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Katherine Renton - One of the best experts on this subject based on the ideXlab platform.
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optimal diet strategy of a large bodied psittacine food resource abundance and nutritional content enable facultative dietary specialization by the military macaw
Avian Research, 2019Co-Authors: Sylvia Margarita De La Parramartinez, Luis Guillermo Munozlacy, Alejandro Salinasmelgoza, Katherine RentonAbstract:Dietary specialization should arise when there is a relatively high abundance of a particular resource, where animals may select food items to obtain an optimal diet that maximizes energy intake. Large-bodied psittacines frequently exhibit a narrow dietary niche with specific habitat use, but few studies have determined whether psittacines select food resources, and how this influences habitat use. We established fruiting phenology transects to evaluate food resource availability for the large-bodied Military Macaw (Ara militaris) in Semi-Deciduous, deciduous, and pine-oak forest at two sites along the coast of Jalisco, during the dry season when macaws are nesting. We also determined Military Macaw diet by observations of foraging macaws along transect routes, and conducted bromatological analysis of the nutritional content of the most consumed resource. Military Macaws used six plant species as food items during the dry season, and had a narrow dietary niche (Levins’ B = 0.28), with 56% of foraging macaws consuming the seeds of Hura polyandra. No food resources were recorded in pine-oak forest during the dry season, with food resources and foraging by macaws concentrated in tropical deciduous and Semi-Deciduous forest, where H. polyandra was the most abundant fruiting tree species. When considering the proportional availability of food resources, we determined a broad Hurlbert dietary niche breadth of H = 0.67, indicating that Military Macaws consumed food resources according to their availability. Furthermore, the seeds of H. polyandra were an important source of protein, carbohydrates, minerals and moisture, and the hard fruit-casing means that these seeds are exclusively available for macaws. By concentrating their diet on the most abundant resources, Military Macaws may increase foraging efficiency in the dry season. The high nutrient content also means that concentrating the diet on seeds of H. polyandra may be an optimal foraging strategy for Military Macaws to meet their energy requirements during the breeding season.
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Optimal diet strategy of a large-bodied psittacine: food resource abundance and nutritional content enable facultative dietary specialization by the Military Macaw
Avian Research, 2019Co-Authors: Sylvia Margarita De La Parra-martínez, Luis Guillermo Muñoz-lacy, Alejandro Salinas-melgoza, Katherine RentonAbstract:Background Dietary specialization should arise when there is a relatively high abundance of a particular resource, where animals may select food items to obtain an optimal diet that maximizes energy intake. Large-bodied psittacines frequently exhibit a narrow dietary niche with specific habitat use, but few studies have determined whether psittacines select food resources, and how this influences habitat use. Methods We established fruiting phenology transects to evaluate food resource availability for the large-bodied Military Macaw ( Ara militaris ) in Semi-Deciduous, deciduous, and pine-oak forest at two sites along the coast of Jalisco, during the dry season when macaws are nesting. We also determined Military Macaw diet by observations of foraging macaws along transect routes, and conducted bromatological analysis of the nutritional content of the most consumed resource. Results Military Macaws used six plant species as food items during the dry season, and had a narrow dietary niche (Levins’ B = 0.28), with 56% of foraging macaws consuming the seeds of Hura polyandra . No food resources were recorded in pine-oak forest during the dry season, with food resources and foraging by macaws concentrated in tropical deciduous and Semi-Deciduous forest, where H. polyandra was the most abundant fruiting tree species. When considering the proportional availability of food resources, we determined a broad Hurlbert dietary niche breadth of H = 0.67, indicating that Military Macaws consumed food resources according to their availability. Furthermore, the seeds of H. polyandra were an important source of protein, carbohydrates, minerals and moisture, and the hard fruit-casing means that these seeds are exclusively available for macaws. Conclusions By concentrating their diet on the most abundant resources, Military Macaws may increase foraging efficiency in the dry season. The high nutrient content also means that concentrating the diet on seeds of H. polyandra may be an optimal foraging strategy for Military Macaws to meet their energy requirements during the breeding season.
