“Two pairs doesn’t always mean four individuals” / “Dos parejas no siempre son cuatro individuos”

Thanks to the plastic rings, we were able to detect a rather singular case. It happened to be a male who was simultaneously breeding in two different nests with two different females. The male devoted his time in hunting to feed both females and relieve them in the hard task of incubation. But sometimes, being too ambitious can be a bad business. The distance between both nest sites was considerable and one of those failed at the end of August. The other nest of the bigamous male is still active.

However, this is not the first time that we see this behavior in the Eleonora’s falcon. In 2015 we witnessed a similar case, but in this occasion, both nests of the same male were only ca. 50 m far from each other. One of the females had been his mate for several years, although they never raised any chick. The other female was a recent widow from a neighbor nest. The male copulated with both females and hunted to feed them in a rather constant and simultaneous way. However, only one of the females (the widow) was able to breed successfully. Maybe the male prioritized his efforts towards one of the females, maybe the two females had different quality-reproductive capacity or maybe, Eleonora’s falcon females need a full-time male during the breeding season to achieve reproductive success.


Las anillas plásticas que muchos halcones portan nos han permitido comprobar un hecho curioso. Se trata de un macho que se encontraba regentando dos nidos con dos hembras diferentes a la vez. El macho repartía su tiempo en cazar para alimentar a ambas hembras y relevarlas en la ardua tarea de la incubación. Pero como suele decirse, el que mucho abarca… poco aprieta. La distancia que separaba ambos nidos era considerable y uno de los nidos fracasó a finales de agosto, mientras que el otro sigue, de momento, activo.

Esta no es la primera vez que detectamos un caso de bigamia en el halcón de Eleonor. En 2015, ocurrió un episodio similar, aunque en esta ocasión, los dos nidos regentados por el mismo macho se encontraban separados por unos escasos 50 metros. Una de las hembras había sido su pareja durante varios años (aunque nunca habían criado con éxito), mientras que la otra era una hembra vecina que se había quedado recientemente viuda. El macho copulaba con ambas hembras y cazaba para alimentarlas de manera constante y casi simultánea. Sin embargo, solo una de sus parejas logró sacar adelante a la prole. Tal vez el macho priorizó sus esfuerzos hacia una de las hembras, tal vez las dos hembras presentaban distinta calidad-capacidad reproductora o tal vez, las hembras de halcón de Eleonor necesitan un macho a tiempo completo durante la época de cría para lograr reproducirse de manera exitosa.