Successful conservation of rare species requires detailed knowledge of the species' distribution.... more Successful conservation of rare species requires detailed knowledge of the species' distribution. Modeling spatial distribution is an efficient means of locating potential habitats. Cerulean Warbler (Dendroica cerulea, Parulidae) was listed as a Vulnerable Species by the International Union for the Conservation of Nature and Natural Resources in 2004. These neotropical migratory birds breed in eastern North America. The entire population migrates to the northern Andes in South America to spend the nonbreeding period. As part of a larger international conservation effort, we developed spatial hypotheses of the bird's occurrence in South America. We summarized physical, climatic, and recent land-cover data for the northern Andes using ESRI software, ArcGIS. We developed five hypothetical distributions based on Mahalanobis D, GARP, Biomapper, MAXENT, and Domain models. Combining results of the different models on the same map allowed us to design a rigorous strategy to ground-truth the map and thus to identify sites for protection of the species in South America.
Although a growing number of studies address how Neotropical birds respond to anthropogenic distu... more Although a growing number of studies address how Neotropical birds respond to anthropogenic disturbance and deforestation, we continue to poorly understand responses of groups of interacting species, such as mixed-species flocks in the Andes. In this study, we examined how attributes at landscape (i.e., percentage of forest cover within 1-km 2) and local (i.e. structural complexity of microhabitat) scales shaped mixed-species flocks within five broadly-defined habitat types in the Northern and Central Andes. From 2007 to 2010, we systematically surveyed flocks along line transects in 97 1-km 2 plots distributed from Venezuela to Peru based on a stratified-random design. We recorded 220 avian species in 186 mixed-species flocks, with the greatest species richness and largest flocks detected in forested habitats. Understory insectivores were most closely associated with mature and secondary forests. Increasing forest cover promoted species richness and size of flocks, with particularly strong associations in successional habitats and shade coffee. Structural complexity was positively associated with flock size in early successional and silvopastoral habitats, where 20% increases in complexity doubled flock size. However, the opposite pattern was true in shade coffee and secondary forests. Encounter rates of flocks were poorly explained by simple metrics of forest cover and structural complexity. Unlike flocks reported in many lowland forests, Andean flocks tended to span all vertical strata, with fewer understory-specializing flocks (e.g. flocks led by Basileuterus warblers and Chlorospingus tanagers). Nonetheless, in such flocks, understory insectivores were most closely associated with mature and secondary forests. Our research supports the idea that managed habitats with overstory trees can contribute to flock conservation. Overall , our results further suggested that understory birds require the more forested of habitats (e.g., mature forest held almost twice as many understory specialists as other habitats), and may be less amenable to conservation with agroecosystems or working landscapes.
Recent population declines have prompted the International Union for the Conservation of Nature t... more Recent population declines have prompted the International Union for the Conservation of Nature to list Cerulean Warbler (Setophaga cerulea: Parulidae) as a Vulnerable species. It is believed that this decline may be related to habitat loss through its entire range, mainly due to deforestation and degradation of its habitats. In response, members of El Grupo Cerúleo, a subcommittee of the Cerulean Warbler Technical Group that addresses wintering ground issues faced by the species, developed a predictive model of winter- ing habitat for Cerulean Warblers throughout the northern and central Andes. From 2006-2010, we conducted field surveys in Venezuela, Colombia, Ecuador and Peru to validate the winter habitat model. In this paper, we share new insights into the distribution of Cerulean Warblers and preview recent analyses of the ability of the habitat model to predict wintering range. First, our data show that Cerulean Warblers occupy a broader altitudinal range than previously thought. Second, wintering Cerulean Warblers utilize a wider variety of habitat types than formerly believed, including different successional stages and intensively-managed agroecosystems. Third, the species shows a strong association with mixed-species flocks, composed mostly of resident bird species. Collectively, these findings have important implications for conservation efforts in the Andes.
