Ecology of the Golden Eagle in Mongolia, Part 1: Breeding Distribution and Nest-site Descriptions
During seven expeditions across Mongolia, we found 40 Golden Eagle (Aquila chrysaetos) breeding territories with eggs or young. At 20 other locations, we either found old eagle nests with Golden Eagle feathers or saw adult eagles but found no eggs or young. Golden Eagles nested in all but the driest portions of the Gobi Desert and the easternmost grasslands. Nearly all pairs had alternate nests. Of 53 nests used, 60% were on cliff ledges as is typical around the world. However, 19% were on the ground or at other sites that were easily accessible to canid predators, with the most vulnerable nests small and seldom or never reused. The most unusual nests included one atop a conical basalt peak, one on relatively flat ground among tall boulders, four on steep hillsides, one on almost flat ground amid rocky protrusions, and three on cliff tops. Where tall cliffs with many ledges were available, the eagles nested at least 7 m above the ground. Nest construction materials were often unusual and included trash, patches of large mammal hides, paper money, and clothing. Ecología de Aquila chrysaetos en Mongolia, Parte 1: Distribución Reproductiva y Descripciones del Lugar de Anidamiento Durante siete expediciones a través de Mongolia, encontramos 40 territorios de cría de Aquila chrysaetos con huevos o juveniles. En otras 20 ubicaciones, encontramos ya sea viejos nidos con plumas de A. chrysaetos u observamos individuos adultos, pero no encontramos ni huevos ni juveniles. A. chrysaetos anidó en todo el Desierto de Gobi exceptuando las partes más secas y en los pastizales más orientales. Casi todas las parejas tuvieron nidos alternativos. De los 53 nidos usados, el 60% estuvo en rebordes de roquedos, como es habitual en otras partes del mundo. Sin embargo, un 19% estuvo en el suelo u otros sitios fácilmente accesibles para los cánidos depredadores, mientras que los nidos más vulnerables fueron pequeños y rara vez o nunca fueron reutilizados. Los nidos más inusuales incluyeron uno encima de un pico cónico de basalto, uno en suelo relativamente plano entre peñascos altos, cuatro en laderas empinadas, uno en suelo casi plano en medio de salientes rocosas y tres en la punta de roquedos. En los sitios donde hubo disponibles roquedos altos con muchos rebordes, las águilas anidaron al menos a 7 m del suelo. Los materiales de construcción del nido fueron frecuentemente inusuales e incluyeron basura, pedazos de piel de mamíferos grandes, billetes y ropa. [Traducción del equipo editorial]Abstract
Resumen
Distribution of Golden Eagle breeding records in Mongolia. Cells marked 
indicate nests with eggs or young found in the seven expeditions reported in this paper; cells marked ▲ indicate additional breeding records summarized by or found by Stubbe et al (2010). Each cell is 0.5° latitude by 1° longitude (1° latitude = 111 km). Each 
or ▲ represents one to four nests found in that cell.
Types of Golden Eagle nesting substrates used in Mongolia (scale variable). Accessible (walk-in) nests include four on hillsides (top center), three on cliff tops (middle left), one on open ground (bottom right) and one each on a conical peak (Fig. 3), and on the ground among tall boulders (Fig. 4). Two nests faced uphill (upper right). The two uphill-facing nests do not represent a unique substrate type: one was tallied as a dike nest and the other as a tall-cliff nest.
A unique peak-top Golden Eagle nest in recently burned grasslands of southeastern Mongolia. The 7-m tall conical peak was accessible to mammalian predators.
A very accessible (walk-in) Golden Eagle nest was hidden between tall boulders and was easily approachable by wolves.
Number of alternate nests at 38 Golden Eagle nesting territories in Mongolia.
Elevation at cliff (or nest) rim by 100-m increments (n = 49) for Golden Eagle nests. Nests at the highest elevations were all in northwestern Mongolia.
Directional exposure of 55 Golden Eagle nests across Mongolia; some of these are alternate nests in clusters with nests used sometime from 1994 through 2012. This total includes only those nests that have at least some shade during the day.
Directional exposure of seven Golden Eagle cliff ledge nests in the Gobi Desert and desert grasslands of south-central or southeastern Mongolia.
Golden Eagle cliff nest in central Mongolia with a clear plastic tarp partially buried in the nest and trailing in the wind. On 17 June 2012, the nest contained two nestlings approximately 32 and 34 d of age. This nest had a very large surface, extending from the left margin of photo, behind the bush, and 0.4 m to the right of the bush.
Height of Golden Eagle nesting cliffs in Mongolia (n = 40). Walk-in nests (n = 10) were not included.
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