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Nest Success (nest + success)

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Life Sciences	100%

Selected Abstracts

Nest usurpation is an ,edge effect' for Carolina chickadees Poecile carolinensis

JOURNAL OF AVIAN BIOLOGY, Issue 1 2002
Paul F. Doherty
During 1995,1997, we monitored Carolina chickadee Poecile carolinensis nests in a fragmented forest landscape in northcentral Ohio, USA. Nest success was positively correlated with woodlot area and most nest loss was due to nest destruction by house wrens Troglodytes aedon. During 1998 and 1999, we conducted an experiment in both large (>6.8 ha) and small (<6.8 ha) woodlots in which we gave chickadees a choice of nesting on edges of woodlots (preferred wren habitat) or in the center of woodlots. We found no difference in nest success between large and small woodlots, but regardless of woodlot size, nest success was lower on edges than in the center. In the experiment, 100% of nest loss was due to nest destruction by house wrens. Given a choice, Carolina chickadees preferred to nest centrally more often than on edges. These results suggest that in fragmented landscapes where house wrens are common, nest destruction by house wrens is a major cause of nest failure in the Carolina chickadee. Such edge-dependent interspecific nest-site usurpation has not been previously recognized as a potentially important selective factor in nest site selection. [source]

Effects of invasive woody plants on avian nest site selection and nesting success in shrublands

ANIMAL CONSERVATION, Issue 3 2010
S. Schlossberg
Abstract Exotic, invasive plants are a growing conservation problem. Birds frequently use invasive plants as nest substrates, but effects of invasives on avian nesting success have been equivocal in past studies. In 2004 and 2005, we assessed effects of invasive woody plants on avian nest-site selection and nesting success in western Massachusetts shrublands. At the nest scale, we tested the effects of invasive versus native substrates on nesting success as well as differences among individual invasive species. At the patch scale, we tested effects of invasive prevalence on nesting success in natives and invasives. We found that, as a whole, shrubland birds preferred invasive substrates. Of two species sufficiently abundant for individual analysis, gray catbirds Dumetella carolinensis preferred invasive substrates, but chestnut-sided warblers Dendroica pensylvanica showed no preference for natives or invasives. At the nest scale, nests of gray catbirds placed in invasive substrates were more successful than those in natives. Chestnut-sided warblers and all species combined, however, had equal nest success in invasives and natives. We found no differences in nest success for nests in different species of invasive substrates or in invasive substrates with and without thorns. At the scale of the patch, nest success in invasive substrates increased with the prevalence of invasives on a site. Nest success in native plants did not change with invasive prevalence. We attribute this finding to the tendency for thickets of invasive plants to be larger on sites with more invasive cover. These findings illustrate the complex interaction of different factors that can determine how invasive plants affect avian nesting success. We conclude that control of invasive woody plants should be neutral for most shrubland birds. [source]

Nesting in a thermally challenging environment: nest-site selection in a rock-dwelling gecko, Oedura lesueurii (Reptilia: Gekkonidae)

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010
DAVID A. PIKE
In egg-laying species, maternal oviposition choice can influence egg survival and offspring phenotypes. According to the maternal-preference offspring-performance hypothesis, females should choose oviposition sites that are optimal for offspring fitness. However, in thermally challenging environments, maternal oviposition behaviour may be constrained by the limited availability of suitable oviposition sites. We investigated nest-site selection in a nocturnal lizard [velvet gecko Oedura lesueurii (Duméril and Bibron)] that inhabits a thermally challenging environment in south-eastern Australia. The viability of these gecko populations is critical for the persistence of an endangered snake species (Hoplocephalus bungaroides Wagler) that feeds heavily on velvet geckos. Female geckos chose nest sites nonrandomly, with 87% of nests (N = 30) being laid in deep crevices. By contrast, only 13% of clutches were laid under rocks, which were the most readily available potential nest sites. Nest success in crevices was high (100%), but no eggs hatched from nests under rocks. Temperatures in nest crevices remained relatively low and constant throughout the incubation period (mean = 22.7 °C, range 21.0,24.5 °C), whereas thermal regimes under rocks showed large diurnal fluctuations. Geckos selected crevices that were deeper, had less canopy cover, and were warmer than most available crevices; in 85% of cases, such crevices were used simultaneously by more than one female. The thermally distinctive attributes of nest sites, and their frequent communal use, suggest that nest sites are a scarce resource for female velvet geckos, and that the shading of rock outcrops through vegetation encroachment may influence nest success in this species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 250,259. [source]

Effects of acidification on the breeding ecology of a stream-dependent songbird, the Louisiana waterthrush (Seiurus motacilla)

