Temporal and spatial variations in the behavior of shrubsteppe birds (original) (raw)
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Resource configuration and abundance affect space use of a cooperatively breeding resident bird
Movement and space use of birds is driven by activities associated with acquiring and maintaining access to critical resources. Thus, the spatial configuration of resources within home ranges should influence bird movements, and resource values should be relative to their locations. We radio-tracked 22 Brown-headed Nuthatches (Sitta pusilla) and related their space use and home range sizes to available resources while taking nest site locations into account. We developed utilization distributions (UDs) from nuthatch locations, and treated the area of each 95% isopleth as home range size and the height of the UD as relative probability of use. We fit models relating home range size to mean resource measures within home ranges, and used lognormal regression to relate intensity of use to resource metrics at random points by ranking linear mixed models. Nuthatch home ranges typically had two centers of activity. Areas of high use were associated with the density of recently killed snags (likely a foraging resource), recent prescribed fire, pine dominance, low tree stocking rates, and grassy herbaceous cover. Home ranges were generally large (median: 7.1 ha; range: 0.3–47.6 ha), and smaller home range sizes were associated with pine dominance and higher nest snag density. Predicted home range sizes decreased by 77% and 69%, respectively, when percent pine and nest snag density were maximized. Our results illustrate that movement decisions within home ranges are driven by both the availability and spatial distribution of resources, while ongoing savannah-woodland management is providing resources that are used by Brown-headed Nuthatches.
Estimating the Effects of Habitat and Biological Interactions in an Avian Community
PLOS ONE, 2015
We used repeated sightings of individual birds encountered in community-level surveys to investigate the relative roles of habitat and biological interactions in determining the distribution and abundance of each species. To analyze these data, we developed a multispecies N-mixture model that allowed estimation of both positive and negative correlations between abundances of different species while also estimating the effects of habitat and the effects of errors in detection of each species. Using a combination of single-and multispecies Nmixture modeling, we examined for each species whether our measures of habitat were sufficient to account for the variation in encounter histories of individual birds or whether other habitat variables or interactions with other species needed to be considered. In the community that we studied, habitat appeared to be more influential than biological interactions in determining the distribution and abundance of most avian species. Our results lend support to the hypothesis that abundances of forest specialists are negatively affected by forest fragmentation. Our results also suggest that many species were associated with particular types of vegetation as measured by structural attributes of the forests. The abundances of 6 of the 73 species observed in our study were strongly correlated. These species included large birds (American Crow (Corvus brachyrhynchos) and Red-winged Blackbird (Agelaius phoeniceus)) that forage on the ground in open habitats and small birds (Red-eyed Vireo (Vireo olivaceus), House Wren (Troglodytes aedon), Hooded Warbler (Setophaga citrina), and Prairie Warbler (Setophaga discolor)) that are associated with dense shrub cover. Species abundances were positively correlated within each size group and negatively correlated between groups. Except for the American Crow, which preys on eggs and nestlings of small song birds, none of the other 5 species is known to display direct interactions, so we suspect that the correlations may have been associated with species-specific responses to habitat components not adequately measured by our covariates.
Niche differentiation enables ecologically similar species to coexist by lessening competition over food and/or shelters and may be critical for reproductive isolation between closely related species in close proximity. Because no extra traits need to evolve, spatial and temporal differentiation may readily take place to complement other isolating mechanisms. Two closely related treefrog species occur together in Korea: the endangered Hyla suweonensis and the widespread H. japonica. Advertisement calls are differentiated, but it is unclear whether call difference is sufficient for reproductive isolation. We tracked individuals of both species to study fine-scale differentiation in microhabitat use in the diel cycle of the breeding season using a Harmonic Direction Finder. Tracking male movement patterns of both species revealed spatial and temporal differentiation in microhabitat use for calling and resting during the breeding season. Males of both H. suweonensis and H. japonica occurred in all five microhabitats identified in this study: rice paddy, ground, buried, grass, and bush. Both treefrog species showed general similarities in calling from rice paddies and resting in grass and bush. However H. suweonensis moved into rice paddies and produced advertisement calls three hours earlier than H. japonica. These differences likely minimize contact between the species and provide an additional isolating mechanism. Additionally, the activity of H. suweonensis may be contributing to the decline of this species, as resting in grass would increase dangers from predatory birds and habitat disturbance.