We conducted full-season raptor migration counts at a watchsite in the northernmost part of the S... more We conducted full-season raptor migration counts at a watchsite in the northernmost part of the South American Andes in the Central Cordillera of Colombia from 1999 to 2004. Twenty-eight species of raptors were recorded over the 6-year period, 10 of which were migratory. Averages of approximately 21,000 and 19,000 migrating raptors were counted each autumn and spring, respectively. Two species, the Broad-winged Hawk (Buteo platypterus) and Swainson’s Hawk (Buteo swainsoni) made up > 99% of the count in both seasons. The migration of Broad-winged Hawks peaked over a 4-day period between 19 and 22 October in the autumn and between 15 and 21 March in the spring. The main migration of Swainson’s Hawks peaked a week later between 27 October and 2 November in the autumn, and 31 March and 3 April in the spring. Of the remaining eight migratory species observed, Ospreys (Pandion haliaetus) and Per- egrine Falcons (Falco peregrinus) were most consistently recorded across all seasons. We occasionally observed migrating American Swallow-tailed Kites (Elanoides forficatus), Mississippi Kites (Ictinia mississippi- ensis) and Merlins (Falco columbarius), and a single Northern Harrier (Circus cyaneus). We made two sightings of Red-tailed Hawks (Buteo jamaicensis) which were the first records for the species in Colombia and South America. Both during autumn and spring, most raptors migrated after midday when thermals were most abundant but they migrated in all types of weather, except heavy rainstorms which they avoided.
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
Foraging behavior in juveniles of Jacana spinosa: Parental care or flock effect. The effect of th... more Foraging behavior in juveniles of Jacana spinosa: Parental care or flock effect. The effect of the presence of adults of Jacana spinosa (Aves: Jacanidae) in the frequency of foraging of juveniles was evaluated at the Palo Verde Biological Station, Costa Rica. This was estimated based on the number of pecks given on the substrate in one minute. There were not
Record of the Brown Pelecan (Pelecanus occidentalis) in the area of the hydroelectric power stati... more Record of the Brown Pelecan (Pelecanus occidentalis) in the area of the hydroelectric power station Porce II, north eastern Antioquia, Colombia. The Brown Pelican (Pelecanus occidentalis) is a coastal marine bird, distributed in the Pacific and Atlantic Ocean of tropical and subtropical America, from South United States to South Chile. An inland record of a juvenal individual of this species was conducted in the Reservoir of the Hydroelectric Power Station Porce II, Northeast of Antioquia province, Colombia, on June 18, 2005. This sighting possibly corresponds to a lost individual which arrived into this area in the Central Andes from the ocean following the course of the rivers.
The descriptive power of morphometric variables of birds on the conformation of food guilds was a... more The descriptive power of morphometric variables of birds on the conformation of food guilds was assessed. Three groups of species were completed based on their morphology separation through Principal Component Analysis. The three groups were associated to three trophic guilds: frugivores, insectivores and nectarivores, the latter presenting the clearest pattern of association. For some species, there was not an evident pattern of association. A high correlation among some morphometric variables was found, suggesting that some measurements are redundant, making possible the choice of a smaller set of variables.
Abstract. – Foraging ecology provides insight into species requirements and focus conservation ef... more Abstract. – Foraging ecology provides insight into species requirements and focus conservation efforts. We studied foraging ecology of the Neotropical migrant Cerulean warbler (Setophaga cerulea) during the winter season in coffee agroforestry ecosystems of the Central and Western Cordillera of the Andes in Colombia. Our findings show that this species is an active foliage gleaner. Cerulean Warbler primarily gleans prey off the upper surface on green leaves and flowers. It frequents shrubs and medium-high trees and forage most often in subcanopy and understory using the outer strata. There were sex differences in the foraging height. Frequently, Cerulean Warbler was encountered in pairs or small groups rather than join in mixed bird flocks. Additionally we documentedteh social behavior and competitive interaction with Setophaga fusca and S. castanea.
