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The West Indies is considered a biodiversity hotspot and a priority for ecological conservation efforts. Understanding how environmental conditions influence the survival of resident avifauna is an important information need given the predicted increases in drought and the frequency and intensity of severe storms in the region. Throughout much of the Caribbean, Coereba flaveola (Bananaquit) are widespread and abundant, traits that may facilitate understanding their response to environmental changes in the region. We used a 10-yr capture–mark–recapture data set to examine C. flaveola survival, recruitment, population growth, and age structure in the context of monthly and seasonal precipitation and temperatures, drought conditions, and occurrence and intensity of storm events. Our models suggested wing length, occurrence of storms, and drought all influenced survival. Both the incidence of storms and drier-than-average conditions in the preceding wet season (April–June) decreased survival. The sex of bird and net hours influenced capture probability, but weather influences on recruitment were equivocal. During nonstorm years, mean population growth was stable at 1.019 (95% confidence interval [CI]: 0.962, 1.098) but dropped to 0.843 (95% CI: 0.795, 0.846) in storm years. Increasing frequency of storms, such as back-to-back years, would likely push the growth rate lower. A protracted pattern of increased storm frequency, especially if coupled with a subsequent drought during the wet season, may lead to localized extirpations or strongly reduced populations. [ABSTRACT FROM AUTHOR] more...

American Kestrel (Falco sparverius) populations are generally declining across the species' North American distribution but the population in the Southern High Plains region currently appears to be stable. Historical evidence suggests the region formerly had a low abundance of kestrels, and that their current numbers are due to landscape changes associated with European settlement. We conducted monthly surveys for American Kestrels across 2 yr to estimate seasonal densities and identify land cover associations in the Southern High Plains of Texas. We found an overall estimated density of 0.99 birds/km2 (95% CI = 0.406, 1.582) across the 2-yr period, with seasonal estimated densities highest in autumn and winter (0.92–2.53/ km2), and lowest in spring (0.49–0.67/km2). Whereas other studies have found that temperature influenced detection of wintering kestrels, we found an interaction of drought conditions and snow most strongly influenced the number of kestrels in our study area. Kestrels largely used land cover types in proportion to availability but there was some evidence of seasonal shifts. Generally, they tended to avoid cotton fields and sometimes selected for areas with woodlots, abandoned or occupied houses, and barns, all of which likely provided nesting and roosting opportunities. Our study provides the first contemporary assessment of seasonal abundance and habitat associations of American Kestrels in the Southern High Plains, where their presence and abundance has been unintentionally facilitated by landscape changes following settlement. We provide a baseline for population monitoring and studies assessing response to additional landscape changes (e.g., development of wind energy facilities) and a changing climate. [ABSTRACT FROM AUTHOR] more...

We studied the natural history of Gray Hawks (Buteo plagiatus) in the Lower Rio Grande Valley of Texas. We used GPS-GSM telemetry to quantify dispersal time and distance, winter home range size of juveniles, and home range size of adults. Home ranges were calculated using the kernel Brownian bridge home range estimator. The median dispersal date for 14 juvenile Gray Hawks was 11 August and they traveled a median straight-line distance of 453 km. Mean winter home range sizes for 11 juveniles was 707 ha. For juveniles, female winter home ranges were larger than those of males, and juvenile winter home ranges were larger in natural than in urban areas. Mean 95% home range sizes for 20 adult Gray Hawks was 530 ha. Mean adult male home range size was larger in natural than in urban areas. Adult Gray Hawks remained in their home ranges year-round. Estudiamos la historia natural de Buteo plagiatus en el Valle Inferior del Río Grande de Texas. Utilizamos telemetría GPS-GSM para cuantificar el tiempo y la distancia de dispersión, el tamaño del área de campeo de los juveniles en invierno y el tamaño del área de campeo de los adultos. Las áreas de campeo se calcularon utilizando el estimador de puentes brownianos del método kernel. La fecha mediana de dispersión de 14 juveniles de B. plagiatus fue el 11 de agosto y recorrieron una distancia mediana en línea recta de 453 km. El tamaño medio del área de campeo de invierno para 11 juveniles fue de 707 ha. Considerando los juveniles, las áreas de campeo de invierno de las hembras fueron más grandes que las de los machos, y las áreas de campeo de invierno de los juveniles fueron más grandes en las áreas naturales que en las urbanas. El tamaño medio del 95% del área de campeo para 22 adultos de B. plagiatus fue de 526 ha. El tamaño promedio del área de campeo de los machos adultos fue mayor en las áreas naturales que en las urbanas. Los adultos de B. plagiatus permanecieron en sus áreas de campeo durante todo el año. [Traducción del equipo editorial] [ABSTRACT FROM AUTHOR] more...