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.

中文翻译：

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大型鹦鹉胺的最佳饮食策略：丰富的食物资源和营养成分可以使军用金刚鹦鹉兼职饮食专业化

当特定资源的相对丰富时，应该出现饮食专业化，动物可以选择食物以获得最佳的饮食，以最大程度地吸收能量。大型鹦鹉螺常会在特定的栖息地用途上显示狭窄的饮食生态位，但很少有研究确定鹦鹉螺素是否选择食物资源，以及它如何影响栖息地的利用。我们建立了果实物候学样面，以评估干燥季节金刚鹦鹉筑巢时哈利斯科州沿岸两个地点的半落叶，落叶和松橡森林中的大型军用金刚鹦鹉（Ara militaris）的食物资源可用性。我们还通过观察横断路线上觅食的金刚鹦鹉来确定军用金刚鹦鹉的饮食，并对最消耗资源的营养成分进行了细菌学分析。军用金刚鹦鹉在旱季使用六种植物作为食物，其饮食生态位狭窄（莱文氏B = 0.28），其中56％的觅食金刚鹦鹉食用虎耳草的种子。在干旱季节，松橡森林没有食物资源记录，金刚鹦鹉的食物资源和觅食集中在热带落叶和半落叶森林中，其中H. polyandra是最丰富的果树种类。考虑到按比例分配食物资源时，我们确定了Hurlbert的广泛饮食生态位宽度H = 0.67，这表明金刚鹦鹉根据食物的可获得性消耗了食物资源。此外，H。polyandra的种子是蛋白质，碳水化合物，矿物质和水分，坚硬的果壳意味着这些种子仅可用于金刚鹦鹉。通过将饮食集中在最丰富的资源上，金刚鹦鹉可以在干旱季节提高觅食效率。高营养素含量还意味着将饮食集中在H. polyandra种子上可能是军用金刚鹦鹉在繁殖季节满足其能量需求的最佳觅食策略。