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tree cavity availability and selection by a large bodied secondary cavity nester the military macaw
Journal of Ornithology, 2015Co-Authors: Sylvia Margarita De La Parramartinez, Katherine Renton, Alejandro Salinasmelgoza, Luis Guillermo MunozlacyAbstract:Large-bodied secondary cavity-nesters are constrained to use cavities of sufficient size to permit access, while also selecting characteristics to reduce predation. However, no information exists on nest-site availability for large-bodied secondary cavity-nesters in tropical forests. We located 12 tree-cavity nests of the threatened Military Macaw (Ara militaris) in tropical dry Semi-Deciduous forest in Jalisco, Mexico. For each nest, we determined cavity characteristics, and compared the structure of nest-trees with nearest-neighbor trees. We also established four 100 × 50 m transects in each of deciduous, Semi-Deciduous, and oak forest to determine tree-cavity availability over 6 ha. Military Macaw nest-sites occurred most frequently in cavities of live Enterolobium cyclocarpum trees. Nest-trees had significantly larger diameter and ramification height than the four nearest-neighbor trees, indicating that macaws selected tall emergent trees as nest-sites. Cavities used as nest-sites by Military Macaws were also in significantly larger trees, at a greater height, and had larger entrance diameter and depth than all accessible cavities. Height above the ground was the main criteria predicting nest-cavity selection, possibly to reduce predation risk. There was also a negative correlation of nest-cavity height with depth, suggesting a trade-off in which Military Macaws may select a nest-cavity high above the ground regardless of depth, but when using lower cavities these tend to be deeper. We found a low density of cavities with characteristics suitable for nesting, and these were concentrated in Semi-Deciduous forest. Our results demonstrate that the Military Macaw exhibits species-specific selection of nest-cavities, with a low density of cavities suitable for large-bodied secondary cavity-nesters in tropical forests.
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Availability and selection of arboreal termitaria as nest-sites by Orange-fronted Parakeets Aratinga canicularis in conserved and modified landscapes in Mexico.
Ibis, 2009Co-Authors: Tania C. Sanchez-martinez, Katherine RentonAbstract:Few studies have investigated the use of termitaria by nesting parrots, or how this may be affected by habitat transformation. We determined selection of termitaria by nesting Orange-fronted Parakeets Aratinga canicularis, and evaluated the effect of habitat transformation on the availability of termitaria nest-sites for Parakeets in the tropical dry forest of Western Mexico. Availability of termitaria was quantified in 24 survey plots in a factorial design of six 1-ha plots in each of conserved and modified, deciduous and Semi-Deciduous forest. Characteristics of termitaria were determined in survey plots, as well as 21 nest-termitaria used by Parakeets, and their nearest adjacent termitarium. There was an overall density of 1.6 termitaria/ha suitable for nesting by Parakeets, which did not differ between habitats, although only 8% of apparently suitable termitaria were occupied by nesting Parakeets. However, termitaria in conserved Semi-Deciduous forest were significantly higher above the ground, and termitaria in conserved deciduous forest were significantly smaller in volume. In the modified landscape, termitaria were significantly lower and their volume significantly larger than in conserved landscapes. Termitaria used by nesting parrots were at a significantly greater height above the ground than the nearest adjacent termitaria. Termitarium volume did not reliably predict the likelihood of nest-site selection, although Parakeets only used termitaria between 15 and 150 l. Parakeets nesting in modified habitats used termitaria at a significantly lower height than Parakeets nesting in conserved habitat. It is unclear whether this represents a decline in nest-site quality in modified habitats, which could affect reproductive success of Parakeet populations in fragmented landscapes.
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LILAC-CROWNED PARROT DIET AND FOOD RESOURCE AVAILABILITY: RESOURCE TRACKING BY A PARROT SEED PREDATOR
The Condor, 2001Co-Authors: Katherine RentonAbstract:Abstract The pattern of food resource availability and use by Lilac-crowned Parrots (Amazona finschi) was evaluated in tropical dry forest of the Reserva de la Biosfera Chamela-Cuixmala, western Mexico. Monthly fruiting phenology transects were conducted throughout the year in deciduous and Semi-Deciduous forest to determine temporal and spatial variability in resource abundance. Resource use by parrots was evaluated through observations of diet and habitat use. There was significant temporal and spatial variability in food resource abundance, with Semi-Deciduous forest providing greater food resources for parrots during the dry season, whereas food resource abundance increased in deciduous forest during the rainy season. The critical period of food resource scarcity occurred during May–June at the end of the long dry season. Lilac-crowned Parrots were pre-dispersal seed predators, and exhibited high flexibility in diet, incorporating dietary switching, as well as niche-breadth contraction and expansion, ...
Hervé Jactel - One of the best experts on this subject based on the ideXlab platform.
