Sara Sanchez - Academia.edu (original) (raw)
Papers by Sara Sanchez
Vegetation structure and composition, and parameters of the bird community (richness and abundanc... more Vegetation structure and composition, and parameters of the bird community (richness and abundance) were studied in managed beech-fir forests in Navarre (Spain). Relationships between bird parameters and vegetation variables differed in different avian nesting guilds. Whereas secondary cavitynesting bird parameters were not significantly related to any vegetation variable, both richness and abundance of bird species that do not rely on existing holes for breeding increased with the proportion of fir trees, but only in the breeding season. Nest-site selection might be the key factor behind this relationship, since firs would provide more suitable nest-sites than beeches for these species, perhaps because beech leaves are not fully developed early in the breeding season. Moreover, during the winter season richness of birds that do not rely on existing holes for breeding was positively related to the percentage of shrub cover. Although this result should be considered with caution, pro...
Ibis, 2009
The habitat association approach has been increasingly used in ecology to resolve problems in wil... more The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia. At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.
Revue d Ecologie
Structure de la végétation en hêtraies-sapinières: effets sur le peuplemnt d'oiseaux.-Entre mai 2... more Structure de la végétation en hêtraies-sapinières: effets sur le peuplemnt d'oiseaux.-Entre mai 2001 et mars 2002, la structure et la composition de la végétation, ainsi que les paramètres de la communauté d'oiseaux (richesse et abondance) dans les forêts mixtes entretenues de hêtres et de sapins (Fagus sylvatica -Abies alba) de Navarre (nord de l'Espagne) ont fait l'objet d'une étude. Les relations entre les paramètres des oiseaux et les variables de la végétation différaient entre divers groupes d'oiseaux en fonction de leurs habitudes de nidiication. Les paramètres des oiseaux utilisant les trous d'arbre pour nicher n'ont montré aucune relation avec les variables de la végétation; en revanche l'abondance tout comme la richesse des espèces ne dépendant pas des trous d'arbre pour se reproduire afichaient une relation positive avec la proportion de sapins, mais uniquement en période de reproduction. Cette relation pourrait s'expliquer par la sélection du lieu de nidiication, les sapins offrant des lieux plus appropriés à la nidiication que les hêtres pour ce groupe d'oiseaux, peut-être parce que les feuilles des hêtres ne sont pas entièrement développées au début de la saison de reproduction. En outre, en hiver la richesse des espèces ne dépendant pas des trous d'arbre pour nicher était en relation positive avec la proportion d'arbustes. Bien que ce résultat doive être interprété avec prudence, la protection vis-à-vis des conditions météorologiques défavorables ou les prédateurs pourrait expliquer cette relation.
Ardeola: revista ibérica de ornitología
Aims: To ascertain whether cavity-nesting bird communities are limited by experimentally-manipula... more Aims: To ascertain whether cavity-nesting bird communities are limited by experimentally-manipulated hole availability at managed beech and pine forests in northern Spanish highlands and to study the responses of non-cavity-nesting birds. Location: North of Navarre (Spain). Methods: Bird censuses were taken at breeding and wintering periods in study plots during 2001, 2002 and 2003. Nest boxes were placed in half of the study plots, and plots with and without nest boxes were compared for variation in nesting guild abundance and richness. Results: Results showed an increase in cavity-nesting bird abundance and species richness between two breeding periods and in abundance between two non-breeding periods in the plots where nest boxes were added in both types of forest. No difference in abundance or richness during breeding was observed for the non-cavity nesting birds in plots where there was an increase in the abundance of cavitynesters. However, an increase in abundance of non-cavi...
Behaviour, 2002
Summary The males' trade-off between caring for the offspring or investi... more Summary The males' trade-off between caring for the offspring or investing in attracting additional mates is well established in the theory of mating systems. The reproductive consequences for males of alternative strategies adopted by them in response to these con icting demands ...
