Publications by authors named "James J Roper"

While bird diversity in the Atlantic Forest can be considered well-known, how the communities have been affected by deforestation and habitat fragmentation is not. We studied birds in 10 forest fragments of distinct sizes (all originally within the Atlantic Forest) in southern Bahia. In 5,391 bird encounters, we found 251 species, with 46 endemics and eight considered globally vulnerable or endangered.

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Article Synopsis
  • Scientists aim to uncover the reasons behind the Neotropical region's high bird diversity by examining factors like climate and human impact on morphological variation.
  • The ATLANTIC BIRD TRAITS dataset includes over 67,000 bird records spanning 711 species in South America’s Atlantic forests, covering up to 44 morphological traits collected over 200 years.
  • This dataset, which is the most extensive of its kind in a biodiversity hotspot, supports both basic scientific research and practical conservation efforts.
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Food limitation may interact with nest predation and influence nesting patterns, such as breeding season length and renesting intervals. If so, reproductive effort should change with food availability. Thus, when food is limited, birds should have fewer attempts and shorter seasons than when food is not limiting.

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Foraging and incubation are mutually exclusive activities for parent birds. A trade-off is generated when a combination of food availability and temperature regulation force birds to choose one and neglect the other, at least temporarily. The Rufous Hornero builds large, oven-like, mud nests, the evolutionary cause of which remains unknown.

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Article Synopsis
  • Annual patterns of fecal corticoid excretion were studied in the Red-tailed parrot, showing lowest levels in May and highest in September, correlating with their breeding period.
  • Corticoid levels appear more linked to reproductive cycles than climate, although climate may influence timing.
  • Fecal corticoid measurements are an effective method for assessing stress and adrenocortical activity in both captive and potentially wild parrots.
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Maternal care of offspring is ubiquitous among primates, but its duration varies across species due to factors such as dispersal patterns and social dynamics, which influence opportunities for and potential benefits of maternal investment in older offspring, respectively. We examined mother-offspring associations in wild northern muriquis (Brachyteles hypoxanthus), in which males are philopatric, females typically disperse before puberty, and social relationships among and between males and females are egalitarian. Associations were systematically recorded between ten mothers, each with two-six offspring in the study group, and all group members from August 2003-May 2004 at the RPPN-Feliciano Miguel Abdala in Minas Gerais, Brazil.

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Ports are important locations for the introduction of marine species, while marinas and pontoons often serve as secondary habitats for these species. In a marina near Paranaguá Port, a major international port in southern Brazil, the encrusting community was studied to (i) identify possibly introduced species, and (ii) examine the use of artificial substrata by these species. Samples (20 x 20 cm) were taken from fibreglass floats (boardwalks and boat hulls) and concrete columns.

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