Sad news: Our baby eagle died

The remains of our baby Black-and-chestnut Eagle....Photo: Luis Recalde/EcoMinga.

The remains of our baby Black-and-chestnut Eagle….Photo: Luis Recalde/EcoMinga.

Just a couple of weeks ago our baby Black-and-chestnut Eagle (Spizaetur isidori) had begun to explore the outer branches of its nest tree and make its first little flights. The most vulnerable stage of a bird’s life is usually the part before it can fly, when it can easily be killed by nest predators. We were delighted that our endangered eagle baby had apparently passed that stage, and we all assumed that the eaglet was now out of serious danger.

However, last week our guards discovered the eaglet’s skeleton on the ground under the nest tree. The head had been removed from the body by some scavenger or predator, and was lying nearby. The news shocked us.

Our young Black-and-chestnut Eagle  making its first tentative forays into the branches of its nest tree. Photo: Santiago Recalde/EcoMinga.

Our young Black-and-chestnut Eagle making its first tentative forays into the branches of its nest tree, shortly before its death. Photo: Santiago Recalde/EcoMinga.

There were no human tracks nor other evidence of any human involvement in the death. Coincidentally, eagle expert Ruth Muñiz Lopez and her team are about to publish an article on juvenile mortality in large eagles, and in response to Juan Pablo Reyes’ letter to all of us announcing the death, she wrote us to give some insight into what might have gone wrong. Here is a translated excerpt from her letter, and the whole Spanish version.

First of all, I’m very sorry for your loss, as this eaglet was a symbol of the health and well-being of the forest that you have been conserving with such effort…..I want to mention some details to help us understand what might have happened to the eaglet in the Rio Zunac, and you can pass this on to Tito [Fausto Recalde] and the other guards who have so lovingly cared for the forest around the nest.

One of the critical moments in the life of a young eagle is the moment it learns to fly…When the juveniles begin to flap their wings, they rise up above the nest and then fall back down into it. Later…they begin to walk out and explore the branches of their nest tree and nearby trees. Sometimes, those first wing-flaps cause some juveniles to lose their balance if an unexpected gust of wind displaces the bird from the place where it should have landed. If this displacement causes a loss of altitude, depending on the age of the bird, it may be able to regain it. However, others in their attempt to keep flying, can keep losing altitude instead of rising, and end up trapped beneath the canopy. I have never seen the adults help the juveniles in this situation. In the case of the Harpy Eagle, several juveniles died this way, in conjunction with difficult weather (rain, winds, etc). On two occasions we found such babies alive, very weak, but we were able to get them to recover and re-insert them successfully. If we hadn’t been there permanently, those two babies would surely have died as well.”

Next time we’ll stay with them during this period….

Ruth’s full letter in Spanish:

“Estimados todos;
Antes de nada, lamento profundamente esta pérdida, puesto que el polluelo era un símbolo de bienestar y de salud del bosque que con tanto esfuerzo están conservando. Gracias, Juan Pablo, por mantenernos informados.
Les quiero comentar un par de detalles para que podamos llegar a entender qué pudo haber pasado con el pollo de Zuñag, y que se lo puedan transmitir también a Tito y a los demás guardaparques que con tanto esmero cuidaron del área de cría. Estamos por publicar un artículo precisamente de mortalidad de grandes rapaces… así que tengo el tema muy fresco. Uno de los momentos críticos para la supervivencia de las jóvenes águilas es el momento en el que aprenden a volar. Luego vendrán los primeros intentos de cacería y más tarde su búsqueda por un territorio propio y la formación de pareja. En cada una de estas etapas existe un pico de mortalidad, puesto que cualquier altercado puede desembocar en la muerte de los ejemplares, ya que aún no son expertos en sobrevivir.
Cuando los juveniles comienzan a aletear, se elevan de la plataforma del nido para volver a caer sobre ella. Después, se convierten en “rameros”… es decir, comienzan a caminar y a explorar las ramas de su árbol del nido y de árboles cercanos. En ocasiones, estos primeros aleteos hacen que algunos jóvenes pierdan el equilibrio si algo como una ráfaga de viento inesperada le desplaza del lugar en el que en principio debía “aterrizar”. Si con el desequilibrio pierden altura, según la edad que tengan, pueden o no volver a retomarla. Otros, sin embargo, en su intento por seguir volando, pueden seguir perdiendo altura en vez de ascender, quedándose atrapados bajo el dosel. Yo nunca he visto que los adultos ayuden a los jóvenes en estas situaciones… en el caso de águila harpía, varios juveniles murieron así, coincidiendo con condiciones meteorológicas difíciles (lluvia, viento, etc.). En dos ocasiones, encontramos vivos a los pollos, algunos muy débiles, pero logramos recuperarlos y reinsertarlos con éxito. Si no hubiésemos estado allí de forma permanente, estos dos polluelos seguramente hubieran muerto también.
Con esto, lo que quiero decir es que no tiene por qué haber una causa de origen antrópico para la muerte de Zuñag, también las aves mueren de forma natural, y cuanto más las conocemos, más podemos tratar de indagar acerca de estas razones, que son bastante desconocidas todavía.
Les animo a seguir monitoreando la zona… si la pareja no repite el lugar del nido (no lo sabremos hasta dentro de unos meses), estarán cerca… Han hecho todos un muy buen trabajo, enhorabuena! Encontrar el cadáver no es tarea nada fácil y ahora podemos saber qué ocurrió con el éxito de cría de la pareja, cosa que no es nada fácil en estado silvestre. El área sigue siendo increíble y, como ya han visto en varias ocasiones… los polluelos también salen adelante!
Un abrazo y mucho ánimo a todos. Ruth”

Lou Jost

9 thoughts on “Sad news: Our baby eagle died

  1. So sorry to read this. Such promise in a young eagle. I’m happy to have read what may have happened & what to watch for next time.

    • We’re especially sad, knowing that we might have been able to save it if we had been there at the right time. We thought it would be better for the bird if we were not there constantly, even though it did not seem disturbed by our presence.

  2. So sorry this important species lost a youngster and so sad for all those involved…maybe the adults will lay a second clutch? I don’t know their biology…

  3. Pingback: Last photos of our young Black-and-chestnut Eagle (Spizaetus isidori) | Fundacion EcoMinga

  4. Pingback: Carnegie Airborne Observatory visits our area | Fundacion EcoMinga

  5. Pingback: This year’s Black-and-chestnut Eagle nest is doing well | Fundacion EcoMinga

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