Exportar el conocimiento del psicoanálisis desde la clínica hacia otros campos del saber no es se... more Exportar el conocimiento del psicoanálisis desde la clínica hacia otros campos del saber no es sencillo, y no debe serlo, si se pretende generar un verdadero diálogo con esos otros campos del saber. El diálogo particular entre el psicoanálisis y la literatura elucida elementos que se escapan en una lectura simple de nuestras páginas favoritas, permitiéndonos vincularnos de otra forma con el texto.
Page 1. Wilson Bull., 101(1), 1989, pp. 62-76 OBSERVATIONS ON THE BREEDING BIOLOGY OF PASSERINES ... more Page 1. Wilson Bull., 101(1), 1989, pp. 62-76 OBSERVATIONS ON THE BREEDING BIOLOGY OF PASSERINES IN A SEASONALLY FLOODED SAVANNA IN VENEZUELA ALEXANDER CRUZ AND ROBERT W. ANDREws' ...
ABSTRACT Background/Question/Methods In riparian areas of the arid and semi-arid western North Am... more ABSTRACT Background/Question/Methods In riparian areas of the arid and semi-arid western North America, tamarisk (Tamrix spp.) and Russian olive (Elaeagnus angustifolia) threaten native cottonwood (Populus fremontii) and willow (Salix spp.) habitats. These native woodlands are known to maintain among the highest avian densities and species richness totals in temperate North America through habitat heterogeneity that provides nesting substrates, cavities, and food resources for many species relative to the surrounding landscape. Although resource managers are actively managing these invasive species, the effects of invasive vegetation on bird communities are site and species specific. Why some species, guilds, and families do poorly and others are either unaffected or thrive in the face of invasion is poorly understood. Utilizing a unique gradient of native to invasive riparian vegetation on the San Juan and Animas Rivers in northwest New Mexico, we used point count surveys, vegetation assessments, and prey surveys to address how avian communities, species, and guilds respond to invasive vegetation, and identify which life history characteristics make them predisposed to avoidance or attraction to invasive vegetation types. Results/Conclusions Overall, sites containing predominantly native vegetation had higher species richness and diversity than predominantly invasive sites. Our results suggest that responses to the vegetation gradient are species specific. We found that occupancy likelihood for omnivores, certain members of the aerial forager guild, and Emberizidae family members increased with invasion. Alternatively, cavity nesting species, frugivorous species, and many insectivorous species decreased with increased proportions of invasive species. Avian prey diversity and evenness showed a negative relationship with increased proportion of invasive vegetation. Our data suggest that the relative abundance of invertebrate orders per dominant vegetation type may be somewhat controlling insectivore abundance. For example, Hymenoptera, a dominant food source of Yellow-breasted chats (Icteria virens), were more abundant in Russian olive, where chats were higher in abundance. Similarly, Hemiptera were more abundant in cottonwood, where Yellow warblers (Setophaga petechia) were more likely to feed. Plecoptera and Trichoptera were strongly related to native dominant vegetation and avian insectivore occupancy. The unique approach of exploring invasion on a gradient scale paired with avian life history characteristics and avian prey abundance measures have provided an interesting and hopefully applicable approach to conservation of avian species.
Background/Question/Methods The Brown-headed Cowbird (Molothrus ater) is an obligate brood parasi... more Background/Question/Methods The Brown-headed Cowbird (Molothrus ater) is an obligate brood parasite that reduces the reproductive success of many of its host species. Cowbird-host research over the past few years has focused heavily on determining the relative effects of parasitism and predation. However, despite extensive efforts, it is still poorly understood to what extent cowbirds reduce host reproductive success. To better address this question, we have created a mechanistic model, based on a 3-year data set, to calculate and assess the relative costs of parasitism and predation for one host species, the Plumbeous Vireo (Vireo plumbeus). This vireo is the primary host of cowbirds within our study area, the Front Range of Colorado, USA. Results/Conclusions The results from this work show that the costs of both parasitism and predation depend sensitively on the Julian date on which eggs are layed. Specifically, cowbirds (at least within the Colorado Front Range population) have s...
We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors (Bo... more We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors (Box Elder, Acer negundo; willow, $alix sp.; cottonwood, Populus sp.) of Boulder County, Colorado (elevation 1550 to 2150 m, 40 ø 00' N, 105 ø 20' W), in 1990 (n = 15) and 1992 (n = 11). Nests were found during different stages of reproduction, and we observed them every three to five days until the nest was successful or failed. We observed nests directly or by mirror-pole, recorded their contents, and determined causes of nest failure. By examining nest contents and condition, we categorized the causes of nest failure as predation, parasitism, weather, or unknown. We used the Mayfield method (Mayfield 1961, 1975) to determine nesting success. The Mayfield method provides a standardized measure of nest success, by taking into account the number of days of exposure, that is comparable to other studies of nesting success. We measured nest height, nest distance to trunk, and nest dist...
