the pairs fledged at least one young. Low annual production was a function of high rates of nest predation (41% of all nests observed, accounting for 44 to 78% of daily nest mortality annually) and nest parasitism by Brown-headed Cowbirds (Molothrus ater; 29% of nests observed, 17 to 37% of daily nest mortality annually). Mean seasonal fecundity was 1.60 young fledged per pair per year (range 1.00 to 1.79). Annual survival of adults was 61 ± 0.04% and was higher than previously reported. We used our estimates of seasonal fecundity and annual survival of adults to determine the finite rate of increase (λ) for our study population. Our study areas seemingly comprised sink habitats (λ = 0.85). Thus, the vireos on our study areas likely were limited by low reproductive success. Population declines also may be caused by habitat loss, which highlights the need for investigation of historical and current rates of loss of grassland-shrub habitat.

scholarly journals Nest Predators, Nest-Site Selection, and Nesting Success of the Dusky Flycatcher in a Managed Ponderosa Pine Forest

The Condor ◽  
2002 ◽  
Vol 104 (3) ◽  
pp. 507-517 ◽  
Author(s):  
Joseph R. Liebezeit ◽  
T. Luke George
Keyword(s):  
Site Selection ◽  
Nest Site ◽  
Nesting Success ◽  
Nest Site Selection ◽  
Potential Prey ◽  
Nest Sites ◽  
Dusky Flycatcher ◽  
Shrub Patches ◽  
Empidonax Oberholseri ◽  
Nest Predators

AbstractAmong hypotheses explaining nest-site selection, the potential-prey-site hypothesis predicts that birds place nests in areas with many potential nest sites, while the nest-concealment hypothesis predicts nest placement in sites with greater surrounding vegetation. We examined these hypotheses by comparing habitat attributes between Dusky Flycatcher (Empidonax oberholseri) nest sites and random sites, successful and unsuccessful nests, and nests depredated by birds versus mammals. Nesting success was 28% (n = 167), and predation was the most important cause of nest failure (96%) during the study (1998–2000) at our site in northeastern California. We identified 28 nest predators using surveillance cameras. Sciurid mammals were the most common predators (17 of 28, 61%), with Cooper's Hawks (Accipiter cooperii; 25%), small owls (11%), and Steller's Jays (Cyanocitta stelleri; 3%) accounting for the rest. Raptors preyed on nestlings more frequently than on eggs, while small mammals depredated nestlings and eggs in proportion to their availability. Dusky Flycatchers nested in larger shrub patches with greater shrub cover than at random sites, supporting the potential-prey-site hypothesis. Successful nests were in larger shrub patches surrounded by fewer seedlings and saplings compared to depredated nests, providing equivocal support for the potential-prey-site hypothesis. Nests depredated by birds were less concealed, located in smaller shrub patches, surrounded by fewer seedlings and saplings, and were closer to the shrub edge than nests depredated by mammals. Our results, strengthened by identification of nest predators, suggest that differences in search strategies among predators may constrain the ability of Dusky Flycatchers to optimize nest-site selection.Depredadores de Nidos, Selección de Sitios de Anidación y Éxito de Anidación de Empidonax oberholseri en un Bosque Manejado de Pino PonderosaResumen. Entre las hipótesis que explican la selección de sitios de anidación, la de “presa potencial” predice que las aves ubican sus nidos en lugares con muchos sitios de anidación, mientras que la de “ocultación del nido” predice la ubicación de nidos en sitios con mayor vegetación circundante. Nosotros examinamos estas hipótesis comparando características del hábitat entre sitios de anidación del mosquerito Empidonax oberholseri y sitios aleatorios, entre nidos exitosos y no exitosos, y entre nidos depredados por aves y por mamíferos. Entre 1998 y 2000 en un área del noreste de California, el éxito de anidación fue del 28% (n = 167) y la depredación fue la causa más importante del fracaso de los nidos (96%). Identificamos 28 depredadores de nidos utilizando cámaras. Los mamíferos sciúridos fueron los depredadores más comunes (17 de 28, 61%), mientras que los demás nidos fueron depredados por Accipter cooperii (25%), búhos pequeños (11%) y Cyanocitta stelleri (3%). Las aves rapaces se alimentaron con mayor frecuencia de pichones que de huevos, mientras que los mamíferos pequeños depredaron pichones y huevos en proporción a su disponibilidad. Los mosqueritos anidaron en parches con mayor cobertura de arbustos que sitios aleatorios, lo cual apoya la hipótesis de presa potencial. Los nidos exitosos se ubicaron en parches de arbustos más grandes rodeados por menos plántulas y renovales en comparación con los nidos depredados, lo que apoya equívocamente la hipótesis de presa potencial. Los nidos depredados por aves estuvieron menos ocultos, ubicados en parches de arbustos más pequeños, rodeados por menos plántulas y renovales, y estuvieron más cerca del borde del matorral que los nidos depredados por mamíferos. Nuestros resultados, fortalecidos por la identificación de los depredadores, sugieren que las diferencias en las estrategias de búsqueda entre depredadores pueden limitar la habilidad de los mosqueritos para optimizar la selección de sitios de anidación.

scholarly journals Factors Influencing Predation on Ovenbird (Seiurus Aurocapilla) Nests in Northern Hardwoods: Interactions Across Spatial Scales

The Auk ◽  
2006 ◽  
Vol 123 (1) ◽  
pp. 82-96
Author(s):  
Brady J. Mattsson ◽  
Gerald J. Niemi
Keyword(s):  
Nest Predation ◽  
Spatial Scales ◽  
Agricultural Practices ◽  
Predation Rate ◽  
Mean Values ◽  
Core Habitat ◽  
Litter Depth ◽  
Seiurus Aurocapilla ◽  
Forest Songbirds ◽  
Main Effects

Abstract Microsite, patch, and landscape conditions may interact to influence nest predation. In northern Minnesota, silvicultural and agricultural practices may be involved in recent increases in nest predators and regional declines in several ground-nesting songbirds. To examine this problem, we evaluated 17 hierarchical models of predation on Ovenbird (Seiurus aurocapilla) nests that included microsite variables, distances to edges, and amount of core forest within a 2-km radius surrounding six study plots. During 2000 and 2001, 157 Ovenbird nests were monitored to estimate nest predation rates. A model that included the main effects of litter depth and core forest area and an interaction term between the two best described variation in predation on Ovenbird nests (AICc weight = 0.83). The nest predation rate from this model was 0.51 ± 0.01 (mean ± SE), assuming mean values of litter depth and amount of core forest. Shallow litter was associated with higher nest predation in three plots surrounded by less core habitat (40–60 ha), whereas there was no relationship in three plots surrounded by more core area (100–150 ha). Management that promotes deep leaf litter and the maintenance of large, intact forest tracts will likely benefit Ovenbirds and other forest songbirds. Factores que Influencian la Depredación de Nidos de Seiurus aurocapilla en los Bosques del Norte: Interacciones a través de las Escalas Espaciales

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