Abundance and Habitat Preferences of Gray Vireos (Vireo Vicinior) on the Colorado Plateau

Schlossberg, Scott

doi:10.1093/auk/123.1.33

Cited by 10 publications

(22 citation statements)

References 15 publications

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“…Monitoring efforts have increased in some areas (Walker and Doster ), but trends are unclear and populations appear to be highly patchy and discontinuous throughout the range. For example, Gray Vireos were observed in only 17% of atlas blocks in Arizona from 1993 to 2000 (Corman ), only 94 birds were detected at 282 points on the Colorado Plateau of Arizona and Utah in 2001 (Schlossberg ), and the estimated total population at 49 known sites in New Mexico ranged from 549 to 827 birds in 2005 (DeLong and Williams ).…”

Section: Discussionmentioning

confidence: 99%

“…Such nest sites could help deter both scrub‐jays and cowbirds by reducing the number of nearby perches from which a nest is more likely to be visible (Sharp and Kus ). In other parts of the range, nest‐site selection has not been studied, but Schlossberg () found that Gray Vireo territories were associated with less pinyon and more juniper mixed with other shrubs, especially sagebrush ( Artemisia tridentata ). However, in pinyon‐juniper in New Mexico, Johnson et al.…”

Section: Discussionmentioning

confidence: 99%

“…Although habitat availability does not appear to be a limiting factor, Gray Vireos occur patchily at low densities in California (1.2–1.6 birds per 40 ha; Johnson et al. , Weathers ) and elsewhere (Corman , DeLong and Williams , Schlossberg , Wickersham and Wickersham ).…”

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confidence: 99%

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Poor reproductive success of Gray Vireos in a declining California population

Hargrove

Unitt

2017

J. Field Ornithol.

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ABSTRACT. Since the 1940s, populations of Gray Vireos (Vireo vicinior) in California have collapsed, presumably because of parasitism by Brown-headed Cowbirds (Molothrus ater). In 2012 and 2013, we studied the vireo's nesting ecology to assess factors affecting two of California's largest remaining populations in the chaparral of San Diego County. Nest success was extremely low, with a model-averaged probability of nest survival of only 0.08 (N = 95). More nest failures were due to predation (83%) than to cowbird parasitism (13%). Video-recording at 30 nests revealed that California Scrub-Jays (Aphelocoma californica) were the most common nest predator (67%). Of eight variables tested, height of shrubs surrounding the nest had the strongest negative influence on nest survival, but was more strongly correlated with cowbird parasitism than with jay predation. Despite frequent renesting, seasonal productivity was well below the level required to sustain a population, especially in northern San Diego County where we found no Gray Vireos at six of seven sites where they had been present from 1997 to 2001 and where cowbird parasitism was more frequent. The vireo's continuing range collapse contrasts with recent climate-change models predicting a range expansion, highlighting the importance of demographic studies. Low nest success is likely contributing to population declines in California, and the additive effect of cowbird parasitism suppresses productivity. Conservation of Gray Vireos in California will likely require development of alternative approaches to cowbird and scrub-jay control appropriate to sites widely scattered in rugged chaparral.RESUMEN. Bajo exito reproductivo de Vireo vicinior en una poblaci on de California en declive Desde la d ecada de 1940, las poblaciones de Vireo vicinior en California se han desplomado, presuntamente por el parasitismo por Molothrus ater. En 2012 y 2013, estudiamos la ecolog ıa de anidaci on de Vireo vicinior, con el objetivo de determinar los factores que afectan las dos poblaciones m as grandes de California en el chaparral del condado de San Diego. El exito reproductivo fue extremadamente bajo, con una probabilidad promedio de supervivencia del nido de solo 0.08 (N = 95). La mayor cantidad fracasos de nidos fue producto de depredaci on (83%) y no de parasitismo por Molothrus ater (13%). Grabaciones de 30 nidos revelaron que el depredador m as com un fue Aphelocoma californica (67%). De las ocho variables evaluadas, la altura de los arbustos alrededor del nido tuvo la influencia negativa m as fuerte sobre la supervivencia del nido, sin embargo, estuvo m as fuertemente correlacionada con el parasitismo por parte de Molothrus ater que por la depredaci on por parte de Aphelocoma californica. A pesar de los intentos frecuentes de re-anidaci on, la productividad estacional fue considerablemente menor al nivel requerido para sostener una poblaci on, especialmente en el norte del condado de San Diego, donde no encontramos Vireo vicinior en seis de las siete localidades donde hab ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Poor reproductive success of Gray Vireos in a declining California population

Hargrove

Unitt

2017

J. Field Ornithol.

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“…Similarly to other southwestern vireos, Gray Vireos (Vireo vicinior) are understudied in many aspects of their life-history (Barlow et al 1999, Schlossberg 2006. Gray Vireos are migratory with a breeding range that includes New Mexico, Colorado, Arizona, Utah, and small populations in California, Nevada, and Texas (Barlow et al 1999).…”

