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.
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.
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.
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!