Successful conservation of rare species requires detailed knowledge of the species' distribution.... more Successful conservation of rare species requires detailed knowledge of the species' distribution. Modeling spatial distribution is an efficient means of locating potential habitats. Cerulean Warbler (Dendroica cerulea, Parulidae) was listed as a Vulnerable Species by the International Union for the Conservation of Nature and Natural Resources in 2004. These neotropical migratory birds breed in eastern North America. The entire population migrates to the northern Andes in South America to spend the nonbreeding period. As part of a larger international conservation effort, we developed spatial hypotheses of the bird's occurrence in South America. We summarized physical, climatic, and recent land-cover data for the northern Andes using ESRI software, ArcGIS. We developed five hypothetical distributions based on Mahalanobis D, GARP, Biomapper, MAXENT, and Domain models. Combining results of the different models on the same map allowed us to design a rigorous strategy to ground-truth the map and thus to identify sites for protection of the species in South America.
Although a growing number of studies address how Neotropical birds respond to anthropogenic distu... more Although a growing number of studies address how Neotropical birds respond to anthropogenic disturbance and deforestation, we continue to poorly understand responses of groups of interacting species, such as mixed-species flocks in the Andes. In this study, we examined how attributes at landscape (i.e., percentage of forest cover within 1-km 2) and local (i.e. structural complexity of microhabitat) scales shaped mixed-species flocks within five broadly-defined habitat types in the Northern and Central Andes. From 2007 to 2010, we systematically surveyed flocks along line transects in 97 1-km 2 plots distributed from Venezuela to Peru based on a stratified-random design. We recorded 220 avian species in 186 mixed-species flocks, with the greatest species richness and largest flocks detected in forested habitats. Understory insectivores were most closely associated with mature and secondary forests. Increasing forest cover promoted species richness and size of flocks, with particularly strong associations in successional habitats and shade coffee. Structural complexity was positively associated with flock size in early successional and silvopastoral habitats, where 20% increases in complexity doubled flock size. However, the opposite pattern was true in shade coffee and secondary forests. Encounter rates of flocks were poorly explained by simple metrics of forest cover and structural complexity. Unlike flocks reported in many lowland forests, Andean flocks tended to span all vertical strata, with fewer understory-specializing flocks (e.g. flocks led by Basileuterus warblers and Chlorospingus tanagers). Nonetheless, in such flocks, understory insectivores were most closely associated with mature and secondary forests. Our research supports the idea that managed habitats with overstory trees can contribute to flock conservation. Overall , our results further suggested that understory birds require the more forested of habitats (e.g., mature forest held almost twice as many understory specialists as other habitats), and may be less amenable to conservation with agroecosystems or working landscapes.
Recent population declines have prompted the International Union for the Conservation of Nature t... more Recent population declines have prompted the International Union for the Conservation of Nature to list Cerulean Warbler (Setophaga cerulea: Parulidae) as a Vulnerable species. It is believed that this decline may be related to habitat loss through its entire range, mainly due to deforestation and degradation of its habitats. In response, members of El Grupo Cerúleo, a subcommittee of the Cerulean Warbler Technical Group that addresses wintering ground issues faced by the species, developed a predictive model of winter- ing habitat for Cerulean Warblers throughout the northern and central Andes. From 2006-2010, we conducted field surveys in Venezuela, Colombia, Ecuador and Peru to validate the winter habitat model. In this paper, we share new insights into the distribution of Cerulean Warblers and preview recent analyses of the ability of the habitat model to predict wintering range. First, our data show that Cerulean Warblers occupy a broader altitudinal range than previously thought. Second, wintering Cerulean Warblers utilize a wider variety of habitat types than formerly believed, including different successional stages and intensively-managed agroecosystems. Third, the species shows a strong association with mixed-species flocks, composed mostly of resident bird species. Collectively, these findings have important implications for conservation efforts in the Andes.
