Ageing Vultures in Spain

An adult Eurasian Griffon glides above a cork oak tree forest on the way to its nest

Spain is home to four species of vultures including the Egyptian Vulture, Eurasian Griffon, Cinereous Vulture and Lammergeier, and it is a fantastic place to observe these majestic birds. Of all of them, the Eurasian Griffon is the most abundant species. In fact, its numbers have increased over the past few years, and Spain is home to the largest portion of this species’ European population.

Typical habitat for the Eurasian Griffon, vertical walls with inaccessible ledges for nesting

For such a large bird – they have a wingspan of 2.80 meters – it might seem surprising that they take off without any apparent difficulty. They use thermal currents in order to gain lift and height and then soar great distances in search of food. Birds that are solely scavengers often travel hundreds of kilometers looking for dead animals, gorging themselves if they have the chance, until they come upon a new food source.

An adult griffon flies against the wind and rain

To challenge our bird identification skills and to heighten our birdwatching knowledge, it can be fun to begin to identify age classes for common or familiar species. With some experience we can learn to identify the ages of individuals of griffon vultures. Though there is some overlap and a lot of individual variation during the process of acquiring adult traits, we can distinguish with a degree of certainty between juveniles, immatures, subadults and adults.

To distinguish between these age groups, we should look first at the color of the bill, the neck and the eye, which change color over the years. Juveniles have dark brown eyes, while those of the adults are light amber. However, the eye color isn’t always easily seen in the field and light conditions can make the eye seem lighter than it really is.  Identifying age groups isn’t always easy!

First year juveniles have black beaks and the ruff around their necks is light brown. These also change with age. If the individual has a ruff that is white like the snow, the beak has turned completely cream-colored, and the primary coverts and secondaries are light brown, you can be sure that this time you are observing an adult. In the following photos we illustrate some of the different age classes.

A juvenile in its second year. All the flying feathers are thin and pointed. It hasn’t molted yet, but note the wearing of its feathers. The dark eyes and buff collar tell us it's indeed a Juvenile. The Beak has paled a little bit already, as it's completely black when they fledge. © Javier Elorriaga

A group of birds while feeding. We have a juvenile (second by the left) and what probably is a subadult with a pale beak but still a buff collar (third by the left with the reddened face). © Miguel González

Third year vulture, immature, with three generations of flight feathers: the retained juvenile outer primaries, darker feathers with one growing in the middle of the primaries, and inner primaries typical of the adults, but not as black (molted during its second year) as the current generation of feathers. © Javier Elorriaga

Subadult individual who has already molted all juvenile feathers, but its iris remains dark and its collar is not as soft or as white as the adults. © Javier Elorriaga

Same bird as in the first picture of this post. Full adult bird, with all adult feathers, very pale beak, amber eyes and white collar

This bird is 19 years old. We know it thanks to its wing tag! But we wouldn't have needed it to say that it is older than 7 years, right? Note the white collar, a full pale beak and amber eyes

However, to further refine our skills, it is necessary to pay attention to their stages of molt. Vultures usually acquire adult plumage at seven years of age (although some individuals do so earlier). The moment that the bird loses its last juvenile primary we have lost any reference to its birth year, and we can only be sure that it is an adult, older than seven years old. We will go into the secrets of recent studies on their molting patterns in future entries.

Thanks to Javier Elorriaga and Miguel González for their help and pictures!