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In Prairie Falcons (Falco mexicanus), females are considerably larger than males, as in most diurnal birds of prey. This phenomenon, known as reversed sexual dimorphism (RSD), is usually associated with asymmetry in parental care: the smaller male provides most of the food during the nesting season, whereas the larger female incubates the eggs, and broods and protects the young. To evaluate this relationship in Prairie Falcons, we quantitatively assessed parental roles of 52 pairs of Prairie Falcons nesting in southwestern Idaho, over a 4-yr period (1984–1987). We collected behavioral observations for each pair, from the establishment of a nesting territory until young were 30–35 d old (fledging age), for a total of 613 observation days (9089 hr). We found that male and female falcons shared some tasks, although not necessarily equally, including incubation, provisioning prey and nest defense. Females accounted for two-thirds of the diurnal incubation responsibility and males for one-third. Males and females made comparable efforts in food provisioning; similarly, nest defense, here defined as aggressive interactions with (potential) nest predators, did not differ between the sexes. Other behaviors, such as brooding, hunting, and nest attendance were performed more by one sex than the other. Brooding was carried out primarily by females, and they showed consistently higher nest attendance compared to males. Males hunted significantly more than females and delivered most prey items to the nest site. Overall, sex roles exhibited by nesting Prairie Falcons in our study largely agreed with predictions based on RSD. En Falco mexicanus, al igual que en la mayoría de las aves rapaces diurnas, las hembras son considerablemente más grandes que los machos. Este fenómeno, conocido como dimorfismo sexual inverso (DSI), generalmente se asocia con asimetría en el cuidado parental: el macho, de menor tamaño que la hembra, proporciona la mayor parte del alimento durante la temporada de nidificación, mientras que la hembra más grande incuba los huevos, abriga y protege a los pollos. Para evaluar esta relación en F. mexicanus, evaluamos cuantitativamente los roles parentales de 52 parejas que nidificaron en el suroeste de Idaho durante un período de 4 años (1984–1987). Recolectamos observaciones de comportamiento para cada pareja desde el establecimiento de un territorio de nidificación hasta que los pollos tuvieron 30–35 días de edad (edad de emplumamiento), durante un total de 613 días de observación (9089 horas). Encontramos que los machos y las hembras de F. mexicanus compartieron algunas tareas, aunque no necesariamente por igual, tales como la incubación, el suministro de presas y la defensa del nido. Las hembras realizaron dos tercios de la incubación diurna y los machos un tercio. Los machos y las hembras hicieron esfuerzos comparables en el suministro de alimento; de manera similar, la defensa del nido, aquí definida como interacciones agresivas con (potenciales) depredadores del nido, no difirió entre los sexos. Otros comportamientos, como el cuidado de la nidada, la caza y la asistencia al nido fueron realizados más por un sexo que por el otro. El cuidado de la nidada fue realizado principalmente por las hembras, las que mostraron una asistencia al nido consistentemente más alta en comparación con los machos. Los machos cazaron significativamente más que las hembras y entregaron la mayoría de las presas al nido. En general, los roles de sexo exhibidos por los individuos de F. mexicanus que nidificaron en nuestro estudio concordaron en gran medida con las predicciones basadas en el DSI. [Traducción del equipo editorial] [ABSTRACT FROM AUTHOR]

The article focuses on a study that evaluates the use of threetip sagebrush relative to big sagebrush as nest cover for sage-grouse and examines habitat characteristics associated with both sagebrush species. It cites the impact of disturbances that change sagebrush Artemisia spp.-steppe communities on greater sage-grouse Centrocercus urophasianus populations. It aims to provide an understanding of sage-grouse use of threetip sagebrush in relation to other sagebrush species. To model factors associated with nest sites located under big sagebrush, a multiple logistic regression approach was used.

The article focuses on a study related to examining the habitats of chinook salmon in three subbasins of the Middle Fork Salmon River (MFSR) in Idaho. An information-theoretic method was used to select the best logistic regression models that linked habitat quality, size, and connectivity to the occurrence of the habitats of chinook salmon. The relationship between the population density of the salmon and habitat changes was also examined. It was found that most of the models were dominated by measures of habitat size and connectivity and habitat quality was of minor importance.