ORDINATIONS OF HABITAT RELATIONSHIPS AMONG BREEDING BIRDS
I N an attempt to express habitat relationships in a new way, I have applied two methods of multivariate analysis to a large set of data pertaining to the habitats of 46 species of common breeding birds. The question asked was : How do these species distribute themselves with respect to the structure of the vegetation? This required (1) devising field techniques that would give quantitative measurements of the vegetation within the breeding territories of individual birds, (2) analyzing these by species in order to obtain a sample of the characteristic habitat dimensions of the species niche, (3) reconstructing the relationships among the species according to their relative habitat separation, and (4) considering the ability of the vegetational variables to describe differences among habitats mathematically. Data were gathered in the spring and summer of 1967 in Arkansas. The vegetation was sampled in O.l-acre circular plots, using singing male birds as the centers of the circles. The statistical procedures used which were principal component analysis and discriminant function analysis provided a tool for describing bird distribution objectively as ordinations of continuously-varying phenomena along gradients of vegetational structure. The relative positions of the species were located within multidimensional "habitat space." The relationship between this approach and studies involving ordinations of plant and animal communities is discussed. FIELD METHODS Estimates of the characteristics of the structure of the vegetation were obtained by means of sampling one 0.1~acre circular plot within the territory of each singing male bird. A 0.1.
The effect of cover and food on space use by wintering Song Sparrows and Field Sparrows
Canadian Journal of Zoology, 1997
The distribution of birds among microhabitats may reflect species-specific resource requirements. Both food availability and predation risk have been shown to influence patterns of microhabitat use by sparrows during winter. We investigated the influence of vegetative cover and food on microhabitat use using a 2 × 2 factorial design. Both woody cover and food were manipulated at the plot level. The presence of screening cover (weed stems) was manipulated within plots. Sparrows showed a positive response to the presence of both cover and food. Within plots, sparrows selected areas with screening cover. The distribution of birds between areas with and without screening cover was influenced by the presence of woody cover and food. Conversely, the presence of screening cover reduced the influence of woody cover on the distribution of birds within patches. Song Sparrows (Melospiza melodia) and Field Sparrows (Spizella pusilla) differed in their response to treatments both within and acro...
Individuals from habitat generalist species are often thought to be habitat generalist themselves, but this assumption should be examined in light of mounting evidence for native and phenotypic habitat preference. We experimentally tested whether the White-throated Sparrow (Zonotrichia albicollis (Gmelin, 1789)) exhibits habitat preferences at the individual level. The White-throated Sparrow was a habitat generalist species in our study area, with high occupancy of clearcuts as well as mature forests. However, males in mature forests whose territories were clear-cut in the winter following their breeding season (n = 14), dispersed twice as far as males from uncut mature forests (n = 21). New territories selected by males after clearcuts contained significantly more mature forest than what remained in the territory that they abandoned, but not as much mature forest as was found in their former territory. Gain in uncut habitat after dispersal was positively correlated with dispersal distance. Clear-cut locations left vacant by dispersing males were colonized by new conspecifics. Our results suggest that individual sparrows use only a subset of their species' wide range of habitats. We question the assumption that individuals from a generalist species are versatile and unlikely to be affected by habitat disturbance.
Current Zoology, 2016
Every species has certain habitat requirements, which may be altered by interactions with other co-occurring species. These interactions are mostly ignored in predictive models trying to identify key habitat variables correlated with species population abundance/occurrence. We investigated how the structure of the urban landscape, food resources, potential competitors, predators, and interaction between these factors influence the abundance of house sparrow Passer domesticus and the tree sparrow P. montanus in sixty 25 ha plots distributed randomly across residential areas of the city of Pozna n (Poland). The abundance of the house sparrow was positively correlated with the abundance of pigeons but negatively correlated with human-related food resources. There were significant interaction terms between abundances of other urban species and habitat variables in statistical models. For example, the abundance of house sparrow was negatively correlated with the abundance of corvids and tree sparrows but only when food resources were low. The abundance of tree sparrows positively correlated with density of streets and the distance from the city center. The abundance of this species positively correlated with the abundance of corvids when food resources were low but negatively correlated at low covers of green area. Our study indicates that associations between food resources, habitat covers, and the relative abundance of two sparrow species are altered by the abundance of other urban species. Competition, niche separation and social facilitation may be responsible for these interactive effects. Thus, biotic
Prey availability and habitat structure explain breeding space use of a migratory songbird
The Condor, 2016
Researchers have long recognized that the spatial distribution of animals relates to habitat requirements. In birds, despite recent advances in tracking techniques, knowledge of habitat needs remains incomplete for most species. Using radio telemetry, we quantified the relative space use of 37 Wood Thrush (Hylocichla mustelina) males, captured over 2 years (2013, 2014) on their breeding grounds in coastal Virginia. Following tracking, we collected data on prey availability (n ¼ 370 plots) and habitat structure (n ¼ 222 plots) within bird home ranges, and modeled bird utilization distribution with both sets of variables using mixed models. Our objectives were to (a) determine the relative importance of habitat structure and prey availability for bird use, (b) identify specific resources that related to bird utilization distribution, (c) test the hypothesis that soil moisture explained prey availability, and (d) evaluate models by determining whether model-identified conditions agreed with data at sites where Wood Thrushes were absent over the preceding 5 years. Of prey variables, high-use areas within bird home ranges were linked to higher biomass of spiders and worm-like invertebrates, which were strongly correlated with soil moisture. Of habitat structure variables, bird use related negatively to red oak (Quercus spp.) count and pine (Pinus spp.) basal area, and positively to forest canopy height, snag basal area, and number and species richness of trees, among others. Evaluation of 12 covariates in our best model revealed that 5 were significant, with conditions at bird absence sites congruent with our models. Goodness-of-fit tests revealed poor fit of the prey-only model, whereas the habitat-only model explained nearly 8 times the variation in bird use. The model utilizing both prey and structure covariates yielded only marginal improvement over the habitat-only model. Consequently, management objectives aimed at habitat improvement for the declining Wood Thrush should particularly consider habitat structure resources.
