2.2. Study species
European honey-buzzards show the greatest distribution compared to other species of the genusPernis , occupying most part of Europe and some parts of Asia during the breeding season (Gamauf and Haring 2004). Wintering areas are distributed throughout sub-Saharan Africa. Post-nuptial migration occurs from late August and pre-nuptial migration mainly from early May.
At the Iberian Peninsula, honey-buzzards breed at low densities populations, mainly at forest masses in the northern Spain and Portugal (Purroy and Purroy 2016). A census by SEO-Birdlife in 2009–2010 estimated a total of 1850 breeding pairs in Spain (Palomino Nantón and Valls 2011). Adults begin the construction of the nest at early May and the first eggs are laid on the second half of May (Rebollo et al.2023). Usually, two eggs are laid in alternating days. Chicks hatch after 33-35 days of incubation. Once the nestlings are 35-40 days old, they start the firsts short flights, coming back for eating until its complete independence around 65 days old (van Manen et al. 2011, Ziesemer and Meyburg 2015).
At the study site, eleven species of eusocial Vespidae wasps can be found (Vega et al . 2022), all of them show annual biological cycles. The surviving queens, which mated before hibernation, emerge at the end of the winter, and begin the cycle building new colonies (Archer 2012). The first generation of workers is raised by the queen/s until they complete their development, and the production of reproductive individuals (males and gynes) takes place at the beginning of autumn. After the mating season, males die and gynes take refuge for wintering (Archer 2012). Asian-hornets usually begin the cycle with a primary underground nest, but in mid-summer, when the colony grows and they need more space, they usually move to the tree canopy and build an aerial secondary nest (Diéguez-Antón et al 2022).