We conducted full-season raptor migration counts at a watchsite in the northernmost part of the S... more We conducted full-season raptor migration counts at a watchsite in the northernmost part of the South American Andes in the Central Cordillera of Colombia from 1999 to 2004. Twenty-eight species of raptors were recorded over the 6-year period, 10 of which were migratory. Averages of approximately 21,000 and 19,000 migrating raptors were counted each autumn and spring, respectively. Two species, the Broad-winged Hawk (Buteo platypterus) and Swainson’s Hawk (Buteo swainsoni) made up > 99% of the count in both seasons. The migration of Broad-winged Hawks peaked over a 4-day period between 19 and 22 October in the autumn and between 15 and 21 March in the spring. The main migration of Swainson’s Hawks peaked a week later between 27 October and 2 November in the autumn, and 31 March and 3 April in the spring. Of the remaining eight migratory species observed, Ospreys (Pandion haliaetus) and Per- egrine Falcons (Falco peregrinus) were most consistently recorded across all seasons. We occasionally observed migrating American Swallow-tailed Kites (Elanoides forficatus), Mississippi Kites (Ictinia mississippi- ensis) and Merlins (Falco columbarius), and a single Northern Harrier (Circus cyaneus). We made two sightings of Red-tailed Hawks (Buteo jamaicensis) which were the first records for the species in Colombia and South America. Both during autumn and spring, most raptors migrated after midday when thermals were most abundant but they migrated in all types of weather, except heavy rainstorms which they avoided.
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately.
Foraging behavior in juveniles of Jacana spinosa: Parental care or flock effect. The effect of th... more Foraging behavior in juveniles of Jacana spinosa: Parental care or flock effect. The effect of the presence of adults of Jacana spinosa (Aves: Jacanidae) in the frequency of foraging of juveniles was evaluated at the Palo Verde Biological Station, Costa Rica. This was estimated based on the number of pecks given on the substrate in one minute. There were not
Record of the Brown Pelecan (Pelecanus occidentalis) in the area of the hydroelectric power stati... more Record of the Brown Pelecan (Pelecanus occidentalis) in the area of the hydroelectric power station Porce II, north eastern Antioquia, Colombia. The Brown Pelican (Pelecanus occidentalis) is a coastal marine bird, distributed in the Pacific and Atlantic Ocean of tropical and subtropical America, from South United States to South Chile. An inland record of a juvenal individual of this species was conducted in the Reservoir of the Hydroelectric Power Station Porce II, Northeast of Antioquia province, Colombia, on June 18, 2005. This sighting possibly corresponds to a lost individual which arrived into this area in the Central Andes from the ocean following the course of the rivers.
The descriptive power of morphometric variables of birds on the conformation of food guilds was a... more The descriptive power of morphometric variables of birds on the conformation of food guilds was assessed. Three groups of species were completed based on their morphology separation through Principal Component Analysis. The three groups were associated to three trophic guilds: frugivores, insectivores and nectarivores, the latter presenting the clearest pattern of association. For some species, there was not an evident pattern of association. A high correlation among some morphometric variables was found, suggesting that some measurements are redundant, making possible the choice of a smaller set of variables.
Abstract. – Foraging ecology provides insight into species requirements and focus conservation ef... more Abstract. – Foraging ecology provides insight into species requirements and focus conservation efforts. We studied foraging ecology of the Neotropical migrant Cerulean warbler (Setophaga cerulea) during the winter season in coffee agroforestry ecosystems of the Central and Western Cordillera of the Andes in Colombia. Our findings show that this species is an active foliage gleaner. Cerulean Warbler primarily gleans prey off the upper surface on green leaves and flowers. It frequents shrubs and medium-high trees and forage most often in subcanopy and understory using the outer strata. There were sex differences in the foraging height. Frequently, Cerulean Warbler was encountered in pairs or small groups rather than join in mixed bird flocks. Additionally we documentedteh social behavior and competitive interaction with Setophaga fusca and S. castanea.
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