Story by: Prof. Thomas Müller (Senckenberg Research Institute Frankfurt) and Prof. Nir Sapir (University of Haifa)

Early life events may strongly affect the reproduction and survival of organisms throughout their life. This is especially relevant to long-lived animals because they are characterized by an extended maturation period during which different aspects of their performance improve. In birds, juveniles are known to have low foraging proficiency compared to adults, resulting in extended searching and handling times that cause deteriorated body condition and high mortality. 

The main goal of the study was to understand the complex role of performance improvement and different risk factors affecting bird survival throughout its maturation. The study focused on the Egyptian vulture (Neophron percnopterus), a migratory and endangered scavenger bird and examined how bird proficiency improves with age, as well as the effects of the upbringing environment.
During the project we intensively studied tens of Egyptian vultures birds in the field and analyzed their behavior and movement.
We published five papers in excellent, peer reviewed scientific journals, while two more manuscripts are currently in advanced stages of preparation.
We accomplished analyses regarding movement performance curves of juvenile birds that were raised in natural and artificial (from captive-bred population), uncovering major between-individual differences in the shape of the curves and uncovering differences between the two rearing conditions. These analyses represents a conceptual advancement in the study of animal ontogeny and specifically among-individual behavioral and movement-related variation that could result from different upbringing circumstances, as well specific environmental conditions that may affect the shape of the performance curves. We also analyzed how different feeding conditions, which varied in space and time due to food management in feeding stations in the south of Israel, affect bird movement during the critical post-fledging period.
We furthermore analyzed bird survival compared the survival of juveniles that were released from the captive-bred population, revealing that the survival of these latter birds is similar to that of wild-hatched birds.

This knowledge is assisting conservation stakeholders, and more specifically the Israeli Nature and Parks Authority, which, following the results of the work, is assessing its conservation practices in order to improve them and their implementation.

Photo: One of the Egyptian Vulture chicks that were marked and attached with a GPS tracking device, after being tagged and before we returned it to the nest.