Habitat Occupancy Patterns of North American Shrubsteppe Birds: The Effects of Spatial Scale
Oikos, 1987
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. . Wiley and Nordic Society Oikos are collaborating with JSTOR to digitize, preserve and extend access to Oikos. . 1987. Habitat occupancy patterns of North American shrubsteppe birds: the effects of spatial scale. -Oikos 48: 132-147.
Habitat Use Patterns of Bobolinks and Savannah Sparrows in the Northeastern United States
Avian Conservation and Ecology, 2010
In the northeastern United States, grassland birds regularly use agricultural fields as nesting habitat. However, birds that nest in these fields regularly experience nest failure as a result of agricultural practices, such as mowing and grazing. Therefore, information on both spatial and temporal patterns of habitat use is needed to effectively manage these species. We addressed these complex habitat use patterns by conducting point counts during three time intervals between May 21, 2002 and July 2, 2002 in agricultural fields across the Champlain Valley in Vermont and New York. Early in the breeding season, Bobolinks (Dolichonyx oryzivorus) used fields in which the landscape within 2500 m was dominated by open habitats. As mowing began, suitable habitat within 500 m became more important. Savannah Sparrows (Passerculus sandwichensis) initially used fields that contained a high proportion of suitable habitat within 500 m. After mowing, features of the field (i.e., size and amount of woody edge) became more important. Each species responded differently to mowing: Savannah Sparrows were equally abundant in mowed and uncut fields, whereas Bobolinks were more abundant in uncut fields. In agricultural areas in the Northeast, large areas (2000 ha) that are mostly nonforested and undeveloped should be targeted for conservation. Within large open areas, smaller patches (80 ha) should be maintained as high-quality, late-cut grassland habitat. RÉSUMÉ. Dans le Nord-est des États-Unis, les oiseaux de prairie nichent régulièrement dans les champs agricoles. Cependant, la nidification de ces oiseaux échoue souvent en raison des activités agricoles, comme le fauchage et le broutement. Il s'avère donc nécessaire de connaître les caractéristiques spatio-temporelles relatives à l'utilisation de l'habitat pour gérer efficacement ces espèces. Nous avons examiné ces patrons complexes de l'utilisation de l'habitat au moyen de dénombrements par points d'écoute effectués à trois périodes entre le 21 mai et le 2 juillet 2002, dans des champs agricoles de la vallée de Champlain dans les États du Vermont et de New York. Tôt dans la saison de nidification, les Goglus des prés (Dolichonyx oryzivorus) ont utilisé des champs situés dans des paysages où les milieux ouverts dominaient dans un rayon de 2 500 m. Lorsque le fauchage a commencé, l'habitat propice dans un rayon de 500 m est devenu plus important. Les Bruants des prés (Passerculus sandwichensis) ont utilisé des champs qui offraient un habitat propice dans un rayon de 500 m dès le début de la saison. Une fois le fauchage terminé, les caractéristiques des champs (c.-à-d. la dimension et la quantité de lisières boisées) sont devenues davantage déterminantes. Les deux espèces ont agi différemment face au fauchage : les bruants ont utilisé les champs fauchés et les champs non fauchés de façon égale, tandis que les goglus étaient plus nombreux dans les champs n'ayant pas subi de fauchage. Dans les zones agricoles du Nord-est, les vastes régions (2 000 ha)