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Lek-mating Long-tailed Manakins (Chiroxiphia linearis) exhibit an unusual pattern of delayed plumage maturation. Each year, males progress through a series of predefinitive plumages before attaining definitive plumage in their fifth calendar year. Females also exhibit variation in plumage coloration, with some females displaying male-like plumage characteristics. Using data from mist-net captures in northwest Costa Rica (n = 1,315) and museum specimens from throughout the range of Long-tailed Manakins (n = 585), we documented the plumage sequence progression of males, explored variation in female plumage, and described the timing of molt in this species. Males progressed through a series of age-specific predefinitive...
The nest and nesting behaviorof a pair of Red-crowned Ant-Tanagers ( Habia rubica rubica) from Paraguay is described. Results are compared with those from studies of other subspecies. Because the species occurs in temperate, subtropical, and tropical habitats from Mexico south to Paraguay, northern Argentina, and southeastern Brazil, we expected details of breeding to differ in different parts of the range. Other than differences in the timing of breeding north and south of the equator, only details of nest structure and egg coloration showed geographic variation.
As governments impose increasingly stringent regulations on the collection of bird specimens and as man alters ever greater areas of habitat with the loss of many of their contained species, museum specimens increase immeasurably in importance. Yet at present, museum collections do not contain an adequate representation of the world's avifauna and, unfortunately, are not likely to do so. Thus, it is imperative that data associated with specimens that are obtained be as complete as possible. To this end, we describe categories of information with wide application to many types of studies, outline character states, and recommend standard forms of data notation. We recognize that under certain circumstances, it may...
The winter ecology and behavior of Alder Flycatchers (Empidonax alnorum) were studied along the Manu, a white-water meander river in Manu National Park, Madre de Dios, Peru?? during October and November, 1993 to 1997. The birds occupied territories in primary-succession habitats on growing point bars. They were most common in mixed stands of Tessaria integrifolia (Asteraceae) and Gynerium sagittatum (Gramineaceae) interspersed with bare sand areas. The uneven height of the Tessaria canopy, which resulted in openings in the vegetation large enough for the birds to flycatch, was an important habitat feature. Birds obtained insects, which formed about 96% of the diet, by aerial hawking (91%), perch gleaning (6%), and...
The winter ecology and behavior of Alder Flycatchers (Empidonax alnorum) were studied along the Manu, a white-water meander river in Manu National Park, Madre de Dios, Peru during October and November, 1993 to 1997. The birds occupied territories in primary-succession habitats on growing point bars. They were most common in mixed stands of Tessaria integrifolia (Asteraceae) and Gynerium sagittatum (Gramineaceae) interspersed with bare sand areas. The uneven height of the Tessaria canopy, which resulted in openings in the vegetation large enough for the birds to flycatch, was an important habitat feature. Birds obtained insects, which formed about 96% of the diet, by aerial hawking (91%), perch gleaning (6%), and...
We report on a collection of 74 frogs, 11 lots of frog eggs or tadpoles, and two snakes collected from the Chapare Region in the yungas of the eastern Andean Cordillera de Cochabamba, Bolivia. Collecting localities range from approximately 300 m to >3200 m in elevation. The specimens pertain to 23 species, probably 10 of which are undescribed. We describe four new species of frogs, one each in the genera Bufo, Centrolenella, Colostethus, and Hyla, and one new species of snake, genus Dipsas. We place Atelopus rugulosus in synonymy with A. tricolor.
I report on handling methods and efficiencies of 26 species of Paraguayan birds freeding on fruits of Allophyllus edulis (Sapindaceae). A bird may swallow fruits whole (Type I: pluck and swallow feeders), hold a fruit and cut the pulp from the seed with the edge of the bill, swallowing the pulp but not the seed (Type II: cut or mash feeders), or take bites of pulp from a fruit that hangs from the tree or that is held and manipulated against a branch (Type III: push and bite feeders). In terms of absolute amount of pulp obtained from a fruit, and amount obtained per unit time. Type I species are far more efficient than Type II and III species. Bill morphology influences feeding methods but is not the only important...
Categories: Publication;
Types: Citation;
Tags: Transactions of the North American Wildlife and Natural Resources Conference
Seeds with 'imitation arils' appear wholly or partially covered by pulp or aril but actually carry no fleshy material. The mimetic seed hypothesis to explain this phenomenon proposes a parasitic relationship in which birds are deceived into dispersing seeds that resemble bird-dispersed fruits, without receiving a nutrient reward. The hard-seed for grit hypothesis proposes a mutualistic relationship in which large, terrestrial birds swallow the exceptionally hard 'mimetic' seeds as grit for grinding the softer seeds on which they feed. They defecate, dispersing the seeds, and abrade the seed surface, enhancing germination. Any fruit mimicry is incidental. Fruiting trees of Ormosia spp. (Leguminosae: Papilionoideae)...
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