FRESHWATER BIOLOGY, Issue 11 2008
ROBERT S. MULVIHILL
Summary 1.,We compared breeding ecology of the Louisiana waterthrush (Seiurus motacilla) on acidified and circumneutral streams in the Appalachian Highlands of Southwestern Pennsylvania from 1996 to 2005. 2.,Headwater streams impacted by acid mine drainage and/or acidic precipitation showed reduced pH (range 4.5,5.5) compared to four circumneutral streams (pH c. 7). Acid-sensitive taxa, including most mayflies (Ephemeroptera), were almost completely absent from acidified streams, whereas several acid-tolerant taxa, especially stonefly (Plecoptera) genera Leuctra and Amphinemura, were abundant. 3.,Louisiana waterthrush breeding density (c. 1 territory km,1) was significantly reduced on acidified streams compared to circumneutral streams (>2 territories km,1). Territories on acidified streams were almost twice as long as on circumneutral streams. Territories usually were contiguous on circumneutral streams, but they were often disjunct on acidified streams. Breeding density declined on one acidified stream that we studied over a 10-year period. 4.,Clutch initiation was significantly delayed on acidified streams, on average by 9 days in comparison to circumneutral streams, and first-egg dates were inversely related to breeding density. Birds nesting along acidified streams laid smaller clutches, and nestlings had shorter age-adjusted wing lengths. Stream acidity had no effect on nest success or annual fecundity (fledglings/female). However, the number of young fledged km,1 was nearly twice as high on circumneutral streams as on acidified streams. 5.,Acidified streams were characterized by a younger, less site-faithful breeding population. Individuals were less likely to return multiple years to breed, allowing inexperienced breeders to settle on acidified streams. Pairing success was lower on acidified streams, and we observed four cases of waterthrushes emigrating from territories on acidified streams to nearby circumneutral streams in the following year. 6.,We conclude that acidified headwaters constitute lower quality habitat for breeding Louisiana waterthrush. However, breeding birds can apparently compensate for reduced prey resources to fledge young on acidified streams by increasing territory size, foraging in peripheral non-acidified areas, and by provisioning young with novel prey. [source]

The effectiveness of volunteer nest protection on the nest success of Northern Lapwings Vanellus vanellus on Dutch arable farms

IBIS, Issue 4 2008
STEVEN KRAGTEN
Clutches of ground-nesting farmland birds are often destroyed by farming operations, resulting in insufficient reproductive success and subsequently declining populations. The aim of this study was to investigate whether volunteer nest protection can enhance nest success of ground-nesting birds. The study compared nest success of protected and unprotected Northern Lapwing Vanellus vanellus nests over 2 years on arable farms in the Netherlands. Because of different crop management, nest success of ground-breeding birds might differ between organic and conventional arable farms. The effectiveness of volunteer nest protection was therefore investigated on both farm types. Although nest protection significantly reduced nest loss due to farming operations, there were no significant differences in total clutch survival of protected and unprotected nests. However, sample sizes of unprotected nests, and protected nests on organic farms, were relatively small, which may have reduced statistical power. There were indications that protected nests were predated or deserted more often. We recommend exploring different ways to improve the effectiveness of volunteer nest protection through a further reduction of nest loss due to farming operations and predation. [source]

Factors affecting nest predation on forest songbirds in North America

IBIS, Issue 2007
FRANK R. THOMPSON III
Nest predation is an important factor in the ecology of passerines and can be a large source of mortality for birds. I provide an overview of factors affecting nest predation of passerines in North America with the goal that it may provide some insight into the ecology and management of woodland birds in the United Kingdom. Although several factors influence productivity, nest success is perhaps the most widely measured demographic characteristic of open-cup-nesting birds, and nest predation is usually the largest cause of nest failure. The identity of predator species, and how their importance varies with habitat and landscape factors, must be known for managers and scientists to design effective conservation plans and place research on nest predation in the appropriate context. Recent studies using video surveillance have made significant contributions to our understanding of the relative importance of different predator taxa in North America. Spatial and temporal variation in nest predation can be better understood when landscapes are placed in a biogeographical context and local habitat and nest-site effects are placed in a landscape context. Low productivity resulting from high nest predation is one of several potential causes of bird population declines in North America and the UK. Although the ,forest fragmentation paradigm' from the eastern US may not apply directly to the UK, thinking about avian demographics from a multiscale perspective, and consideration of factors affecting nest predation with knowledge of the dominant predator species, may provide insight into population declines. [source]

Wood thrush nest success and post-fledging survival across a temporal pulse of small mammal abundance in an oak forest