Animal Behaviour, 2002
Female mating status may affect reproductive success in avian polygynous mating systems through a... more Female mating status may affect reproductive success in avian polygynous mating systems through a combination of differences in female parental quality and status-dependent male assistance in parental care. Traditionally the literature has emphasized male assistance, neglecting evidence for consistency in female parental quality independent of mating status or repeatability in status. We studied the effects of male assistance on breeding
Ibis, 2008
Latitude, a surrogate of climatic conditions, is commonly used in the examination of life-history... more Latitude, a surrogate of climatic conditions, is commonly used in the examination of life-history variation. However, the climatic mechanisms underlying latitudinal life-history variation have only rarely been tested. Here, we test whether the number of climates to which species are subjected in their ranges predicts geographical life-history variation. In particular, we examine whether eurytopic species, the range of which covers more climates, show different reproductive effort to stenotopic species, which are distributed over climatically more homogeneous environments. We examined female body mass, egg mass controlled for female body mass, clutch size and the number of breeding attempts per season for 34 sedentary and short-distance migratory passerine species of the Western Palearctic. For each species, we assessed how many climate zones extend over the species' wintering and breeding ranges. We found that avian body mass, and also clutch size, significantly increases with the number of climatic zones extended over the species' wintering range. In turn, species whose breeding ranges span more climates show more breeding attempts per season. Whereas the mass of a single egg declines, clutch size increases with increasing climatic variation in breeding ranges. Our study suggests that the level of climatic variation over species' ranges during and outside the breeding season might be responsible for variation in life-history traits in open-nesting Western Palearctic passerines.
Behaviour, 2002
Summary The males' trade-off between caring for the offspring or investi... more Summary The males' trade-off between caring for the offspring or investing in attracting additional mates is well established in the theory of mating systems. The reproductive consequences for males of alternative strategies adopted by them in response to these con icting demands ...
Animal Behaviour, 2002
Female mating status may affect reproductive success in avian polygynous mating systems through a... more Female mating status may affect reproductive success in avian polygynous mating systems through a combination of differences in female parental quality and status-dependent male assistance in parental care. Traditionally the literature has emphasized male assistance, neglecting ...
Acta Ornithologica, 2007
Characteristics of the habitat have a strong influence on food resources and shelter possibili-ti... more Characteristics of the habitat have a strong influence on food resources and shelter possibili-ties available for birds and other animal groups, and both food and predation are among the most important forces which constraint avian life histo-ries (Martin 1995). Most of the ...
Ibis, 2009
The habitat association approach has been increasingly used in ecology to resolve problems in wil... more The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia . At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.
Vegetation structure and composition, and parameters of the bird community (richness and abundanc... more Vegetation structure and composition, and parameters of the bird community (richness and abundance) were studied in managed beech-fir forests in Navarre (Spain). Relationships between bird parameters and vegetation variables differed in different avian nesting guilds. Whereas secondary cavitynesting bird parameters were not significantly related to any vegetation variable, both richness and abundance of bird species that do not rely on existing holes for breeding increased with the proportion of fir trees, but only in the breeding season. Nest-site selection might be the key factor behind this relationship, since firs would provide more suitable nest-sites than beeches for these species, perhaps because beech leaves are not fully developed early in the breeding season. Moreover, during the winter season richness of birds that do not rely on existing holes for breeding was positively related to the percentage of shrub cover. Although this result should be considered with caution, pro...
Ibis, 2009
The habitat association approach has been increasingly used in ecology to resolve problems in wil... more The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia. At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.
Revue d Ecologie
Structure de la végétation en hêtraies-sapinières: effets sur le peuplemnt d'oiseaux.-Entre mai 2... more Structure de la végétation en hêtraies-sapinières: effets sur le peuplemnt d'oiseaux.-Entre mai 2001 et mars 2002, la structure et la composition de la végétation, ainsi que les paramètres de la communauté d'oiseaux (richesse et abondance) dans les forêts mixtes entretenues de hêtres et de sapins (Fagus sylvatica -Abies alba) de Navarre (nord de l'Espagne) ont fait l'objet d'une étude. Les relations entre les paramètres des oiseaux et les variables de la végétation différaient entre divers groupes d'oiseaux en fonction de leurs habitudes de nidiication. Les paramètres des oiseaux utilisant les trous d'arbre pour nicher n'ont montré aucune relation avec les variables de la végétation; en revanche l'abondance tout comme la richesse des espèces ne dépendant pas des trous d'arbre pour se reproduire afichaient une relation positive avec la proportion de sapins, mais uniquement en période de reproduction. Cette relation pourrait s'expliquer par la sélection du lieu de nidiication, les sapins offrant des lieux plus appropriés à la nidiication que les hêtres pour ce groupe d'oiseaux, peut-être parce que les feuilles des hêtres ne sont pas entièrement développées au début de la saison de reproduction. En outre, en hiver la richesse des espèces ne dépendant pas des trous d'arbre pour nicher était en relation positive avec la proportion d'arbustes. Bien que ce résultat doive être interprété avec prudence, la protection vis-à-vis des conditions météorologiques défavorables ou les prédateurs pourrait expliquer cette relation.
