Treesearch

ln response to A. Marguerite Baumgartner's request for information on the phenomenon of sex reversals in wild birds "Sex Reversal in Banded Cardinal" (North American Bird Bander 11(1|:11, 19861 I would like to report a similar e_xperience and a plausible explanation offered by Dr. Kenneth Parkes of the Carnegie Museum, pittsburgh, Pennsylvania.

Periodic disturbances caused by hurricanes constitute an integral phase of forest growth and development in the Caribbean region. The 35-year recovery in seven permanent plots in the Colorado Forest of the Luquillo Mountains in Puerto Rico covering the 14 through 49 year period after a major disturbance was characterized by: (1) ingrowth and mortality rates of 20 stems/ha/yr, or 1.1% yr of the initial number of stems; (2) shifts to larger tree diameters and heights; (3) a 3% decline in the number of trees in the intermediate and dominant crown classes and a 6% increase in the number of...

The causes of bill deformities in birds have been summarized in an excellent review by Pomeroy (Brit. Birds 55:49-72, 1962). Causes include genetic mutations, disease, accident, poor nutrition, and, in caged birds, an absence of bill-filing substrates (e.g., stones, coarse bark). In wild birds, however, bill deformities are most often associated with injury to the bill. Easterla and Todd (Auk 88: 677•678, 1971) reported such an apparent injury in a free-living Yellow-headed Blackbird {Xanthocephalus xanthocephalus} from Clay County, Missouri. The blackbird apparently had suffered a...

Pathogenesis of myiasis due to the muscid fly Philornis decepttous in nestling pearlyeyed thrashers (Margurops fuscatus) in the Luquillo Rain Forest, Puerto Rico was investigated. Philornid larvae penetrated the host integument, underwent a period of development and growth, and established, as third instar larvae, between the dermis and the body musculature. Movement into this location plus growth and development of the fly larva appeared to be linked to the ingestion of host tissues including red blood cells, mononuclear cells which infiltrated from focal accumulations adjacent to the...

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...