The birds that help us at Sil keep the number of processions under control

Increase pine procession (Thaumetopoea pityocampa) is a phenomenon that affects many forests and parks in Italy and is among the most affected areas in southern Italy Sila National Park. This little moth has become so widespread that recently some of its nests were found at over 1,900 meters above sea level. Montenero, where scientists thought they would never arrive because of the hostile climate. However, it seems that all is not lost and help in keeping this little moth under control comes from some winged predators such as Great Tit (Parus major), boogie (Bagpipe epic), Cuckoo (Cuculus canorus), potty (Caprimulgus europaeus) and bee eater (Merops apiaster).

Some studies and observations are made to confirm this phenomenon Gianluca Congi, vice president Italian Ornithological Society and coordinator GLC LIPU from Sila. Congi, during the summer of 2022, while focusing on the study of bee-eaters during their nesting season, discovered that these birds can feed on emerging adult orb moths and then feed them to chicks. Last December, however, he also photographed the titmice, which decided to catch the caterpillars and eat them between the branches of the trees.

“Data on bee-eater predation is new data – explains ornithologist Kodami – Regarding this information, several contacts were also made with the regional forestry department and with some Spanish scientists project Prowarmwhich aims to understand spatio-temporal changes in defoliation caused by processionary moths in the Mediterranean, also thanks to discussions with the management of the Sila National Park.’

Process caterpillars

These results allowed Congi to publish his studies in the ornithological journal “Gli birds of Italy” and also to focus the attention of biologists on the ecological role of these animals, which are potentially useful in keeping moth populations under control. However, for which area is this insect so feared? This species is known for being one of the most important phytophagous insects and for its “stinging touch”. Its body is actually covered in hair that triggers a inflammatory skin reaction very strong among both domestic animals and humans.

The serial threads with which they cover their cocoons and nests can also make trees look like large spider webs, causing further damage to the leaf structure of the branches, while their “hair” if dispersed in the air can also cause allergic crisis. In fact, scientists are still trying to understand why the population of this species in the Mediterranean is increasing demographically, even in winter, when in theory the annual biological cycle of the species should cause the caterpillars to slow down their metabolism.

However, the theory most widely accepted by scientists claims that it causes these repeated winter population boom whether climate change. For example, the particularly high temperatures of recent weeks, together with the absence of snow, have actually allowed the caterpillars of this species to resist being away from their nests for a long time, even after late autumn. This meant that the procession not only gave them more opportunities to move through the forest, but also allowed the adults to produce more eggs and the caterpillars to eat longer among the tree branches.

A pair of bee-eaters in Sila. Photo by Gianluca Congi

Obviously, it’s still a little early to consider these native species as an effective tool for controlling the process moth, ornithologists say. «I would like to emphasize that the bee-eater and other species found in the Sila Mountains they are not the solution to the problem procession”. In fact, their colonies are still too small to face this challenge against phytophagous insects that have spread over a fairly large area. Ten years ago, Sila was considering, among other things, a bee eater only a migratory speciesso its population is really small.

Unfortunately, as Congi explains, releasing or mass-introducing these bird species into an area—as some laypeople would like—to actively start a “fight” against processions is not that simple. For one thing, it is very difficult to breed these small insectivorous birds. Taking them from nature is neither feasible nor ethical and could also cause a lot of damage to the environment. In addition, all the species we are talking about are strictly protected, both nationally and internationally: «These species have completely different adaptations, techniques and methods of predation on the processionary moth and are natural allies present in nature in our forests and to our countryside. However, I want to point this out they are all species protected by law, therefore it is strictly forbidden to catch, keep or kill them.”

Finally, in order to consider titmouses, bee-eaters, cuckoos and other insectivorous birds in a possible biological control plan, experts should carry out further very in-depth studies, since it is not easy to predict the impact of these species on the ecosystem. “What we do know is that climate change is inevitably promoting the spread of the pine moth, paradoxically even at high altitudes,” says Congi. – This is claimed by various studies carried out on insects and it seems that the action of some important natural antagonists (such as Hymenoptera Ooencyrtus pityocampae, which parasitizes the eggs of processions ed) are greatly influenced by these factors. In some areas, to encourage the growth of local predators, we might consider installing some at this time nest boxesto support their nesting.” Certainly a simpler and more sustainable operation from an economic point of view.

But how do these species manage to hunt such a stinging species as the pine moth? To understand their secret, just observe these birds while they eat, ornithologists say. Great tit feeds on larvae, and the great tit in particular is capable of this pierce their nest. These birds are also able to overturn caterpillars and eat them from the abdomen, which is devoid of stinging hairs. However, the cuckoo eats the larvae whole, because it has an esophagus capable of withstanding the inflammatory and stinging action of the caterpillars. While the woodpecker can prey pupaehe looked for them directly in the ground.

Finally, the potty prefers to hunt adults that emerge during the night. And the ornithologist Congi saw all these birds in action against processions in the territory of Acri and San Giovanni in Fiore, in the area of ​​Cosenza and in Savelli in the area of ​​Crotone.

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