Section: Introductionmentioning

confidence: 99%

A multiscale analysis of Gray Vireo (Vireo vicinior) nest-site selection in central New Mexico

Harris¹,

Smith²,

McMurry³

2020

ACE

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There are many gaps in our understanding of Gray Vireo (Vireo vicinior) life history especially as it relates to nesting ecology. Our objective was to determine habitat features selected by Gray Vireos for nesting to improve management strategies for breeding populations. We searched for Gray Vireo nests on Kirtland Air Force Base in Albuquerque, New Mexico from 2016 to 2017. We estimated Gray Vireo nest-site selection at the tree level, the surrounding vegetation, and at two broader scales corresponding to selection within territories. Nest-site selection was estimated for 99 Gray Vireo nests. For tree-level selection, we compared characteristics of nesting trees with mean characteristics from groups of six randomly selected one-seed junipers (Juniperus monosperma) within a 25m radius. We also compared overall vegetation characteristics at the 25-m scale for nesting plots and 66 randomly selected plots. Broadscale cover proportions of nest sites and random points were estimated at 50-and 100-m radius spatial scales using a geographic information system. Gray Vireos selected nesting trees that were taller and wider than other adjacent junipers. Selection of vegetation characteristics surrounding nests showed a similar pattern, where Gray Vireos nested in areas where junipers were taller, wider, and had greater foliage density than was randomly available. Broad-scale analyses suggested that Gray Vireos selected nest sites in areas with higher proportions of junipers at low elevations (< 1954 m), and lower proportions of junipers in higher elevations (> 1954 m); however, juniper proportions at nest sites consistently ranged from 15 to 30% of available cover. Gray Vireos also tended to select areas with less pinyon pine than what was randomly available at the 100-m radius scale. Future management strategies should provide large patches of old-growth juniper to optimize Gray Vireo nesting habitat. Analyse multiéchelle de la sélection du site de nidification du Viréo gris (Vireo vicinior) dans le centre du Nouveau-Mexique RÉSUMÉ. Notre compréhension du cycle biologique du Viréo gris (Vireo vicinior) est incomplète, particulièrement en ce qui a trait à l'écologie de nidification. Notre objectif était de déterminer les caractéristiques d'habitat recherchées par les Viréos gris durant la nidification afin d'améliorer les stratégies d'aménagement destinées aux populations nicheuses. Nous avons cherché des nids de viréos sur la base des forces aériennes de Kirtland à Albuquerque, au Nouveau-Mexique, en 2016 et 2017. Nous avons évalué la sélection des sites de nidification des viréos à l'échelle de l'arbre, de la végétation environnante et à deux autres échelles plus grandes à l'intérieur des territoires des oiseaux. Nous avons analysé la sélection du site de 99 nids de Viréos gris. En matière de sélection à l'échelle de l'arbre, nous avons comparé les caractéristiques des arbres abritant un nid avec les caractéristiques moyennes de groupes de six genévriers monospermes (Juniperus monosperma) tirés aléatoirement dans un ray...

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“…Hardy (1945) and Short and McCulloch (1977) described juniper as a preferred nesting substrate; however, few data were presented in these reports. Cicero (2000) reported that the juniper titmouse ( Baeolophus ridgwayi ) is more common where juniper is the dominant tree and Schlossberg (2006) found that gray vireo ( Vireo vicinior ) densities increase as juniper becomes more prevalent than piñon, yet neither of these studies described nest substrate use.…”

Section: Discussionmentioning

confidence: 99%

Importance of juniper to birds nesting in piñon–juniper woodlands in northwest New Mexico

2011

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Piñon–juniper (Pinus spp.–Juniperus spp.) woodlands are common throughout western North America, yet relatively little is known about the habitat use and requirements for many members of its avian community. During summer 2005–2007, we assessed avian nesting substrates within piñon (Pinus edulis)–juniper (Juniperus osteosperma) woodlands in northwestern New Mexico. Of all nests in live trees, 86% were in junipers. The selection of juniper as a nest tree was significantly higher than expected from the region's piñon–juniper ratio (1:1.06) for the community as a whole, for both open cup and cavity nesting species, and for 8 species (of which 6 are piñon–juniper obligate or semi‐obligate species). Nest survival, however, was not higher in juniper than in piñon for the nesting community as a whole or for chipping sparrows (Spizella passerina), the single species that was well represented nesting in piñon. The high use of juniper as a nesting substrate differs from previous studies, which have suggested that a presence of piñon is among the most important habitat features for many piñon–juniper species. Because of their importance to nesting birds, managers should avoid preferential thinning of junipers within piñon–juniper woodlands. © 2011 The Wildlife Society.

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Abundance and Habitat Preferences of Gray Vireos (Vireo Vicinior) on the Colorado Plateau

Cited by 10 publications

References 15 publications

Poor reproductive success of Gray Vireos in a declining California population

Poor reproductive success of Gray Vireos in a declining California population

A multiscale analysis of Gray Vireo (Vireo vicinior) nest-site selection in central New Mexico

Importance of juniper to birds nesting in piñon–juniper woodlands in northwest New Mexico

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