THE SECRET OF CUADA, WANDERING GRIFFON VULTURE
15/11/2019
"Behind a mirage there is always a mirage to consider." To tell the story of Cuada's journey we spontaneously entrusted ourselves to the verses of De Gregori. When this Spanish griffon vulture reached the area between Guspini and Terralba at the end of 2018, we thought that its mirage was a land similar to its country of origin, Aragon.
Then, while thinking about the possibility of activating power stations in those parts, her flight took her northwards to the area between Osilo, Martis and Laerru, and then south again via the Supramonte, straight to the Seven Brothers area. At this point we changed our mind and began to think that he was looking for the best place to make the big jump, cross the sea and reach Spain.
Over time this theory lost its courage and in the end we thought that Sardinia, with its trophic resources and quiet and peaceful places, had become a good place for Cuada. The griffon vulture's behaviour confirmed this judgement: it seemed more and more residential in the project area, with sporadic new patrols throughout the Sardinian territory. Curiosity is an unstoppable search engine and when we read the publication of Orr Spiegel* and others - which analyses the reasons for dispersion in the most erratic animals - we saw that "new mirage to consider" in Cuada's actions.
In fact, she is unique: the only adult female freed in the repopulation action of 12 December 2018. She therefore began to frequent the skies of Sardinia before mid-December, at the beginning of the breeding season. In the monitoring group initially flashed the idea that Cuada could already reproduce in the current season. We discarded this hypothesis because in the following three months Cuada travelled far and wide Sardinia without passing through the Bosano and Algherese, the areas where griffon vultures reproduce.
Yet, this hypothesis remains standing. The mirage Cuada is chasing has to do with reproduction: while we were hypothesizing that it could nest in the 2018-2019 season, we assumed that Cuada would find a companion. But for the scientific literature it is not so obvious. Generally the natural sex ratio - i.e. the number of males and females in a population - is 50 and 50, with "deviations" often attributable to randomness and environmental factors. In a population like Sardinia, small and with few exchanges with the Continent, this deviation could have caused the missed "appointment" with a new companion.
So his wandering can be interpreted, trivially, as the search for a partner. A primitive but fascinating hypothesis and more suggestive than the previous ones. A behaviour that would sink its motivation into instinct and not into reason.
Soon the new breeding season will begin: observing the first wedding dances we will find out if his wandering has been profitable. And if it will be the beginning of a new story to tell
*Moving beyond Curve Fitting: Using Complementary Data to Assess Alternative Explanations for Long Movements of Three Vulture Species, vol. 185, no. 2 The American Naturalist February 2015