JOURNAL OF ANIMAL ECOLOGY, Issue 4 2008
Kenneth A. Schmidt
Summary 1Synchronized mass production of seed crops, such as acorns, produces a resource pulse that may have far-reaching consequences for songbird populations through its effects on avian predators. Seed production in these forests represents only the first of several pulsed events. Secondary pulses emerge as mast-consuming rodents numerically respond to seed production and tertiary pulses emerge as generalist predators, such as raptors, numerically respond to rodents. In turn, these two groups reduce nest productivity and juvenile survivorship 1 and 2 years, respectively, after the initial pulse in seed production. 2At our study site in south-eastern New York, USA, autumn acorn abundance (primary pulse) largely determines rodent abundance (secondary pulse) the following spring. We tested the hypotheses that the population dynamics of a shrub-nesting passerine (wood thrush Hylocichla mustelina), is influenced by rodents through the: (a) direct effect of predation by rodents; (b) indirect effect of rodents on the abundance of raptors (tertiary pulse); and (c) indirect effect of rodent abundance on raptor diet. The latter specifically hypothesizes that a crash in the rodent population in the wake of region-wide failure of acorn production leads to an extreme diet shift in raptors that increases post-fledging mortality in birds. 3We conducted a 3-year study to examine variation in wood thrush nest success and fledgling survival, using radio telemetry, across a pulse of rodent abundance (i.e. low, medium and high). We also updated and reanalysed regional wood thrush population growth rates as a function of the annual variation in rodent abundance. 4Fledgling survivorship, but not nest success, varied in relation to annual rodent abundance. Raptors and eastern chipmunks Tamias striatus were the most commonly identified predators on fledglings. Fledgling survivorship was greatest at intermediate rodent abundance consistent with a shift in raptor diet. Regional rate of wood thrush population growth showed a unimodal relationship with rodent abundance, peaking during years with intermediate rodent abundance. This unimodal pattern was due to wood thrush population growth rates near or below zero during rodent population crashes. 5The telemetry study, pattern of regional abundance and synchronized population dynamics of coexisting thrushes suggest a common mechanism of behavioural changes in raptors in response to declines in rodent prey, which in turn affects thrush population dynamics. [source]

Parental behaviour of a precocial species: implications for juvenile survival

JOURNAL OF APPLIED ECOLOGY, Issue 4 2009
Victoria J. Dreitz
Summary 1., Parents determine habitat selection for precocial young by leading their young to foraging areas until the chicks attain full independence. There are potential benefits and costs to reproductive success associated with changing habitats while caring for young. This study investigated the relationship between different types of habitats and their quality on chick survival and brood movements of a declining upland shorebird, the mountain plover Charadrius montanus. 2., From 2004 to 2006, a total of 153 mountain plover broods were monitored on the primary breeding habitats in eastern Colorado, USA; two shortgrass prairie habitats that were either occupied or unoccupied by black-tailed prairie dogs Cynomys ludovicianus and agricultural lands. Habitat quality hypotheses were tested using newly developed statistical applications to estimate survival of chicks and brood movement patterns. 3., Chick survival and brood movements were influenced by habitat. Chick survival over the 30-day brood-rearing period was substantially higher on nesting habitat of shortgrass occupied by prairie dogs compared with agricultural land and shortgrass unoccupied by prairie dogs. The rate of brood movement away from shortgrass with prairie dogs was lower than shortgrass without prairie dogs, but higher than agricultural lands for each year of the study. 4., This study suggests that complex processes influence how different habitats affect brood-rearing activity of mountain plovers. Even though broods moved off nesting habitat of shortgrass occupied by prairie dogs, this habitat had the highest survival rate and is highly important to mountain plover reproductive success. 5.,Synthesis and applications. In order to develop effective conservation strategies, the provision of adequate breeding habitat should include information on patterns of habitat selection for all stages of the breeding cycle, including the nesting and dependent young periods. From a conservation perspective, understanding the habitat use of young birds is critical when population dynamics show great sensitivity to survival of young. Previous studies on mountain plovers have suggested that nest success is similar among shortgrass prairie habitats and agricultural lands. Thus, conservation measures that increase nest success may be ineffective for mountain plovers unless they are accompanied by measures promoting chick survival. [source]

Assessments of habitat preferences and quality depend on spatial scale and metrics of fitness

JOURNAL OF APPLIED ECOLOGY, Issue 5 2007
ANNA D. CHALFOUN
Summary 1Identifying the habitat features that influence habitat selection and enhance fitness is critical for effective management. Ecological theory predicts that habitat choices should be adaptive, such that fitness is enhanced in preferred habitats. However, studies often report mismatches between habitat preferences and fitness consequences across a wide variety of taxa based on a single spatial scale and/or a single fitness component. 2We examined whether habitat preferences of a declining shrub steppe songbird, the Brewer's sparrow Spizella breweri, were adaptive when multiple reproductive fitness components and spatial scales (landscape, territory and nest patch) were considered. 3We found that birds settled earlier and in higher densities, together suggesting preference, in landscapes with greater shrub cover and height. Yet nest success was not higher in these landscapes; nest success was primarily determined by nest predation rates. Thus landscape preferences did not match nest predation risk. Instead, nestling mass and the number of nesting attempts per pair increased in preferred landscapes, raising the possibility that landscapes were chosen on the basis of food availability rather than safe nest sites. 4At smaller spatial scales (territory and nest patch), birds preferred different habitat features (i.e. density of potential nest shrubs) that reduced nest predation risk and allowed greater season-long reproductive success. 5Synthesis and applications. Habitat preferences reflect the integration of multiple environmental factors across multiple spatial scales, and individuals may have more than one option for optimizing fitness via habitat selection strategies. Assessments of habitat quality for management prescriptions should ideally include analysis of diverse fitness consequences across multiple ecologically relevant spatial scales. [source]

