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Sexual size dimorphism is a conspicuous trait of many wild bird species. Differences in body size between the sexes might reflect selective pressures and trade-offs to optimize performance. Here, we analyze the size dimorphism of the Galapagos Dove (Zenaida galapagoensis) using principal component and discriminant analyses with samples obtained from six islands: Santiago, Santa Fe, Santa Cruz, Espanola, Genovesa, and Wolf. We also reanalyze published morphological data but also including additional samples from Wolf Island to account for morphological differences among islands. Males were significantly larger than females. Discriminant analyses correctly classified 98% of males and 100% of females, and cross-validation of the model correctly classified 97% of males and 98% of females. We created two sexual size dimorphism indices using wing chord and tarsus as body-size surrogates. Significant differences were found in the sexual size dimorphism index for both measurements among islands. Significant differences in sexual size dimorphism among islands might indicate the role of different selective pressures acting on individual islands (e.g., competition, predation, resources, sexual selection), which might result in life history variation of the species among islands. For the first time, we provide significant morphological evidence supporting the classification of the Galipagos Dove into two subspecies: Z. g. galapagoensis and Z. g. exsul. Key words: Galapagos, morphology, sexual size dimorphism. Zenaida galapagoensis. El dimorfismo sexual de tamano es una caracteristica comun de muchas especies de aves. Las diferencias en el tamano corporal entre machos y hembras puede reflejar la accion de factores de seleccion y soluciones de costo-beneficio que actuan para optimizar el rendimiento de las aves en su ambiente. Analizamos el dimorfismo de tamano de Zenaida galapagoensis por medio de anilisis de componentes principales y anilisis de discriminacion utilizando muestras colectadas en seis islas: Santiago, Santa Fe, Santa Cruz, Espanola, Genovesa y Wolf. Tambien reanalizamos informacion morfologica previamente publicada, en donde incluimos muestras provenientes de la isla Wolf la cual no estuvo comprendida en el esudio anterior, para analizar diferencias morfologicas entre las islas. Los machos fueron significativamente mas grandes que las hembras. El analisis de discriminacion clasifico correctamente el 98% de los machos y el 100% de las hembras, el analisis de validacion del modelo de discriminacion clasifico correctamente el 97% de los machos y el 98% de las hembras. Creamos un indice de dimorfismo sexual de tamano utilizando la cuerda alar y el tarso como medidas de tamano corporal. Se encontraron diferencias significativas en el dimorfismo sexual de tamano entre algunos pares de islas para ambas medidas. Diferencias significativas en el dimorfismo sexual de tamano pueden indicar la accion de diferentes presiones selectivas en diferentes islas (e.g., competicion, depredacion, recursos, seleccion sexual), lo cual puede crear variaciones en la biologia de la especie entre las distintas islas. Por primera vez, proveemos resultados morfologicos significativos que apoyan la separacion de Z. galapagoensis en dos subespecies: Z. g. galapagoensis y Z. g. exsul.

The demography of Zenaida Doves (Zenaida aurita) was studied on Cayo del Agua, Culebra, Puerto Rico. We collected capture-recapture and reproductive success data and monitored annual changes in the density of ground nests in 1987-1993 and 2000. Models with time-specific apparent survival and constant capture rates ([[phi].sub.t], [p.sub.c]) and constant apparent survival and time-specific capture rates ([[phi].sub.c], [p.sub.t]) were equally parsimonious, with the former having 1.5 times more support from the data. Rainfall of the first six months of the year was positively related to nest density, and crab density was negatively related to nesting success and the number of doves fledged per nest. Crabs are the main predators of dove nests on Cayo del Agua. Models, parameterized with field data, were used to simulate full and reduced stochastic variation in environmental and demographic conditions, and predict annual changes in population size. High recruitment (births or births + immigrants) offset high losses (deaths + emigrants) in all instances. Our field data suggest that Zenaida Doves suffered an ecological crunch between 1989 and 1990, when weather (a hurricane followed by a drought), food availability, and nest predation interacted, lowering the number of locally fledged doves that survived the hatching year (1989-1990) and reproductive success (1990). Under severe conditions, population size and recovery mainly depended on immigration. Apparent survival returned to pre-hurricane levels between 1990 and 1991, and reproductive success was about average in 1991. Key words: capture-recapture, Cayo del Agua, Culebra, demography, ground nests, predators, Puerto Rico, reproduction, Zenaida aurita, Zenaida Dove.

The utility of isotopic potassium in the estimation of fat mass of birds was tested using the carcasses of 29 pigeons, Columba livia. This noninvasive technique relies on the fixed ratio between isotopic and total potassium in the body, to the presence of potassium in lean tissue and its absence from adipose tissue. Regression analyses were conducted to evaluate the utility of this method. Results reveal that the measurement of isotopic potassium cannot accurately predict fat mass in pigeons.

A negative relationship exists between the body mass of 44 species of New World doves and the frequencies that they use in their songs. Even among 13 pairs of closely related species, no relationship was detected between body mass and song frequencies. Meanwhile, after removing the effect of phylogeny and body mass, residuals of variation in song frequencies were found to vary among habitats. The findings are expected to impact on some hypotheses regarding avian phylogeny, character evolution, and values of both acoustic frequencies and body mass.

Columbid nests covering eight species of pigeons and doves were observed in three life zones of Puerto Rico from Feb. 1987 to Jun. 1992. Nest density peaked in May and June, while decline marked the July-October flocking period. Nest tree height, nest above-ground height and other variables were evaluated. Nest cover emerged as the most important microhabitat variable for nest failure or success.

Ten species of Columbidae (pigeons and doves) are native to Puerto Rico. The abundance of columbids in the wet and moist zones peaked during spring and declined after early summer. The abundance of columbids in the dry zone were bimodal, with peaks occurring during spring and fall. The seasonal patterns of relative abundance of columbids detected in the life zones represent its basic population dynamics. Rainfall in the dry zone and fruiting phenology of key tree species in the moist and wet zones are important environmental stimuli influencing the seasonal patterns of relative abundance of columbids.

Geographic variations in size variables in the female wild Rock Dove are evident, similar to those seen in males. Except for bill size, features tend to be smaller in northern Africa and the Near East, becoming progressively larger in Europe, the Middle East, and the southwestern regions of central Asia. A factor representing overall size accounted for 42% of the variation; one representing shape accounted for 29%; and one representing bill length accounted for 28% of the variation. Data was gathered from museum specimens.

Research describing factors affecting nest density for pigeons and doves is presented. An analysis of transect surveys recording such parameters as rainfall, food and predators in relation to nest sites is examined.