Community Structure, Nesting Success, and Isolation Effects in a Tropical Forest Bird Community

Rates of tropic deforestation have escalated in recent decades. Although the influence of deforestation on temperate communities has been studied in detail, few studies have been conducted in the tropics. Basic information describing local levels of species richness, population densities, and productivity are frequently completely lacking for most tropical sites, even for relatively well-studied taxa such as birds. I studied three aspects of the bird community in the central lowlands of the Republic of Panama. First, I inventoried and measured abundances of birds on a 104-ha study site (the Limbo plot) in the forest interior of Soberania National Park. I compared the community structure to the only two other Neotropical sites censused on a comparable spatial scale, both of which lie in the Amazonian drainage system. Limbo hosted twice as many total birds, had 25% fewer species, but community-wide biomass was similar among all sites. At Limbo, 17% of species were present in densities of $\le$1 pair/100 ha, whereas 33% of species were equally rare in Amazonia. Second, I measured the nesting success of 68 species breeding in the forest understory at Limbo and three nearby sites. Nesting success varied greatly among species, and was significantly different between the two years of the study. In general, nesting success was significantly lower than nesting success of temperate species with similar reproductive ecologies. Third, I inventoried the avifauna of Barro Colorado Island (BCI), a 1600-ha hilltop isolated from the nearby mainland forest in 1914 during construction of the Panama Canal, to evaluate effects of isolation on bird community structure. Sixty-five species have disappeared from BCI in the intervening 84 years. My inventory revealed that several species are on the brink of disappearing, having declined precipitously in abundance since the last island survey in 1970. My efforts provide the basic data required to establish benchmark measures of abundance and productivity in forest interior sites, as well as documenting the continuing changes in the avifauna of a famous forest fragment.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Robinson, William Douglas, Jr

Contributors dc:contributor

• Robinson, Scott K.
• Brawn, Jeffrey D.

• Biology, Zoology

Language dc:language

eng

Identifier

(MiAaPQ)AAI9904571

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85401