Transect Surveys of Columbid Nests on Puerto Rico, Vieques, and Culebra Islands

Abstract

I conducted transect surveys of pigeon and dove (Columbidae) nests on Puerto Rico, Vieques, and Culebra islands. Nest detection probability and density differed between study areas in January–August 1991 and 1992. Nest detection probability and density did not differ between years or among species, so I used transect data from a larger study (1986–1999) to assess the relationships between nest density and rainfall, food abundance, food diversity, and predator abundance along transects. Food abundance was the most important predictor of annual changes in nest density on the surveyed transects in mesic and xeric habitats during May–June 1986–1999. Positive correlations of annual nest density estimates suggested parallel responses among columbid species to similar or covarying resources in mesic and xeric habitats.

Field trials of line-transect surveys of bird carcasses in agro-ecosystems of Argentina’s Pampas region

“…All teams used the same search strategy. One observer walked slowly along the centerline while the other observers walked parallel at each side at a distance <5 m (Rivera-Milán 2001). The observer at the centerline recorded the data, helped measure perpendicular distance, guarded the centerline to ensure g(0) = 1, and coordinated searching effort among observers to maintain high detectability as far as possible from the centerline (Buckland et al 2001).…”

Monitoring and modeling of population dynamics for the harvest management of scaly-naped pigeons in Puerto Rico

“…Moreover, because model‐based estimates are regularly updated with monitoring data, our assessment and decision‐making approach may be responsive to long‐term environmental changes (e.g., an increase in K as a result of forest recovery in agricultural areas since the 1980s) and annual fluctuations of the pigeon population in a variable environment (e.g., an increase of reproductive output when food is abundant). Ideally, we would like to develop more explicit process models associated with hypotheses about how r and K may change in relation to food abundance and other resources needed for pigeon survival and reproduction, but we lack the demographic and habitat data necessary to represent this additional complexity (Rivera‐Milán , , ; Vilella et al ).…”

“…The scaly‐naped pigeon can nest year‐round, but nest density usually is highest in April–June, and flocking becomes conspicuous in July–November (Rivera‐Milán , , , , ). We surveyed points from sunrise to midmorning and from midafternoon to sunset in April–June (1–3 visits/point) to increase the chance of counting breeding and nonbreeding pigeons available to be detected within the area of a circle with a maximum detection radius of 440 m. Survey effort accounted for the number of visits per point (Buckland et al ).…”

“…The scaly‐naped pigeon is a habitat generalist with a diverse frugivorous diet, capable of rapid population recovery from natural and anthropogenic disturbances because of life history characteristics, such as multiple brooding and early sexual maturity (Pérez‐Rivera ; Rivera‐Milán , , , ; Wunderle ). Wildlife managers have limited means by which to mitigate the effects of habitat loss and hurricanes, but they can indirectly control hunting mortality through harvest regulations (United States Department of the Interior [USDOI] ).…”

Estimation of density and population size and recommendations for monitoring trends of Bahama parrots on Great Abaco and Great Inagua

“…Our knowledge of the ecology of the Bahama parrot on Inagua is meager. For example, because Inagua is drier than Abaco, parrots may have higher variation in the timing of nesting on the former than the latter and respond faster to rainfall and the production of fruits of key plant species (Grant and Grant 1989, Bancroft et al 2000, Rivera-Milan 2001. Some pairs may lay eggs as early as March (Snyder et al 1982; F. F. Rivera-Milan, United States Fish and Wildlife Service, unpublished data).…”