Treesearch

Growth rates varied little among unparasitized (normally developing) Pearly eyed Thrasher nestlings. Botfiy ectoparasitism, however, significantly retarded growth and development in parasitized young. Parasitized nestlings showed different growth patterns at various ages, depending on the timing of the initial parasitic attack and the extent of larval infestation. Nestling growth was most affected within the first 1.5 weeks after hatching, the period of maximum growth rate in 4 of 5 sampled growth characters (body mass, culmen, ulna, tarsus). The ninth primary feather showed accelerated...

A rain-forest population of the Pearly-eyed Thrasher (Margarops fuscatus) suffered heavy ectoparasitism from the larvae of a tropical fly recently identified as Philornis deceptivus. The impact of parasitic attack was of less consequence to adult thrashers than to nestlings. Nestling mortality was high and was caused mostly by philomid ectoparasitism, other factors being negligible (3%). The extent of larval infestations fluctuated seasonally and was related to monthly rainfall. Infestation did not have to be heavy to cause debilitation and death. Larval infestation sites varied with the...

Post and Wiley (1977a) have reviewed the spread of the Shiny Cowbird (Molothrusb onariensisw) within the last 100 years from northern South America through the Lesser Antilles and into the Greater Antilles as far west as Hispaniola. This species is an obligate brood parasite with a wide host specificity (Friedmann 1963). Its parasitic habits and tolerance for disturbed habitats have facilitated population increases throughout its traditional (South American) range as well as its extended range (Friedmann 1929, Johnson 1967, Post and Wiley 1977a). Here we document further dispersal of...

Keast and Morton (1980) provided insights into the complex interactions between migrant birds and permanent residents with which they live in the Neotropics much of the year. While previous authors had made generalities about the ecological traits of winter resident warblers in tropical habitats, the message from this symposium is that even within the Parulinae, a variety of wintering "strategies" seems to exist.

Long-term studies on the population dynamics of Neotropical bird communities have been primarily limited to Panama (see Karr et al. [1982] for a mainland site and Willis [1974] for Barro Colorado Island). An earlier paper (Faaborg 1982a) contained the first long-term population measurements from a West Indian island, specifically a seasonally-dry forest site in southwest Puerto Rico. This Syear study apparently spanned a population peak followed by drought conditions and a severe population decline. The effects of drought on total populations, membership in different foraging guilds, and...

I studied ant coexistence in adjacent areas of upland tropical forest, grassland, and agricultural land in San Lorenzo, Puerto Rico. Data on food utilization, daily activity, nesting sites, microhabitat utilization and interspecific aggression were collected. Ants' tolerance to 45 degree C was determined in the laboratory. Agricultural and grassland ants eat grain, liquid food or insects, or grow fungus; only liquid drinking and insectivorous ants occurred in the forest. Some species within food groups in the agricultural and grassland ants differed in size of food consumed or daily...

I studied ants in upland tropical forest, grassland and agricultural land in San Lorenzo, Puerto Rico, to uncover factors responsible for the distribution and number of species in these communities. Observations, laboratory studies and field experiments were used. Microclimate influenced the distributions of Pheidole fallax, Solenopsis geminata and Monomorium ebeninum; forest ants had lower tolerance to high temperatures than ants from non-forest areas. In addition, Ponerinae ants did not tolerate high temperatures as well as ants in the Formicinae, Myrmicinae and Dolichoderinae. The...

Puerto Rico and the Virgin Islands together have about 551 species of native trees, of which 539 are found in Puerto Rico. More than one-fourth, or 142, are known only from these islands (endemic). Only about 13 rare endemic tree species need additional protection and have been proposed as endangered. Also, 22 are to be watched or monitored and have been proposed as threatened. About 100 others listed as rare are native also beyond (nonendemic). The economic possibilities of endemic tree species merit special attention.

Measurements over approximately a 30-year period in a Dacryodes-Sloanea forest indicate two distinctive phases in stand development. Secondary species were common in the early stand (1940's), and rapid accumulations of biomass and basal area were measured. Many new species entered the stand, and the number of stems increased. In contrast, the stand of the 1970's approached steady-state for biomass and basal area accumulations, and, relative to earlier measurements, fewer stems and fewer species were recorded in the plot. This apparent dichotomy can be correlated to the periodic disturbance...

Buck Island is located in the Caribbean Sea only 1 2/3 miles north of the eastern part of St. Croix and about 5 miles northeast of Christiansted, United States Virgin Islands (map, figure 1, and figure 2). This "beautiful little uninhabited island" scarcely 1 mile long and less than half as wide supports a rich and representative land flora of the seasonal or relatively dry forest, tropical zone, totaling 228 listed species of seed plants but no ferns. A major objective of this study was to obtain records at Buck Island Reef National Monument for the 2-volume illustrated reference on the...