Snake activity affects seasonal variation in nest predation risk for birds

JOURNAL OF AVIAN BIOLOGY, Issue 4 2008
Jinelle H. Sperry
Variation in predator behavior has been proposed, but not tested, as a mechanism producing seasonal declines in avian nest success. We test this hypothesis by documenting seasonal activity of Texas ratsnakes Elaphe obsoleta and nest failure of endangered black-capped vireos Vireo atricapilla and golden-cheeked warblers Dendroica chrysoparia on which the snakes prey. Nest survival analysis was based on 880 vireo and 228 warbler nests and 3,060 snake locations from 62 radio-tracked snakes. Although nest success varied with snake activity for both birds, specific patterns differed substantially. Vireo daily nest survival was negatively correlated with snake activity over the three-year study, despite substantial variation among years in weather, and the fact that these birds are almost certainly a minor prey species of the ratsnakes. Warblers exhibited less clear-cut seasonal variation in nest success, and the association between nest success and snake activity was less pronounced than for vireos. Increased activity at warmer temperatures explained some of the seasonal change in snake movements, although mating may have accounted for a mid-season peak in activity. These results indicate that variation in predator behavior can be associated with and potentially cause seasonal changes in nest success, but also that these relationships are species specific even within the same community and may depend on aspects of the nesting ecology of the prey such as nest site selection. [source]

Nest usurpation is an ,edge effect' for Carolina chickadees Poecile carolinensis

Temporal fluctuation in abundance of Brown-headed Cowbirds and their hosts in riparian habitat in the Okanagan Valley, British Columbia, Canada

JOURNAL OF FIELD ORNITHOLOGY, Issue 4 2006
Tawna C. Morgan
ABSTRACT We tested the hypothesis that the abundance of Brown-headed Cowbirds (Molothrus ater) and their hosts, as well as parasitism rates, changed between 1992,1993 and 2001,2003 in riparian habitats in the Okanagan Valley, British Columbia, Canada, where riparian habitat has been reduced in area by more than 85% over the past 60 years. Cowbird abundance declined from a mean of 2.1 and 1.9 individuals per census plot in 1992 and 1993, respectively, to 0.66 individuals per plot in 2001,2002. The mean number of potential host individuals per census plot was also lower in 2001,2002 (5.5) than in 1992 (7.0) and 1993 (7.8). Although the percentage of Yellow Warbler (Dendroica petechia) nests parasitized declined (77% in 1992,1993 to 50% in 2002,2003), Yellow Warblers and Song Sparrows (Melospiza melodia) in the Okanagan Valley continue to be parasitized at high rates and have low nesting success. Host species and the distance of nests from the edge of nest patches were the strongest predictors of both nest success and parasitism, indicating the importance of large continuous patches of shrubs that allow nests to be located further from edges. SINOPSIS Se expuso a pruebas la hipótesis de la abundancia de tordos (Molothrus ater) y sus huespedes y como la tasa de parasitismo cambiaron durante el 1992,1993 y el 2001,2002 en un hábitat ripario en el valle Okanagan, Columbia Británica, Canada. En dicha localidad el hábitat ripario se redujo en un 85% en los últimos 60 años. La abundancia de tordos se redujo en un promedio de 2.1 y 1.9 de individuos/censo en 1992 y 1992, respectivamente, a 0.66 individuos en 2001,2002. El número promedio de hospederos potenciales por localidad censada (5.5) fue menor para el mismo periodo en comparación con el 1992 (7.0) y el 1993 (7.8). Aunque el porcentaje de nidos parasitados (77% en el 1992,1993 a 50% en 2002,2003) en Dendroica petechia, se redujo, tanto la especie como Melospiza melodia, tuvieron un alto grado de parasitismo y un bajo éxito de anidamiento. Tanto las especies hospederas y la distancia del nido al borde del parcho de anidamiento resultaron ser los elementos de predicción más fuertes con respecto al parasitismo y el éxito de anidamiento. Esto es un indicativo claro de la importancia de parchos de arbustos amplios y contínuos, que permitan el anidamiento lejos del borde. [source]