Several urban-adapted species sing at a higher frequency in noisy urban areas than in quiet locat... more Several urban-adapted species sing at a higher frequency in noisy urban areas than in quiet locations. Yet it remains unclear whether the ability to adjust signals in response to noise is related to an ability to persist in noisy areas, because signal change and habitat use are infrequently measured within a single study. We investigated occupancy and signal change in response to noise in the Blue-gray Gnatcatcher (Polioptila caerulea) and the Spotted Towhee (Pipilo maculatus) using a study system that eliminates uncontrolled effects of habitat features that may influence song frequency or habitat use and controls for the negative effect of noise on bird surveys. We predicted that species that alter the frequency of their vocalizations in response to noise would use noisy and quiet areas similarly, and that species that do not adjust their vocalizations in response to noise may avoid noisy areas. Both study species were uninfluenced by noise in their habitat occupancy, but only Spotted Towhees sang at a higher frequency with increased noise exposure. This may be explained by low-frequency noise having a greater acoustic masking potential for low-frequency Spotted Towhee songs than for higher-pitched Blue-gray Gnatcatcher songs. These findings suggest that an ability to shift song frequency may not directly correspond to an ability to remain in noisy areas. Although many factors can influence habitat use by birds, habitat occupancy in noisy areas may depend on whether the noise has acoustic energy at frequencies that can mask a species’ song; if so, signal flexibility may be important.
The historic range of the bison (Bison bison) on the Great Plains has been well documented. In Co... more The historic range of the bison (Bison bison) on the Great Plains has been well documented. In Colorado the range of bison included both the eastern grasslands and higher-elevation ridges and mountain parks, up to an elevation of 3900 m. Based on the commensal relationship of the brood-parasitic Brown-headed Cowbird (Mohthrus ater) with the bison, we suggest that the cowbird had a larger historical elevational range in Colorado than previously known and consequently has had a long-term host-parasite relationship with high-elevation breeding songbirds.
During the summers,of 1999 to 2004 we studied the breeding bird community,in the Ponderosa Pine h... more During the summers,of 1999 to 2004 we studied the breeding bird community,in the Ponderosa Pine habitats of the Boulder County Open Space property, Heil Ranch. To date, we have located and monitored 397 nests of 25 species, as well as surveyed birds at 30-point count locations on the property to determine the distribution and abundance,of these species. This study
... We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors... more ... We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors (Box Elder, Acer negundo; willow, $alix sp.; cottonwood, Populus sp.) of Boulder County, Colorado (elevation 1550 to 2150 m, 40 ø ... Smith, JNM, Arcese, P., and McLean, IG 1984. ...
Exportar el conocimiento del psicoanálisis desde la clínica hacia otros campos del saber no es se... more Exportar el conocimiento del psicoanálisis desde la clínica hacia otros campos del saber no es sencillo, y no debe serlo, si se pretende generar un verdadero diálogo con esos otros campos del saber. El diálogo particular entre el psicoanálisis y la literatura elucida elementos que se escapan en una lectura simple de nuestras páginas favoritas, permitiéndonos vincularnos de otra forma con el texto.
Page 1. Wilson Bull., 101(1), 1989, pp. 62-76 OBSERVATIONS ON THE BREEDING BIOLOGY OF PASSERINES ... more Page 1. Wilson Bull., 101(1), 1989, pp. 62-76 OBSERVATIONS ON THE BREEDING BIOLOGY OF PASSERINES IN A SEASONALLY FLOODED SAVANNA IN VENEZUELA ALEXANDER CRUZ AND ROBERT W. ANDREws' ...
ABSTRACT Background/Question/Methods In riparian areas of the arid and semi-arid western North Am... more ABSTRACT Background/Question/Methods In riparian areas of the arid and semi-arid western North America, tamarisk (Tamrix spp.) and Russian olive (Elaeagnus angustifolia) threaten native cottonwood (Populus fremontii) and willow (Salix spp.) habitats. These native woodlands are known to maintain among the highest avian densities and species richness totals in temperate North America through habitat heterogeneity that provides nesting substrates, cavities, and food resources for many species relative to the surrounding landscape. Although resource managers are actively managing these invasive species, the effects of invasive vegetation on bird communities are site and species specific. Why some species, guilds, and families do poorly and others are either unaffected or thrive in the face of invasion is poorly understood. Utilizing a unique gradient of native to invasive riparian vegetation on the San Juan and Animas Rivers in northwest New Mexico, we used point count surveys, vegetation assessments, and prey surveys to address how avian communities, species, and guilds respond to invasive vegetation, and identify which life history characteristics make them predisposed to avoidance or attraction to invasive vegetation types. Results/Conclusions Overall, sites containing predominantly native vegetation had higher species richness and diversity than predominantly invasive sites. Our results suggest that responses to the vegetation gradient are species specific. We found that occupancy likelihood for omnivores, certain members of the aerial forager guild, and Emberizidae family members increased with invasion. Alternatively, cavity nesting species, frugivorous species, and many insectivorous species decreased with increased proportions of invasive species. Avian prey diversity and evenness showed a negative relationship with increased proportion of invasive vegetation. Our data suggest that the relative abundance of invertebrate orders per dominant vegetation type may be somewhat controlling insectivore abundance. For example, Hymenoptera, a dominant food source of Yellow-breasted chats (Icteria virens), were more abundant in Russian olive, where chats were higher in abundance. Similarly, Hemiptera were more abundant in cottonwood, where Yellow warblers (Setophaga petechia) were more likely to feed. Plecoptera and Trichoptera were strongly related to native dominant vegetation and avian insectivore occupancy. The unique approach of exploring invasion on a gradient scale paired with avian life history characteristics and avian prey abundance measures have provided an interesting and hopefully applicable approach to conservation of avian species.