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Importance of semi-natural habitats for the conservation of butterfly communities in landscapes dominated
Biodiversity and Conservation, 2008Co-Authors: Inge Van Halder, Emmanuel Corcket, Luc Barbaro, Hervé JactelAbstract:While the area of plantation forests continues to increase worldwide, their contribution to the conservation of biodiversity is still controversial. There is a particular concern on the central role played by natural habitat remnants embedded within the plantation matrix in conserving species-rich insect communities. We surveyed butterflies in maritime pine plantation landscapes in south-western France in 83 plots belonging to seven habitat types (five successional stages of pine stands, native deciduous woodlands and herbaceous firebreaks). The effect of plot, habitat and landscape attributes on butterfly species richness, community composition and individual species were analysed with a General Linear Model (GLM), partial Canonical Correspondence Analysis (CCA) and the IndVal method. The most important factors determining butterfly diversity and community composition were the presence of semi-natural habitats (deciduous woodlands and firebreaks) at the landscape scale and the composition of understorey vegetation at the plot scale. Pure effects of plot variables explained the largest part of community variation (12.8%), but landscape factors explained an additional, independent part (6.7%). Firebreaks were characterized by a higher species richness and both firebreaks and deciduous woodlands harboured species not or rarely found in pine stands. Despite the forest-dominated landscape, typical forest butterflies were rare and mainly found in the deciduous woodlands. Threatened species, such as Coenonympha oedippus and Euphydryas aurinia, were found in pine stands and in firebreaks, but were more abundant in the latter. In the studied plantation forest, the conservation of butterflies depends mainly on the preservation of semi-natural habitats, an adequate understorey management and the maintenance of soil moisture levels.
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Importance of semi-natural habitats for the conservation of butterfly communities in landscapes dominated by pine plantations
Biodiversity and Conservation, 2007Co-Authors: Inge Van Halder, Emmanuel Corcket, Luc Barbaro, Hervé JactelAbstract:While the area of plantation forests continues to increase worldwide, their contribution to the conservation of biodiversity is still controversial. There is a particular concern on the central role played by natural habitat remnants embedded within the plantation matrix in conserving species-rich insect communities. We surveyed butterflies in maritime pine plantation landscapes in south-western France in 83 plots belonging to seven habitat types (five successional stages of pine stands, native deciduous woodlands and herbaceous firebreaks). The effect of plot, habitat and landscape attributes on butterfly species richness, community composition and individual species were analysed with a General Linear Model (GLM), partial Canonical Correspondence Analysis (CCA) and the IndVal method. The most important factors determining butterfly diversity and community composition were the presence of semi-natural habitats (deciduous woodlands and firebreaks) at the landscape scale and the composition of understorey vegetation at the plot scale. Pure effects of plot variables explained the largest part of community variation (12.8%), but landscape factors explained an additional, independent part (6.7%). Firebreaks were characterized by a higher species richness and both firebreaks and deciduous woodlands harboured species not or rarely found in pine stands. Despite the forest-dominated landscape, typical forest butterflies were rare and mainly found in the deciduous woodlands. Threatened species, such as Coenonympha oedippus and Euphydryas aurinia, were found in pine stands and in firebreaks, but were more abundant in the latter. In the studied plantation forest, the conservation of butterflies depends mainly on the preservation of semi-natural habitats, an adequate understorey management and the maintenance of soil moisture levels.
Derek Eamus - One of the best experts on this subject based on the ideXlab platform.
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seasonal patterns of xylem sap ph xylem abscisic acid concentration leaf water potential and stomatal conductance of six evergreen and deciduous australian savanna tree species
Australian Journal of Botany, 2002Co-Authors: Dane S Thomas, Derek EamusAbstract:Deciduous trees of Australia's northern savannas typically have less-negative leaf water potentials than evergreen species and their stomata are more sensitive to soil drought than those of evergreen species. This paper presents the first investigation of the role of xylem sap pH and abscisic acid content in explaining stomatal behaviour of Australian trees in the field. We measured stomatal conductance, leaf-to-air vapour pressure difference (D) and leaf water potential, xylem abscisic acid (ABA) concentration and xylem sap pH of evergreen, Semi-Deciduous and fully deciduous tree species in the field over a 15-month period. Measurements were made during both the wet and the dry seasons. Stomata closed in response to increasing D in both evergreen and deciduous species and were equally sensitive to increasing D or declining leaf water potential. Xylem ABA concentration increased with declining leaf water potential in evergreen and Semi-Deciduous species, but not deciduous species. Similarly, there was an inverse correlation between stomatal conductance and xylem ABA concentration. Xylem sap pH increased as leaf water potential declined from wet to dry season for evergreen and Semi-Deciduous species but not for deciduous species. Deciduous species had less-negative water potentials and lower xylem ABA concentrations than evergreen species or Semi-Deciduous species. We conclude that changes in xylem sap pH and ABA content do occur seasonally in the wet-dry tropics of Australia and that these changes influence stomatal conductance, but only in evergreen and Semi-Deciduous species. Deciduous species do not appear to modulate either of these chemical signals.