Ardeola: revista ibérica de ornitología
Aims: To ascertain whether cavity-nesting bird communities are limited by experimentally-manipula... more Aims: To ascertain whether cavity-nesting bird communities are limited by experimentally-manipulated hole availability at managed beech and pine forests in northern Spanish highlands and to study the responses of non-cavity-nesting birds. Location: North of Navarre (Spain). Methods: Bird censuses were taken at breeding and wintering periods in study plots during 2001, 2002 and 2003. Nest boxes were placed in half of the study plots, and plots with and without nest boxes were compared for variation in nesting guild abundance and richness. Results: Results showed an increase in cavity-nesting bird abundance and species richness between two breeding periods and in abundance between two non-breeding periods in the plots where nest boxes were added in both types of forest. No difference in abundance or richness during breeding was observed for the non-cavity nesting birds in plots where there was an increase in the abundance of cavitynesters. However, an increase in abundance of non-cavi...
Behaviour, 2002
Summary The males' trade-off between caring for the offspring or investi... more Summary The males' trade-off between caring for the offspring or investing in attracting additional mates is well established in the theory of mating systems. The reproductive consequences for males of alternative strategies adopted by them in response to these con icting demands ...
Animal Behaviour, 2002
Female mating status may affect reproductive success in avian polygynous mating systems through a... more Female mating status may affect reproductive success in avian polygynous mating systems through a combination of differences in female parental quality and status-dependent male assistance in parental care. Traditionally the literature has emphasized male assistance, neglecting evidence for consistency in female parental quality independent of mating status or repeatability in status. We studied the effects of male assistance on breeding
Ibis, 2008
Latitude, a surrogate of climatic conditions, is commonly used in the examination of life-history... more Latitude, a surrogate of climatic conditions, is commonly used in the examination of life-history variation. However, the climatic mechanisms underlying latitudinal life-history variation have only rarely been tested. Here, we test whether the number of climates to which species are subjected in their ranges predicts geographical life-history variation. In particular, we examine whether eurytopic species, the range of which covers more climates, show different reproductive effort to stenotopic species, which are distributed over climatically more homogeneous environments. We examined female body mass, egg mass controlled for female body mass, clutch size and the number of breeding attempts per season for 34 sedentary and short-distance migratory passerine species of the Western Palearctic. For each species, we assessed how many climate zones extend over the species' wintering and breeding ranges. We found that avian body mass, and also clutch size, significantly increases with the number of climatic zones extended over the species' wintering range. In turn, species whose breeding ranges span more climates show more breeding attempts per season. Whereas the mass of a single egg declines, clutch size increases with increasing climatic variation in breeding ranges. Our study suggests that the level of climatic variation over species' ranges during and outside the breeding season might be responsible for variation in life-history traits in open-nesting Western Palearctic passerines.
Behaviour, 2002
Summary The males' trade-off between caring for the offspring or investi... more Summary The males' trade-off between caring for the offspring or investing in attracting additional mates is well established in the theory of mating systems. The reproductive consequences for males of alternative strategies adopted by them in response to these con icting demands ...
Animal Behaviour, 2002
Female mating status may affect reproductive success in avian polygynous mating systems through a... more Female mating status may affect reproductive success in avian polygynous mating systems through a combination of differences in female parental quality and status-dependent male assistance in parental care. Traditionally the literature has emphasized male assistance, neglecting ...
Acta Ornithologica, 2007
Characteristics of the habitat have a strong influence on food resources and shelter possibili-ti... more Characteristics of the habitat have a strong influence on food resources and shelter possibili-ties available for birds and other animal groups, and both food and predation are among the most important forces which constraint avian life histo-ries (Martin 1995). Most of the ...
Ibis, 2009
The habitat association approach has been increasingly used in ecology to resolve problems in wil... more The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia . At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.