Background/Question/Methods The Brown-headed Cowbird (Molothrus ater) is an obligate brood parasi... more Background/Question/Methods The Brown-headed Cowbird (Molothrus ater) is an obligate brood parasite that reduces the reproductive success of many of its host species. Cowbird-host research over the past few years has focused heavily on determining the relative effects of parasitism and predation. However, despite extensive efforts, it is still poorly understood to what extent cowbirds reduce host reproductive success. To better address this question, we have created a mechanistic model, based on a 3-year data set, to calculate and assess the relative costs of parasitism and predation for one host species, the Plumbeous Vireo (Vireo plumbeus). This vireo is the primary host of cowbirds within our study area, the Front Range of Colorado, USA. Results/Conclusions The results from this work show that the costs of both parasitism and predation depend sensitively on the Julian date on which eggs are layed. Specifically, cowbirds (at least within the Colorado Front Range population) have s...
We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors (Bo... more We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors (Box Elder, Acer negundo; willow, $alix sp.; cottonwood, Populus sp.) of Boulder County, Colorado (elevation 1550 to 2150 m, 40 ø 00' N, 105 ø 20' W), in 1990 (n = 15) and 1992 (n = 11). Nests were found during different stages of reproduction, and we observed them every three to five days until the nest was successful or failed. We observed nests directly or by mirror-pole, recorded their contents, and determined causes of nest failure. By examining nest contents and condition, we categorized the causes of nest failure as predation, parasitism, weather, or unknown. We used the Mayfield method (Mayfield 1961, 1975) to determine nesting success. The Mayfield method provides a standardized measure of nest success, by taking into account the number of days of exposure, that is comparable to other studies of nesting success. We measured nest height, nest distance to trunk, and nest dist...
Several urban-adapted species sing at a higher frequency in noisy urban areas than in quiet locat... more Several urban-adapted species sing at a higher frequency in noisy urban areas than in quiet locations. Yet it remains unclear whether the ability to adjust signals in response to noise is related to an ability to persist in noisy areas, because signal change and habitat use are infrequently measured within a single study. We investigated occupancy and signal change in response to noise in the Blue-gray Gnatcatcher (Polioptila caerulea) and the Spotted Towhee (Pipilo maculatus) using a study system that eliminates uncontrolled effects of habitat features that may influence song frequency or habitat use and controls for the negative effect of noise on bird surveys. We predicted that species that alter the frequency of their vocalizations in response to noise would use noisy and quiet areas similarly, and that species that do not adjust their vocalizations in response to noise may avoid noisy areas. Both study species were uninfluenced by noise in their habitat occupancy, but only Spotted Towhees sang at a higher frequency with increased noise exposure. This may be explained by low-frequency noise having a greater acoustic masking potential for low-frequency Spotted Towhee songs than for higher-pitched Blue-gray Gnatcatcher songs. These findings suggest that an ability to shift song frequency may not directly correspond to an ability to remain in noisy areas. Although many factors can influence habitat use by birds, habitat occupancy in noisy areas may depend on whether the noise has acoustic energy at frequencies that can mask a species’ song; if so, signal flexibility may be important.
The historic range of the bison (Bison bison) on the Great Plains has been well documented. In Co... more The historic range of the bison (Bison bison) on the Great Plains has been well documented. In Colorado the range of bison included both the eastern grasslands and higher-elevation ridges and mountain parks, up to an elevation of 3900 m. Based on the commensal relationship of the brood-parasitic Brown-headed Cowbird (Mohthrus ater) with the bison, we suggest that the cowbird had a larger historical elevational range in Colorado than previously known and consequently has had a long-term host-parasite relationship with high-elevation breeding songbirds.
During the summers,of 1999 to 2004 we studied the breeding bird community,in the Ponderosa Pine h... more During the summers,of 1999 to 2004 we studied the breeding bird community,in the Ponderosa Pine habitats of the Boulder County Open Space property, Heil Ranch. To date, we have located and monitored 397 nests of 25 species, as well as surveyed birds at 30-point count locations on the property to determine the distribution and abundance,of these species. This study
... We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors... more ... We located 26 Western Wood-Pewee nests in the Ponderosa Pines and adjacent riparian corridors (Box Elder, Acer negundo; willow, $alix sp.; cottonwood, Populus sp.) of Boulder County, Colorado (elevation 1550 to 2150 m, 40 ø ... Smith, JNM, Arcese, P., and McLean, IG 1984. ...
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