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ecophysiological traits of deciduous and evergreen woody species in the seasonally dry tropics
Trends in Ecology and Evolution, 1999Co-Authors: Derek EamusAbstract:Seasonally dry tropical ecosystems occur in the Americas, Africa, India and Australia. They sustain large human populations, determine regional climate, are sites of biological and cultural conservation, and have significant economic value. Evergreen, deciduous and semi- and brevideciduous trees frequently co-occur. Recent research reveals how these various phenological groups respond to changes in soil and atmospheric water content. Cost–benefit analyses of evergreen and deciduous species show how leaves of deciduous species live fast and die young, whereas leaves of evergreen species live slowly but for longer.
Thomas Adjei-gyapong - One of the best experts on this subject based on the ideXlab platform.
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Nematode distribution in cultivated and undisturbed soils of Guinea Savannah and Semi-Deciduous Forest zones of Ghana
Elsevier, 2019Co-Authors: Obed Asiedu, Charles Kodia Kwoseh, Haddish Melakeberhan, Thomas Adjei-gyapongAbstract:Climate change affects air temperature, sea levels as well as the soil and its ecosystem. The Guinea Savannah and Semi-Deciduous Forest zones of Ghana are characterized by different climatic conditions and vegetative cover. Annual average temperature has been steadily increasing whilst annual total rainfall has been decreasing in both zones, and this has been causing a southward shift of the Savannah into the Forest zone. Soil organisms provide crucial ecosystem services which are required for sustainable agriculture and food production yet crop cultivation disturbs the soil ecosystem. The harsh conditions associated with the Savannah further expose the soil ecosystem to disturbance and loss of biodiversity which threatens food production and security. Soil nematodes are the most abundant animals in the soil and play a central and critical role in the soil food web complex. Studying the nematode community structure gives a reflection of the status of the entire soil ecosystem. Soil samples were taken from cultivated and natural landscapes in the Guinea Savannah and Semi-Deciduous Forest agroecological zones to analyse the nematode community. Results from the study showed the Guinea Savannah zone recording warmer soil temperatures, lower organic matter percentage and lower nematode diversity (Genus Richness) as compared to the Semi-Deciduous Forest zone. If the Savannah continues to shift southward, the Forest zone soil ecosystem risks disturbance and loss of biodiversity due to the harsh Savannah conditions. Our findings indicate that prevailing crop cultivation practices also disturb soil ecosystem in the two ecological zones which span across West Africa. A disturbed soil ecosystem endangers the future of food production and food security. Keywords: Climate change, Guinea Savannah, Semi-Deciduous Forest, Soil temperature, Soil nematode diversit
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Nematode distribution in cultivated and undisturbed soils of Guinea Savannah and Semi-Deciduous Forest zones of Ghana
Geoscience Frontiers, 2019Co-Authors: Obed Asiedu, Charles Kodia Kwoseh, Haddish Melakeberhan, Thomas Adjei-gyapongAbstract:Abstract Climate change affects air temperature, sea levels as well as the soil and its ecosystem. The Guinea Savannah and Semi-Deciduous Forest zones of Ghana are characterized by different climatic conditions and vegetative cover. Annual average temperature has been steadily increasing whilst annual total rainfall has been decreasing in both zones, and this has been causing a southward shift of the Savannah into the Forest zone. Soil organisms provide crucial ecosystem services which are required for sustainable agriculture and food production yet crop cultivation disturbs the soil ecosystem. The harsh conditions associated with the Savannah further expose the soil ecosystem to disturbance and loss of biodiversity which threatens food production and security. Soil nematodes are the most abundant animals in the soil and play a central and critical role in the soil food web complex. Studying the nematode community structure gives a reflection of the status of the entire soil ecosystem. Soil samples were taken from cultivated and natural landscapes in the Guinea Savannah and Semi-Deciduous Forest agroecological zones to analyse the nematode community. Results from the study showed the Guinea Savannah zone recording warmer soil temperatures, lower organic matter percentage and lower nematode diversity (Genus Richness) as compared to the Semi-Deciduous Forest zone. If the Savannah continues to shift southward, the Forest zone soil ecosystem risks disturbance and loss of biodiversity due to the harsh Savannah conditions. Our findings indicate that prevailing crop cultivation practices also disturb soil ecosystem in the two ecological zones which span across West Africa. A disturbed soil ecosystem endangers the future of food production and food security.
Sylvia Margarita De La Parramartinez - One of the best experts on this subject based on the ideXlab platform.
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optimal diet strategy of a large bodied psittacine food resource abundance and nutritional content enable facultative dietary specialization by the military macaw
Avian Research, 2019Co-Authors: Sylvia Margarita De La Parramartinez, Luis Guillermo Munozlacy, Alejandro Salinasmelgoza, Katherine RentonAbstract:Dietary specialization should arise when there is a relatively high abundance of a particular resource, where animals may select food items to obtain an optimal diet that maximizes energy intake. Large-bodied psittacines frequently exhibit a narrow dietary niche with specific habitat use, but few studies have determined whether psittacines select food resources, and how this influences habitat use. We established fruiting phenology transects to evaluate food resource availability for the large-bodied Military Macaw (Ara militaris) in Semi-Deciduous, deciduous, and pine-oak forest at two sites along the coast of Jalisco, during the dry season when macaws are nesting. We also determined Military Macaw diet by observations of foraging macaws along transect routes, and conducted bromatological analysis of the nutritional content of the most consumed resource. Military Macaws used six plant species as food items during the dry season, and had a narrow dietary niche (Levins’ B = 0.28), with 56% of foraging macaws consuming the seeds of Hura polyandra. No food resources were recorded in pine-oak forest during the dry season, with food resources and foraging by macaws concentrated in tropical deciduous and Semi-Deciduous forest, where H. polyandra was the most abundant fruiting tree species. When considering the proportional availability of food resources, we determined a broad Hurlbert dietary niche breadth of H = 0.67, indicating that Military Macaws consumed food resources according to their availability. Furthermore, the seeds of H. polyandra were an important source of protein, carbohydrates, minerals and moisture, and the hard fruit-casing means that these seeds are exclusively available for macaws. By concentrating their diet on the most abundant resources, Military Macaws may increase foraging efficiency in the dry season. The high nutrient content also means that concentrating the diet on seeds of H. polyandra may be an optimal foraging strategy for Military Macaws to meet their energy requirements during the breeding season.
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tree cavity availability and selection by a large bodied secondary cavity nester the military macaw
Journal of Ornithology, 2015Co-Authors: Sylvia Margarita De La Parramartinez, Katherine Renton, Alejandro Salinasmelgoza, Luis Guillermo MunozlacyAbstract:Large-bodied secondary cavity-nesters are constrained to use cavities of sufficient size to permit access, while also selecting characteristics to reduce predation. However, no information exists on nest-site availability for large-bodied secondary cavity-nesters in tropical forests. We located 12 tree-cavity nests of the threatened Military Macaw (Ara militaris) in tropical dry Semi-Deciduous forest in Jalisco, Mexico. For each nest, we determined cavity characteristics, and compared the structure of nest-trees with nearest-neighbor trees. We also established four 100 × 50 m transects in each of deciduous, Semi-Deciduous, and oak forest to determine tree-cavity availability over 6 ha. Military Macaw nest-sites occurred most frequently in cavities of live Enterolobium cyclocarpum trees. Nest-trees had significantly larger diameter and ramification height than the four nearest-neighbor trees, indicating that macaws selected tall emergent trees as nest-sites. Cavities used as nest-sites by Military Macaws were also in significantly larger trees, at a greater height, and had larger entrance diameter and depth than all accessible cavities. Height above the ground was the main criteria predicting nest-cavity selection, possibly to reduce predation risk. There was also a negative correlation of nest-cavity height with depth, suggesting a trade-off in which Military Macaws may select a nest-cavity high above the ground regardless of depth, but when using lower cavities these tend to be deeper. We found a low density of cavities with characteristics suitable for nesting, and these were concentrated in Semi-Deciduous forest. Our results demonstrate that the Military Macaw exhibits species-specific selection of nest-cavities, with a low density of cavities suitable for large-bodied secondary cavity-nesters in tropical forests.
